Delayed myelination at the onset of cryptogenic West syndrome.

To evaluate the prognostic value of delayed myelination at the onset of cryptogenic West syndrome, the relationship between the seizure or developmental outcome and myelination was examined. Cranial magnetic resonance imaging studies were performed in nine cryptogenic cases. Infantile spasms were controlled in all patients, but three cases showed a mild developmental delay at 2 years after onset. Delayed myelination was observed in three cases (33.3%) on T(1)-weighted images and in two cases (22.2%) on T(2)-weighted images. In the present study, neither the seizure outcome nor developmental status was positively correlated with the existence of delayed myelination at the onset of cryptogenic West syndrome.