Changes in a measure of cardiac vagal activity before and after epileptic seizures

In previous studies of the relationship between the cardiac autonomic activ ity and seizures, assessment of autonomic changes has relied on alterations in heart rate or R-K intervals. We have used a recently developed continuo us index of cardiac parasympathetic activity (CIPA) to examine 20 seizures in 10 patients during pre-surgical evaluation in a video-telemetry unit. Th e patients had localization related seizures due to non-progressive patholo gy and both complex partial seizures (CPS) and complex partial with seconda ry generalised tonic clonic seizures (STCS) were examined. Mean CIPA prior to the onset of STCS was elevated above normal values and fell significantl y to previously established normal values following the seizure. CPS were n ot associated with elevated mean CIPA pre-or post-seizure. STCS were associ ated with a reduction in anti-convulsant dosage and with elevation of pre-i ctal CIPA. We propose that elevation of cardiac parasympathetic activity pr e-ictally may be a marker for secondary generalisation of seizures. (C) 199 9 Elsevier Science B.V. All rights reserved.