A complex brain malformation syndrome with rhombencephalosynapsis, preaxial hexadactyly plus facial and skull anomalies.

We report on a 15-year-old boy with epilepsy and mental retardation who had been repeatedly shunted since birth for hydrocephalus. This child showed at imaging an unusual, severe and complex brain malformation consisting of distorted gyral patterns with deeply infolded mantle in the parietal-lateral and posterior-temporal lobes, normal versus dysplastic cortex, unseparated thalami, thin white matter, collapsed ventricles, partial frontal corpus callosum agenesis, closely apposed superior and middle cerebral peduncles with narrow fourth ventricle, continuity of posterior cerebellum hemispheric foliar patterns across the midline, closely apposed cerebellar peduncles, asymmetrical hypogenesis of the vermis and herniation of the cerebellar hemispheric pattern up through the tentorial incisure. In addition, this boy had congenital skeletal and skin anomalies including pre-axial hexadactyly with thumb duplication, wide bone occipital lacunae (catlin mark) with partial occipital suture synostosis, cutis vertex rigirata and a tuft of hair in the outer region of the right eyebrow. Several of these cerebral and cerebellar abnormalities were suggestive of rhombencephalosynapsis. Nonetheless, many of these brain abnormalities are also recorded in Chiari type 2 malformation after operative shunting. To the best of our knowledge, however, this complex constellation of nervous system, skeletal and skin abnormalities has not been previously reported.