Neuroimaging study of myotonic dystrophy. I. Magnetic resonance imaging of the brain.

Magnetic resonance imaging scans of the brain were obtained in 13 patients with myotonic dystrophy, seven with congenital myotonic dystrophy and six with adult-type myotonic dystrophy. All seven patients with congenital myotonic dystrophy had ventriculomegaly and a low IQ (DQ). Cerebral white matter lesions were observed in six cases, a small corpus callosum in four cases, a small brainstem in two cases, and a cerebellar white matter lesion in one case. Cerebral white matter lesions were observed in five of the six cases with adult-type myotonic dystrophy of which one had ventriculomegaly. The IQ (DQ) was significantly lower in patients with congenital myotonic dystrophy than in those with adult-type myotonic dystrophy. The incidence of a small corpus callosum or ventricular enlargement was higher in congenital myotonic dystrophy than in adult-type myotonic dystrophy. These findings may be related to the presence of neurologic impairment in congenital myotonic dystrophy.