Abstracts

To describe a large pediatric surgical series with vagus nerve stimulation (VNS) at a tertiary care epilepsy center and to review morbidity and surgical safety. The charts of all children who underwent implantation of the vagus nerve stimulator between 1996 and 2005 were retrospectively reviewed. Complications were captured. Two hundred thirty children between ages 1 and 17 years were implanted in this nine-year period. The mean age was 8.4 years. Twenty-eight patients (12%) were re-implanted once and 2 children were re-implanted twice due to end-of-service.
Typically the surgeon (JB) made a 2.5 centimeter (cm) neck incision to expose the vagus nerve and a 4.0 cm chest wall incision to place the generator below the pectoralis muscle. Only minimal blood loss occurred. Epileptologists performed a lead test in the operating room (OR). There were no cases of asystole or bradycardia. The output current was set at 0.25 milliamps (20 Hz, 250 microsecond pulse width, 7 seconds on, and 0.2 minutes off) in the OR. The duration of surgery was approximately 40 minutes. Patients recieved 1 dose of cefazolin intravenously prior to surgery and 3 doses post-operatively.
The most common complication was infection. Seventeen infections occurred in 14 patients (6%), all requiring removal of the VNS. Five of these infections occurred in 2 children. Four infections were related to a inadequate sterilization of equipment by the operating room staff following a change in catheter tunneler packaging. Most infections presented within 2 weeks of surgery. All infections were due to Staphylococcus. Superficial infections (wound edge erythema) were treated successfully with intravenous or oral antibiotics. All 3 attempts to treat deep infections with intravenous antibiotics alone failed. All deep infections involving the generator pocket required removal of the device and intravenous antibiotics for 2 weeks.
There were 2 cases of temporary vocal cord paralysis. One of the cases occurred after explantation and re-implantation following an infection. Both patients recovered within 3 months.
Lead wire fracture occurred in 6 patients (3%). All patients presented with increased seizure frequency. Most fractures occurred at the level of the clavicle, and blunt trauma was the cause in all cases.
One patient with psychosis following a viral encephalitis opened her neck incision and removed the lead from the nerve. There was no nerve injury. Vagus nerve stimulation has a very low morbidity in children and should be considered early on as a treatment option for intractable epilepsy. In our series of 230 patients, infection, while rare, was the most common complication. All deep infections required intravenous antibiotics and removal of the device. Further studies would be helpful to determine the best protocol to prevent and treat infection.