Mesial temporal sclerosis. A clinicopathologic study of 27 patients, including 5 with coexistent cortical dysplasia.

Abstract

OBJECTIVE Mesial temporal sclerosis (MTS) is a fairly well-recognized cause of intractable epilepsy. Its coexistence with cortical dysplasia is less commonly described. Herein, we describe the clinical and pathologic features of MTS, including cases in which cortical dysplasia was also identified. DESIGN Retrospective surgical series of 27 patients. SETTING Tertiary referral center with a high volume of epilepsy surgery. PATIENTS Patients with medically intractable epilepsy who underwent hippocampal resections and in whom an unequivocal histologic diagnosis of MTS could be made. RESULTS The patients studied included 18 males and 9 females ranging in age from 15 to 48 years (mean 32 years). Mesial temporal sclerosis was characterized by severe neuronal loss accompanied by gliosis occurring in the CA1/prosubiculum (27 patients, 100%), focally in the dentate gyrus (12 patients, 44%), and in the CA4 region (11 patients, 41%). Five patients (24%) had coexistent cortical dysplasia with increased molecular layer neurons (five patients), gyral fusion (two patients), diffuse architectural disorganization of the cortex (one patient), and clusters of atypical neurons and glial cells within the cortex (one patient). Twenty-five (93%) of the 27 patients had white matter neuronal heterotopia. Follow-up data were available for each patient (mean 23 months). Twenty-two of the patients are free of seizures postoperatively, including all five with coexistent cortical dysplasia; the five remaining patients have fewer seizures. There appeared to be no difference clinically between patients with MTS and no dysplasia and those with coexistent cortical dysplasia. CONCLUSION We conclude that (1) MTS most severely involves the CA1/prosubiculum and CA4 regions of the hippocampus (the dentate gyrus may also be focally severely involved); (2) MTS and cortical dysplasia do occasionally exist; and (3) surgical outcome for MTS appears to be independent of coexistent cortical dysplasia.

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