Abstracts

Rationale: The University of Colorado's Comprehensive Epilepsy Center is a tertiary referral center in the Rocky Mountain region, where we have reported on an association of new onset seizures in visitors from lower elevations. Researchers from Swedish Epilepsy Center in Seattle have noted an interesting and related trend. Doherty et al. recently reported an OR=2.8 of a seizure happening if an atmospheric pressure change of 5.5 mBar occurs the same day. Through a joint collaboration, we repeated their methodology in our Epilepsy Monitoring Unit, at an elevation of 5280 feet.Methods: We retrospectively reviewed patients seen in our Epilepsy Monitoring Unit during the same time period of the original study, April 2005-April 2006. Each seizure was categorized into three groups: epileptic, non-epileptic, and other. Atmospheric pressure data was gathered from the National Oceanic and Atmospheric Administration weather station at Denver International Airport. Daily maximum, minimum, and pressure range was correlated to daily number of events per patient. Results: 151 patients were monitored, 570 epileptic seizures, 278 non-epileptic seizures, and 139 other events occurred. Preliminary results reveal epileptic seizures, and 'other' events were increasingly likely to occur with only drop in atmospheric pressure as opposed to a change in absolute pressure difference. As would be expected, and similarly to the Seattle data, non-epileptic events were not effected by pressure changes at all. Conclusions: Our preliminary findings seem to corroborate an association between atmospheric pressure and seizure frequency. While absolute pressure changes were associated with increasing seizure frequency at sea level, we found only pressure drops associated with increasing frequency in our EMU at 5280 ft of elevation. The observation that 'other' events were also effected by pressure drops suggests that these events may contain a large number of epileptic events that were not characterized by visual inspection of extracranial electoencephalography.