Abstracts

Rationale: The interest and controversy around the medical use of cannabis as treatment for epilepsy has increased in the last decade.  While there is some anecdotal evidence that certain strains of cannabis may have anticonvulsant properties and research on cannabidiol (CBD) is ongoing, there have also been several case reports on cannabis-induced seizures. Despite the different notions all current literature uses seizure frequency and freedom as the primary outcome, which is either reported by the patients themselves and/or their caregiver(s) and therefore rather subjective. We report the first case that shows the potential effect of regular cannabis consumption on epileptiform activity objectively measured by the Responsive Neurostimulation^®(RNS^®) device in a patient with bihemispheric independent, mesial temporal lobe epilepsy. Methods: A 38-year-old man with medically and VNS-refractory, multifocal, bihemispheric independent epilepsy as a result of a biking accident at age 13 had the RNS^®device with bilateral, mesial temporal depth electrodes implanted following the confirmation of the epileptogenic zones utilizing stereo-EEG. Post-implantation the patient continued the habit of smoking cannabis on a regular basis, which reportedly resulted in improved seizure control prior to implant of the RNS^® device.The difference in epileptiform activity registered by the RNS^®device during periods with and without daily cannabis consumption was evaluated for each time frame, during which the RNS^® detection and stimulation parameters were kept constant. The mean daily and overall mean epileptiform activity were calculated for the four RNS^® programming periods.  A one-sample t-test was used to compare the average daily epileptiform activity to the overall average of activity for each period. Results: The changes in epileptiform activity was followed for six months post RNS^® implant. The patient regularly consumed cannabis during the first half of each calendar month. Due to lack of documentation we were unable to control the results for strain of cannabis or the exact quantity and timing of cannabis consumption. During all four RNS^® programming periods there were more days with significant reduction of epileptiform activity during periods with daily cannabis consumption than without (Figure 1). During three of four RNS^® programming periods there were either more days with significantly less or no seizure activity during periods with daily cannabis consumption than without (Figure 2). Conclusions: This is the first case report showing potentially objective evidence for a positive impact of regular cannabis consumption on epileptiform activity in a patient with medically and VNS refractory, bitemporal independent epilepsy.    Funding: There was no funding support for this abstract.