Hemimegalencephaly: cranial sonographic findings in neonates.

Hemimegalencephaly is a rare neuronal migration disorder characterized by overgrowth of part or all of 1 cerebral hemisphere. Lissencephaly, pachygyria, polymicrogyria, heterotopia, and glial abnormalities are usually noted pathologically in the enlarged hemisphere. We report the sonographic changes associated with hemimegalencephaly in 2 neonates presenting with seizures and correlate these changes with the magnetic resonance imaging findings. (c) 2005 Wiley Periodicals, Inc. J Clin Ultrasound 33:243-247, 2005.