Hemihydranencephaly is a severe brain condition characterized by complete or almost complete absence of cerebral cortex with preservation of meninges, basal ganglia, pons, medulla, cerebellum, and falx. It is a special type of Hydranencephaly
It is a very rare disease. As it stands, only 7 cases have been reported.
References:
Greco F, Finocchiaro M, Pavone P, Trifiletti RR, Parano E. Hemihydranencephaly: case report and literature review. J Child Neurol. 2001;16 :218 –221