Abstracts

Polymicrogyria (PMG) is a relatively common malformation of cortical development. However, the pathogenesis, epileptogenesis and anatomo-clinical correlation of PMG require further clarification. We aim to 1. study the extent and type of pathological changes in polymicrogyric lesions as well as in adjacent non-polymicrogyric tissue 2. study the presence of other malformations of cortical development, as well as other pathological conditions previously reported in association with PMG 3. study the anatomo-clinical correlation in order to better understand language impairment and motor involvement frequently seen in PMG patients 4. study the correlation between pathology and imaging findings 5. obtain further insight into the pathogenesis and epileptogenesis of PMG. Medical records, EEG, imaging and autopsy data on seven patients from four tertiary centers were reviewed. Two patients had symmetrical and 2 had asymmetrical bilateral perisylvian PMG, 1 had unilateral hemispheric PMG and a small contralateral PMG lesion, 1 had parieto-occipital PMG. Multiple associated CNS lesions were identified, including periventricular nodular heterotopia, non-laminated heterotopic neurons in the cerebral white matter, microscopic neuroglial heterotopias in the cerebellar white matter, and DNT. Associated congenital malformations included cardiac malformations, congenital hemiparesis, club foot, arthrogryposis, and cranio-facial dysmorphism. When detailed seizure history was available, pathology findings correlated with seizure patterns present during life. The cause of death was seizure related in 2 patients. This is the first series of brain autopsy findings in PMG patients. Our study illustrates that PMG is often associated with diffuse microscopic migration disorders that may contribute to the epileptogenesis in PMG patients. The absence of underlying infectious or vascular pathology reflects the developmental origin of PMG and supports the involvement of genetic factors in its pathogenesis. The extent of the polymicrogyric lesion can be more widespread than detected by current MRI techniques. Associated congenital malformations seem more frequent than recognized to date. (Supported by Savoy Foundation for Epilepsy Research)