muscular dystrophy (MD) [L, musculus + Gk, dys, bad, trophe, nourishment] , a group of genetically transmitted diseases characterized by progressive atrophy of symmetric groups of skeletal muscles without evidence of involvement or degeneration of neural tissue. In all forms of muscular dystrophy an insidious loss of strength with increasing disability and deformity occurs, although each type differs in the groups of muscles affected, the age of onset, the rate of progression, and the mode of genetic inheritance. The basic cause is unknown but appears to be an inborn error of metabolism. Serum creatine phosphokinase level is increased in affected individuals and acts as a diagnostic aid, especially in asymptomatic children in families at risk. Diagnostic confirmation is made by muscle biopsy, electromyography, and genetic pedigree. Treatment of the muscular dystrophies consists primarily of supportive measures, such as physical therapy and orthopedic procedures to minimize deformity. The main types of the disease are pseudohypertrophic (Duchenne’s muscular dystrophy), limb-girdle muscular dystrophy, and facioscapulohumeral muscular dystrophy. Rarer forms include Becker’s muscular dystrophy, distal muscular dystrophy, ocular myopathy, and myotonic muscular dystrophy. Also called myodystrophy. See also myotonic myopathy.
