Abstracts

Rationale: Resective surgery for refractory focal epilepsy is underutilized. While several factors likely contribute, a prominent concern both on the part of treating neurologists as well as patients is the perceived risk of surgical interventions. This concern takes two forms – one relates to risks intrinsic to a craniotomy and/or the placement of intracranial electrodes to localize the epileptogenic zone, the other relates to specific cognitive deficits that could result from resective strategies devised in each individual case. The availability of MR guided laser interstitial thermal therapy (MRgLITT) has provided a more focused surgical approach to certain types of focal epilepsies. However, in many cases, the target of such intervention cannot be defined by MR imaging or by non-invasive electrophysiology and intracranial monitoring is needed. The combination of two minimally invasive approaches – stereo-electro-encephalography (SEEG) with MRgLITT, could provide epilepsy surgeons with the ability to localize and destroy a seizure focus without the performance of a craniotomy. Here, we report on the first ever series of patients who were managed in this manner at our institution and evaluate the decision process, the surgical strategy, risks and the outcomes of such an approach.Methods: A prospectively compiled database of patients undergoing surgical interventions for medically intractable epilepsy was used to identify all patients undergoing minimally invasive procedures for their epilepsy. Demographic and seizure related data were compiled. All patients undergoing resection were followed for as long as possible and the neurological as well as the seizure outcomes were compiled.Results: Over a two-year interval, 8 patients (two female, six males) underwent localization of the seizure focus using SEEG techniques, followed then by MRgLITT using the Visualase ™ system. Mean age at intervention was 37.5 yrs (range 18-61). All patients had failed at least 2 medications prior to surgical intervention. Of the eight patients, four underwent MRgLITT of the left and one of the right hippocampus and amygdala, one underwent a traditional right temporal lobe resection followed by ablation of PVNH, one underwent PVNH ablation alone, while one patient underwent a parietal neocortical resection followed by right medial temporal ablation. Six patients have an Engel 1a outcome (ILAE class1) and two had an Engel 3a (ILAE class 4) outcome.Conclusions: We report here the rationale, the strategy and the outcomes in 8 consecutive patients managed using a strategy of minimally invasive localization and then selective ablation – this represents a paradigm shift in the management of epilepsy. While thermo-coagulation with SEEG electrodes is a similar approach, it is heavily biased to locations where the electrodes are implanted rather than targeting particular structures or networks. Additionally there is no real time confirmation of the damage zone using this approach. Such approaches may lead to a greater utilization of surgery for focal epilepsy.