Hemimegalencephaly associated with contralateral hemispheral volume loss.

Hemimegalencephaly is a rare malformation characterized by overdevelopment of one cerebral hemisphere. The opposite hemisphere is usually normal. This paper presents a 2-day-old patient with hemimegalencephaly associated with diffuse volume loss in the contralateral hemisphere. To the best of the author's knowledge such an association has not been reported previously. This finding suggested that these patients may suffer from a congenital hemispheral insult of varying degree of severity and variable time of onset.