Influence of subtraction ictal SPECT on surgical management in focal epilepsy of indeterminate localization: a prospective study.

The impact of functional imaging tests on the decision-making and planning process for epilepsy surgery has never been prospectively assessed. We prospectively evaluated 50 consecutively eligible patients whose noninvasive evaluations showed nonlocalized findings and determined how their SISCOM (subtraction ictal SPECT [single photon emission computed tomography] co-registered to MRI [magnetic resonance imaging]) data altered consensus decisions for epilepsy surgery. At an epilepsy surgery conference where each patient was discussed, consensus decisions were documented after a standardized presentation of data from the noninvasive evaluation (SISCOM findings initially were excluded). Consensus decisions were again documented after presentation of SISCOM data. Consensus decisions changed for 10 of 32 patients (31%) with localizing SISCOM results, whereas the decision changed in only 1 of 18 patients (6%) with nonlocalizing SISCOM results (P<.05). Changes in consensus decisions were as follows: (1) intracranial electrode implantation (IEI) was obviated and resective surgery was recommended (n=2); (2) resective surgery or further evaluation for patients initially not considered surgical candidates (n=2); (3) IEI in patients for whom it was not recommended initially (n=3); (4) increased IEI coverage (n=3); and (5) antiepileptic drug trial or vagal nerve stimulation was recommended instead of IEI (n=1). For some patients whose noninvasive evaluations did not clearly localize a surgical focus, SISCOM data can have a major impact on decisions to recommend resective epilepsy surgery or IEI.

Neurostimulation therapy for epilepsy: current modalities and future directions.

Neurostimulation is a recent development in the treatment of epilepsy. Vagus nerve stimulation (VNS), the only approved neurostimulation therapy for epilepsy to date, has proved to be a viable adjunctive treatment option. The exact mechanism of action of VNS is not fully understood. In 2 randomized double-blind trials, seizure frequency declined approximately 30% after 3 months of treatment. Long-term follow-up studies suggest that response improves over time, with approximately 35% of patients experiencing a 50% reduction and 20% experiencing a 75% reduction in seizure frequency after 18 months of treatment. Unfortunately, the number of patients rendered medication-free and seizure-free with VNS is low. Vagus nerve stimulation is best viewed as an option for patients who are not surgical candidates or who hesitate to take the risk of surgery yet continue to have seizures despite maximal medical therapy. Stimulation of other regions of the central nervous system for treating epilepsy, including the anterior and centromedian nuclei of the thalamus, the hippocampus, the subthalamic nucleus, and the cerebral neocortex, is currently under investigation. We review the history, proposed mechanisms of action, clinical trials, adverse effects, and future direction of VNS and other modalities of neurostimulation therapy for epilepsy.