Outcome of frontal lobe epilepsy surgery.

There is still controversy in deciding which patients with frontal lobe epilepsy (FLE) should undergo resective surgery, even though it is a well-established therapy. The aim of this study is to define multiple outcome measures and determine whether there are certain subpopulations of preferred surgical candidates that have a more favorable seizure prognosis. Fifty-eight patients underwent resective FLE surgery with a mean follow-up period of 79.3 months (range 12-208 months). Patient demographics, clinical seizure characteristics, seizure-onset zone within the frontal lobes, and diagnostic tests were tabulated. Engel class, International League Against Epilepsy (ILAE) class, postoperative seizure patterns, time to first recurrent seizure, and seizures and employment during the last year of follow-up were used as outcome measures. Neuropsychological performance and Beck Depression Inventory (BDI) scores were used to define neuropsychological outcome and examined as predictors of seizure outcome. Thirty-three (57%) patients with resective surgery had an Engel class I outcome and 29 (50%) had an ILAE class I outcome. Mean time to first seizure after surgery was 33.3 months (range 0-208). Only 14 patients (24%) were completely seizure-free without auras (Engel IA) throughout the entire follow-up period. The most common pattern of seizure recurrence was mixed, with prolonged periods of seizure freedom intermixed with recurrences. In addition, 32% of patients made gains in employment and 52% were able to reduce use of antiepileptic drugs (AEDs), although only 9% discontinued AEDs. No significant association was found between class I or class IA outcome and the presence of a focal magnetic resonance imaging (MRI) abnormality, any specific localization of seizure focus within the frontal lobe, or neuropsychological change. Findings indicate that that long-term outcome is generally favorable in FLE resective surgery, and support the need for considering multiple outcome measures to more fully characterize clinically relevant postsurgical changes. Outcome can be favorable even in MRI-negative patients.

Lazow SP ，Thadani VM ，Gilbert KL ，Morse RP ，Bujarski KA ，Kulandaivel K ，Roth RM ，Scott RC ，Roberts DW ，Jobst BC ... -  《-》

Intracranial EEG in predicting surgical outcome in frontal lobe epilepsy.

Surgery in frontal lobe epilepsy (FLE) has a worse prognosis regarding seizure freedom than anterior lobectomy in temporal lobe epilepsy. The current study aimed to assess whether intracranial interictal and ictal EEG findings in addition to clinical and scalp EEG data help to predict outcome in a series of patients who needed invasive recording for FLE surgery. Patients with FLE who had resective surgery after chronic intracranial EEG recording were included. Outcome predictors were compared in patients with seizure freedom (group 1) and those with recurrent seizures (group 2) at 19-24 months after surgery. Twenty-five patients (16 female) were included in this study. Mean age of patients at epilepsy surgery was 32.3 ± 15.6 years (range 12-70); mean duration of epilepsy was 16.9 ± 13.4 years (range 1-48). In each outcome group, magnetic resonance imaging revealed frontal lobe lesions in three patients. Fifteen patients (60%) were seizure-free (Engel class 1), 10 patients (40%) continued to have seizures (two were class II, three were class III, and five were class IV). Lack of seizure freedom was seen more often in patients with epilepsy surgery on the left frontal lobe (group 1, 13%; group 2, 70%; p = 0.009) and on the dominant (27%; 70%; p = 0.049) hemisphere as well as in patients without aura (29%; 80%; p = 0.036), whereas sex, age at surgery, duration of epilepsy, and presence of an MRI lesion in the frontal lobe or extrafrontal structures were not different between groups. Electroencephalographic characteristics associated with lack of seizure freedom included presence of interictal epileptiform discharges in scalp recordings (31%; 90%; p = 0.01). Detailed analysis of intracranial EEG revealed widespread (>2 cm) (13%; 70%; p = 0.01) in contrast to focal seizure onset as well as shorter latency to onset of seizure spread (5.8 ± 6.1 s; 1.5 ± 2.3 s; p = 0.016) and to ictal involvement of brain structures beyond the frontal lobe (23.5 ± 22.4 s; 5.8 ± 5.4 s; p = 0.025) in patients without seizure freedom. The distribution of ictal onset patterns was similar in both groups, and fast rhythmic activity in the beta to gamma range was found in 57% of seizure-free patients compared to 70% of patients with recurrent seizures. Analysis of the temporal relation between first clinical alterations and EEG seizure onset did not reveal significant differences between both groups of patients. In multivariate analysis, resection in the left hemisphere (odds ratio [OR] 12.197 95% confidence interval [95% CI] 1.33-111.832; p = 0.027) and onset of seizure spread (odds ratio [OR] 0.733, 95% CI 0.549-0.978, p = 0.035) were independent predictors of ongoing seizures. Widespread epileptogenicity as indicated by rapid onset of spread of ictal activity likely explains lack of seizure freedom following frontal resective surgery. The negative prognostic effect of surgery on the left hemisphere is less clear. Future study is needed to determine if neuronal network properties in this hemisphere point to intrinsic interhemispheric differences or if neurosurgeons are restrained by proximity to eloquent cortex.

