What is the most common region affected and how common is polymicrogyria bilateral?
Perisylvian (60%) / frontal lobe (70%). Bilateral involvement is common seen in up to 60% of cases (not in this case).
How is polymicrogyria best identified on imaging?
MRI is the modality of choice. The cortex appears thicker than normal. The grey-white junction is often the best location to identify the 'bumpy' contour which on thicker slices may manifest as blurring.
What other congenital abnormality of cortical formation is frequently present, and should be carefully sought?
Schizencephaly is frequently encountered, and is 'always' lined by polymicrogyric cortex.
The grey matter on the left side along the Sylvian fissure and more anteriorly along the lateral aspect of the frontal lobe (middle and inferior frontal gyri) and posterior temporal lobe, is abnormally thickened, nodular with poorly defined grey white matter junction.