Posterior agyria-pachygyria with polymicrogyria: evidence for an inherited neuronal migration disorder.

We describe two brothers with mental retardation and refractory epilepsy. MRI revealed symmetrical agyria-pachygyria of the temporo-occipito-parietal regions, areas of deeply infolded polymicrogyric parietal cortex, and dilated occipital horns (colpocephaly). The stereotyped clinical, EEG, and MRI findings suggest that this may be a distinct inherited condition and imply that agyria-pachygyria with polymicrogyria is not always sporadic.