Index of Diseases


Machado-Joseph Disease

Definition: A dominantly-inherited ataxia first described in people of Azorean and Portuguese descent, and subsequently identified in Brazil, Japan, China, and Australia. This disorder is classified as one of the SPINOCEREBELLAR ATAXIAS (Type 3) and has been associated with a mutation of the MJD1 gene on chromosome 14. Clinical features include progressive ataxia, dysarthria, postural instability, nystagmus, eyelid retraction, and facial fasciculations. Dystonia is prominent in younger patients (referred to as Type I Machado-Joseph Disease). Type II features ataxia and ocular signs; Type III features muscle atrophy and a sensorimotor neuropathy; and Type IV features extrapyramidal signs combined with a sensorimotor neuropathy. (From Clin Neurosci 1995;3(1):17-22; Ann Neurol 1998 Mar;43(3):288-96) Annotation: ID#: D017827


Definition: The presence of an excessively large tongue, which may be congenital or may develop as a result of a tumor or edema due to obstruction of lymphatic vessels, or it may occur in association with hyperpituitarism or acromegaly. It also may be associated with malocclusion because of pressure of the tongue on the teeth. (From Jablonski, Dictionary of Dentistry, 1992) Annotation: overlarge tongue, congen or acquired ID#: D008260


Definition: Greatly exaggerated width of the mouth, resulting from failure of union of the maxillary and mandibular processes, with extension of the oral orifice toward the ear. The defect may be unilateral or bilateral. (Dorland, 27th ed) Annotation: overwide mouth; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008265

Macular Degeneration

Definition: Degenerative changes in the macula lutea of the retina. Annotation: macular refers to macula lutea of retina; includes "macular dystrophy" ID#: D008268

Macular Edema, Cystoid

Definition: Macular degeneration characterized by edema and cystic spaces which may lead to a macular depression or hole. Annotation: macular refers to macula lutea of retina; a form of MACULAR DEGENERATION ID#: D008269


Definition: A disease caused by various fungi (Madurella mycetomi) or actinomycetes (Nocardia brasiliensis). It usually affects the foot, hand, and legs with tissues becoming necrosed and swollen after infection. Annotation: caused by various fungi or bacteria; coord with causative organism (IM) or precoord organism/dis (IM) if pertinent ID#: D008271

Magnesium Deficiency

Definition: A nutritional condition produced by a deficiency of magnesium in the diet, characterized by anorexia, nausea, vomiting, lethargy, and weakness. Symptoms are paresthesias, muscle cramps, irritability, decreased attention span, and mental confusion, possibly requiring months to appear. Deficiency of body magnesium can exist even when serum values are normal. In addition, magnesium deficiency may be organ-selective, since certain tissues become deficient before others. (Harrison's Principles of Internal Medicine, 12th ed, p1936) Annotation: DF: MAGNESIUM DEFIC ID#: D008275

Malabsorption Syndromes

Definition: General term for syndromes of malnutrition due to failure of normal intestinal absorption of nutrients. Annotation: form of malnutrition caused by failure of normal intestinal absorp ID#: D008286


Definition: The formation of soft patches on the mucous membrane of a hollow organ, such as the urogenital tract or digestive tract. Annotation: ID#: D008287


Definition: A protozoan disease caused in humans by four species of the genus PLASMODIUM (P. falciparum (MALARIA, FALCIPARUM); P. vivax (MALARIA, VIVAX); P. ovale, and P. malariae) and transmitted by the bite of an infected female mosquito of the genus Anopheles. Malaria is endemic in parts of Asia, Africa, Central and South America, Oceania, and certain Caribbean islands. It is characterized by extreme exhaustion associated with paroxysms of high fever, sweating, shaking chills, and anemia. Malaria in animals is caused by other species of plasmodia. Annotation: GEN or unspecified; specify Plasmodium species IM if possible but note P. falciparum malaria = MALARIA, FALCIPARUM; P. vivax malaria = MALARIA, VIVAX; tertian malaria = MALARIA, VIVAX, quartan malaria: coord IM with PLASMODIUM MALARIAE (IM); malariotherapy = HYPERTHERMIA, INDUCED: do not confuse with MALARIA /ther; /drug ther: consider also ANTIMALARIALS ID#: D008288

Malaria, Avian

Definition: Any of a group of infections of fowl caused by protozoa of the genera PLASMODIUM, Leucocytozoon, and Haemoproteus. The life cycles of these parasites and the disease produced bears strong resemblance to those observed in human malaria. Annotation: coord with BIRDS (NIM) or specific bird or fowl (IM) ID#: D008289

Malaria, Cerebral

Definition: A condition characterized by somnolence or coma in the presence of an acute infection with PLASMODIUM FALCIPARUM (and rarely other Plasmodium species). Initial clinical manifestations include HEADACHES, SEIZURES, and alterations of mentation followed by a rapid progression to COMA. Pathologic features include cerebral capillaries filled with parasitized erythrocytes and multiple small foci of cortical and subcortical necrosis. (From Adams et al., Principles of Neurology, 6th ed, p136) Annotation: coord IM with Plasmodium species (IM) but do not coord with PLASMODIUM FALCIPARUM unless particularly discussed ID#: D016779

Malaria, Falciparum

Definition: Malaria caused by PLASMODIUM FALCIPARUM. This is the severest form of malaria and is associated with the highest levels of parasites in the blood. This disease is characterized by irregularly recurring febrile paroxysms that in extreme cases occur with acute cerebral, renal, or gastrointestinal manifestations. Annotation: ID#: D016778

Malaria, Vivax

Definition: Malaria caused by PLASMODIUM VIVAX. This form of malaria is less severe than MALARIA, FALCIPARUM, but there is a higher probability for relapses to occur. Febrile paroxysms often occur every other day. Annotation: ID#: D016780

Malignant Carcinoid Syndrome

Definition: A symptom complex associated with CARCINOID TUMOR and characterized by attacks of severe flushing of the skin, diarrheal watery stools, bronchoconstriction, sudden drops in blood pressure, edema, and ascites. The carcinoid tumors are usually located in the gastrointestinal tract and metastasize to the liver. Symptoms are caused by tumor secretion of serotonin, prostaglandins, and other biologically active substances. Cardiac manifestations constitute CARCINOID HEART DISEASE. (Dorland, 27th ed; Stedman, 25th ed) Annotation: do not use /blood supply /chem /second /secret /ultrastruct; for cardiac manifest use CARCINOID HEART DISEASE ID#: D008303

Malignant Catarrh

Definition: A herpesvirus infection of cattle characterized by catarrhal inflammation of the upper respiratory and alimentary epithelia, keratoconjunctivitis, encephalitis and lymph node enlargement. Syn: bovine epitheliosis, snotsiekte. Annotation: caused by a herpesvirus; usually animal; check tag ANIMAL; don't forget also CATTLE (NIM) but do not index under CATTLE DISEASES ID#: D008304

Malignant Hyperthermia

Definition: Rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia. Annotation: ID#: D008305

Mallory-Weiss Syndrome

Definition: Mucosal tears usually linear and confined to the esophagogastric junction but may be located in the fundus of the stomach or in the distal esophagus. Upper gastrointestinal bleeding from these lacerations is often precipitated by retching or vomiting. Annotation: mucosal tears at usually esophagogastric junction ID#: D008309


Definition: Such malposition and contact of the maxillary and mandibular teeth as to interfere with the highest efficiency during the excursive movements of the jaw that are essential for mastication. (Jablonski, Illustrated Dictionary of Dentistry, 1982) Annotation: X ref ANGLE'S CLASSIFICATION: Angle's classes MALOCCLUSION, ANGLE CLASS I & MALOCCLUSION, ANGLE CLASS II & MALOCCLUSION, ANGLE CLASS III are also available but index Angle's classification in general or unspecified as MALOCCLUSION /class ID#: D008310

Malocclusion, Angle Class I

Definition: Malocclusion in which the mandible and maxilla are anteroposteriorly normal as reflected by the relationship of the first permanent molar (i.e., in neutroclusion), but in which individual teeth are abnormally related to each other. Annotation: Angle refers to Edward Hartley Angle, Amer orthodontist ID#: D008311

Malocclusion, Angle Class II

Definition: Malocclusion in which the mandible is posterior to the maxilla as reflected by the relationship of the first permanent molar (distoclusion). Annotation: Angle refers to Edward Hartley Angle, Amer orthodontist ID#: D008312

Malocclusion, Angle Class III

Definition: Malocclusion in which the mandible is anterior to the maxilla as reflected by the first relationship of the first permanent molar (mesioclusion). Annotation: Angle refers to Edward Hartley Angle, Amer orthodontist ID#: D008313

Mammary Neoplasms

Definition: Tumors of the mammary gland. Their occurrence is uncommon with the exception of the female dog, in which they account for 25% of all neoplasms. Annotation: animal only but MAMMARY NEOPLASMS, EXPERIMENTAL is also available; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with histol type of neopl (IM) + precoord animal/dis term (IM) + specific animal (NIM); do not coord with NEOPLASMS, EXPERIMENTAL; check tag ANIMAL ID#: D015674

Mammary Neoplasms, Experimental

Definition: Annotation: animal only; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with histol type of neopl (IM); don't forget also specific animal (NIM) & check tag ANIMAL; DF: MAMMARY NEOPL EXPER ID#: D008325

Mandibular Diseases

Definition: Annotation: ID#: D008336

Mandibular Fractures

Definition: Fractures of the lower jaw. Annotation: ID#: D008337

Mandibular Injuries

Definition: Injuries to the lower jaw bone. Annotation: ID#: D008338

Mandibular Neoplasms

Definition: Tumors or cancer of the MANDIBLE. Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with histol type of neopl (IM) ID#: D008339

Mandibulofacial Dysostosis

Definition: A hereditary disorder occurring in two forms: the complete form (Franceschetti's syndrome) is characterized by antimongoloid slant of the palpebral fissures, coloboma of the lower lid, micrognathia and hypoplasia of the zygomatic arches, and microtia. It is transmitted as an autosomal trait. The incomplete form (Treacher Collins syndrome) is characterized by the same anomalies in less pronounced degree. It occurs sporadically, but an autosomal dominant mode of transmission is suspected. (Dorland, 27th ed) Annotation: a form of craniofacial dysostosis; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008342

Manganese Poisoning

Definition: Manganese poisoning is associated with chronic inhalation of manganese particles by individuals who work with manganese ore. Clinical features include CONFUSION; HALLUCINATIONS; and an extrapyramidal syndrome (PARKINSON DISEASE, SECONDARY) that includes rigidity; DYSTONIA; retropulsion; and TREMOR. (Adams, Principles of Neurology, 6th ed, p1213) Annotation: coord IM with specific manganese cpd (IM) if given ID#: D020149


Definition: Inborn error of metabolism marked by a defect in alpha-mannosidase activity that results in lysosomal accumulation of mannose-rich substrates. Virtually all patients have psychomotor retardation, facial coarsening, and some degree of dysostosis multiplex. It is thought to be an autosomal recessive disorder. Annotation: an inborn error of carbohydrate & lysosomal storage dis; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008363


Definition: Infection with nematodes of the genus MANSONELLA. Symptoms include pruritus, headache, and articular swelling. Annotation: /drug ther: consider FILARICIDES ID#: D008368

Maple Syrup Urine Disease

Definition: An autosomal recessive inherited disorder with multiple forms of phenotypic expression, caused by a defect in the oxidative decarboxylation of branched-chain ammino acids (AMINO ACIDS, BRANCHED-CHAIN). These metabolites accumulate in body fluids and render a "maple syrup" odor. The disease is divided into classic, intermediate, intermittent, and thiamine responsive subtypes. The classic form presents in the first week of life with ketoacidosis, hypoglycemia, emesis, neonatal seizures, and hypertonia. The intermediate and intermittent forms present in childhood or later with acute episodes of ataxia and vomiting. (From Adams et al., Principles of Neurology, 6th ed, p936) Annotation: ID#: D008375

Marburg Virus Disease

Definition: An RNA virus infection of rhesus, vervet, and squirrel monkeys transmissible to man. Annotation: ID#: D008379

Marek Disease

Definition: A transmissible viral disease of birds caused by avian herpesvirus 2 (HERPESVIRUS 2, GALLID) and other MAREK'S DISEASE-LIKE VIRUSES. There is lymphoid cell infiltration or lymphomatous tumor formation in the peripheral nerves and gonads, but may also involve visceral organs, skin, muscle, and the eye. Annotation: don't forget also BIRDS or POULTRY (NIM) or specific bird or fowl (IM); check tag ANIMAL ID#: D008380

