Abstracts

Rationale: Hypermotor seizures (HMS) consist of complex movements involving proximal segments of the limbs and trunk, that appear violent and inappropriate for the situation (Lüders 1998). They are felt to be due to involvement of the orbitofrontal and mesial frontal cortices as well as the temporal lobe, basal ganglia and brainstem. We evaluated the network involved in HMS using ictal SPECT, PET and intracranial EEG (ICEEG).Methods: Videos of HMS from seizure-free epilepsy surgery patients (Engel class I) were analyzed. Ictal SPECT studies were reviewed by two readers who blindly scored the images for presence/absence of a focus of dominant hyperperfusion as well as lateralization and localization. Results were correlated with subtype of HMS, localization of the epileptogenic zone (EZ), ICEEG, and PET.Results: 116 patients with HMS were identified from our database and 33 patients underwent resection between 1996-2013. 19/33 (57%) patients were seizure free for > 6 months (mean follow up 3.4 years) and 9/19 patients underwent ictal SPECT. Five patients showed only hypermotor semiology; 2 had non-specific aura and 1 somatosensory aura progressing to focal motor semiology. Mean seizure duration was 50 s (range 21 -78 s); hypermotor phase lasted a mean of 25 s (range 9-62 s). In 7 patients (77%) hypermotor activity was seen at/within 10 seconds of clinical seizure onset. Type I HMS was seen in 6 patients, type II semiology in 3 patients (Rheims 2008) occurring in both frontal and extra-frontal epilepsy. Six patients had abnormal MRI, 3 patients were non-lesional. Five patients (55%) had frontal lobe resection, 4 (45%) patients had extra-frontal resection. Mean timing of injection was 11.7 s (range 4-27 s). Ictal hyperperfusion was seen in the cingulum(anterior and middle > posterior), orbitofrontal region, mesial frontal region, basal ganglia, brainstem, cerebellum, and in 2 patients, the temporal lobe. Four out of six patients with Type 1 semiology showed significant hyperperfusion in the anterior cingulate, orbitofrontal and anterior insula regions; 1 in the parietal lobe, and 1 in the temporal lobe. Three patients with Type II semiology showed significant hyperperfusion in the dorsal and mesial frontal regions. In addition, hyperperfusion was seen in the mesial temporal region (1 patient) and middle cingulate region (1 patient). SPECT was correctly localized and lateralized to the side of the epileptogenic zone in all patients. Seven of 9 patients had PET and 5 underwent ICEEG.Conclusions: Ictal SPECT in HMS showed involvement of a network comprising the mesial frontal lobe, cingulate, and orbitofrontal cortices. HMS semiology was also seen in seizures from the insula, parietal and temporal region. Type I HMS patients had significant hyperperfusion involved the anterior cingulate, orbitofrontal and anterior insula regions. In Type 2 HMS patients. more posterior regions were activated, including middle cingulate gyrus and temporal lobe. Subcortical structures (basal ganglia, cerebellum and brainstem) were also involved suggesting their involvement in both subtypes of HMS.