Epilepsy is a chronic disease of the central nervous system characterized by recurrent unprovoked seizures. Up to 30% of patients continue to have seizures despite treatment with appropriate anticonvulsant medications. The presence of abnormal oscillatory events within neural networks is a major feature of epileptogenesis. The endocannabinoid system can modulate these oscillatory events and alter neuronal activity making the phytocannabinoids found in Cannabis a potential therapeutic option for patients with treatment resistant epilepsy. Many in vitro and in vivo studies have demonstrated the anticonvulsant effects of several phytocannabinoids including Δ 9-tetrahydrocannabinol (Δ 9-THC) and Cannabidiol (CBD). Several small observational studies demonstrated a favorable response to cannabis herbal extracts (CHE) containing high concentrations of CBD in children with treatment resistant epilepsy. Two large double blinded clinical trials assessing the efficacy of pharmaceutical grade CBD have also been performed in children with treatment resistant seizures in Dravet syndrome and Lennox-Gastaut syndrome. Both studies demonstrated an improvement in seizure reduction in children taking CBD as compared to the placebo groups. To date there is very limited data regarding the use of cannabis based products to treat adult patients with treatment resistant epilepsy with only one randomized double blinded placebo controlled clinical trial underway.

Background: About 35% of patients with epilepsy may develop drug-resistant epilepsy (DRE). Identifying risk factors associated with DRE will allow us to identify earlier patients in the course of the disease. Methods: This is a case-control study nested within a cohort. Chart reviews of subjects who full fi ll inclusion criteria were completed. Inclusion criteria included age > 18 years, focal epilepsy determined by clinical correlation and EEG. DRE was determined by ILAE criteria. Results: 149 subjects were included. Seventy had DRE (cases), and seventy-nine did not have DRE (controls). DRE group had a mean age of 41 years (SD + 14.8) compared to the control group (49 + 17.5) (p=0.003). DRE group had a mean age at diagnosis of epilepsy of 19 + 15.3 compared to the control group with a mean of 33.6 + 21. (p=<0.001). The main risk factors identifi ed in this study were; cortical dysplasia OR 8.67 (CI 1.04-72.3, p= 0.026); mesial temporal sclerosis (MTS) (OR 2.69; CI 1.12-6.47; p= 0.024); and presence of complex partial seizures (OR 2.04. Conclusions: Young age at diagnosis of focal epilepsy, diagnosis of cortical dysplasia, MTS, and presence of complex partial seizures are risk factors for DRE P.023