Marfan Syndrome

Definition: A hereditary disorder of connective tissue characterized by tall stature, elongated extremities, subluxation of the lens, dilatation of the ascending aorta, and "pigeon breast." It is inherited as an autosomal dominant trait. Annotation: ID#: D008382

Mastigophora Infections

Definition: Infections with protozoa of the subphylum MASTIGOPHORA. Annotation: protozoan infect; GEN: prefer specifics ID#: D016772


Definition: Inflammatory disease of the breast, or mammary gland. Annotation: inflamm of breast or mammary tissue; cystic mastitis = FIBROCYSTIC DISEASE OF BREAST & do not coord with CHRONIC DISEASE ID#: D008413

Mastitis, Bovine

Definition: Annotation: inflamm of udder in cows; don't forget also CATTLE (NIM) & check tags ANIMAL & FEMALE ID#: D008414


Definition: A group of diseases resulting from proliferation of mast cells. Annotation: proliferation of mast cells ID#: D008415


Definition: Inflammation of the cavity and air cells in the mastoid part of the temporal bone. Annotation: ID#: D008417

Maxillary Diseases

Definition: Annotation: must be of the MAXILLA, not for "jaws" ( = JAW DISEASES) ID#: D008439

Maxillary Fractures

Definition: Fractures of the upper jaw. Annotation: must be of the MAXILLA, not for "jaws" ( = JAW FRACTURES) ID#: D008440

Maxillary Neoplasms

Definition: Cancer or tumors of the MAXILLA or upper jaw. Annotation: must be of the MAXILLA, not for "jaws" ( = JAW NEOPLASMS); /blood supply /chem /second /secret /ultrastruct permitted; coord IM with histol type of neopl (IM) ID#: D008441

Maxillary Sinus Neoplasms

Definition: Neoplasms or tumors of the maxillary sinus. The majority of paranasal sinus neoplasms arise here. They develop silently when confined to the sinus and produce symptoms on extension through the walls. Annotation: coord IM with histol type of neopl (IM); /blood supply /chem /second /secret /ultrastruct permitted ID#: D008444

Maxillary Sinusitis

Definition: Inflammation of the maxillary sinus. In most cases it is the result of infection by the bacteria HAEMOPHILUS INFLUENZAE; STREPTOCOCCUS PNEUMONIAE; and STAPHYLOCOCCUS AUREUS. This condition may be acute or chronic. Annotation: ID#: D015523

Maxillofacial Abnormalities

Definition: Congenital structural deformities, malformations, or other abnormalities of the maxilla and face or facial bones. Annotation: GEN or unspecified & involving both the maxilla & the face: not a substitute for MAXILLA /abnorm or FACE /abnorm or FACIAL BONES /abnorm; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MAXILLOFACIAL ABNORM ID#: D019767

Maxillofacial Injuries

Definition: General or unspecified injuries involving the face and jaw (either upper, lower, or both). Annotation: GEN or unspecified & involving both a jaw & the face: not a substitute for MANDIBULAR INJURIES or MAXILLA /inj or FACIAL INJURIES or FACIAL BONES /inj ID#: D008446


Definition: A highly contagious infectious disease caused by MORBILLIVIRUS, common among children but also seen in the nonimmune of any age, in which the virus enters the respiratory tract via droplet nuclei and multiplies in the epithelial cells, spreading throughout the reticuloendothelial system. (From Dorland, 27th ed) Annotation: caused by a morbillivirus; do not confuse X ref RUBEOLA with RUBELLA (German measles); French for measles = rougeole (not rubéole which = RUBELLA), Ital for measles = rosolia (not rubeola which = RUBELLA); Span for measles = sarampi (not rubeola which = RUBELLA) ID#: D008457

Meckel's Diverticulum

Definition: An occasional sacculation or appendage of the ileum, derived from an unobliterated yolk stalk. (Dorland, 27th ed) Annotation: ileal abnorm; use only Cat C qualif; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; Meckel's diverticulitis: coord IM with DIVERTICULITIS (IM) ID#: D008467

Meconium Aspiration

Definition: Syndrome caused by sucking of thick meconium into the lungs, usually by term or post-term infants (often small for gestational age) either in utero or with first breath. The resultant small airway obstruction may produce respiratory distress, tachypnea, cyanosis, pneumothorax, and/or pneumomediastinum. Annotation: sucking of meconium into lungs in utero or at birth; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008471

Median Neuropathy

Definition: Disease involving the median nerve, from its origin at the BRACHIAL PLEXUS to its termination in the hand. Clinical features include weakness of wrist and finger flexion, forearm pronation, thenar abduction, and loss of sensation over the lateral palm, first three fingers, and radial half of the ring finger. Common sites of injury include the elbow, where the nerve passes through the two heads of the pronator teres muscle (pronator syndrome) and in the carpal tunnel (CARPAL TUNNEL SYNDROME). Annotation: pronator nerve syndrome: coord (IM) with NERVE COMPRESSION SYNDROMES ID#: D020423

Mediastinal Cyst

Definition: Cysts of one of the parts of the mediastinum: the superior part, containing the trachea, esophagus, thoracic duct and thymus organs; the inferior middle part, containing the pericardium; the inferior anterior part containing some lymph nodes; and the inferior posterior part, containing the thoracic duct and esophagus. Annotation: non-neoplastic; simple mediastinal cysts commonly adjacent to pericardium; note X refs: do not coord pericardial, thoracic, thymic or tracheal cysts with respective organs or organ/dis precoord: index only under MEDIASTINAL CYST ID#: D008476

Mediastinal Diseases

Definition: Disorders of the mediastinum, general or unspecified. Annotation: inflamm dis = MEDIASTINITIS ID#: D008477

Mediastinal Emphysema

Definition: Presence of air in the mediastinal tissues due to leakage of air from the tracheobronchial tree, usually as a result of trauma. Annotation: do not confuse with radiogr pneumomediastinum ( = PNEUMOMEDIASTINUM, DIAGNOSTIC) ID#: D008478

Mediastinal Neoplasms

Definition: Tumors or cancer of the MEDIASTINUM. Annotation: coord IM with histol type of neopl (IM) ID#: D008479


Definition: Inflammation of the mediastinum, the area between the pleural sacs. Annotation: ID#: D008480


Definition: A malignant neoplasm that may be classified either as a glioma or as a primitive neuroectodermal tumor of childhood (see NEUROECTODERMAL TUMOR, PRIMITIVE). The tumor occurs most frequently in the first decade of life with the most typical location being the cerebellar vermis. Histologic features include a high degree of cellularity, frequent mitotic figures, and a tendency for the cells to organize into sheets or form rosettes. Medulloblastoma have a high propensity to spread throughout the craniospinal intradural axis. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2060-1) Annotation: coord IM with CEREBELLAR NEOPLASMS (IM) ID#: D008527


Definition: Pathological enlargement of the colon. Annotation: note MEGACOLON, TOXIC is also available ID#: D008531

Megacolon, Toxic

Definition: Acute dilatation of the colon associated with amebic or ulcerative colitis. The dilatation may precede perforation of the colon. (Dorland, 27th ed) Annotation: assoc with ulcerative colitis ID#: D008532

Meige Syndrome

Definition: A syndrome characterized by orofacial DYSTONIA; including BLEPHAROSPASM; forceful jaw opening; lip retraction; platysma muscle spasm; and tongue protrusion. It primarily affects older adults, with an incidence peak in the seventh decade of life. (From Adams et al., Principles of Neurology, 6th ed, p108) Annotation: note X refs: do not confuse with Meige Syndrome of familial lymphedema ( = MILROY'S DISEASE see LYMPHEDEMA) nor with MEIGS' SYNDROME ID#: D008538

Meigs' Syndrome

Definition: Ascites and hydrothorax associated with ovarian fibroma or other pelvic tumors. Annotation: ovarian tumor with ascites & pleural effusion; note apostrophe: s' , not 's; do not confuse with MEIGE SYNDROME; do not use /blood supply /chem /second /secret /ultrastruct ID#: D008539


Definition: A malignant neoplasm derived from cells that are capable of forming melanin, which may occur in the skin of any part of the body, in the eye, or, rarely, in the mucous membranes of the genitalia, anus, oral cavity, or other sites. It occurs mostly in adults and may originate de novo or from a pigmented nevus or malignant lentigo. Melanomas frequently metastasize widely, and the regional lymph nodes, liver, lungs, and brain are likely to be involved. The incidence of malignant skin melanomas is rising rapidly in all parts of the world. (Stedman, 25th ed; from Rook et al., Textbook of Dermatology, 4th ed, p2445) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM); MELANOMA, EXPERIMENTAL is also available ID#: D008545

Melanoma, Amelanotic

Definition: An unpigmented malignant melanoma. It is an anaplastic melanoma consisting of cells derived from melanoblasts but not forming melanin. (Dorland, 27th ed; Stedman, 25th ed) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with SKIN NEOPLASMS (IM) + site (IM or NIM) if relevant ID#: D018328

Melanoma, Experimental

Definition: Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM); DF: MELANOMA EXPER ID#: D008546


Definition: Disorders of increased melanin pigmentation that develop without preceding inflammatory disease. Annotation: for neurocutaneous melanosis, coord with NEUROCUTANEOUS SYNDROMES ID#: D008548

MELAS Syndrome

Definition: A mitochondrial disorder characterized by focal or generalized seizures, episodes of transient or persistent neurologic dysfunction resembling strokes, and ragged-red fibers on muscle biopsy. Affected individuals tend to be normal at birth through early childhood, then experience growth failure, episodic vomiting, and recurrent cerebral insults resulting in visual loss and hemiparesis. The cortical lesions tend to occur in the parietal and occipital lobes and are not associated with vascular occlusion. VASCULAR HEADACHE is frequently associated and the disorder tends to be familial. (From Joynt, Clinical Neurology, 1992, Ch56, p117) Annotation: DF: MELAS ID#: D017241


Definition: Black, tarry feces containing digested blood. Annotation: ID#: D008551


Definition: A disease of humans and animals that resembles GLANDERS. It is caused by BURKHOLDERIA PSEUDOMALLEI and may range from a dormant infection to a condition that causes multiple abscesses, pneumonia, and bacteremia. Annotation: caused by Burkholderia pseudomallei; in India, Malay & Indonesia ID#: D008554

Melkersson-Rosenthal Syndrome

Definition: An idiopathic syndrome characterized by one or more of the following; recurrent orofacial swelling, relapsing facial paralysis, and fissured tongue (lingua plicata). The onset is usually in childhood and relapses are common. Cheilitis granulomatosa is a monosymptomatic variant of this condition. (Dermatol Clin 1996 Apr;14(2):371-9; Magalini & Magalini, Dictionary of Medical Syndromes, 4th ed, p531) Annotation: ID#: D008556


Definition: A form of osteosclerosis or hyperostosis extending in a linear track through one of the long bones of an extremity, and consisting of proliferated ivory-like new bone. "Melo-" is from the Greek, limb and "-rheostosis" refers to streaks (rheo- from the Greek, flow), in the bones. (Dorland, 27th ed) Annotation: a form of osteosclerosis ID#: D008557

Meniere's Disease

Definition: A disease of the inner ear characterized by vertigo, tinnitus, and fluctuating hearing loss often accompanied by fullness in the affected ear. ENDOLYMPHATIC HYDROPS (swelling of the endolymph-containing structures) is the main pathologic finding. Annotation: an inner ear dis; spell with one accent (Menière's) in translations; note see related ID#: D008575

Meningeal Neoplasms

Definition: Benign and malignant neoplastic processes that arise from or secondarily involve the meningeal coverings of the brain and spinal cord. Annotation: coord IM with histol type of neopl (IM); for intracranial or spinal meningioma, see note on MENINGIOMA; intradural extramedullary neopl do not go here: index under SPINAL CORD NEOPLASMS & do not try to locate "intradural" or "extramedullary"; meningeal leukemia does not go here: index under MENINGES /pathol (IM) + LEUKEMIC INFILTRATION (IM) (see note there) + specific type of leukemia (IM) if relevant ID#: D008577


Definition: A relatively common neoplasm of the central nervous system that arises from arachnoidal cells. The majority are well differentiated vascular tumors which grow slowly and have a low potential to be invasive, although malignant subtypes occur. Meningiomas have a predilection to arise from the parasagittal region, cerebral convexity, sphenoidal ridge, olfactory groove, and spinal canal. They tend to present in the fourth to sixth decades of life with signs indicative of a slowly progressive mass lesion. Specific clinical manifestations depend on the location of the tumor, but may include INTRACRANIAL HYPERTENSION, cranial neuropathies, ataxia, and other focal neurologic signs. (From DeVita et al., Cancer: Principles and Practice of Oncology, 5th ed, pp2056-7) Annotation: benign or malignant; coord IM with MENINGEAL NEOPLASMS (IM) but not with BRAIN NEOPLASMS nor SPINAL CORD NEOPLASMS for intracranial or spinal meningioma unless site is particularly discussed ID#: D008579


