Though the underlying cause of<unk>  is unknown, it is thought to arise from improper migration of neuroblasts (neuronal stem cells) to the cerebral cortex in the embryonic brain. This causes the layers of the cerebral cortex to not form properly, and too many small folds (gyri) to form on the surface of the brain. This condition is called<unk><unk>  polymicrogyria. The sulci, deep grooves on the brain, may also not form correctly. Cranial nerves are affected and cause muscle paralysis and spasms in the face and throat.
Congenital bilateral perisylvian syndrome
Dandy–Walker malformation
Congenital mirror movement disorder
Cerebellar agenesis
Cranio-lenticulo-sutural dysplasia
Hemimegalencephaly
Acrocallosal syndrome
Robinow syndrome