Cerebral abnormalities in congenital myotonic dystrophy.

The brain structure of 14 infants born with congenital myotonic dystrophy at 2 hospitals was evaluated by cranial ultrasonography, and the findings were correlated with clinical and neuropathologic data. Ventricular dilation was diagnosed in 11 infants (78%). Seven infants died during the neonatal period; all had ventricular dilation which remained essentially static. In the ultrasound scans of the 5 infants with ventricular dilation. Of the 7 survivors, 4 had ventricular dilation born at 1 hospital, 4 had widening of the interhemispheric fissure. Macrocephaly, a previously unrecognized finding in congenital myotonic dystrophy, was present in 10 infants (71%), 8 of whom presented with ventricular dilation. None had clinical evidence of increased intracranial pressure. There was no ventricular obstruction in the 4 brains examined pathologically. Histologic examination revealed minor expression of neuronal migrational disturbances in each patient. Macrocephaly together with the ultrasonographic and neuropathologic findings in our patients suggest that these abnormalities may originate in an external hydrocephalus.