Definition: A condition characterized by neck stiffness, headache, and other symptoms suggestive of meningeal irritation, but without actual inflammation of the meninges (MENINGITIS). Spinal fluid pressure may be elevated but spinal fluid is normal. (DeJong, The Neurologic Examination, 4th ed, p673) Annotation: ID#: D008580


Definition: Inflammation of the coverings of the brain and/or spinal cord, which consist of the PIA MATER; ARACHNOID; and DURA MATER. Infections (viral, bacterial, and fungal) are the most common causes of this condition, but subarachnoid hemorrhage (HEMORRHAGES, SUBARACHNOID), chemical irritation (chemical MENINGITIS), granulomatous conditions, neoplastic conditions (e.g., carcinomatous meningitis), and other inflammatory conditions may produce this syndrome. (From Joynt, Clinical Neurology, 1994, Ch24, p6) Annotation: GEN: prefer specifics; for pachymeningitis (DURA MATER) or leptomeningitis (ARACHNOIDITIS or PIA MATER) do not specify meninx unless particularly discussed; purulent, suppurative or pyogenic: do not coord with SUPPURATION (NIM) unless particularly discussed ID#: D008581

Meningitis, Aseptic

Definition: A syndrome characterized by headache, neck stiffness, low grade fever, and CSF lymphocytic pleocytosis in the absence of an acute bacterial pathogen. Viral meningitis is the most frequent cause although MYCOPLASMA INFECTIONS; RICKETTSIA INFECTIONS; diagnostic or therapeutic procedures; NEOPLASTIC PROCESSES; septic perimeningeal foci; and other conditions may result in this syndrome. (From Adams et al., Principles of Neurology, 6th ed, p745) Annotation: coord IM with specific cause (IM) if pertinent ID#: D008582

Meningitis, Bacterial

Definition: Bacterial infections of the leptomeninges and subarachnoid space, frequently involving the cerebral cortex, cranial nerves, cerebral blood vessels, spinal cord, and nerve roots. The type of causative organism varies with age and clinical status (e.g., post-operative, immunodeficient, or post-traumatic states). Clinical manifestations include the acute onset of fever, stiff neck, altered mentation, seizures, and focal neurologic deficits. Death may occur within 24 hours of disease onset. Pathologic features include a purulent exudate in the subarachnoid space, and diffuse inflammation of neural and vascular structures. (From Joynt, Clinical Neurology, 1994, Ch24, pp1-5) Annotation: coord IM with specific bacterial infection (IM) but note indentions here ID#: D016920

Meningitis, Cryptococcal

Definition: Meningeal inflammation produced by CRYPTOCOCCUS NEOFORMANS, an encapsulated yeast that tends to infect individuals with ACQUIRED IMMUNODEFICIENCY SYNDROME and other immunocompromised states. The organism enters the body through the respiratory tract, but symptomatic infections are usually limited to the lungs and nervous system. The organism may also produce parenchymal brain lesions (torulomas). Clinically, the course is subacute and may feature HEADACHE; NAUSEA; PHOTOPHOBIA; focal neurologic deficits; SEIZURES; cranial neuropathies; and HYDROCEPHALUS. (From Adams et al., Principles of Neurology, 6th ed, pp721-2) Annotation: ID#: D016919

Meningitis, Escherichia coli

Definition: A form of gram-negative meningitis that tends to occur in neonates, in association with anatomical abnormalities (which feature communication between the meninges and cutaneous structures) or as OPPORTUNISTIC INFECTIONS in association with IMMUNOLOGIC DEFICIENCY SYNDROMES. In premature neonates the clinical presentation may be limited to ANOREXIA; VOMITING; lethargy; or respiratory distress. Full-term infants may have as additional features FEVER; SEIZURES; and bulging of the anterior fontanelle. (From Menkes, Textbook of Child Neurology, 5th ed, pp398-400) Annotation: DF: MENINGITIS E COLI ID#: D020814

Meningitis, Fungal

Definition: Meningitis caused by fungal agents which may occur as OPPORTUNISTIC INFECTIONS or arise in immunocompetent hosts. Annotation: coord IM with specific fungus (IM) or specific fungal disease (IM) ID#: D016921

Meningitis, Haemophilus

Definition: BACTERIAL INFECTIONS of the nervous system caused by HAEMOPHILUS organisms, and marked by prominent inflammation of the meninges. HAEMOPHILUS INFLUENZAE TYPE B is the most common causative organism. The condition primarily affects children under 6 years of age but may occur in adults. Clinical manifestations include fever; nuchal rigidity; PHOTOPHOBIA; SEIZURES; HEARING LOSS; SENSORINEURONAL; COMA; and cerebrovascular thrombosis. The organism tends to enter the central nervous system following infections of adjacent structures, including the middle ear (see also OTITIS MEDIA), sinuses, and pharynx. (From Menkes, Textbook of Child Neurology, 5th ed, pp396-7) Annotation: coord IM with Haemophilus species if available ID#: D008583

Meningitis, Listeria

Definition: Inflammation of the meninges caused by LISTERIA MONOCYTOGENES infection, usually occuring in individuals under the age of 3 years or over the age of 50 years. It may occur at any age in individuals with IMMUNOLOGIC DEFICIENCY SYNDROMES. Clinical manifestations include FEVER, altered mentation, HEADACHE, meningeal signs, focal neurologic signs, and SEIZURES. (From Medicine 1998 Sep;77(5):313-36) Annotation: do not coord with LISTERIA MONOCYTOGENES unless organism is particularly discussed ID#: D008584

Meningitis, Meningococcal

Definition: A fulminant infection of the meninges and subarachnoid fluid by the bacterium NEISSERIA MENINGITIDIS, producing diffuse inflammation and peri-meningeal venous thromboses. Clinical manifestations include FEVER, nuchal rigidity, SEIZURES, severe HEADACHE, petechial rash, stupor, focal neurologic deficits, HYDROCEPHALUS, and COMA. The organism is usually transmitted via nasopharyngeal secretions and is a leading cause of meningitis in children and young adults. Neisseria meningitidis serogroups A, B, and C have been reported to cause meningitis. (From Adams et al., Principles of Neurology, 6th ed, pp689-701; Curr Opin Pediatr 1998 Feb;10(1):13-8) Annotation: do not coord with NEISSERIA MENINGITIDIS unless organism is particularly discussed ID#: D008585

Meningitis, Pneumococcal

Definition: An acute purulent infection of the meninges and subarachnoid space caused by Streptococcus pneumoniae, most prevalent in children and adults over the age of 60. This illness may be associated with OTITIS MEDIA; MASTOIDITIS; SINUSITIS; RESPIRATORY TRACT INFECTIONS; sickle cell disease (ANEMIA, SICKLE CELL); skull fractures; and other disorders. Clinical manifestations include FEVER; HEADACHE; neck stiffness; and somnolence followed by SEIZURES; focal neurologic deficits (notably DEAFNESS); and COMA. (From Miller et al., Merritt's Textbook of Neurology, 9th ed, p111) Annotation: do not coord with STREPTOCOCCUS PNEUMONIAE unless organism is particularly discussed ID#: D008586

Meningitis, Viral

Definition: Viral infections of the leptomeninges and subarachnoid space. TOGAVIRIDAE INFECTIONS; FLAVIVIRIDAE INFECTIONS; RUBELLA; BUNYAVIRIDAE INFECTIONS; ORBIVIRUS infections; PICORNAVIRIDAE INFECTIONS; ORTHOMYXOVIRIDAE INFECTIONS; RHABDOVIRIDAE INFECTIONS; ARENAVIRIDAE INFECTIONS; HERPESVIRIDAE INFECTIONS; ADENOVIRIDAE INFECTIONS; JC VIRUS infections; and RETROVIRIDAE INFECTIONS may cause this form of meningitis. Clinical manifestations include fever, headache, neck pain, vomiting, PHOTOPHOBIA, and signs of meningeal irritation. (From Joynt, Clinical Neurology, 1996, Ch26, pp1-3) Annotation: coord IM with specific virus dis (IM) ID#: D008587


Definition: A congenital or acquired protrusion of the meninges, unaccompanied by neural tissue, through a bony defect in the skull or vertebral column. Annotation: meningoencephalocele: coord IM with ENCEPHALOCELE (IM) ID#: D008588

Meningococcal Infections

Definition: Infections with bacteria of the species NEISSERIA MENINGITIDIS. Annotation: MENINGITIS, MENINGOCOCCAL is also available; DF: MENINGOCOCCAL INFECT ID#: D008589


Definition: An inflammatory process involving the brain (ENCEPHALITIS) and meninges (MENINGITIS), most often produced by pathogenic organisms which invade the central nervous system, and occasionally by toxins, autoimmune disorders, and other conditions. Annotation: coord IM with precoord or specific infection term (IM) or other cause (IM); DF: MENINGOENCEPH ID#: D008590


Definition: Congenital, or rarely acquired, herniation of meningeal and spinal cord tissue through a bony defect in the vertebral column. The majority of these defects occur in the lumbosacral region. Clinical features include PARAPLEGIA, loss of sensation in the lower body, and incontinence. This condition may be associated with the ARNOLD-CHIARI MALFORMATION and HYDROCEPHALUS. (From Joynt, Clinical Neurology, 1992, Ch55, pp35-6) Annotation: ID#: D008591

Menkes Kinky Hair Syndrome

Definition: An inherited disorder of copper metabolism transmitted as an X-linked trait and characterized by the infantile onset of HYPOTHERMIA, feeding difficulties, hypotonia, SEIZURES, bony deformities, pili torti (twisted hair), and severely impaired intellectual development. Defective copper transport across plasma and endoplasmic reticulum membranes results in copper being unavailable for the synthesis of several copper containing enzymes, including PROTEIN-LYSINE 6-OXIDASE; CERULOPLASMIN; and SUPEROXIDE DISMUTASE. Pathologic changes include defects in arterial elastin, neuronal loss, and gliosis. (From Menkes, Textbook of Child Neurology, 5th ed, p125) Annotation: ID#: D007706


Definition: Excessive menstrual flow. Annotation: ID#: D008595

Menstruation Disturbances

Definition: Variations of menstruation which may be indicative of disease. Annotation: human only; GEN or unspecified: prefer specifics; note X refs ID#: D008599

Mercury Poisoning

Definition: Annotation: GEN only: consider also /pois with specific mercury terms; occup mercury pois: coord IM with OCCUPATIONAL DISEASES (IM) but not also ENVIRONMENTAL EXPOSURE (see note there) ID#: D008630

Mercury Poisoning, Nervous System

Definition: Neurologic disorders associated with exposure to inorganic and organic forms of MERCURY. Acute intoxication may be associated with gastrointestinal disturbances, mental status changes, and PARAPARESIS. Chronic exposure to inorganic mercury usually occurs in industrial workers, and manifests as mental confusion, prominent behavioral changes (including psychosis), DYSKINESIAS, and NEURITIS. Alkyl mercury poisoning may occur through ingestion of contaminated seafood or grain, and its characteristic features include POLYNEUROPATHY; ATAXIA; vision loss; NYSTAGMUS; and DEAFNESS. (From Joynt, Clinical Neurology, 1997, Ch20, pp10-15) Annotation: coord IM with specific mercury cpd (IM) if given ID#: D020262

MERRF Syndrome

Definition: A mitochondrial encephalomyopathy characterized clinically by a mixed seizure disorder, myoclonus, progressive ataxia, spasticity, and a mild myopathy. Dysarthria, optic atrophy, growth retardation, deafness, and dementia may also occur. This condition tends to present in childhood and to be transmitted via maternal lineage. Muscle biopsies reveal ragged-red fibers and respiratory chain enzymatic defects. (From Adams et al., Principles of Neurology, 6th ed, p986) Annotation: DF: MERRF ID#: D017243


Definition: A mixed mesenchymal tumor composed of two or more mesodermal cellular elements not commonly associated, not counting fibrous tissue as one of the elements. Mesenchymomas are widely distributed in the body and about 75% are malignant. (Dorland, 27th ed; Holland et al., Cancer Medicine, 3d ed, p1866) Annotation: benign or malignant; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D008637

Mesenteric Cyst

Definition: A congenital thin-walled cyst of the abdomen between the leaves of the mesentery, which may be of wolffian or lymphatic duct origin. As it enlarges it may cause colicky pain and intestinal obstruction. (Dorlamd, 27th ed) Annotation: non-neoplastic; /blood supply /chem /secret /ultrastruct permitted ID#: D008639

