A first in vivo MRI documentation of the postmigrational postnatal evolution of a case of polymicrogyria is reported from the Children’s Hospital, Boston, MA. The infant was born premature at 27 weeks’ gestation. He suffered respiratory distress and cerebral ischemia, and was maintained on a ventilator for 17 days. Ultrasound scans showed bilateral intraventricular hemorrhages at 1 day, and a cystic periventricular leukomalacia that evolved over 3 weeks. MRIs with ultrafine slices were performed at 4 postnatal weeks, term, and at 6 months of age. A minor perisylvian abnormality noted at 4 weeks had developed into extensive bilateral cortical polymicrogyria by 6 months of age, in addition to mineralization of the cystic leukomalacia changes noted earlier. The postnatal evolution of polymicrogyria, associated with the simultaneous occurrence of periventriucular leukomalacia, points to an ischemic encephaloclastic mechanism. 
COMMENT. Congenital bilateral perisylvian polymicrogyria presents with facial diplegia, dysarthria, pseudobulbar palsy, seizures, and retardation. The present case report associated with premature birth, cerebral ischemia, and periventricular leukomalacia is described as unique, although the histopathology is not known.
RM Norman, in Greenfield’s Neuropathology (London, Edward Arnold, 1958), refers to sclerotic microgyria (ulegyria) and polygyria among the neuropathological sequelae of birth injury, cerebral ischemia and anoxia. A review of these earlier neuropathological reports is recommended reading.
Genetics of bilateral perisylvian polymicrogyria (BPPMG) is discussed in a report of 6 affected members of 3 consecutive generations of a family . The severity of the manifestations in one boy affected and the transmission of the disorder through women suggest an X-linked dominant trait. BPPMG is a heterogeneous disorder, in some cases genetically determined, and in others, related to ischemic injury.