Abstracts

Rationale: Stereo-electroencephalography (sEEG) has been proved as a safe and effective modality of defining seizure onset zone with precision and less-invasiveness compared to subdural electrodes placement requiring open craniotomy. Stereotactically-placed depth electrodes record signals better from depths of sulci and regions of cortex such as the insular cortex, orbitofrontal cortex, cingulate gyrus, and basal temporal cortex. However, the limitation of functional mapping of sEEG has been considered because a contiguous mapping of the superficial cortex is not available in contrast to subdural electrode-based mapping. This study aimed to describe our experience in the functional mapping technique and capacity of sEEG to localized motor function area in young children. Methods: Three patients underwent sEEG monitoring and cortical stimulation for motor mapping as a part of the treatment for medically intractable neocortical epilepsy at Children's Healthcare of Atlanta (CHOA) Comprehensive Epilepsy Center in 2016. Cortical stimulation was performed using biphasic square-wave pulses of constant current stimuli in a bipolar fashion. Two different stimulation protocols were applied as low frequency stimulation (3 mA current, 2 Hz frequency, 20 seconds duration) and high frequency stimulation (1-3 mA, 50 Hz, 5 seconds), which were modified from the protocol of Sainte Anne Hospital, Paris, France. Results: Median age was 5 years (5-8 years) at sEEG monitoring and 3 years (5 months- 6 years) at seizure onset. Median duration of epilepsy was 2 years (2-4.5 years). Median numbers of electrode contacts were 180 (110-180). Median duration of sEEG monitoring was 12 days (7-21 days). All were tolerable to monitoring and cortical stimulation. All 3 patients had symptomatogenic zones over primary or supplementary motor areas. Two patients had seizure onset zone in anterior parietal region close to primary motor cortex and 1 patient had seizure onset zone in orbitofrontal and fronto-polar regions. Each case will be depicted as figures. Conclusions: Monitoring and functional mapping with sEEG was safely performed in young children. The currently used cortical simulation provided the accurate information on the function of depths of sulci. sEEG allowed us to evaluate the 3-dimensional relationship between seizure onset zone and motor function areas, which might not be available from subdural electrodes-based mapping over the superficial cortex. Funding: None