Mesenteric Lymphadenitis

Definition: Inflammation of the mesenteric lymph nodes. Annotation: coord IM with specific infection (IM) ID#: D008640

Mesenteric Vascular Occlusion

Definition: Obstruction of the flow in the mesenteric circulation by atherosclerosis, emboli or thrombi, stenosis, trauma, and compression or intrinsic pressure from adjacent tumors. Rare causes are drugs, intestinal parasites, and vascular immunoinflammatory diseases such as periarteritis nodosa and thromboangiitis obliterans. (From Juergens et al., Peripheral Vascular Diseases, 5th ed, pp295-6) Annotation: obstruct of external or internal origin; coord IM with MESENTERIC ARTERIES (NIM) or MESENTERIC VEINS (NIM); embolism or thrombosis: see notes under MESENTERIC ARTERIES & MESENTERIC VEINS; coord IM with target organ losing its blood supply (COLON /blood supply, JEJUNUM /blood supply) (IM or NIM) only if particularly discussed; do not confuse with SUPERIOR MESENTERIC ARTERY SYNDROME (duodenal compression BY the superior mesenteric artery, not OF) ID#: D008641


Definition: A rare tumor of the female genital tract, most often the ovary, formerly considered to be derived from mesonephric rests. Two varieties are recognized: (1) clear cell carcinoma, so called because of its histologic resemblance to renal cell carcinoma, and now considered to be of muellerian duct derivation and (2) an embryonal tumor (called also ENDODERMAL SINUS TUMOR and yolk sac tumor), occurring chiefly in children. The latter variety may also arise in the testis. (Dorland, 27th ed) Annotation: benign or malignant; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D008649


Definition: A tumor derived from mesothelial tissue (peritoneum, pleura, pericardium). It appears as broad sheets of cells, with some regions containing spindle-shaped, sarcoma-like cells and other regions showing adenomatous patterns. Pleural mesotheliomas have been linked to exposure to asbestos. (Dorland, 27th ed) Annotation: benign or malignant; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D008654

Mesothelioma, Cystic

Definition: A peritoneal mesothelioma affecting mainly young females and producing cysts of variable size and number lined by a single layer of benign mesothelial cells. The disease follows a benign course and is compatible with a normal life expectancy, requiring occasionally partial excision or decompression for relief of pain or other symptoms. Malignant potential is exceptional. (From Holland et al., Cancer Medicine, 3d ed, p1345) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with PERITONEAL NEOPLASMS (IM) ID#: D018261

Metabolic Diseases

Definition: Generic term for diseases caused by an abnormal metabolic process. It can be congenital due to inherited enzyme abnormality (METABOLISM, INBORN ERRORS) or acquired due to disease of an endocrine organ or failure of a metabolically important organ such as the liver. (Stedman, 26th ed) Annotation: GEN: prefer specifics; TN 194: differentiate from DEFICIENCY DISEASES; DF: METAB DIS ID#: D008659

Metabolism, Inborn Errors

Definition: Errors in metabolic processes resulting from inborn genetic mutations that are inherited or acquired in utero. Annotation: GEN: prefer specific types; differentiate from DEFICIENCY DISEASES; DF: METAB INBORN ERR ID#: D008661

Metal Metabolism, Inborn Errors

Definition: Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; coord IM with specific metal /metab (IM); DF: METAL METAB INBORN ERR ID#: D008664


Definition: A condition in which there is a change of one adult cell type to another similar adult cell type. Annotation: NIM; coord with organ /pathol (IM) ID#: D008679


Definition: The presence of methemoglobin in the blood, resulting in cyanosis. A small amount of methemoglobin is present in the blood normally, but injury or toxic agents convert a larger proportion of hemoglobin into methemoglobin, which does not function reversibly as an oxygen carrier. Methemoglobinemia may be due to a defect in the enzyme NADH methemoglobin reductase (an autosomal recessive trait) or to an abnormality in hemoglobin M (an autosomal dominant trait). (Dorland, 27th ed) Annotation: presence of methemoglobin in blood ID#: D008708


Definition: Uterine bleeding, usually irregular or acyclic, between periods. Annotation: ID#: D008796


Definition: Abnormal smallness of the head, usually associated with mental retardation. (Dorland, 27th ed) Annotation: abnormally small head; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008831


Definition: Unusual or undue smallness of the jaws. (Dorland, 27th ed) Annotation: abnormally small jaw; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008844


Definition: Congenital or developmental anomaly in which the eyeballs are abnormally small. Annotation: abnormally small eyeball; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008850


Definition: Infections with protozoa of the phylum MICROSPORA. Annotation: do not confuse with Microsporum infections, one of the DERMATOMYCOSES (see note at MICROSPORUM) ID#: D016881


Definition: A congenital defect in which the mouth is unusually small. (Dorland, 27th ed) Annotation: unusually small mouth; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D008865

Middle Lobe Syndrome

Definition: Atelectasis of the right middle pulmonary lobe, with chronic pneumonitis. (Dorland, 27th ed) Annotation: atelectasis of middle lobe of right lung ID#: D008878


Definition: A subtype of vascular headaches characterized by periodic unilateral pulsatile headaches which begin in childhood, adolescence, or early adult life and recur with diminishing frequency during advancing years. The two major subtypes are CLASSIC MIGRAINE (i.e., migraine with aura) and COMMON MIGRAINE (i.e., migraine without aura). Migrainous episodes may be associated with alterations in cerebral blood flow. (From Adams et al., Principles of Neurology, 6th ed, p172) Annotation: consider also ANALGESICS /ther use ID#: D008881

Mikulicz' Disease

Definition: A chronic, benign, and usually painless inflammatory swelling of the lacrimal and salivary glands. It is considered by some to include the glandular enlargement associated with other diseases, such as Sjogren's syndrome, sarcoidosis, lupus erythematosus, etc. Annotation: an inflamm dis of the lacrimal & salivary glands ID#: D008882


Definition: A syndrome of cutaneous changes associated with sweat retention and extravasation of sweat at different levels in the skin. Miliaria rubra, or prickly heat, results from apocrine duct obstruction. The sweat then seeps into the epidermis, producing pruritic erythematous papulovesicles. (From Dorland, 27th ed) Annotation: a sweat gland dis ID#: D008883

Milk Hypersensitivity

Definition: Allergic reaction to milk (usually cow's milk) or milk products. MILK HYPERSENSITIVITY should be differentiated from LACTOSE INTOLERANCE, an intolerance to milk as a result of congenital deficiency of lactase. Annotation: coord IM with specific milk product /adv eff (IM) if pertinent; do not confuse with LACTOSE INTOLERANCE, a lactase defic ID#: D016269

Milk Sickness

Definition: An acute, often fatal disease caused by the ingestion of milk, milk products, or the flesh of cattle or sheep which have a disease known as trembles. It is marked by weakness, anorexia, vomiting, constipation, and sometimes muscular tremors. It is caused by poisoning by white snakeroot (Eupatorium rugosum) and the rayless goldenrod (Haplopappus heterophyllus). (From Dorland, 27th ed) Annotation: a form of plant pois: see MeSH definition ID#: D018602

Miller Fisher Syndrome

Definition: A variant of the GUILLAIN-BARRE SYNDROME characterized by the acute onset of oculomotor dysfunction, ataxia, and loss of deep tendon reflexes with relative sparing of strength in the extremities and trunk. The ataxia is produced by peripheral sensory nerve dysfunction and not by cerebellar injury. Facial weakness and sensory loss may also occur. The process is mediated by autoantibodies directed against a component of myelin found in peripheral nerves. (Adams et al., Principles of Neurology, 6th ed, p1313; Neurology 1987 Sep;37(9):1493-8) Annotation: X ref FISHER SYNDROME: do not confuse with the Fisher one-and-a-half syndrome, an eye movement disorder caused by a brain stem lesion ID#: D019846


Definition: Pupillary constriction. This may result from congenital absence of the dilatator pupillary muscle, defective sympathetic innervation, or irritation of the CONJUNCTIVA or CORNEA. Annotation: do not confuse with MEIOSIS nor with MITOSIS, both cell division concepts ID#: D015877

Mite Infestations

Definition: Infestations with arthropods of the subclass ACARI, superorder Acariformes. Annotation: ID#: D008924

Mitochondrial Diseases

Definition: Diseases caused by abnormal function of the MITOCHONDRIA. They may be caused by mutations, acquired or inherited, in mitochondrial DNA or in nuclear genes that code for mitochondrial components. They may also be the result of acquired mitochondria dysfunction due to adverse effects of drugs, infections, or other environmental causes. Annotation: GEN or unspecified; prefer specifics ID#: D028361

Mitochondrial Encephalomyopathies

Definition: A heterogenous group of disorders characterized by alterations of mitochondrial metabolism that result in muscle and nervous system dysfunction. These are often multisystemic and vary considerably in age at onset (usually in the first or second decade of life), distribution of affected muscles, severity, and course. (From Adams et al., Principles of Neurology, 6th ed, pp984-5) Annotation: GEN or unspecified; prefer specifics; coord with specific dysfunction if pertinent; DF: MITOCHONDRIAL ENCEPH ID#: D017237

Mitochondrial Myopathies

Definition: A group of muscle diseases associated with abnormal mitochondria function. Annotation: GEN or unspecified; prefer specifics; NARP syndrome (neuropathy, ataxia and retinitis pigmentosa) = MITOCHONDRIAL MYOPATHIES + ATAXIA + RETINITIS PIGMENTOSA + SYNDROME ID#: D017240

Mitral Valve Insufficiency

Definition: Backflow of blood from the left ventricle into the left atrium, owing to imperfect functioning of the mitral valve. Annotation: imperfect closing of valve ID#: D008944

Mitral Valve Prolapse

Definition: Abnormal protrusion of one or both of the leaflets of the mitral valve into the left atrium during systole. This may be accompanied by mitral regurgitation, systolic murmur, nonejection click, or cardiac arrhythmia. Annotation: ID#: D008945

Mitral Valve Stenosis

Definition: A rheumatic disease causing diffuse thickening of the mitral valve leaflets by fibrous tissue or calcific deposits. (Harrisons' Principles of Internal Medicine, 13th ed, p1052) Annotation: atresia = MITRAL VALVE /abnorm ID#: D008946

Mixed Connective Tissue Disease

Definition: A syndrome with overlapping clinical features of systemic lupus erythematosus, scleroderma, polymyositis, and Raynaud's phenomenon. The disease is differentially characterized by high serum titers of antibodies to ribonuclease-sensitive extractable (saline soluble) nuclear antigen and a "speckled" epidermal nuclear staining pattern on direct immunofluorescence. Annotation: disease entity: read definition & do not confuse with CONNECTIVE TISSUE DISEASES; DF: MCTD ID#: D008947

Mixed Tumor, Malignant

Definition: A malignant tumor composed of more than one type of neoplastic tissue. (Dorland, 27th ed) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with organ/neopl term (IM) ID#: D018198

Mixed Tumor, Mesodermal

Definition: A sarcoma of the body of the uterus arising in older women, composed of more than one mesenchymal tissue, especially including striated muscle cells. It is associated with previous pelvic radiation exposure in 20% of patients. (Stedman, 25th ed; Holland et al., Cancer Medicine, 3d ed, p1702) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with probably UTERINE NEOPLASMS (IM) ID#: D018199

Mixed Tumor, Mullerian

Definition: A tumor, basically a carcinoma with a single sarcoma such as leiomyosarcoma or angiosarcoma or multiple sarcomas of uterine origin. The role of estrogen has been postulated as a possible etiological factor in this tumor. (Holland et al., Cancer Medicine, 3d ed, p1703) Annotation: in titles & translations use diacrit: Müllerian; /blood supply /chem /second /secret /ultrastruct permitted; coord IM with probably UTERINE NEOPLASMS (IM) ID#: D018200

Mobius Syndrome

Definition: A syndrome of congenital facial paralysis, frequently associated with abducens palsy and other congenital abnormalities including lingual palsy, clubfeet, brachial disorders, cognitive deficits, and pectoral muscle defects. Pathologic findings are variable and include brain stem nuclear aplasia, facial nerve aplasia, and facial muscle aplasia, consistent with a multifactorial etiology. (Adams et al., Principles of Neurology, 6th ed, p1020) Annotation: ID#: D020331

Molluscum Contagiosum

Definition: A common, benign, usually self-limited viral infection of the skin and occasionally the conjunctivae by a poxvirus (MOLLUSCUM CONTAGIOSUM VIRUS). (Dorland, 27th ed) Annotation: a skin dis caused by a poxvirus ID#: D008976


