Short- and long-term surgical outcomes of temporal lobe epilepsy associated with hippocampal sclerosis: Relationships with neuropathology.

Abstract

Hippocampal sclerosis (HS) is the most frequent neuropathologic finding in patients undergoing surgery for intractable temporal lobe epilepsy (TLE). The International League Against Epilepsy (ILAE) has recently proposed a new classification of HS based on specific patterns of cell loss. The aim of this study was to investigate the relationships between HS types, their etiologic factors, and the short- and long-term postsurgical outcomes of patients undergoing surgery because of drug-resistant TLE with HS. Two hundred thirteen patients with a neuropathologic diagnosis of HS and a minimum follow-up of 2years were divided on the basis of their ILAE HS type and further classified into: (1) isolated HS, (2) HS associated with focal cortical dysplasia (FCD IIIa), or (3) HS associated with other lesions. Their clinical and neuropathologic data were correlated with their Engel class postsurgical outcomes. The main findings were the following: (1) HS type 1 was associated with a longer duration of epilepsy; (2) >80% of the patients had an Engel class I short- and long-term outcomes, regardless of HS type and associated pathology; (3) short- and long-term postsurgical outcomes were less satisfactory in the patients who were completely seizure-free (Engel class Ia), and patients with HS type 2 had better long-term seizure outcomes than those with type 1; (4) the concomitant presence of FCD contributed to a worse outcome, regardless of HS type; and (5) a shorter duration of epilepsy significantly correlated with an Engel class Ia outcome. These data suggest that HS type and associated pathologies may predict the risk of recurrence, but other variables such as the duration of epilepsy need to be considered. A common neuropathologic classification system may help to identify preoperative predictive factors and improve the selection of patients who may benefit from epilepsy surgery.