Rates and predictors of long-term seizure freedom after frontal lobe epilepsy surgery: a systematic review and meta-analysis

Clinical article

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Frontal lobe epilepsy (FLE) is the second-most common focal epilepsy syndrome, and seizures are medically refractory in many patients. Although various studies have examined rates and predictors of seizure freedom after resection for FLE, there is significant variability in their results due to patient diversity, and inadequate follow-up may lead to an overestimation of long-term seizure freedom.


In this paper the authors report a systematic review and meta-analysis of long-term seizure outcomes and predictors of response after resection for intractable FLE. Only studies of at least 10 patients examining seizure freedom after FLE surgery with postoperative follow-up duration of at least 48 months were included.


Across 1199 patients in 21 studies, the overall rate of postoperative seizure freedom (Engel Class I outcome) was 45.1%. No trend in seizure outcomes across all studies was observed over time. Significant predictors of long-term seizure freedom included lesional epilepsy origin (relative risk [RR] 1.67, 95% CI 1.36–28.6), abnormal preoperative MRI (RR 1.64, 95% CI 1.32–2.08), and localized frontal resection versus more extensive lobectomy with or without an extrafrontal component (RR 1.71, 95% CI 1.26–2.43). Within lesional FLE cases, gross-total resection led to significantly improved outcome versus subtotal lesionectomy (RR 1.99, 95% CI 1.47–2.84).


These findings suggest that FLE patients with a focal and identifiable lesion are more likely to achieve seizure freedom than those with a more poorly defined epileptic focus. While seizure freedom can be achieved in the surgical treatment of medically refractory FLE, these findings illustrate the compelling need for improved noninvasive and invasive localization techniques in FLE.

Abbreviations used in this paper:ECoG = electrocorticography; EEG = electroencephalography; FLE = frontal lobe epilepsy; RR = relative risk; SMA = supplementary motor area; TLE = temporal lobe epilepsy.

Article Information

Address correspondence to: Dario J. Englot, M.D., Ph.D., Department of Neurological Surgery, University of California, San Francisco, 505 Parnassus Avenue, Box 0112, San Francisco, California 94143-0112. email: englotdj@neurosurg.ucsf.edu.

Please include this information when citing this paper: published online February 3, 2012; DOI: 10.3171/2012.1.JNS111620.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Seizure-freedom rates across all studies by year. Each data point represents 1 study, with rate of seizure freedom (Engel Class I outcome) after FLE surgery plotted against year of publication. A line of best fit is provided. No significant trend is observed (r = 0.26, p = 0.25).

  • View in gallery

    Forest plots of meta-analysis results. Effect size for each study is shown as RR with 95% CI reflecting likelihood of postoperative seizure freedom for: lesional over nonlesional FLE (A), abnormal over normal preoperative MRI (B), partial lobectomy/focal resection over lobectomy or extended resection (C), and gross-total over subtotal resection for lesional cases (D). Each box represents 1 study, with box size proportional to number of patients. Overall effect size and 95% CI represented by X at the bottom of each panel. Data are displayed using logarithmic scale. Number of patients for each study is provided in Table 1.



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