Abstracts

Except in case of Mesial Temporal Lobe Epilepsy Syndrom (MTLE), and despite their more recent refinement, the noninvasive techniques still often fail to clearly localize the epileptogenic zone in a large number of patients presenting with drug-resistant temporal lobe epilepsy. Different techniques of intracranial recordings are currently available. StereoElectroEncephaloGraphy (SEEG), which consists in the stereotactic orthogonal implantation of depth electrodes (5 to 15, 11 on average) into the brain, is the only one allowing to record the mesial as well as the lateral aspects of the temporal lobe, including the depth of the sulci. The object of this paper is to display the curent usefulness of SEEG in terms of surgical strategy related to temporal resection, in 100 consecutive procedures., 100 patients, suffering from drug-resistant epilepsy arising from a temporal onset, underwent a SEEG procedure between 2000 and 2005. For each of these patients, the non invasive investigation, which included clinical and neuropsychological examination, long-term video-EEG recording, functional imaging, and MRI scan, were not in favor of a MTLE syndrom, and were not congruent enough to clearly identify the epileptogenic focus. Consequently, the sites of implantation of the electrodes were chosen in order to precise: either the side of the onset of seizures, or their uni or multilobar feature, or a possible strictly neocortical or insular onset of the seizures, and also, using direct electrode stimulation, the proximity of speech area., Complications occurred in 3 patients (1 superficial infection, and 2 breakages of electrodes).
- SEEG was helpful in most (91%) of the 100 patients to confirm, or cancel, surgical indication, and to adjust the extent of the resection :
- In 33% of cases, SEEG-recordings led to an indication of a strictly extra-limbic lobectomy, i.e. a tailored (temporo-basal or lateral) neocortectomy sparing the temporo-mesial structures.
- In 20% of cases, SEEG led to a limited limbic resection, which included the amygdala, as well as the pole, while sparing most of the (non-atrophic) hippocampus.
- In 25% of cases, SEEG allowed to plan an enlarged temporal resection, despite the fact that it showed a wide, or even multiple, epileptogenic zone.
- In 13% af cases, SEEG allowed to definitly exclude the patients from surgery.
- In 9% of cases, SEEG confirmed the indication of a conventional limbic resection (anterior temporal lobectomy)., SEEG proved to be a safe and a very useful method for complex cases
candidate for temporal lobe epilepsy surgery. It should be considered as soon as the non invasive investigation do not display a clear MTLE syndrome.,