Abstracts

Rationale: Lennox Gastaut Syndrome (LGS) and Dravet's syndrome (DS) are 2 types of epilepsy that are generally refractory to multiple seizure medications and cause high morbidity and poor quality of life. Cannabidiol (CBD) is a newer therapy that has been approved to treat such patients and current studies have used subjective, patient reported changes in seizure burden as a measure of response to CBD therapy. We sought to use objective quantitative EEG analyses to establish response to CBD therapy and to help find measures to help predict responsiveness to CBD therapy in this population of patients. Methods: Fifteen patients treated with cannabidiol therapy for refractory LGS or DS were included in the study. Patient chart reviews were performed retrospectively. All patients underwent routine EEGs prior to starting CBD, after 1 month of CBD therapy and after 13 months of CBD therapy (T1, T2 & T3). We performed coherence estimates across different frequencies for all electrode pairs on these EEGs to establish synchronization measures. We then compared these measures to their outcomes to evaluate the nature and strength of these associations. Results: 10/15 patients had >70% seizure reduction with the use of CBD therapy and qualified as responders in our study. At baseline (T1), we found that future responders to CBD treatment, relative to future non-responders, showed globally higher coherence in the delta frequency band (t(189)=6.34, p<.0001). Comparing topographic patterns of coherence between T1 and T3 measurements revealed large-scale increases in coherence in the non-responder group, whereas the responder group showed greater reductions in coherence. Between-group comparisons revealed broader patterns of coherence reductions in responders relative to non-responders in all frequency ranges: delta (t(378)=-7.05, p<.0001), theta (t(378)=-2.75, p=.006), alpha (t(378)=-5.46, p<.0001), and beta (t(378)=-3.79, p=.0002). Conclusions: Refractory LGS / DS patiens generally responded positively to CBD, leading to a significant reduction in seizure frequency. Higher delta frequency coherence in patients may serve as a pretreatment marker of responsiveness to CBD therapy. CBD induced desynchronization can be objectively measured and act as a marker of improvement responsiveness to therapy in refractory LGS / DS patients. More research must be considered to study the efficacy of CBD in refractory epilepsy. Funding: No funding