Abstracts

Rationale: Background: Hypermotor seizures (HMS) consist of complex movements involving proximal segments of the limbs and trunk, which appear violent and inappropriate for the situation (Lüders 1998). Rheims et al differentiated two sub-types of HMS: type I if the axis of the movement is anterior/posterior and type II if the axis is horizontal/rotational. They also attempted to correlate HMS semiology with the ictal onset zone using stereo-EEG (Rheims 2008). Objectives: To analyze videos of patients with HMS in patients with focal epilepsy who were seizure free after resective epilepsy surgery, in order to characterize their semiology, lateralizing features and localizing value. Methods: We queried our database to identify patients with HMS who had resective epilepsy surgery and were seizure free (Engel class I) for a minimum of 6 months. Four investigators jointly reviewed the seizure videos. We noted the various symptoms and signs and the order in which they occurred. MRI scans were reviewed only after video analysis was completed. Results: Search of our database yielded 116 patients classified with HMS between 1996-2013. From this subset 17/31 (55%) patients became seizure free for > 6 months (mean follow up 3.3 years). Four patients reported auras (1 somatosensory, 3 nonspecific). Fourteen patients showed only hypermotor semiology; in 3 this progressed to other semiologies. Mean seizure duration was 35 s (range 6 -91 s), of which the hypermotor phase lasted a mean of 22 s (range 3-53 s). In 16 patients (95%) hypermotor activity was seen at or within 10 seconds of clinical seizure onset. Fear was noted in 6 patients at the onset of the hypermotor phase usually accompanied by vocalizations in 11 during or after the hypermotor phase. Asymmetry of limb movement was seen in 9 (52%) patients consisting of limb posturing in 2 patients or reduced movements on one side in 8 patients - this did not show consistent pattern of lateralization. Type I semiology occurred in 6 patients, type II semiology in 10 patients and 1 patient exhibited features of both. Type I and type II semiologies were noted in patients who had frontal lobe as well as extra-frontal resections. Non-versive head and body turning occurred in 10 patients (ranging from 90^o - 270^o). It was ipsilateral to the side of resection in all patients and seen both in frontal and extra-frontal resection patients. Six out of 11 patients with abnormal MRI and 4/6 patients with non-lesional MRI, underwent invasive EEG evaluation. Eight patients (47%) had frontal lobe resection, 4/17 (23%) patients had temporal lobe resection, and one patient each had parietal lobe, insular, posterior quadrant resection or motor sparing procedure; 1 patient had functional hemispherectomy. Conclusions: Hypermotor semiology typically occurs at or within 10 seconds after seizure onset. Ipsilateral head/body turning appears to be of lateralizing value whereas asymmetry of limb movement was not lateralizing. HMS semiology is most frequently seen in frontal lobe epilepsy, but can also occur in seizures arising from other locations.