Morbidity associated with the use of foramen ovale electrodes

Purpose: The identification of the epileptic zone in patients with mesial temporal lobe epilepsy sometimes requires intracranial recordings, for example, with foramen ovale electrodes (FOE). This paper reviews and analyzes the resulting complications in a series of patients studied with bilateral FOE for presurgical evaluation. Methods: The clinical records of 331 consecutive FOE implantations in 329 patients were reviewed. Complications related to FOE were divided into two groups: those that were non-life-threatening or not directly attributable to FOE, or life-threatening complications and those clearly related to FOE. Results: The mean length of hospital stay in the v-EEG unit with FOE was 5.8 +/- 0.2 days (range 1-19) following a bimodal distribution (peaks at 4 and 8 days). Complications were observed in 6.64% of patients, but in 4.83% of cases, complications were non-life-threatening (moderate disaesthesia, cheek bleeding, FOE expulsion). Complications were only severe in 1.81% of patients (clotting or intracranial hemorrhage). One patient died more than 20 days after FOE removal and after several episodes of status epilepticus. Patients suffering from life-threatening complications were more likely to be female (83.3%) than patients experiencing no complications or non-life-threatening complications. Patients with life-threatening complications had a more prolonged stay in the v-EEG unit during monitoring with FOE (8.2 +/- 0.7; n = 6) than the group without complications (5.7 +/- 0.2; n = 309; p < 0.01; Kruskal-Wallis test). Discussion: FOE is a reasonably safe intracranial technique for v-EEG monitoring with low rates of potentially severe complications, but its indication should be carefully evaluated, especially if monitoring for more than 8 days is expected.