Abstracts

RATIONALE: Seizures can produce a wide variety of autonomic alterations. These alterations may occur by evoked autonomic reflexes or as a direct cortical effect on autonomic control. Investigators have shown in animals a link between interictal discharges and changes in autonomic output. However, the association of interictal discharges and autonomic output is not as well established in humans. METHODS: To evaluate the potential influence of interictal discharges on the autonomic regulation of the cardiac cycle, we compared the two R to R intervals just preceding and following interictal discharges in 32 patients with epilepsy (20 left sided, 12 right sided discharges). Patients were recorded in the awake state in the supine position. Changes in the R to R interval greater than 10 msec were considered significant. We compared the two groups (left verses right sided) utilizing a student t test. RESULTS: We found that in 13 of 20 patients with left sided discharges, the R to R interval immediately following the interictal discharge shortened compared to the pre-discharge intervals, whereas, 5 of 20 patients had prolonged of the post-discharge intervals. We also found that 8 of 12 patients with right sided discharges, had prolongation of the R to R interval immediately following the interictal discharge, whereas, 2 of the 12 patients had shortening of the R to R interval. We found no consistent differences between frontal verses temporal localization of the interictal discharges from the same side. CONCLUSIONS: These findings suggest that interictal discharges, in some patients, may influence autonomic control over the cardiac cycle and agree with animal studies demonstrating a direct effect of interictal activity on autonomic output. Further study of the relationship of interictal discharges to autonomic output is needed to delineate the potential lateralized influences over autonomic nervous system.