Abstracts

A retrospective review of all surgical procedures at a single center for treatment of refractory epilepsy yielded 296 vagus nerve stimulation (VNS) operations. The consecutive series spans 5 years beginning in 1997 when VNS received FDA approval. Demographics, outcome and efficacy, complications, patient selection criteria, and general surgical technical descriptions are discussed.
Inclusion criteria was VNS surgery for epilepsy, for which at least one year follow up was available. This yielded 296 (24%) operations out of 1221 consecutive epilepsy procedures.of any type. The author performed all the procedures. 159 (54%) patients had only VNS surgery for the treatment of epilepsy and 138 had other forms of epilepsy surgery such as craniotomy or burr holes for survey electrodes. Average age at time of surgery was 27.1 years (+/- 14.7 years, max = 73 years, min = 1 year). 145 patients were female. 28 patients one, 24 had two, 4 had three, and 12 had 5 or more non-VNS epilepsy procedures.
There were 248 first time implants and 48 revisions that included 30 replacements for battery depletion and 19 removals without replacement. Complications included: 5 infections, 2 wire lead erosion though skin, 1 wire lead failure in a [quot]twiddler[quot], and 1 explant for side effect intolerance. Two patients experienced vocal cord paralysis from vagus nerve injury, both injuries resolving after 5 months. Two other patients sustained vagus nerve injury during electrode removal in setting of infection; one was permanent. Two other patients developed a partial vagus nerve injury beginning 48 hours after implant that resolved by 4 weeks, thought to be due to edema. 75% of implanted patients had complete followup information. For these patients the average Engel score pre and post implant was 3.89 (s.d. = 0.40) and 2.96 (s.d. = 0.80) respectively. Pre and post VNS Engle score of 1/2/3/4 were 0.7/1.3/6/92% and 7/12/58/23% respectively. Changes in score of -1/-2/-3/-4 were represented by 62/11/1/2% of patients. Seven patients experienced worsening (increase) in scores.
Our data is consistent with accepted efficacy and relative safety of VNS therapy for medically refractory Epilepsy. It also provides guidelines for expected outcome and complications. Surgery nuances and risk avoidance is discussed.