Abstracts

RATIONALE:To measure ictal heart rate changes in patients with secondary generalized tonic-clonic seizures (SGTCS) who have intractable localization-related epilepsy. METHODS:Continuous heart rate monitoring with pulse oximetery was performed in patients admitted to the video-EEG monitoring unit who had a history of SGTCS. Nine patients with 13 secondary generalized tonic-clonic seizures were evaluated. Ictal semiology as well as ictal EEG results were also evaluated. The presence or absence of supplemental oxygen administration was also evaluated. RESULTS: Of the nine patients 4 were female. Mean baseline preictal heart rate was 75 (range 60 to 98). Mean highest ictal heart rate in all the seizures evaluated was 143 (range 125 to 165). In ten out of the 13 seizures recorded the slope of the ictal tachycardia was interupted by one or more significant peaks prior to which the maximum tachycardia was acheived. In all the seizures monitored, the onset of the rise of heart rate took place prior to the motor phase of the seizure. The beginning of the second peak in eight of the ten seizures with two or more peaks began at the maximum point of desaturation and during the motor phase of the seizure. The onset of the secondary peaks were not affected by delivery of supplemental oxygen to the patient during the SGTCS. CONCLUSIONS:Intractable localization-related epilepsy with secondary generalization is associated with a significant tachycardia which in many patient represents a doubling of their baseline preictal heart rates. In a substantial portion of these patients the ictal tachycardia is composed of two separate peaks. The onset of tachycardia begins prior to the motor manifestation in these patients, suggesting a mechanism other than metabolic drive as the cause of the tachycardia. The patients with a second peak in their tachycardia had the onset of that peak during the midst of the motor manifestion and at the peak desaturation. The mechanism of this peak may be a result of metabolic drive caused by motor manifestation of the seizure.