Abstracts

Rationale: Pre-surgical evaluation in patients with intractable complex motor and hypermotor seizures can be challenging as movement artifact and rapid seizure spread often precludes from lateralization or localization with surface EEG, thus necessitating SEEG explorations. The notion that hyeprmotor seizures are pathognomonic of frontal lobe epilepsy has been challenged recently with data demonstrating insula or temporal lobe in generating seizure that has similar complex motor semiology. In this setting, stereo-electroencephalography(S-EEG) might be advantageous over conventional grids as it allows three-dimensional exploration of superficial and deep cortex over a larger area without requiring craniotomy. Here we report our experience of SEEG exploration in patients with difficult-to-localize sleep-related complex motor intractable seizures.Methods: We performed a five-year (Jan 2009- April 2014) retrospective analysis of consecutive S-EEG evaluations in adults and children (less than 18 years-old) at a level-IV epilepsy center. Only patients with complex motor (CMS) and hypermotor seizures were included in. CMS were defined as abrupt onset, complex movements simulating natural but inappropriate movements for the situation. Hypermotor seizures which were defined as repetitive, high amplitude, hyperkinetic complex movements involving the proximal segments of the limb and trunk such as pedaling, pelvic thrusting, rocking. The history of seizure predominance during sleep obtained from chart review and as classified by the clinician. Demographics, characteristics, complications related to S-EEG and epilepsy surgical outcomes were analyzed. For the seizure outcome analysis, patients with a minimum follow-up of 6 months following resection were included and Engel outcome classification was used. The study was approved by IRB.Results: Nineteen patients (7 female) with a mean age of 34 (range 16-58 year) underwent S-EEG evaluation in the five-year period. Among 19 patients with 272 electrodes implanted : 11 had bilateral implants, 4 had high-density implants in caged fashion and 3 had multiple staged S-EEG exploration. All but three underwent implantation over multiple contiguous brain regions (few illustrations in Fig 1) : frontal (pre-frontal, orbito-frontal, centro-median ), cingulate cortex (anterior and posterior), insula (anterior and posterior), temporal (mesial, lateral, temporo-occipital) and parietal. Seizure-onset zone was identified as: 7 (37%) in frontal, 9 (48%) in temporal and 1 in parietal. In two patients seizure-onset zone was not identified. Epilepsy surgery was subsequently performed in 15 patients (7 frontal, 7 temporal, 1 parietal). Overall, 72% of patients had Engel I outcome after a minimum of 6 months follow up. Complications of S-EEG were: 5 (27%) had intracranial hemorrhage as detected by CT brain.Conclusions: Mapping seizure -onset zone for complex motor and hypermotor seizures are challenging, often requiring bilateral multi-lobar SEEG exploration that had complications. Nevertheless, seizure freedom after resective surgery can be achieved.