Abstracts

RATIONALE: Vagus nerve stimulation (VNS) has shown efficasy in both children and adults with refractory epilepsy. Effects of VNS on cognitive function has not been thorougly studied. Better control of seizures, need for fewer antiepileptic medications and with lower doses may contribute to the improvement of cognitive function in epileptic patients. We studied seizure outcome and neuropsychological evaluation in childhood onset refractory epilepsy following VNS. METHODS:Nine patients, aged between 12-20 years, with seizure onset ranging between one month and 8 years of age, were studied. The minumum follow up duration after VNS was three months. Six patients had symptomatic partial epilepsy, one had cryptogenic partial epilepsy, 2 had Lennox- Gastaut Syndrome. Two patients failed corpus callosotomy. All patients had cognitive and/or behavioral issues. Seven patients had a baseline neuropsychological evaluation and 5 underwent re-evaluation at 3 months. Record of seizure type and frequency was obtained during one month baseline period, and continued following implantation. At the implantation the stimulator was activated to deliver 0.25 mA for 30 seconds to repeat every 5 minutes. During follow up visits parameters were changed and medications were adjusted. RESULTS:Two patients had ~50% decrease in seizure frequency, one had ~60% decrease, and 2 had >90% decrease. Four patients had no significant change in seizure frequency, however seizure severity and duration remarkably decreased. Neuropsyhological evaluation of 5 patients at 3 months revealed significant gains in higher cortical functions in one, and no obvious change in the remaining four. Mild voice alteration was the most common side effect. CONCLUSIONS: VNS is efficacious and is well tolerated in childhood onset refractory epilepsy. Further studies are required to evaluate the long term effects of VNS on cognitive function.