Definition: Infection of ruminants with tapeworms of the genus Moniezia. Annotation: tapeworm infect; usually animal; check tag ANIMAL; for organism index CESTODA (IM) + MONIEZIASIS (NIM) ID#: D008989

Monkey Diseases

Definition: Diseases of Old World and New World monkeys. This term includes diseases of baboons but not of chimpanzees or gorillas (= APE DISEASES). Annotation: IM GEN or unspecified; coord IM with specific dis /vet (IM) or specific monkey dis (IM); coord IM with specific monkey (IM); for abnormalities or injuries, index under specific monkey heading /abnorm or /inj; does not include diseases of chimpanzees: CHIMPANZEE is an ape, not monkey ( = APE DISEASES: see note there); don't forget also MONKEYS (NIM) if no specific monkey is indexed; also check tag ANIMAL; DF: MONKEY DIS ID#: D008992

Monoclonal Gammopathies, Benign

Definition: Conditions characterized by the presence of a monoclonal serum (or urine) protein without clinical manifestations of plasma cell dyscrasia. Annotation: a hypergammaglobulinemia ID#: D008998

Mononegavirales Infections

Definition: Infections with viruses of the order MONONEGAVIRALES. The concept includes FILOVIRIDAE INFECTIONS, PARAMYXOVIRIDAE INFECTIONS, and RHABDOVIRIDAE INFECTIONS. Annotation: GEN or unspecified; prefer specifics ID#: D018701


Definition: Disease or trauma involving a single peripheral nerve in isolation, or out of proportion to evidence of diffuse peripheral nerve dysfunction. Mononeuropathy multiplex refers to a condition characterized by multiple isolated nerve injuries. Mononeuropathies may result from a wide variety of causes, including ISCHEMIA; traumatic injury; compression; CONNECTIVE TISSUE DISEASES; CUMULATIVE TRAUMA DISORDERS; and other conditions. Annotation: GEN: prefer specifics ID#: D020422


Definition: A fetus or infant with such pronounced developmental anomalies as to be grotesque and usually nonviable. (Dorland, 27th ed) Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; fetus in fetu: index under FETUS /abnorm ID#: D009008

Monteggia's Fracture

Definition: Fracture in the proximal half of the shaft of the ulna, with dislocation of the head of the radius. Annotation: ulna fract with radius disloc ID#: D009011

Morbillivirus Infections

Definition: Infections with viruses of the genus MORBILLIVIRUS, family PARAMYXOVIRIDAE. Infections mainly cause acute disease in their hosts, although in some cases infection is persistent and leads to degenerative conditions. Annotation: caused by a member of the Paramyxoviridae family; GEN or unspecified; prefer specifics ID#: D018185

Motion Sickness

Definition: Sickness caused by motion, as sea sickness, train sickness, car sickness, and air sickness. Annotation: on sea or air or in cars or trains but SPACE MOTION SICKNESS is available ID#: D009041

Motor Neuron Disease

Definition: Diseases characterized by a selective degeneration of the motor neurons of the spinal cord, brainstem, or motor cortex. Clinical subtypes are distinguished by the major site of degeneration. In AMYOTROPHIC LATERAL SCLEROSIS there is involvment of upper, lower, and brainstem motor neurons. In progressive muscular atrophy and related syndromes (see MUSCULAR ATROPHY, SPINAL) the motor neurons in the spinal cord are primarily affected. With progressive bulbar palsy (BULBAR PALSY, PROGRESSIVE), the initial degeneration occurs in the brainstem. In primary lateral sclerosis, the cortical neurons are affected in isolation. (Adams et al., Principles of Neurology, 6th ed, p1089) Annotation: GEN or unspecified; prefer specifics ID#: D016472

Mouth Abnormalities

Definition: Congenital absence of or defects in structures of the mouth. Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D009056

Mouth Breathing

Definition: Abnormal breathing through the mouth, usually associated with obstructive disorders of the nasal passages. Annotation: note category: use all pertinent qualif ID#: D009058

Mouth Diseases

Definition: Annotation: GEN only: prefer specifics; inflamm dis = STOMATITIS; mucositis: index under STOMATITIS (IM) + MOUTH MUCOSA (NIM) ID#: D009059

Mouth Neoplasms

Definition: Tumors or cancer of the MOUTH. Annotation: coord IM with histol type of neopl (IM) ID#: D009062

Mouth, Edentulous

Definition: Having teeth in neither the mandible nor the maxilla. Annotation: total lack of teeth through disease or extraction; do not confuse with ANODONTIA (congen absence of one or more teeth); differentiate from JAW, EDENTULOUS & JAW, EDENTULOUS, PARTIALLY (see definitions under JAW, EDENTULOUS) ID#: D009066

Movement Disorders

Definition: Syndromes which feature DYSKINESIAS as a cardinal manifestation of the disease process. Included in this category are degenerative, hereditary, post-infectious, medication-induced, post-inflammatory, and post-traumatic conditions. Annotation: see also DYSKINESIAS for manifestations of disease; use MOVEMENT DISORDERS for diseases ID#: D009069

Moyamoya Disease

Definition: A chronic cerebral vasculopathy primarily occurring in childhood and characterized by slowly progressive carotid artery narrowing and occlusion at the base of the brain. An extensive network of anastomoses forms between branches of the carotid arteries, resulting in a characteristic angiographic appearance. The condition may be idiopathic (classic moyamoya disease) or occur in association with ANEMIA, SICKLE CELL; DOWN SYNDROME; CRANIOCEREBRAL TRAUMA; RADIOTHERAPY induced arterial injury; NEUROFIBROMATOSIS; and other diseases. Clinical manifestations include hemiparesis, headache, seizures, and delayed mental development. In older individuals, this disease may present as SUBARACHNOID HEMORRHAGE. (From Adams et al., Principles of Neurology, 6th ed, p831; Clin Neurol Neurosurg 1997 Oct;99 Suppl 2:S36-8) Annotation: ID#: D009072

MPTP Poisoning

Definition: A condition caused by the neurotoxin 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE. MPTP causes selective destruction of nigrostriatal dopaminergic neurons. Clinical features include irreversible parkinsonian signs including rigidity and bradykinesia (PARKINSON DISEASE, SECONDARY). MPTP toxicity is also used as an animal model for the study of PARKINSON DISEASE. (Adams et al., Principles of Neurology, 6th ed, p1072; Neurology 1986 Feb;36(2):250-8) Annotation: ID#: D020267


Definition: Mucoid states characterized by the elevated deposition and accumulation of mucin (mucopolysaccharides) in dermal tissue. The fibroblasts are responsible for the production of acid mucopolysaccharides (GLYCOSAMINOGLYCANS) in the ground substance of the connective tissue system. When fibroblasts produce abnormally large quantities of mucopolysaccharides as hyaluronic acid, chondroitin sulfate, or heparin, they accumulate in large amounts in the dermis. Annotation: elevated deposition of mucin in skin ID#: D017520

Mucinosis, Follicular

Definition: A disease of the pilosebaceous unit, presenting clinically as grouped follicular papules or plaques with associated hair loss. It is caused by mucinous infiltration of tissues, and usually involving the scalp, face, and neck. It may be primary (idiopathic) or secondary to mycosis fungoides or reticulosis. Annotation: a sebaceous gland dis ID#: D000507


Definition: A retention cyst of the salivary gland, lacrimal sac, paranasal sinuses, appendix, or gallbladder. (Stedman, 26th ed) Annotation: a type of cyst; non-neoplastic ID#: D009078

Mucocutaneous Lymph Node Syndrome

Definition: An acute, febrile, mucocutaneous condition accompanied by swelling of cervical lymph nodes in infants and young children. The principal symptoms are fever, congestion of the ocular conjunctivae, reddening of the lips and oral cavity, protuberance of tongue papillae, and edema or erythema of the extremities. Annotation: DF: MLNS or MCLS ID#: D009080

Mucoepidermoid Tumor

Definition: A malignant epithelial tumor of glandular tissue, especially the salivary glands, characterized by acini with mucus-producing cells and by the presence of malignant squamous elements. Most mucoepidermoid tumors are low-grade lesions readily cured by adequate excision. They may appear in any age group. They grow slowly. If high-grade, they behave aggressively, widely infiltrating the salivary gland and producing lymph node and distant metastases. (Dorland, 27th ed; from DeVita Jr et al., Cancer: Principles & Practice of Oncology, 3d ed, p575) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D018298


Definition: A group of inherited metabolic diseases characterized by the accumulation of excessive amounts of acid mucopolysaccharides, sphingolipids, and/or glycolipids in visceral and mesenchymal cells. Abnormal amounts of sphingolipids or glycolipids are present in neural tissue. Mental retardation and skeletal changes, most notably dysostosis multiplex, occur frequently. (From Joynt, Clinical Neurology, 1992, Ch56, pp36-7) Annotation: ID#: D009081


Definition: Group of lysosomal storage diseases each caused by an inherited deficiency of an enzyme involved in the degradation of glycosaminoglycans (mucopolysaccharides). The diseases are progressive and often display a wide spectrum of clinical severity within one enzyme deficiency. Annotation: lysosomal storage dis; types I through VII except V are available as main headings: V = MUCOPOLYSACCHARIDOSIS V see MUCOPOLYSACCHARIDOSIS I; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES ID#: D009083

Mucopolysaccharidosis I

Definition: Systemic lysosomal storage disease caused by a deficiency of alpha-L-iduronidase (IDURONIDASE) and characterized by progressive physical deterioration with urinary excretion of dermatan sulfate and heparan sulfate. There are three recognized phenotypes representing a spectrum of clinical severity from severe to mild: Hurler's syndrome, Hurler-Scheie syndrome and Scheie's syndrome (formerly mucopolysaccharidosis V). Symptoms may include dwarfism, hepatosplenomegaly, gargoyle-like facies, corneal clouding, cardiac complications, and noisy breathing. Hunter syndrome (MUCOPOLYSACCHARIDOSIS II) and Hurler syndrome were each originally called "gargoylism" because of the coarsness of the facial features of affected individuals. Annotation: DF: MPS I ID#: D008059

Mucopolysaccharidosis II

Definition: Systemic lysosomal storage disease marked by progressive physical deterioration and caused by a deficiency of L-sulfoiduronate sulfatase. This disease differs from MUCOPOLYSACCHARIDOSIS I by slower progression, lack of corneal clouding, and X-linked rather than autosomal recessive inheritance. The mild form produces near-normal intelligence and life span. The severe form usually causes death by age 15. Annotation: DF: MPS II ID#: D016532

Mucopolysaccharidosis III

Definition: Mucopolysaccharidosis characterized by heparitin sulfate in the urine, progressive mental retardation, mild dwarfism, and other skeletal disorders. There are four clinically indistinguishable but biochemically distinct forms, each due to a deficiency of a different enzyme. Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MPS III ID#: D009084

Mucopolysaccharidosis IV

Definition: Genetic disorder of mucopolysaccharide metabolism characterized by skeletal abnormalities, joint instability, development of cervical myelopathy, and excessive urinary keratan sulfate. There are two biochemically distinct forms, each due to a deficiency of a different enzyme. Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MPS IV ID#: D009085

Mucopolysaccharidosis VI

Definition: Mucopolysaccharidosis with excessive chondroitin sulfate B in urine, characterized by dwarfism and deafness. It is caused by a deficiency of N-acetylgalactosamine-4-sulfatase (arylsulfatase B). Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MPS VI ID#: D009087

Mucopolysaccharidosis VII

Definition: Mucopolysaccharidosis characterized by excessive dermatan and heparan sulfates in the urine and Hurler-like features. It is caused by a deficiency of beta-glucuronidase. Annotation: do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MPS VII ID#: D016538


Definition: Infection in humans and animals caused by any fungus in the order Mucorales (e.g., Absidia, Mucor, Rhizopus etc.) There are many clinical types associated with infection of the central nervous system, lung, gastrointestinal tract, skin, orbit and paranasal sinuses. In humans, it usually occurs as an opportunistic infection in patients with a chronic debilitating disease, particularly uncontrolled diabetes, or who are receiving immunosuppressive agents. (From Dorland, 28th ed) Annotation: fungus dis caused by various MUCORALES ID#: D009091

Multicystic Dysplastic Kidney

Definition: A severe form of dysplasia where the kidney typically appears as a bunch of grapes without a reniform configuration or calyceal drainage system. It occurs in-utero and is the most common form of nongenetic renal cystic disease. Annotation: X ref MULTICYSTIC KIDNEY: do not confuse with POLYCYSTIC KIDNEY DISEASES ID#: D021782

Multiple Carboxylase Deficiency

Definition: A deficiency in the activities of biotin-dependent enzymes (propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, and PYRUVATE CARBOXYLASE) due to one of two defects in BIOTIN metabolism. The neonatal form is due to HOLOCARBOXYLASE SYNTHETASE DEFICIENCY. The late-onset form is due to BIOTINIDASE DEFICIENCY. Annotation: ID#: D009100

