Microdysgenesis in surgical specimens from patients with epilepsy: occurrence and clinical correlations.

Malformations of cortical development are commonly associated with epilepsy. In the first 139 consecutive patients in the Göteborg epilepsy surgery series, parenchymal malformations were found in 56. 1% of the children and in 23.1% of the adults. Microdysgenesis (MDG), which was the most common parenchymal malformation, was found in 35. 1% of the children and in 16.7% of the adults. The aim of this study was to identify clinical characteristics of patients with MDG. Mental retardation was found to be significantly more common in patients with major parenchymal malformations and in patients with MDG compared with patients without parenchymal malformations. Patients with major parenchymal malformations as well as patients with MDG also had a significantly earlier onset of seizures than patients without parenchymal malformations, also when adjusting for mental retardation. Patients with MDG were in these clinical aspects shown to closely resemble patients with major malformations. These findings suggest that MDG is a pathoanatomical entity of clinical relevance, with implications both in mental retardation and in epileptogenesis.