June 10, 2013

Polymicrogyria-Associated Epilepsy: a Multi-Center Phenotypic Study from the Epilepsy Phenome/Genome Project

Purpose: Polymicrogyria (PMG) is an epileptogenic malformation of cortical development. Researchers describe the clinical epilepsy and imaging features of a large cohort with PMG-related epilepsy.

Methods: Participants were recruited through the Epilepsy Phenome/Genome Project, a multi-center collaborative effort to collect detailed phenotypic data on individuals with epilepsy. Researchers reviewed phenotypic data from participants with epilepsy and PMG.

Key Findings: This study identified 87 participants, 43 female and 44 male, with PMG and epilepsy. Median age of seizure onset was 3 years (range <1 month-37 years). Most presented with focal epilepsy (87.4%), some in combination with seizures generalized from onset (23.0%). Focal seizures with dyscognitive features were most common (54.3%). Of those presenting with generalized seizure types, infantile spasms were most prevalent (45.2%). The most common topographic pattern was perisylvian PMG (77.0%), of which the majority was bilateral (56.7%). Generalized PMG presented with an earlier age of seizure onset (median age of 8 months) and an increased prevalence of developmental delay prior to seizure onset (57.1%). Of the focal, unilateral and asymmetric bilateral groups where PMG was more involved in one hemisphere, the majority (71.4%) of participants had seizures that lateralized to the same hemisphere as the PMG or the hemisphere with greater involvement.

Significance: Participants with polymicrogyria had both focal and generalized onset of seizures. The data confirm the involvement of known topographic patterns of polymicrogyria and suggest that more extensive distributions of polymicrogyria present with an earlier age of seizure onset and increased prevalence of developmental delay prior to seizure onset.

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