Association of hippocampal sclerosis with cortical dysgenesis in patients with epilepsy.

The possible dual occurrence of hippocampal sclerosis (HS) and other structural lesions (especially cortical dysgenesis [CD]) is well established in patients with chronic partial epilepsy. We describe the frequency of additional CD in a series of 100 patients with evidence of HS, using volumetric MRI. Additional, often subtle, CD was present in 15 patients: subependymal heterotopia (six), forme fruste of tuberous sclerosis (two), focal macrogyria (two), focal cortical dysplasia (one), laminar heterotopia (one), bilateral schizencephaly (one), and simplified gyral patterns (two). In contrast, in 46 healthy volunteers, only one had possible CD (p < 0.05). Only 2 of 15 patients had a history of childhood febrile convulsions. HS is a heterogeneous condition; patients being evaluated for temporal lobe surgery should be carefully screened for additional CD using appropriate MR techniques.