Abstracts

Vagus nerve stimulation (VNS) is an alternative treatment for patients with medically intractable and inoperable seizures. VNS experience is still small in children below age12 years. We report our single-institution experience with 43 children [lt] 12 years undergoing VNS implantation. We performed a retrospective/chart review of 43 children (24 boys) younger than 12 years at the time of VNS implantation with [gt] 6 months follow up. Institutional Review Board approval was obtained. All patients had medically refractory epilepsy and were not candidates for resective surgery based on MRI and EEG data. Parents were notified that VNS is not approved by the Food and Drug Administration for this age group and consent was obtained. Pre- and post-implantation seizure frequency, antiepileptic drugs (AEDs) and seizure type were recorded. An average of the seizure frequency of [ge] 2 months prior the clinic visit was recorded. The VNS was turned on approximately 2 weeks after surgery. Subsequent ramping up of the current (every 2 weeks) was based on clinical response and tolerability. The mean duration of follow up after implantation was 18 months (range 7 [ndash] 40 months). The mean age at implantation was 8 years (range 2.6 [ndash] 11.9 years). Average age of seizure onset was 23.6 months (range 1 [ndash] 89 months). Prior to VNS an average of 5.6 +/- 2.6 AEDs (range 2 [ndash] 13) were used. Twenty patients had generalized seizures, 8 had partial seizures, and 15 had mixed. The pre-implantation median seizure frequency was 105/month (range = 1 [ndash] 16,200). The average duty cycle was 30 seconds off and 3 minutes on (time) and average output was 2.00 milliamperes. The median seizure reduction was 84% (mean = 129/month, range 0 [ndash] 1146). Seizure reduction tended to improve between 6-18 months post-implantation. The median seizure reduction in relation to the follow up duration groups was 33% for [lt] 12 months (5 patients); 55% for 12-17 months (16 patients) and 42% for [underline][gt][/underline] 18 months (22 patients). Thirteen patients had [lt] 50% response and 8 (19%) patients had a mild increase in seizure frequency. Efficacy ([underline][gt][/underline] 50% seizure reduction) did not seem to depend on seizure type. No patient who initially responded to VNS demonstrated increased seizures at subsequent follow-up visits. There were 4 short term complications (6%): two infections (3%) required explantation; one patient developed worsening of respiratory symptoms (1.5%) which later resolved; and, one patient experienced device failure (1.5%) due to a loose connection. VNS is an effective add-on therapy for medically refractory seizures in children below age 12 years seizures that improves over time. Consideration should be made to have this modality approved for this age range.