Abstracts

Rationale: Epileptic seizures have been associated with changes in autonomic nervous system (ANS) function, such as variations in blood pressure, heart and respiratory rate as well as cardiac arrhythmias; especially in temporal lobe epilepsy (TLE). Electrical stimulation of limbic structures and insula may elicit changes in the cardiovascular regulatory system by exciting the central autonomic network. Likewise, increased activity ANS activity may be associated with increased frequency of seizures. Often cardiac rhythm changes may precede EEG or clinical changes at the onset of seizures by more than a few seconds. Tachycardia is more frequently seen with seizures arising from the temporal lobe, however significant ictal bradycardia (rarely leading to asystole) may also been seen. Temporal lobectomy is an established treatment modality for intractable TLE, rendering on average two thirds of patients seizure-free. Whether a surgical resection has an effect on the accompanying cardiac dysautonomia is less clear. Methods: In this retrospective study we identified patients in our epilepsy database from 1997 to 2007 who had recorded ictal cardiac dysrhythmias while undergoing electrophysiological evaluation for resective surgery. This list was then cross-matched with a cardiac database of those patients who received a pacemaker (PM). We report six patients who presented with ictal asystole and subsequent PM placement. Results: Our patients’ (50.5 ± 12.6 years) average age of onset of seizures was at 18.5 ± 5.7 years occuring as a result of head trauma, a glioblastoma, temporal MCD and in three patients of unknown etiology. All patents had TLE (3 left, 2 right, 1 bilateral). Five had an aura, although only two had a lateralizing somatosensory aura. Four had automotor seizures, two of which were preceded by a dialeptic component, the others had motor seizures. Only two had abnormal neuroimaging studies suggesting MCD and encephalomalcia, and none had evidence of mesial temporal sclerosis. Seizure frequency, as reported by patients, before PM placement was 18 ± 14.3 seizures per month, decreasing to 1.5 ± 1.4 seizures per month after PM placement. Only three patients underwent resective epilepsy surgery, and there was no change in average seizure frequency (3 ±1) post-operatively. Conclusions: Electrical stimulation studies in both animals and humans have shown effects of both cortical and subcortical structures on cardiac rhythm and their potential role in seizure-induced arrhythmias. However, there is little evidence to show an “antidromic” effect from firing of the sinus node on cerebral dysfunction. All patients responded to PM placement with a decrease in seizure burden. Interestingly, only three patients underwent subsequent surgery, one patient’s seizure burden remained unchanged. Some AEDs, such as carbemazepine and phenytoin, are known to have modulatory effects on the ANS, but these patients received neither. This case series illustrates the intricate relationship between the heart and brain in TLE, and provides the impetus to further investigate this relationship and its therapeutic potential.