Abstracts

Rationale: Vagal Nerve Stimulation (VNS) therapy is an adjunctive treatment for patients with intractable epilepsy (IE). Evaluation of efficacy and safety of VNS in treatment of patients with intractable epilepsy not candidates for epilepsy surgery. Methods: Prospective clinical follow-up of patients treated with VNS for IE. Inclusion criteria includes patients with intractable epilepsy not candidates for epilepsy surgery i.e. those with more than 1 disabling seizure/month despite adequate antiepileptic drugs AEDs for at least 2 years. The patients should have failed at least 2 AED trials. Each patient should have documented seizure frequency before VNS implantation and every 3 months after VNS implantation. The minimum follow up period is 6 months. The safety is measured by number and type of adverse events appeared each visit during the post implantation follow-up. The efficacy is measured by the number and percentage of patients that show significant seizure reduction post implantation. Results: A total of 44 patients with IE were implanted with VNS from December 2006 to December 2011. Only 40 patients were included in this evaluation, 12 males and 28 females. Age of the patients ranged from 10 to 37 years with average age onset at 4 years. Average epilepsy duration before VNS implantation was 10 years. Epilepsy type included 28 patients with focal epilepsy and 12 patients with generalized epilepsy. In the focal epilepsy group 8 patients had frontal lobe epilepsy, 2 had temporal lobe epilepsy, 8 had parieto-occipital epilepsy, 7 had multilobar partial epilepsy and 3 had unclassified partial epilepsy. In the generalized epilepsy group 8 patients had Lennox Gastaut Syndrome, 3 had Unverricht Lundborg Disease and 1 had Juvenile Neuronal Ceroid Lipofuscinosis. The average seizure frequency was 1 generalized tonic clonic seizure per week before VNS. At the time of VNS implantation 16 patients were on 3 AEDs, 16 patients on 2 AEDs and 8 patients on 4 AEDs. At latest follow-up, 32 patient (80%) showed significant improvement (>50% seizure reduction). Four patients (10%) showed less improvement (<50% seizure reduction) and 4 patients (10%) showed no improvement. A trend towards better seizure control with low current output - high frequency stimulation. No serious adverse event encountered. All 40 patients had transient hoarseness and throat irritation and 35 patients had cough. Less common adverse events in 6 patients (15%) with refractory focal status epilepticus post operative (1) patient, superficial infection (1) patient, sagging of the device (1) patient, malfunction of the wire (1) patient, transient recurrent aspiration (1) patient and aspiration pneumonia and adult respiratory distress syndrome post operative (1) patient. Conclusions: VNS is efficient and safe adjunctive antiepileptic therapy in patients with intractable epilepsy not candidates for epilepsy surgery.