Prognostic Factors for the Surgery for Mesial Temporal Lobe Epilepsy: Longitudinal Analysis

Abstract

Summary:Purpose: Determining long-term prognostic factors of surgery for mesial temporal lobe epilepsy (MTLE) is important for identifying ideal candidates and predicting the prognosis for individual patients. We tried to identify the prognostic factors of anterior temporal lobectomy (ATL) for MTLE with longitudinal multivariate analysis.Methods: Two hundred twenty-seven patients with MTLE were included in this study. The primary outcome variable was patient status 1-5 years after surgery: seizure free, or not. Clinical characteristics and recent diagnostic modalities were considered as prognostic factors. Univariate and standard multiple logisticregression analysis for outcome at 1 and 5 years after surgery and the generalized estimation equation (GEE) model for longitudinal multiple logistic regression of the 5-year follow-up period were used.Results: The seizure-free rate at 1 year was 81.1% and decreased to 75.2% at 5 years after surgery. By the univariate or standard multiple logistic-regression analysis, age at surgery or hippocampal sclerosis on magnetic resonance imaging (MRI) ipsilateral to surgery was significant for the postsurgical outcome. However, the longitudinal analysis by the GEE model revealed that younger age at surgery [odds ratio (OR), 0.59; 95% confidence interval (CI), 0.43-0.81], absence of secondarily generalized tonic-clonic seizure (2 • GTCS; OR, 0.45; 95% CI, 0.26-0.79), and hippocampal sclerosis on MRI (OR, 2.44; 95% CI, 1.11-5.26) were significant predictors of a good surgical outcome.Conclusions: Age at surgery, presence of 2 • GTCS, and hippocampal sclerosis on MRI are independent prognostic factors for ATL in MTLE. These findings suggest that MTLE is a progressive disorder, and surgical outcome is better when early ATL is performed. Key Words: Anterior temporal lobectomyMesial temporal lobe epilepsy-Prognostic factors-Repeated measures data-Multivariate analysis.Mesial temporal lobe epilepsy (MTLE) is a wellrecognized epilepsy syndrome with hippocampal sclerosis (HS) and a major target for epilepsy surgery. Anterior temporal lobectomy (ATL) performed for the treatment of medically intractable MTLE yielded worthwhile improvement (75-95%), including complete remission of seizure (68%-85%) in most patients (1-3). However, ≤30% of patients continue to experience seizures after surgery. Therefore determining prognostic factors is very important in identifying ideal candidates for surgery and predicting the prognosis of individual patients.Even though some authors have performed multivariate analyses for the prognosis of epilepsy surgery (4-12),

Long-Term Seizure Outcome in Patients Undergoing Resection of Lesions Detected by Magnetic Resonance Imaging

“…13,15,16,24,29,34) Children operated on after 6 years of age had no better outcome than children operated on in infancy or at preschool age. 15) Younger age at surgery is a significant and independent predictor and an independent prognostic factor of good surgical outcome.…”

“…15) Younger age at surgery is a significant and independent predictor and an independent prognostic factor of good surgical outcome. 13) Longer preoperative illness predicts poorer outcome 34) or late recurrence. 25) The duration of preoperative epilepsy is not a reliable predictor of final surgical outcome among patients with medial temporal sclerosis, 18,19) whereas the duration of epilepsy is inversely and significantly correlated with seizure outcome among patients with extratemporal epilepsy.…”

Shorter epilepsy duration is associated with better seizure outcome in temporal lobe epilepsy surgery

“…Other studies have observed that a longer epilepsy duration before surgical treatment predicted worse seizure outcome 19,22 . However, Baldauf et al did not reach those conclusions 24 .…”

“…Jeong et al 19 and Junna et al 20 observed that a younger age at surgery was predictive of a favorable postsurgical outcome. Additionally, Sirven et al 21 studied a large number of patients undergoing temporal lobectomy and observed that patients younger than 50 years had a higher likelihood of seizure freedom compared with those older than 50 years, although the procedure was considered safe and beneficial in both groups.…”

“…Postoperative outcome distribution according to age. Age I II III IV Total 10-19 7 3 0 3 13 20-29 21 3 1 2 27 30-39 39 17 5 8 69 40-49 44 18 4 4 70 50-59 28 11 1 0 40 60-69 5 4 0 1 10 Total 144 56 11 18 229 in other brain areas not involved in the primary epileptogenic zone, and this could be associated with the persistence of disabling seizures 19,20,21,22,23,24 . However, further clinical and experimental investigations are necessary to validate this hypothesis.…”