Abstracts

Rationale: Vagus nerve stimulation (VNS) is an FDA approved treatment for refractory epilepsy patients in children 12 years and older. About 50 VNS surgeries are done annually at the Children's Hospital of Pittsburgh of UPMC. VNS related complications are generally low, ranging from 3 to 10 %. Children of young age and presence of cognitive impairment have been suggested as risk factors for VNS related complications. The goal of this study is to review our most recent cases and identify potential risk factors for complications. Methods: The authors retrospectively reviewed the charts of patients 21 years of age and younger who had VNS surgeries between November 2011 and April 2014. Two Pediatric Neurosurgeons performed all the procedures. Patients with less than 3 months post VNS implantation and patients with no follow up visit with a neurologist were excluded from the study. Quantitative methods were used for data analysis. Results: A total of 168 patients had VNS surgery during the study period (male 95); and 156 of those had sufficient follow up data for analysis. The median age at surgery was 10.9 years (1.7 y - 20.6 y in 76 patients with first time implant, 13.1 years (5.7y-20.3y) in 62 patients with 2nd time procedure due to battery replacement, 16.3 years (8.7y-21.7y) in 23 patients with 3rd time procedure (battery replacement or post complication). Two patients had VNS surgery for the 4th time for battery replacement and were 10.4 years and 20.4 years respectively. Median follow up after the VNS surgery was 5.5 months. Complications were seen in 21/156 (13%). No patient had recurring complications. Of these, 14/21 were due to infection and 16/156 (10%) patients had VNS removed. Two cases of infections were managed with aggressive antibiotics treatment and did not require removal of VNS. Non-infectious complications were 5/156 [(3%) vocal cord dysfunction, local site discomfort, lead fracture or battery malfunction]. Autism/Intellectual disability was present in 107/156 (68%) patients and was present in 16/21 (76%) patients with complications. Most complications [17/21 (80%)] occurred within the first 2 months of VNS procedure (range ~ 1 week to 15 months). No statistically significant association was present between complication rate and age (p= 0.93), gender (p=0.2), autism/ID (p=0.6) or number of surgery (p=0.17). Conclusions: This study describes the characteristics of complications seen at a busy VNS surgery center. Typically considered risk factors such as age and presence of autism/intellectual disability were not associated with a higher complication rate. Our patient population was younger than most other centers and also had relatively high rates of autism/intellectual disability. As infection is the most common complication seen in our series, close surveillance for signs of infection in the immediate and early postoperative periods may allow for early identification and prompt treatment of infection so that device explant is not required.