Abstracts

RATIONALE: To investigate the heart rate in patients with otherwise subclinical seizures in relation of the localization of the epileptogenic zone.
METHODS: We reviewed the data base of our Epilepsy Monitoring Unit for the term [dsquote]subclinical seizure[dsquote] in all patients with focal epilepsies. The term subclinical seizure was defined as EEG seizure pattern, which was not associated with any disturbance of consciousness, sensory phenomena or motor functions. 22 patients (10 male, 12 female) were identified, in whom ictal EEG and videos could be retrieved for analysis. Heart rate before and during the EEG seizure pattern was analyzed in these patients and correlated to localization and duration of the seizure patterns. Heart rate was calculated from RR distances in the ECG channel. Heart rate was plotted depending on time. Responding curves were fitted to calculate the point of maximum velocity of heart rate increase. Increase of heart rate greater than 1.8 times and an increase of velocity greater than 50% were considered significant.
RESULTS: Of the 22 patients with subclinical seizures, 13 patients had temporal and 9 patients had extratemporal seizure patterns (frontal n=8, occipital n=1). Ictal heart rate increase greater than 50% was observed more often in patients with temporal EEG seizure patterns (61%, 8 of 13) than in those with extratemporal seizure patterns (11%, 1 of 9) (p[lt] 0.018). There was no correlation between duration of seizure patterns and change of heart rate (Mann-Whitney-Test, p=0,261) or lateralization of the EEG pattern. There was no significant decrease of heart rate during seizures.
CONCLUSIONS: We conclude that pure ictal tachycardia can be induced by spread of epileptic seizure activity to the temporal cortex and is not secondary to physical or psychic stress factors during seizures. Our findings support cortical representation of autonomic function such as heart rate in the temporal lobe region.