Because of the small size of the brain, the skull is also small. Affected children are microcephalic, have intractable seizures, and their neurological development is severely impaired.
Affected infants survive and are severely neurologically impaired with intractable seizures.
Affected infants are moderately to severely neurologically impaired depending on the extent of the malformation. The extent of heterotopias determines the degree of neurological impairment and seizures. Depending on the extent of the clefts, affected infants may have weakness contralateral to the cleft, and seizures or be moderately or severely neurologically impaired. Defects in neurulation and neuronal migration can lead to this malformation. Affected infants may be normal or may have seizures and be neurologically impaired.