Effects of Centro-Median Nucleus Stimulation on Interictal scalp EEG burden in LGS.

Deep brain stimulation (DBS) targeting the centromedian (CM) thalamic nucleus is an emerging treatment option for patients with Lennox-Gastaut syndrome. Ten LGS patients with CM-DBS underwent one-hour scalp EEG approximately one-month post-surgery. Following a 10-minute baseline EEG, stimulation commenced at 1V for 5 minutes, increasing in 1V increments up to 5V or until paresthesias occurred. Interictal discharges (IED) were identified by automated detection (Persyst v14c) and then screened by an expert human reader. All but one patient experienced a reduction in IED burden (31% to 100%). Eight patients were responders (at least 50% reduction in seizure frequency) and two non-responders at one year. Overall, IED burden improvement did not correlate with seizure reduction rate at one year (p=0.35, spearman rank correlation 0.3). A 50% reduction of IED burden (7/7 vs. 1/3, p=0.06) appeared to suggest a trend towards identifying responders but was not significant. This study has several limitations. The small sample size and high responder rate limit generalizability, and the short duration of EEG recording may not fully capture fluctuations in interictal activity over time. As such, our findings should be viewed as preliminary and hypothesis-generating. Larger studies with extended EEG sampling are needed to validate the clinical utility of acute EEG changes as predictive biomarkers in LGS.