Abstracts

Vagus nerve stimulation (VNS) is an effective treatment option for specific patients with medically refractory epilepsy. The generator component is typically implanted in the subcutaneous space of the superior left chest region. Cosmetic and mechanical concerns especially in children and aesthetic adults were addressed with an alternative implantation of the generator. We report a series of VNS cases in which the generator was inserted into a subpectoral plane between the pectoralis major and minor. Merit of this surgical modification was assessed by comparing a subpectoral VNS population to a subcutaneous control group. We retrospectively reviewed and compared demographics, complications, and side effects, from patients receiving either subcutaneous (SQ) or subpectoral (SP) VNS implants, performed by one neurosurgeon from 1999-2003. Selection of implant location was made during the preoperative surgeon-patient consultation based on patient preferences and surgeon recommendations. There were 107 SP implants in 106 patients; 55 patients (51.9%) were female. Median age was 19 years (95% CI, 15 to 23; range 2-72 years). Thirty-one SP patients (29.2%) were younger than 12 years. The SQ group was comprised of 138 implants in 138 patients; 66 (47.8%) were female. Median age was 29 years (95% CI, 25 to 32; range 6-73 years). Nineteen SQ patients (13.8%) were younger than 12 years. In the SP group, there were 4 infections occurring in 3 patients, or 2.8% per patient. In the SQ group there were 4 infections, or 2.9% per patient. Average follow up times for the SQ and the SP groups were 52.0 months and 28.4 months, respectively. Infections tended to present longer after implant in the SP group than the SQ group.
An additional 16 patients (including seven from the control SQ cohort) were revised from a previous SQ to SP placement. Including these patients, overall infection rate per SP patient was 2.5% (3.3% per implant). In at least three patients within this group, specific complaints of pain and/or looseness of the generator contributed to the decision for SP conversion. One planned SP patient was converted to a SQ implant due to obesity that compromised telemetry with the generator when it was SP. This patient was included in the SQ group. There were no intra-operative complications in either group. The subpectoral VNS implant is an acceptable alternative to standard subcutaneous implants. Compared to the SQ group, our SP population was younger and had a slightly higher female ratio; the SP group also had more co-morbidities, which may reflect the surgeon[apos]s selection bias. Advantages of the SP implant include: cosmesis and protection from mechanical complications such as migration and pain. SP implantation offers broader utility in the younger population. Infection rate of SP is comparable to SQ implants. Surgical technique and recommendations for appropriate patient selection are discussed. (Supported by Fight Against Childhood Epilepsy and Seizures)