Abstracts

Rationale: Literature on the effects of medical marijuana on electroencephalography (EEG) is sparse and conflicting. We report the effects of medical marijuana on two patients with refractory epilepsy. Methods: We performed a retrospective review of two patients who had EEGs performed while using medical marijuana. Patient 1 is a 24 year-old woman with intractable IGE who had three studies performed over the course of 2 years. The first study was a 24-hour video EEG performed while patient was only on antiepileptic drugs (AEDs). The second study was a 72-hour EEG with mixed Cannabis sativa and indica use on days one and three in addition to traditional AEDs. The third study was a 48-hour EEG with higher concentration C. indica use on day two in addition to her AEDs. Patient 2 is a 24 year-old man with refractory IGE and left temporal epileptiform discharges who had 1 48-hour EEG while using medical marijuana in addition to his AEDs. Generalized spike-wave discharges or focal epileptiform discharges were categorized as interictal and ictal, based on duration of less than 10 seconds or greater, respectively. Only patient 1 had ictal events. The number of ictal and interictal events per hour from both patients was pooled to form a single time series, and was modeled as a time dependent function of marijuana use and patient designation using a repeated measure, 2 x 2 ANOVA. Values are reported as marginal means standard error. Time series analysis was performed for ictal events in patient 1. Results: Marijuana use significantly reduced the number of interictal events from 17.05 1.72 to 6.571.62 (p < 0.0001). The number of interictal events was significantly different between the two patients, regardless of marijuana use (10.01.36 v. 15.92.38, p=0.019; patient 1 v. 2, respectively), and use of marijuana had a greater effect on patient 2, who showed a larger reduction in number of interictal events as compared to patient 1 (Figure 1). For patient 1, regression analysis did not show a significant negative correlation between marijuana use and ictal events (p=0.075). However, time series analysis showed significant inverse correlation for marijuana use with ictal (p=0.002) events. Conclusions: These two case reports in patients with refractory epilepsy show that medical marijuana appears to have a significant effect in reducing interictal discharges, and possibly ictal events. Although a novel report, studies involving large number of patients with standardized strains of medical marijuana will be needed to further validate our findings. Funding: None