Hypotonia with decreased or
normal dynamic tone is generalized, proximal more than distal, and particularly
involves the face and neck muscles. Dysphagia and respiratory compromise
are less common. Extraocular movements are usually normal. The disease
is always progressive but an apparent initial improvement in muscle strength
sometimes occurs during the neonatal period. Some patients with congenital
muscular dystrophy have associated brain anomalies. Fukuyama congenital
muscular dystrophy is associated with cerebral and cerebellar gyral abnormalities
(migrational errors) and occasionally white matter hypodensity on CT.
Congenital muscular dystrophy with white matter hypodensity on CT, but
without gyral abnormalities, have been reported. Walker-Warburg syndrome
consists of congenital muscular dystrophy with cerebral and cerebellar
gyral abnormalities, white matter hypodensity on CT, and ocular abnormalities
(congenital glaucoma, retinal and optic nerve hypoplasia, and cataracts).
The absence of brain malformation on CT or MRI is highly indicative of
normal intellect. Treatment of all congenital muscular dystrophies is
Polymyositis produces marked
hypotonia with decreased dynamic tone (especially in neck muscles), weak
cry, and poor sucking and feeding ability. Serum creatine phosphokinase
is very elevated. Electromyography shows fibrillations and brief and small
motor unit potentials. Muscle biopsy shows muscle destruction with lymphocytic
infiltration. Steroid treatment is beneficial.