Multiple Chemical Sensitivity

Definition: An acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful effects. No single widely accepted test of physiologic function can be shown to correlate with symptoms. (Cullen MR. The worker with multiple chemical sensitivities: an overview. Occup Med 1987;2(4):655-61) Annotation: a type of hypersensitivity usually to occup or environ chemicals; often affects multiple organs; specific chemicals are seldom at issue: if discussed coord IM with specific chem heading IM or NIM; DF: MULTIPLE CHEM SENSITIVITY ID#: D018777

Multiple Endocrine Neoplasia

Definition: A group of autosomal dominant, often overlapping diseases characterized by hyperplasia or neoplasia of more than one endocrine gland, many of which are made up of APUD cells. (From Segen, Dictionary of Modern Medicine, 1992) Annotation: IM; GEN or unspecified; prefer specifics; coord with specific endocrine/neopl precoords (IM) + specific histol type (IM) if pertinent; DF: MULTIPLE ENDOCRINE NEOPL ID#: D009377

Multiple Endocrine Neoplasia Type 1

Definition: A rare syndrome characterized by hyperplasia and/or neoplasms of the pituitary, parathyroid glands, and pancreatic islets. Hyperparathyroidism occurs in 90% of the cases and is usually the first manifestation of the syndrome. The most frequent pancreatic manifestation is gastrinoma typically leading to Zollinger-Ellison Syndrome. The appearance of this condition has been limited to the loss of allelic heterozygosity at the 11q13 locus on the long arm of chromosome 11. Patients overall exhibit long survival times. Chemotherapy is rare and surgical management is generally dependent on the genetic expression in individual patients. (From Holland et al., Cancer Medicine, 3d ed, pp1169-72) Annotation: IM; coord with specific endocrine/neopl precoords (IM) + specific histol type (IM) if pertinent; MULTIPLE ENDOCRINE NEOPLASIA TYPE 2a & MULTIPLE ENDOCRINE NEOPLASIA TYPE 2b are also available; DF: note short X refs ID#: D018761

Multiple Endocrine Neoplasia Type 2a

Definition: A type of multiple endocrine neoplasia characterized by a virtually 100% incidence of medullary thyroid carcinoma, a 50% incidence of pheochromocytoma, and a lesser incidence of parathyroid adenomas associated with hyperparathyroidism. The condition is always transmitted through autosomal dominant inheritance. Genetic testing can identify individuals with the trait in early infancy. Treatment is usually excision of the enlarged parathyroid glands. (From Holland et al., Cancer Medicine, 3d ed, pp1172-75) Annotation: IM; coord with specific endocrine/neopl precoords (IM) + specific histol type (IM) if pertinent; MULTIPLE ENDOCRINE NEOPLASIA TYPE 2b is also available; DF: note short X ref ID#: D018813

Multiple Endocrine Neoplasia Type 2b

Definition: A type of multiple endocrine neoplasia occurring as an isolated congenital presentation or as a distinct autosomal dominant disease. It is characterized by the 100% incidence of medullary thyroid carcinoma and frequent pheochromocytomas; patients seldom exhibit hyperparathyroidism. It is distinguished from MEN 2a by its characteristic physical appearance resulting from numerous neural defects including mucosal neuromas of the eyelids, lips, and tongue. The neural abnormalities also include widespread neurogangliomatosis of the gastrointestinal tract leading to abnormal gut motility. Treatment usually requires total thyroidectomy following evaluation for the presence of pheochromocytomas. Annotation: IM; coord with specific endocrine/neopl precoords (IM) + specific histol type (IM) if pertinent; MULTIPLE ENDOCRINE NEOPLASIA TYPE 2a is also available; DF: note short X ref ID#: D018814

Multiple Myeloma

Definition: A malignant tumor of plasma cells usually arising in the bone marrow; characterized by diffuse involvement of the skeletal system, hyperglobulinemia, Bence-Jones proteinuria, and anemia. Annotation: myeloma unspecified is probably MULTIPLE MYELOMA; solitary myeloma = PLASMACYTOMA ID#: D009101

Multiple Organ Failure

Definition: A progressive condition usually characterized by combined failure of several organs such as the lungs, liver, kidney, along with some clotting mechanisms, usually postinjury or postoperative. Annotation: ID#: D009102

Multiple Sclerosis

Definition: An autoimmune disorder mainly affecting young adults and characterized by destruction of myelin in the central nervous system. Pathologic findings include multiple sharply demarcated areas of demyelination throughout the white matter of the central nervous system. Clinical manifestations include visual loss, extra-ocular movement disorders, paresthesias, loss of sensation, weakness, dysarthria, spasticity, ataxia, and bladder dysfunction. The usual pattern is one of recurrent attacks followed by partial recovery (see MULTIPLE SCLEROSIS, RELAPSING-RE;MITTING), but acute fulminating and chronic progressive forms (see MULTIPLE SCLEROSIS, CHRONIC PROGRESSIVE) also occur. (Adams et al., Principles of Neurology, 6th ed, p903) Annotation: ID#: D009103

Multiple Sclerosis, Chronic Progressive

Definition: A form of multiple sclerosis characterized by a progressive deterioration in neurologic function which is in contrast to the more typical relapsing remitting form. If the clinical course is free of distinct remissions, it is referred to as primary progressive multiple sclerosis. When the progressive decline is punctuated by acute exacerbations, it is referred to as progressive relapsing multiple sclerosis. The term secondary progressive multiple sclerosis is used when relapsing remitting multiple sclerosis evolves into the chronic progressive form. (From Ann Neurol 1994;36 Suppl:S73-S79; Adams et al., Principles of Neurology, 6th ed, pp903-914) Annotation: DF: MS CHRONIC PROGRESSIVE ID#: D020528

Multiple Sclerosis, Relapsing-Remitting

Definition: The most common clinical variant of MULTIPLE SCLEROSIS, characterized by recurrent acute exacerbations of neurologic dysfunction followed by partial or complete recovery. Common clinical manifestations include loss of visual (see OPTIC NEURITIS), motor, sensory, or bladder function. Acute episodes of demyelination may occur at any site in the central nervous system, and commonly involve the optic nerves, spinal cord, brain stem, and cerebellum. (Adams et al., Principles of Neurology, 6th ed, pp903-914) Annotation: DF: MS RELAPSING REMITTING ID#: D020529

Multiple System Atrophy

Definition: A syndrome complex composed of three conditions which represent clinical variants of the same disease process: STRIATONIGRAL DEGENERATION; SHY-DRAGER SYNDROME; and the sporadic form of OLIVOPONTOCEREBELLAR ATROPHIES. Clinical features include autonomic, cerebellar, and basal ganglia dysfunction. Pathologic examination reveals atrophy of the basal ganglia, cerebellum, pons, and medulla, with prominent loss of autonomic neurons in the brain stem and spinal cord. (From Adams et al., Principles of Neurology, 6th ed, p1076; Baillieres Clin Neurol 1997 Apr;6(1):187-204; Med Clin North Am 1999 Mar;83(2):381-92) Annotation: a specific neurodegenerative syndrome complex; not for atrophy in other systems ID#: D019578

Multiple Trauma

Definition: Physical insults or injuries occurring simultaneously in several parts of the body. Annotation: coord IM with specific inj term or organ/inj IM or NIM if pertinent ID#: D009104


Definition: An acute infectious disease caused by RUBULAVIRUS, spread by direct contact, airborne droplet nuclei, fomites contaminated by infectious saliva, and perhaps urine, and usually seen in children under the age of 15, although adults may also be affected. (From Dorland, 28th ed) Annotation: caused by the MUMPS VIRUS, a rubulavirus ID#: D009107

Murine Acquired Immunodeficiency Syndrome

Definition: Acquired defect of cellular immunity that occurs in mice infected with mouse leukemia viruses (MuLV). The syndrome shows striking similarities with human AIDS and is characterized by lymphadenopathy, profound immunosuppression, enhanced susceptibility to opportunistic infections, and B-cell lymphomas. Annotation: caused by a retrovirus; don't forget also MICE (NIM) & check tag ANIMAL; DF: note short X ref ID#: D016183

Muscle Cramp

Definition: A sustained and usually painful contraction of muscle fibers. This may occur as an isolated phenomenon or as a manifestation of an underlying disease process (e.g., UREMIA; HYPOTHYROIDISM; MOTOR NEURON DISEASE; etc.). (From Adams et al., Principles of Neurology, 6th ed, p1398) Annotation: ID#: D009120

Muscle Hypertonia

Definition: Abnormal increase in skeletal or smooth muscle tone. Skeletal muscle hypertonicity may be associated with PYRAMIDAL TRACT lesions or BASAL GANGLIA DISEASES. Annotation: coord IM with specific muscle/physiopathol (IM) if available ID#: D009122

Muscle Hypotonia

Definition: A diminution of the skeletal muscle tone marked by a diminished resistance to passive stretching. Annotation: ID#: D009123

Muscle Neoplasms

Definition: Tumors or cancer located in muscle tissue or specific muscles. They are differentiated from NEOPLASMS, MUSCLE TISSUE which are neoplasms composed of skeletal, cardiac, or smooth muscle tissue, such as MYOSARCOMA or LEIOMYOMA. Annotation: neopl located in muscles: do not confuse with NEOPLASMS, MUSCLE TISSUE, neopl composed of muscle tissue; coord IM with specific muscle (IM) + histol type of neopl (IM); DF: MUSCLE NEOPL ID#: D019042

Muscle Rigidity

Definition: Continuous involuntary sustained muscle contraction which is often a manifestation of BASAL GANGLIA DISEASES. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from MUSCLE SPASTICITY. (From Adams et al., Principles of Neurology, 6th ed, p73) Annotation: ID#: D009127

Muscle Spasticity

Definition: A form of muscle hypertonia associated with upper MOTOR NEURON DISEASE. Resistance to passive stretch of a spastic muscle results in minimal initial resistance (a "free interval") followed by an incremental increase in muscle tone. Tone increases in proportion to the velocity of stretch. Spasticity is usually accompanied by HYPERREFLEXIA and variable degrees of MUSCLE WEAKNESS. (From Adams et al., Principles of Neurology, 6th ed, p54) Annotation: skeletal muscle only; note category: not physiological; spastic paralysis: coord NIM with PARALYSIS (IM); spasticity in cerebral palsy: coord NIM with CEREBRAL PALSY only if musc spasticity is especially discussed ID#: D009128

Muscle Weakness

Definition: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251) Annotation: GEN or unspecified as a clin state or clin manifest: specific musc or neuromusc dis of which this is a manifest are also available; do not confuse "myasthenia" (my-, muscle + asthenia, weakness) in foreign titles with "muscle weakness": it is more likely to refer to MYASTHENIA GRAVIS; do not confuse with MUSCLE HYPOTONIA or MUSCLE FATIGUE ID#: D018908

Muscular Atrophy

Definition: Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation. Annotation: MUSCULAR ATROPHY, SPINAL is also available ID#: D009133

Muscular Atrophy, Spinal

Definition: A group of disorders marked by progressive degeneration of motor neurons in the spinal cord resulting in weakness and muscular atrophy, usually without evidence of injury to the corticospinal tracts. Diseases in this category include Werdnig-Hoffmann disease and later onset SPINAL MUSCULAR ATROPHIES OF CHILDHOOD, most of which are hereditary. (Adams et al., Principles of Neurology, 6th ed, p1089) Annotation: MUSCULAR ATROPHY, SPINAL, INFANTILE see SPINAL MUSCULAR ATROPHIES OF CHILDHOOD is also available ID#: D009134

Muscular Diseases

Definition: Acquired, familial, and congenital disorders of skeletal muscle (MUSCLE, SKELETAL) and smooth muscle (MUSCLE, SMOOTH). Annotation: GEN; prefer specifics; inflamm dis = MYOSITIS. /congen: consider also Myopathies, Structural, Congenital & its indentions ID#: D009135

Muscular Disorders, Atrophic

Definition: Disorders characterized by an abnormal reduction in muscle volume due to a decrease in the size or number of muscle fibers. Atrophy may result from diseases intrinsic to muscle tissue (e.g., MUSCULAR DYSTROPHY) or secondary to PERIPHERAL NERVOUS SYSTEM DISEASES that impair innervation to muscle tissue (e.g., MUSCULAR ATROPHY, SPINAL). Annotation: ID#: D020966

Muscular Dystrophies

Definition: A general term for a group of inherited disorders which are characterized by progressive degeneration of skeletal muscles (MUSCLE, SKELETAL). Annotation: GEN: prefer specifics; do not confuse with MYOTONIC DYSTROPHY ID#: D009136

