= hamartomatous overgrowth of all / part of a cerebral hemisphere with neuronal migration defects

• intractable seizure disorder at early age, hemiplegia
• developmental delay
• moderate / marked enlargement of one hemisphere
• ipsilateral ventriculomegaly proportionate to enlargement of affected hemisphere
• straightened frontal horn of ipsilateral ventricle pointing anterolaterally
• neuronal migration defects:
  • polymicrogyria
  • pachygyria
  • heterotopia of gray matter
  • white matter gliosis (low density in white matter on CT, prolonged T1 + T2 relaxation times on MR)

Rx: partial / complete hemispheric resection