• G L Morris and W M Mueller.
• Department of Neurology, Medical College of Wisconsin, Milwaukee 53226, USA.
• Neurology. 1999 Nov 10;53(8):1731-5.

ObjectiveTo perform an open-label, long-term efficacy and safety/tolerability study of vagus nerve stimulation (VNS) of 454 patients with refractory epilepsy.MethodsSubjects were enrolled from five clinical trials of VNS between 1988 and 1995 after undergoing an implantation of a pulse generator in the chest and a left cervical vagus nerve-stimulating lead coil. Patients were assessed at 6-month intervals until device approval. Seizure frequencies, medication treatment, and adverse events (AEs) were recorded and entered into a database.ResultsA total of 454 patients were implanted, and 440 patients yielded assessable data. A > or =50% seizure reduction postimplantation occurred in 36.8% of patients at 1 year, in 43.2% at 2 years, and in 42.7% at 3 years. Median seizure reductions compared with baseline were 35% at 1 year, 44.3% at 2 years, and 44.1% at 3 years. Most common AEs postimplantation at 1 year were hoarseness (28%) and paraesthesias (12%), at 2 years were hoarseness (19.8%) and headache (4.5%), and at 3 years was shortness of breath (3.2%). Continuation rates were 96.7% at 1 year, 84.7% at 2 years, and 72.1% at 3 years.ConclusionLong-term, open-label vagus nerve stimulation (VNS) provided seizure reduction similar to or greater than acute studies, for median reductions and for those reaching a > or =50% seizure reduction. VNS remained safe and well tolerated, with nearly three-quarters of the patients choosing to continue therapy.

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