Vagal nerve stimulation (VNS) is indicated in cases of epilepsy which are refractory to medical treatment. Under general anesthesia, a left cervical incision is made to expose the vagus nerve. Electrodes are then placed over the nerve and connected to a generator which is inserted to a subclavicular skin pocket. The procedure is safe, well tolerated and effective.
19 Vagal Nerve Stimulation
Approximately one-third of all patients with epilepsy will suffer from refractory seizures despite optimal antiepileptic drug therapy, or they will experience unacceptable side effects of their medications. 1 In July 1997, the US Food and Drug Administration (FDA) approved the use of intermittent stimulation of the left vagal nerve “… as adjunctive therapy in reducing the frequency of seizures in adults and adolescents over 12 years of age with partial onset seizures which are refractory to antiepileptic medications.” 1 Since then, VNS has been used as an effective treatment for medically intractable seizures. The elaboration of indications to include children younger than 12 years has gained popularity during the past decade, with mounting evidence demonstrating the procedure as being safe and effective. 2 – 5 Coykendall et al. 6 concluded that VNS treatment is safe in young children, with a reported efficacy surpassing 50% in reducing frequency of attacks. The procedure is well tolerated and was reported to carry a low complication rate. 7 There is as yet no consensus regarding the mechanism of action of VNS, but it most probably acts at multiple sites. 8 Alternating synchronization and de-synchronization of electrical activity may reflect the mechanism of action of VNS in achieving seizure control. 9
19.2 Preoperative Evaluation and Anesthesia
Preoperative antibiotics are administered (first-generation cephalosporins) intravenously. A short-acting muscle relaxant is used for the procedure. General endotracheal anesthesia is performed. The patient is placed in the supine position. A shoulder roll is placed to allow for head extension. The patient’s head is turned to the right and the surgical field is scrubbed and draped (▶ Fig. 19.1).