Abstracts

RATIONALE: Seizure induced heart rate changes appear to show similar patterns. Heart rate change can occur before or at ictal onset suggesting it is a sensitive index of seizure activity. Unexplained tachycardia presenting to a cardiologist may be due to seizures. Quantitative measures of heart rate change in seizures have been documented. Simple algorithms to describe qualitative changes differentiating tachycardia due to seizures from that due to other cardiac causes have been infrequently reported.We analyzed temporal lobe seizures to see the relationship of heart rate change to EEG seizure onset and determine the rate of ictal heart rate change using R-R intervals. METHODS: 105 temporal lobe seizures in 39 patients during VEEG were analyzed. The time relationship of heart rate change to EEG seizure onset was determined and the slope of the seizure-induced heart rate increase was calculated in beats per minute based on the R-R. RESULTS: Heart rate increase preceded EEG seizure onset in 72% (n=76)of seizures and was simultaneous with EEG seizure onset in 9%(n=9). EEG onset preceded heart rate change in 17% of seizures. 14%(n=15)of seizures showed a heart rate decrease as the initial seizure change and 3%(n=3) showed an increase followed by a decrease. In these events(n=18)heart rate change preceded EEG seizure onset in 55%(n=10) of patients. Heart rate change preceded EEG change by a mean interval of 15 seconds(median 12 secs,range 1 to 59 secs). In the seizures with a uniform increase in heart rate at onset, the slope of the rate of increase ranged from 0.9 beats to 2.3 beats per second with a mean of 1.4 seconds. CONCLUSIONS: Heart rate change is usually the first manifestation of seizure onset and is a sensitive measure. This may be useful in VideoEEG where clinical and EEG onset of seizures may be difficult to determine which is critical in presurgical evaluations with scalp and invasive EEG monitoring. The abrupt and uniform increase seen in ictal heart rate appears specific for seizure activity and may help differentiate it from other physiological and pathological causes of tachycardia. Supported by Developmental Technology Award,#B-01-96,NCBH,Winston-Salem.