Relationship of Ictal Heart Rate Changes During VEEG and Response to Vagal Nerve Stimulator Therapy for Epilepsy.
Abstract number :
3.219
Submission category :
Year :
2000
Submission ID :
2484
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Mathew C Wallack, Maria C Sam, Diana Balletta, Patricia Greene, Michelle Vriesma, Theresa J Long, William L Bell, Stephen S Glazier, Cormac A O'Donovan, Wake Forest University Baptist Medical Ctr, Winston-Salem, NC.
RATIONALE: Vagal nerve stimulator therapy is an effective treatment for medically intractable epilepsy. The mechanism of action is unknown and identifying patients who are likely to be good responders to VNS remains a challenge. Autonomic changes occur during seizures and vagal reflexes may play a role in seizure termination. Epinephrine has been shown experimentally to have anti-convulsant activity that is mediated through vagal afferents. We sought to deteremine if the degree of heart rate change during seizures prior to VNS inplantation is predictive of seizure reduction after implantation. METHODS: 29 patients who had undergone vagal nerve stimulator placement for intractable epilepsy who had preoperative video EEG (VEEG) and at least 6 months of follow-up were studied. Six patients in whom heart rate estimation was limited due to brief duration of seizures or generalized convulsions and four patients with moderate improvement in seizure control were excluded from this study. Nineteen patients were then divided into two groups: Group A who had greater than a 50% reduction in seizures(12 patients) and group B who had no significant change in seizure frequency (7 patients). We reviewed the VEEG to determine the percentage change in heart rate during seizures from baseline to maximum in comparing responders (Group A) and non-responders (Group B). RESULTS: In patients who responded to VNS (Group A) the mean percentage change from baseline to maximum heart rate during a seizure was 60% (median = 59%, S.D. = 24%, range = 15 to 100%). In patients who did not have a significant response to VNS the mean percentage change from baseline to maximum heart rate during a seizure was 29% (median = 27%, S.D. = 26.5, range = 1 to 85%) CONCLUSIONS: Patients who had a greater then 50% reduction in seizures with VNS therapy showed a tendency to have a greater change in heart rate during a seizure than those who did not have a significant response to VNS. Although this is a small number of patients it suggests that there are autonomic seizure profiles which may be important to elicit when contemplating VNS therapy. Further studies are neccesary.