Abstracts

Rationale: The SANTE trial showed anterior thalamus (ANT) stimulation can reduce seizure frequency by over 70%. Variance in treatment response may be partly explained by electrode engagement with the mammillothalamic tract. However, we suggest that the standard duty cycle periodic (145 Hz) pulse pattern (PP) may not be optimal for seizure suppression in all patients. We evaluated the effects of a non-periodic pulse pattern (NPP) ANT stimulation on epileptic biomarkers and cortical excitability measures in combined seizure onset and irritative zones (SOZ).


Methods: Four patients were consented and participated in an IRB approved ANT stimulation protocol during stereo-EEG evaluations. PP and NPP were delivered to the ANT (two left, two right) at two current levels (3mA and 0.5mA). Stimulation was flanked by no-stimulation periods and cortico-cortical evoked potential (CCEP) acquisition. High frequency oscillations (HFOs) and epileptic spikes were detected and described as events per minute [1,2]. Significant modification of these rates with stimulation was evaluated at each channel (KS-test comparison before therapy and after stimulation condition; p< 0.05) and region-wide (ANOVA with pair-wise comparison (PWC) before therapy and after stimulation; p< 0.05). CCEPs were tested for significant response using canonical response parameterization [3] with significant modifications evaluated by latency (t-test comparison between pre and post stimulation distributions at discrete timepoints; Bonferroni corrected per-patient for number of channels C; p< 0.05/C).