Abstracts

Rationale: Since the approval of vagus nerve stimulation (VNS) in 1997 for the adjunctive treatment of partial-onset seizures that are refractory to antiepileptic medications (AEDS), many physicians have regarded VNS as a treatment of last resort and prescribed it primarily for patients experiencing multiple seizures. This study describes the outcomes of patients who were experiencing relatively few medically refractory seizures and received VNS. Methods: A retrospective record review of a community-based neurology practice identified and recorded results of patients with minimally intractable seizures and receiving VNS. Minimally intractable seizures were defined as seizures refractory to 2 or more AEDs and occurring about once per month or less frequently when the patient was implanted with VNS. After VNS implantation, parameters were adjusted at intervals with the goal of reducing seizure frequency Results: Record review identified 18 patients (9 women and 9 men) receiving VNS and experiencing seizures that met the criteria for minimally intractable when the patients were implanted with VNS. The baseline mean of previously ineffective AEDs was 5.2 (range 2-11). Mean age at onset of seizures was 22.5 years (range 5-60). Mean duration of epilepsy at baseline was 23.6 years (range 1-57). Mean seizures per year at baseline were 9.1 (range auras only to 13). After receiving VNS, 11 patients reported no seizures for at least 3 months to more than 2 years. An additional 2 patients who had reported no seizures later had a seizure because of non-adherence to AED regimens but again reported no seizures after resuming their AED regimens. A third patient who had reported no seizures encountered cost issues related to the AEDs and subsequently reported experiencing seizures. Of the 4 patients who continued to experience seizures after receiving VNS, one patient, who had reported 1 seizure per month at baseline, experienced 1-2 seizures per month. This patient did not adhere to treatment prescribed for sleep apnea and could not tolerate a VNS output current greater than 1.0 mA. For the other 3 patients, seizure frequency was reduced by at least half. With regard to side effects, 7 patients reported hoarseness, voice change, or occasional throat discomfort. Another patient reported a sharp sensation at the implantation site on 2 occasions and unrelated to stimulation. Conclusions: In this cohort of patients with minimally intractable seizures and who received VNS adjunctively with AEDs, 11 of 18 patients reported no seizures, and 3 additional patients reported no seizures after resuming their AED regimens. VNS may play an important role in helping patients with minimally intractable seizures attain the goal of seizure freedom.