Holtkamp M ，Sharan A ，Sperling MR 《-》

Surgical outcome and prognostic factors of frontal lobe epilepsy surgery.

Jeha LE ，Najm I ，Bingaman W ，Dinner D ，Widdess-Walsh P ，Lüders H ... -  《-》

Long-term seizure outcome after resective surgery in patients evaluated with intracranial electrodes.

Despite advances in "noninvasive" localization techniques, many patients with medically intractable epilepsy require the placement of subdural (subdural grid electrode, SDE) and/or depth electrodes for the identification and definition of extent of the epileptic region. This study investigates the trends in longitudinal seizure outcome and its predictors in this group. We reviewed the medical records, and electroencephalography (EEG) data of 414 consecutive patients who underwent intracranial electrode placement (SDE and/or depth electrodes) at Cleveland Clinic Epilepsy Center between 1998 and 2008. A favorable outcome was defined as complete seizure freedom, discounting any auras or seizures that occurred within the first postoperative week. Survival curves were constructed, and Cox proportional hazard modeling was used to identify outcome predictors. The estimated probability of complete seizure freedom was 61% (95% confidence interval [CI] 58-64%) at one postoperative year, 47% (95% CI 44-50%) at 3 years, 42% (95% CI 39-45%) at 5 years, and 33% (95% CI 28-38%) at 10 years. Half of all seizure recurrences occurred within the first two postoperative months. Subsequently, the rate of seizure freedom declined by 4-5% every 2-3 years. After multivariate analysis, two independent predictors of seizure recurrence were identified: (1) prior resective surgery (p ≤ 0.002), mostly in patients with temporal lobe resections, and (2) sublobar or multilobar resection (p ≤ 0.02), mostly in patients following frontal lobe resections. Favorable seizure outcomes are possible in the complex epilepsy population requiring invasive EEG studies. We propose that mislocalization of the epileptogenic zone or its incomplete resection account for early postoperative recurrences, whereas epileptogenesis may lead to later relapses.

Bulacio JC ，Jehi L ，Wong C ，Gonzalez-Martinez J ，Kotagal P ，Nair D ，Najm I ，Bingaman W ... -  《-》

Improved outcomes with earlier surgery for intractable frontal lobe epilepsy.

To explore the prognostic implications of epilepsy duration and age at surgery for seizure outcomes after frontal lobe epilepsy (FLE) surgery. We reviewed 158 patients who underwent FLE surgery from 1995 to 2010. The primary outcome was seizure freedom at last follow-up (Engel class IA). Analyses employed Cox proportional and multiphase hazard modeling. The mean age at surgery was 20.4 years, and mean epilepsy duration was 12.0 years. The estimated chance of seizure freedom was 66% (95% confidence interval [CI] = 62-68) at 1 postoperative year, 52% (95% CI = 48-56) at 2 years, and 44% (95% CI = 39-49) at 5 years and beyond. Seventy-five percent of recurrences occurred within 6 postoperative months. Both younger age at surgery (<18 years) and shorter epilepsy duration (<5 years) correlated with better seizure outcomes on univariate analysis, but only epilepsy duration remained statistically significant after multivariate modeling. Independent poor prognostic indicators included left-sided resections and acute postoperative seizures (APOSs; whole model log-rank test p < 0.0001). APOSs were particularly predictive of early epilepsy recurrence, starting within 6 postoperative months (adjusted risk ratio [RR] = 4.42, p < 0.0001), whereas long epilepsy duration correlated with late recurrences (RR = 6.25, p < 0.0001). Worse outcomes were seen with longer epilepsy duration for duration cutoffs of 2, 5, and 10 years independently for adults and children, although statistical significance was only achieved in children (66% seizure free at 5 postoperative years if operated on within 5 years of epilepsy onset vs 31% if later; p = 0.01). Early resection may improve seizure outcomes of FLE surgery, particularly in children.

Simasathien T ，Vadera S ，Najm I ，Gupta A ，Bingaman W ，Jehi L ... -  《-》