Atmospheric pressure and seizure frequency in the epilepsy unit: preliminary observations

To demonstrate that seizure frequency in patients undergoing video EEG telemetry does not correlate with atmospheric pressure (AP) changes.

Historical automated AP data from weather stations in the Seattle Metropolitan area were correlated to seizure frequency and type in consecutive patients undergoing video EEG telemetry at our institution from April 2005-April 2006. Daily maximum, minimum and range of atmospheric pressures were correlated to daily number of events (seizures, pseudoseizures, unknown) per patient. Alternatively, whether or not events occurred during a change of greater or less than 5.5 mBar per day were used to evaluate odds ratios of events occurring.

Of 191 patients, 96 were diagnosed with epilepsy, 60 with pseudoseizures, and 40 had different diagnoses. A total of 159 seizures, 59 pseudoseizures, and 40 unknown events occurred. No correlation between daily mean, maximum or minimum pressure change with seizure or other event frequency was seen. With increased daily AP range an increase in daily seizure per known seizure patient occurred (P = 0.03). Patients with known epilepsy showed an OR of a seizure occurring of 2.80 (95% CI 1.22-6.42 P = 0.02) if pressure changed more than 5.5 mBar that day.

Surprisingly, in patients with known epilepsy, increased seizure frequency occurred with changes in barometric pressure, particularly over 5.5 mBar range per day. Speculative mechanisms of AP change on seizure susceptibility are discussed.