Muscular Dystrophy, Animal

Definition: Annotation: exper or vet but do not use /vet; don't forget to check tag ANIMAL ID#: D009137

Muscular Dystrophy, Duchenne

Definition: An X-linked recessive muscle disease caused by an inability to synthesize DYSTROPHIN, which is involved with maintaining the integrity of the sarcolemma. Muscle fibers undergo a process that features degeneration and regeneration. Clinical manifestations include proximal weakness in the first few years of life, pseudohypertrophy, cardiomyopathy (see MYOCARDIAL DISEASES), and an increased incidence of impaired mentation. Becker muscular dystrophy is a closely related condition featuring a later onset of disease (usually adolescence) and a slowly progressive course. (Adams et al., Principles of Neurology, 6th ed, p1415) Annotation: ID#: D020388

Muscular Dystrophy, Emery-Dreifuss

Definition: An X-linked recessive muscular dystrophy that may present in children or adults. The disease is characterized by a clinical triad: (1) CONTRACTURE of the elbows, ACHILLES TENDON, and posterior cervical muscles; (2) slowly progressive muscle atrophy and weakness; and (3) a cardiomyopathy usually presenting as an atrioventricular block (HEART BLOCK). The weakness initially affects the upper arm and chest muscles, followed by pelvic and leg muscle paresis. Sudden death (DEATH, SUDDEN, CARDIAC) may occur as the result of the cardiac conduction defect. (Adams et al., Principles of Neurology, 6th ed, p1419; Curr Opin Neurol 1997;10(5):421-425) Annotation: ID#: D020389

Muscular Dystrophy, Facioscapulohumeral

Definition: An autosomal dominant degenerative muscle disease characterized by slowly progressive weakness of the muscles of the face, upper-arm, and shoulder girdle. The onset of symptoms usually occurs in the first or second decade of life. Affected individuals usually present with impairment of upper extremity elevation. This tends to be followed by facial weakness, primarily involving the orbicularis oris and orbicuaris oculi muscles. (Neuromuscul Disord 1997;7(1):55-62; Adams et al., Principles of Neurology, 6th ed, p1420) Annotation: ID#: D020391

Musculoskeletal Abnormalities

Definition: Congenital structural abnormalities and deformities of the musculoskeletal system. Annotation: for congen struct abnorm only; GEN or unspecified; prefer specifics or specific organ /abnorm; do not use /congen & do not coord with INFANT, NEWBORN, DISEASES; DF: MUSCULOSKELETAL ABNORM ID#: D009139

Musculoskeletal Diseases

Definition: Diseases of the muscles and their associated ligaments and other connective tissue and of the bones and cartilage viewed collectively. Annotation: GEN: prefer MUSCULAR DISEASES & BONE DISEASES or specifics ID#: D009140

Mushroom Poisoning

Definition: Poisoning from ingestion of mushrooms, primarily from, but not restricted to, toxic varieties. Annotation: = pois by mushroom toxins; TN 133: relation to food pois from canned mushrooms ID#: D009145

Myasthenia Gravis

Definition: A disorder of neuromuscular transmission characterized by weakness of cranial and skeletal muscles. Autoantibodies directed against acetylcholine receptors damage the motor endplate portion of the NEUROMUSCULAR JUNCTION, impairing the transmission of impulses to skeletal muscles. Clinical manifestations may include diplopia, ptosis, and weakness of facial, bulbar, respiratory, and proximal limb muscles. The disease may remain limited to the ocular muscles. THYMOMA is commonly associated with this condition. (Adams et al., Principles of Neurology, 6th ed, p1459) Annotation: "myasthenia" unqualified in foreign titles is more often MYASTHENIA GRAVIS than MUSCLE WEAKNESS but check text; congen consider MYASTHENIC SYNDROMES, CONGENITAL or specifics ID#: D009157

Myasthenia Gravis, Experimental Autoimmune

Definition: Any autoimmune animal disease model used in the study of MYASTHENIA GRAVIS. Injection with purified neuromuscular junction acetylcholine receptor (AChR) (see RECEPTORS, CHOLINERGIC) components results in a myasthenic syndrome that has acute and chronic phases. The motor endplate pathology, loss of acetylcholine receptors, presence of circulating anti-AChR antibodies, and electrophysiologic changes make this condition virtually identical to human myasthenia gravis. Passive transfer of AChR antibodies or lymphocytes from afflicted animals to normals induces passive transfer experimental autoimmune myasthenia gravis. (From Joynt, Clinical Neurology, 1997, Ch 54, p3) Annotation: ID#: D020720

Myasthenia Gravis, Neonatal

Definition: A disorder of neuromuscular transmission that occurs in a minority of newborns born to women with myasthenia gravis. Clinical features are usually present at birth or develop in the first 3 days of life and consist of hypotonia and impaired respiratory, suck, and swallowing abilities. This condition is associated with the passive transfer of acetylcholine receptor antibodies through the placenta. In the majority of infants the myasthenic weakness resolves (i.e., transient neonatal myasthenia gravis) although this disorder may rarely continue beyond the neonatal period (i.e., persistent neonatal myasthenia gravis). (From Menkes, Textbook of Child Neurology, 5th ed, p823; Neurology 1997 Jan;48(1):50-4) Annotation: ID#: D020941

Myasthenic Syndromes, Congenital

Definition: A heterogeneous group of disorders characterized by a congenital defect in neuromuscular transmission at the NEUROMUSCULAR JUNCTION. This includes presynaptic, synaptic, and postsynaptic disorders (that are not of autoimmune origin). The majority of these diseases are caused by mutations of various subunits of the nicotinic acetylcholine receptor (RECEPTORS, NICOTINIC) on the postsynaptic surface of the junction. (From Arch Neurol 1999 Feb;56(2):163-7) Annotation: do not confuse with MYASTHENIA GRAVIS, NEONATAL, a transient condition seen in neonates born to myasthenic mothers ID#: D020294

Mycobacterium avium-intracellulare Infection

Definition: A nontuberculous infection when occurring in humans. It is characterized by pulmonary disease, lymphadenitis in children, and systemic disease in AIDS patients. Mycobacterium avium-intracellulare infection of birds and swine results in tuberculosis. Annotation: DF: MAI INFECT ID#: D015270

Mycobacterium Infections

Definition: Infections with bacteria of the genus MYCOBACTERIUM. Annotation: gram-pos bact infect; GEN; consider also TUBERCULOSIS; DF: MYCOBACT INFECT ID#: D009164

Mycobacterium Infections, Atypical

Definition: Infections with so called atypical mycobacteria (tuberculoid bacilli): M. kansasii (Kansas), M. marinum, M. SCROFULACEUM, M. flavescens, M. gordonae, M. obuense, M. gilvum, M. duvali, M. szulgai, M. intracellulare (see MYCOBACTERIUM AVIUM COMPLEX), M. xenopi (littorale), M. ulcerans, M. buruli, M. terrae, M. fortuitum (minetti, giae), M. CHELONAE. Annotation: see MYCOBACTERIUM, ATYPICAL for a list of atypical Mycobact or MeSH definition here; DF: MYCOBACT INFECT ATYPICAL ID#: D009165

Mycoplasma Infections

Definition: Infections with species of the genus MYCOPLASMA. Annotation: gram-neg bact infect ID#: D009175

Mycoplasmatales Infections

Definition: Infections with bacteria of the order MYCOPLASMATALES. Annotation: gram-neg bact infect ID#: D009180


Definition: Annotation: GEN: prefer specifics; of skin = DERMATOMYCOSES; /drug ther: consider also ANTIFUNGAL AGENTS ID#: D009181

Mycosis Fungoides

Definition: A chronic malignant T-cell lymphoma of the skin. In the late stages the lymph nodes and viscera are affected. Annotation: a type of malignant T-cell lymphoma of the skin; coord IM with SKIN NEOPLASMS (IM) ID#: D009182


Definition: Poisoning caused by the ingestion of mycotoxins (toxins of fungal origin). Annotation: "caused by ingestion of mycotoxins (toxins of fungal origin)" ID#: D015651


Definition: Dilation of pupils to greater than 6 mm combined with failure of the pupils to constrict when stimulated with light. This condition may occur due to injury of the pupillary fibers in the oculomotor nerve, in acute angle-closure glaucoma, and in ADIE SYNDROME. Annotation: pathol dilation of the pupils; do not use for state after admin of mydriatics ( = PUPIL /drug eff) but MYDRIATICS is available ID#: D015878

Myelinolysis, Central Pontine

Definition: A demyelinating condition affecting the PONS and characterized clinically by an acute progressive QUADRIPLEGIA; DYSARTHRIA; DYSPHAGIA; and alterations of consciousness. Pathologic features include prominent demyelination in the central PONS with sparing of axons and neurons. This condition is usually associated with systemic disorders such as HYPONATREMIA; chronic ALCOHOLISM; LIVER FAILURE; severe BURNS; malignant NEOPLASMS; hemorrhagic PANCREATITIS; HEMODIALYSIS; and SEPSIS. The rapid medical correction of hyponatremia has been cited as a cause of this condition. (From Adams et al., Principles of Neurology, 6th ed, pp1125-6) Annotation: ID#: D017590


Definition: Inflammation of the spinal cord. Relatively common etiologies include infections; AUTOIMMUNE DISEASES; SPINAL CORD; and ischemia (see also SPINAL CORD VASCULAR DISEASES). Clinical features generally include weakness, sensory loss, localized pain, incontinence, and other signs of autonomic dysfunction. Annotation: do not confuse with inflamm of the bone marrow ( = OSTEOMYELITIS); SMON (subacute-myelo-optico-neuropathy) is indexed here + OPTIC NEURITIS + SYNDROME; coord IM with specific cause (IM) if pertinent ID#: D009187

Myelitis, Transverse

Definition: Inflammation of a transverse portion of the spinal cord characterized by acute or subacute segmental demyelination or necrosis. The condition may occur sporadically, follow an infection or vaccination, or present as a paraneoplastic syndrome (see also ENCEPHALOMYELITIS, ACUTE DISSEMINATED). Clinical manifestations include motor weakness, sensory loss, and incontinence. (Adams et al., Principles of Neurology, 6th ed, pp1242-6) Annotation: post-vaccinal or postinfectious inflammation of the spinal cord only goes here, in central nervous system or brain see X refs at ENCEPHALOMYELITIS, ACUTE DISSEMINATED ID#: D009188

Myelodysplastic Syndromes

Definition: Conditions in which the bone marrow shows qualitative and quantitative changes suggestive of a preleukemic process, but having a chronic course that does not necessarily terminate as acute leukemia. Annotation: myelo- here = bone marrow, not spinal cord ID#: D009190


Definition: Replacement of the bone marrow by fibrous tissue, occurring in association with a myeloproliferative disorder or secondary to another, unrelated condition. (Dorland, 27th ed) Annotation: myelo- here = bone marrow, not spinal cord: note X refs ID#: D009191

Myeloid Metaplasia

Definition: The occurrence of myeloid tissue in extramedullary sites. Specifically it is a syndrome characterized by splenomegaly, anemia, the presence of nucleated erythrocytes and immature granulocytes in the circulating blood, and extramedullary hemoatopoiesis in the liver and spleen. The primary form is also known as agnogenic myeloid metaplasia, myelosclerosis, and myelofibrosis. The secondary or symptomatic form may be associated with various diseases, including carcinomatosis, tuberculosis, leukemia, and polycythemia vera. (Dorland, 27th ed) Annotation: myeloid here = bone marrow, not spinal cord ID#: D009193


Definition: A rare benign tumor of the adrenal gland, several centimeters in diameter, composed in varying proportions of adipose tissue, lymphocytes, and primitive myeloid cells, probably a developmental abnormality. (Dorland, 27th ed) Annotation: /blood supply /chem /secret /ultrastruct permitted; coord IM with ADRENAL GLAND NEOPLASMS (IM) ID#: D018209

Myeloproliferative Disorders

Definition: Disorders in which one or more stimuli cause proliferation of hemopoietically active tissue or of tissue which has embryonic hemopoietic potential. Annotation: myelo- here = bone marrow, not spinal cord; GEN; prefer specifics ID#: D009196


Definition: The invasion of living tissues of man and other mammals by dipterous larvae. Annotation: infestation by fly maggots ID#: D009198

Myocardial Diseases

Definition: Diseases of the myocardium. Annotation: disease of myocardial tissue: differentiate from HEART DISEASES, diseases of function; for bact, parasitic & other infections of the myocardium, coord here (IM), not HEART DISEASES + infection (IM); CHAGAS CARDIOMYOPATHY is available but see note there for coords; CARDIOMYOPATHY, CONGESTIVE is also available ID#: D009202

