Absolute spike frequency and etiology predict the surgical outcome in epilepsy due to amygdala lesions.

Purpose: To identify surgical prognostic factors for temporal lobe epilepsy (TLE) due to amygdala lesions.

Methods: We included 42 patients (mean age: 31.4 ± 11) who underwent presurgical evaluation including long-term video-EEG and in whom the high-resolution MRI showed amygdala lesions without hippocampal abnormalities. All patients had apical temporal lobe resection without hippocampectomy. We distinguished patients with frequent spikes (spike frequency ≥ 60/h) and with non-frequent spikes (< 60 spikes/h).

Results: At the 2-year postoperative evaluation, 30 patients (71%) were seizure-free. The presence of infrequent spikes (p = 0.013), tumor on the MRI (p = 0.027), and no epilepsy history in the family (p = 0.027) were independently associated with 2-year seizure-free outcome. Of 33 patients with infrequent spikes, 79% became seizure-free, while of 9 patients with frequent spikes only 4 had a favorable surgical outcome (44%).

Conclusion: In TLE patients due to amygdala lesions, high spike frequency and family history of epilepsy predicted an unfavorable, while tumoral etiology a favorable outcome after apical temporal lobe resection without hippocampectomy. Seventy-one percent of patients with amygdalar epilepsy who underwent this novel type of epilepsy surgery became seizure-free. This is comparable with results of "classical" anterior temporal lobe resections where hippocampus is NOT spared. Moreover, the surgical outcome may be predictable.