Abstracts

RATIONALE: Anterior temporal lobectomy (ATL) is an effective surgical option for patients with medically refractory temporal lobe epilepsy (TLE). The typical EEG abnormalities in this population include focal anterior temporal spikes and sharp waves. The presence of generalized interictal epileptogenic discharges (IEDs) in a patient with TLE may suggest a concurrent diagnosis of idiopathic generalized epilepsy. The outcome of temporal lobectomy in such patients is not known. In this study, we reviewed the outcome of ATL in patients with TLE who showed generalized IEDs in addition to focal temporal IEDs. The reader will learn the prognosis of ATL in patients with TLE and generalized IEDs after reviewing this study, and be able to identify the factors predictive of outcome.
METHODS: We retrospectively reviewed the EEG reports of all 608 patients who underwent ATL for medically intractable TLE at our institution from 1989-2000, and selected those who showed generalized IEDs on any pre-operative Mayo EEG. All patients underwent MRI with a special protocol designed to evaluate hippocampal volume, and underwent a comprehensive presurgical evaluation including video-EEG monitoring to confirm seizure localization. Patient demographics, pre-surgical epilepsy duration, seizure types, the presence of aura and febrile seizures, MRI results, pre and post-operative EEG findings, and outcome were determined by review of the medical records. The modified Engel classification system was used to classify post-operative seizure outcome. An excellent outcome was defined as a post-operative score of [lte]4, and a non-excellent outcome [gt] 4. A favorable outcome was defined as an improvement of [gte]2 points, and an improvement of [lt] 2 points designated a poor outcome. Fisher[ssquote]s Exact Test (2-tailed) was used to compare the frequency of different clinical variables with respect to outcome.
RESULTS: Twenty patients were identified (11 females and 9 males), with a mean age ([plusminus] 1 SD) of 28.5[plusminus]13 years (range 10-54 years). The mean pre-surgery epilepsy duration was 22.6[plusminus]14.1years (range 2-52 years) and mean post surgery follow up was 45.9[plusminus]33.9 months (range 5-150 months). MRI showed mesial temporal sclerosis (MTS) in 14 patients, anterior temporal glioma in 1, post-encephalitic changes in 1, and was normal in 4. Seizure outcome was excellent in 10 (50%), favorable in 6 (30%), and poor in 4 (20%). Factors correlating with an excellent outcome were the presence of an aura (p=0.03), and complex partial seizures (CPS) only without generalized tonic-clonic seizures (p= 0.02). The presence of focal MRI abnormalities approached but did not reach statistical significance as a favorable prognostic factor (p=0.08). The presence of generalized IEDs on follow-up EEG correlated with a non-excellent outcome (p= 0.005).
CONCLUSIONS: Fifty percent of patients in this series with TLE and generalized IEDs had an excellent outcome following ATL. The presence of CPS only and aura correlated with an excellent outcome. The persistence of generalized IEDs following ATL correlated with a non-excellent outcome. A focal temporal lobe abnormality on MRI favored an excellent outcome, but this did not reach statistical significance.