Myocardial Infarction

Definition: Gross necrosis of the myocardium, as a result of interruption of the blood supply to the area. (Dorland, 27th ed) Annotation: do not coord with ACUTE DISEASE for "acute infarct"; DF: MYOCARDIAL INFARCT ID#: D009203

Myocardial Ischemia

Definition: A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (CORONARY ARTERIOSCLEROSIS), to obstruction by a thrombus (CORONARY THROMBOSIS), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Severe interruption of the blood supply to the myocardial tissue may result in necrosis of cardiac muscle (MYOCARDIAL INFARCTION). Annotation: = defic of myocard blood supply; may lead to MYOCARDIAL INFARCTION ID#: D017202

Myocardial Reperfusion Injury

Definition: Functional, metabolic, or structural changes in ischemic heart muscle thought to result from REPERFUSION to the ischemic areas. Changes can be fatal to muscle cells and may include edema with explosive cell swelling and disintegration, sarcolemma disruption, fragmentation of mitochondria, contraction band necrosis, enzyme washout, and calcium overload. Other damage may include hemorrhage and ventricular arrhythmias. One possible mechanism of damage is thought to be oxygen free radicals. Treatment currently includes the introduction of scavengers of oxygen free radicals, and injury is thought to be prevented by warm blood cardioplegic infusion prior to reperfusion. Annotation: ID#: D015428

Myocardial Stunning

Definition: Prolonged dysfunction of the myocardium after a brief episode of severe ischemia, with gradual return of contractile activity. It occurs frequently, both in the experimental laboratory and in clinical medicine. Since stunned myocardium occurs adjacent to necrotic tissue after prolonged coronary occlusion, many myocardial infarcts may be a mixture of necrotic and stunned tissue. (Braunwald, Heart Disease, 1992, p1176) Annotation: a type of myocardial ischemia, often caused by myocardial reperfusion ID#: D017682


Definition: Inflammation of the muscular walls of the heart. (Stedman, 25th ed) Annotation: inflamm of walls of heart ID#: D009205

Myoclonic Cerebellar Dyssynergia

Definition: A condition marked by progressive CEREBELLAR ATAXIA combined with MYOCLONUS usually presenting in the third decade of life or later. Additional clinical features may include generalized and focal SEIZURES, spasticity, and DYSKINESIAS. Autosomal recessive and autosomal dominant patterns of inheritance have been reported. Pathologically, the dentate nucleus and brachium conjunctivum of the CEREBELLUM are atrophic, with variable involvement of the spinal cord, cerebellar cortex, and basal ganglia. (From Joynt, Clinical Neurology, 1991, Ch37, pp60-1) Annotation: do not confuse X ref RAMSAY HUNT CEREBELLAR SYNDROME with RAMSAY HUNT AURICULAR SYNDROME see HERPES ZOSTER OTICUS or RAMSAY HUNT PARALYSIS SYNDROME see PARKINSONIAN DISORDERS ID#: D002527

Myoclonic Epilepsies, Progressive

Definition: A heterogeneous group of primarily familial disorders characterized by myoclonic seizures, tonic-clonic seizures, ataxia, progressive intellectual deterioration, and neuronal degeneration. These include LAFORA DISEASE; MERRF SYNDROME; NEURONAL CEROID-LIPOFUSCINOSIS; sialidosis (see MUCOLIPIDOSES), and UNVERRICHT-LUNDBORG SYNDROME. Annotation: ID#: D020191

Myoclonic Epilepsy, Juvenile

Definition: A disorder characterized by the onset of myoclonus in adolescence, a marked increase in the incidence of absence seizures (see EPILEPSY, ABSENCE), and generalized major motor seizures (see EPILEPSY, TONIC-CLONIC). The myoclonic episodes tend to occur shortly after awakening. Seizures tend to be aggravated by sleep deprivation and alcohol consumption. Hereditary and sporadic forms have been identified. (From Adams et al., Principles of Neurology, 6th ed, p323) Annotation: ID#: D020190


Definition: Involuntary shock-like contractions, irregular in rhythm and amplitude, followed by relaxation, of a muscle or a group of muscles. This condition may be a feature of some CENTRAL NERVOUS SYSTEMS DISEASES (e.g., EPILEPSY, MYOCLONIC). Nocturnal myoclonus may represent a normal physiologic event or occur as the principal feature of the NOCTURNAL MYOCLONUS SYNDROME. (From Adams et al., Principles of Neurology, 6th ed, pp102-3). Annotation: for "myoclonic seizure" consider MYOCLONUS or EPILEPSY, MYOCLONIC or SPASMS, INFANTILE; NOCTURNAL MYOCLONUS SYNDROME is also available ID#: D009207


Definition: A usually benign tumor made up predominantly of myoepithelial cells. Annotation: coord IM with precoord organ/neopl term (IM) ID#: D009208

Myofascial Pain Syndromes

Definition: Muscular pain in numerous body regions that can be reproduced by pressure on trigger points, localized hardenings in skeletal muscle tissue. Pain is referred to a location distant from the trigger points. A prime example is the TEMPOROMANDIBULAR JOINT DYSFUNCTION SYNDROME. Annotation: do not confuse with MYOFASCIAL PAIN DYSFUNCTION SYNDROME, TEMPOROMANDIBULAR JOINT see TEMPOROMANDIBULAR JOINT DYSFUNCTION SYNDROME ID#: D009209


Definition: A condition characterized by multiple formations of myofibromas (LEIOMYOMA). Annotation: do not use /blood supply /chem /second /secret /ultrastruct; coord IM with organ/neopl term (IM) ID#: D018224


Definition: Annotation: myoglobinuria in rhabdomyolysis: index under RHABDOMYOLYSIS (IM) + MYOGLOBINURIA (NIM) only if myoglobinuria is particularly discussed ID#: D009212


Definition: Successive and rapid contractions of motor units associated with chronic nerve injury. The discharges arise from the peripheral aspects of regenerating nerves, and clinically impart a nearly continuous undulation of the body surface overlying the muscle. (Adams et al., Principles of Neurology, 6th ed, p1491) Annotation: consider also FASCICULATION; for continuous myokymia use ISAACS SYNDROME ID#: D020385


Definition: A benign neoplasm of muscular tissue. (Stedman, 25th ed) Annotation: uterine = LEIOMYOMA + UTERINE NEOPLASMS; /blood supply /chem /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D009214

Myopathies, Nemaline

Definition: A group of inherited congenital myopathic conditions characterized clinically by weakness, hypotonia, and prominent hypoplasia of proximal muscles including the face. Muscle biopsy reveals large numbers of rod-shaped structures beneath the muscle fiber plasma membrane. This disorder is genetically heterogeneous and may occasionally present in adults. (Adams et al., Principles of Neurology, 6th ed, p1453) Annotation: ID#: D017696

Myopathies, Structural, Congenital

Definition: A heterogeneous group of diseases characterized by the early onset of hypotonia, developmental delay of motor skills, non-progressive weakness. Each of these disorders is associated with a specific histologic muscle fiber abnormality. Annotation: ID#: D020914

Myopathy, Central Core

Definition: An inherited congenital myopathic condition characterized by weakness and hypotonia in infancy and delayed motor development. Muscle biopsy reveals a condensation of myofibrils and myofibrillar material in the central portion of each muscle fiber. (Adams et al., Principles of Neurology, 6th ed, p1452) Annotation: ID#: D020512


Definition: A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus in front of the retina, as a result of the eyeball being too long from front to back. It is also called nearsightedness because the near point is less distant than it is in emmetropia with an equal amplitude of accommodation. (Dorland, 27th ed) Annotation: refractive error: note X ref ID#: D009216


Definition: A general term for a malignant neoplasm derived from muscular tissue. (Stedman, 25th ed) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D009217


Definition: Inflammation of skeletal muscle (MUSCLE, SKELETAL). Infectious, autoimmune, and paraneoplastic processes represent some of the more common conditions that may be associated with myositis. (From Adams et al., Principles of Neurology, 6th ed., pp 1402-13) Annotation: DERMATOMYOSITIS & POLYMYOSITIS are also available ID#: D009220

Myositis Ossificans

Definition: A disease characterized by bony deposits or the ossification of muscle tissue. Annotation: myositis with bony deposits or muscle ossification ID#: D009221

Myositis, Inclusion Body

Definition: Progressive myopathies characterized by the presence of inclusion bodies on muscle biopsy. Sporadic and hereditary forms have been described. The sporadic form is an acquired, adult-onset inflammatory vacuolar myopathy affecting proximal and distal muscles. Familial forms usually begin in childhood and lack inflammatory changes. Both forms feature intracytoplasmic and intranuclear inclusions in muscle tissue. (Adams et al., Principles of Neurology, 6th ed, pp1409-10) Annotation: do not coord with INCLUSION BODIES but coord with INCLUSION BODIES, VIRAL if relevant (IM or NIM) ID#: D018979


Definition: Prolonged failure of muscle relaxation after contraction. This may occur after voluntary contractions, muscle percussion, or electrical stimulation of the muscle. Myotonia is a characteristic feature of MYOTONIC DISORDERS. Annotation: ID#: D009222

Myotonia Congenita

Definition: A dominantly inherited muscle disease that begins in early childhood and is characterized by severe myotonia (delayed relaxation of a muscle) after forceful voluntary contractions. Muscular hypertrophy is common and myotonia may impair ambulation and other movements. Myotonia typically becomes less severe with repetitive voluntary contractions of the affected muscles. Generalized myotonia (of Becker) is an autosomal recessive variant of myotonia congenita that may feature more severe myotonia and muscle wasting. (From Adams et al., Principles of Neurology, 6th ed, pp1476-7; Joynt, Clinical Neurology, 1997, Ch53, p18) Annotation: ID#: D009224

Myotonic Disorders

Definition: Diseases characterized by MYOTONIA, which may be inherited or acquired. Myotonia may be restricted to certain muscles (e.g., intrinsic hand muscles) or occur as a generalized condition. These disorders may be associated with abnormal muscle SODIUM CHANNEL and CHLORIDE CHANNELS. MYOTONIC DYSTROPHY and MYOTONIA CONGENITA represent two relatively common forms of this disorder. Proximal myotonic myopathy often presents with myotonia and muscle pain in early adulthood and later in life thigh muscle weakness and cataracts develop. (From Adams et al., Principles of Neurology, 6th ed, p1392) Annotation: ID#: D020967

Myotonic Dystrophy

Definition: An autosomal dominant neuromuscular disorder which usually presents in early adulthood, characterized by progressive muscular atrophy (most frequently involving the hands, forearms, and face), myotonia, frontal baldness, lenticular opacities, and testicular atrophy. Cardiac conduction abnormalities, diaphragmatic weakness, and mild mental retardation may also occur. Congenital myotonic dystrophy is a severe form of this disorder, characterized by neonatal MUSCLE HYPOTONIA, feeding difficulties, respiratory muscle weakness, and an increased incidence of MENTAL RETARDATION. (From Adams et al., Principles of Neurology, 6th ed, pp1423-5; Joynt, Clinical Neurology, 1997, Ch16, pp16-7) Annotation: do not confuse with MUSCULAR DYSTROPHIES ID#: D009223


Definition: A condition characterized by a dry, waxy type of swelling with abnormal deposits of mucin in the skin and other tissues. It is produced by a functional insufficiency of the thyroid gland, resulting in deficiency of thyroid hormone. The skin becomes puffy around the eyes and on the cheeks and the face is dull and expressionless with thickened nose and lips. The congenital form of the disease is CRETINISM. Annotation: caused by hypothyroidism; pretibial = MYXEDEMA (IM) + LEG DERMATOSES (IM) ID#: D009230


Definition: A benign neoplasm derived from connective tissue, consisting chiefly of polyhedral and stellate cells that are loosely embedded in a soft mucoid matrix, thereby resembling primitive mesenchymal tissue. It occurs frequently intramuscularly where it may be mistaken for a sarcoma. It appears also in the jaws and the skin. (From Stedman, 25th ed) Annotation: /blood supply /chem /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM) ID#: D009232

Myxomatosis, Infectious

Definition: Annotation: caused by a poxvirus; usually animal; check tag ANIMAL ID#: D009234


Definition: A sarcoma, usually a liposarcoma or malignant fibrous histiocytoma, with an abundant component of myxoid tissue resembling primitive mesenchyme containing connective tissue mucin. (Stedman, 25th ed) Annotation: /blood supply /chem /second /secret /ultrastruct permitted; coord IM with precoord organ/neopl term (IM); myxosarcoma of breast = PHYLLODES TUMOR ID#: D009236