Surgery to treat focal frontal lobe epilepsy in adults

To report clinical, neuropathological, and outcome data for a series of adult patients with focal frontal lobe epilepsy (fFLE) who underwent nonlobar resection restricted to the frontal lobe.

Sixty-eight adult cases (24 female and 44 male patients) were included in the study, on the basis of prospectively collected data that were retrospectively evaluated. There were 68 lesionectomies, 17 of which were combined with multiple subpial transection, with a mean follow-up period of 28.4 +/- 23.3 months. Cases involving additional extrafrontal surgery were excluded.

Thirty-seven patients underwent invasive preoperative evaluations, and 31 underwent noninvasive evaluations. Intraoperative electrocorticography was used in 32% of cases. There were 24 tumors, 18 dysgenetic lesions, 14 gliotic lesions, and 10 vascular malformations. Fifteen tumors were of glial origin, one was a dysembryoplastic neuroepithelial tumor, and eight were gangliogliomas. The most common dysgenetic lesions were hamartomas (15 cases). Outcomes (classified into four Engel groups) were as follows: Class I, 54%; Class II, 19%; Class III, 15%; Class IV, 12%. Seizure-free rates were comparable for tumor and dysgenesis cases and were not as good for vascular malformation and gliosis cases. Outcome differences were not significant with respect to aura presence, side of surgery, age at the time of surgery, and age at seizure onset. There were 3 cases of surgical complications, 10 cases of transient neurological disturbances, and 1 case involving a permanent neurological deficit. No deaths occurred.

Outcomes with fFLE surgery have improved, compared with historical series. fFLE resections restricted to the frontal lobe did not yield seizure-free rates as good as those for comparable nonfocal frontal lobe epilepsy series. All fFLE cases demonstrated histological lesions. fFLE surgery was associated with a higher risk of transient neurological deficits, most likely because of the necessity for multiple subpial transection. The outcomes and higher rates of invasive evaluations and intraoperative electrocorticography indicate the special complexities of frontal lobe epilepsy. The permanent neurological disability rate was low in this series, and there were no deaths.