Abstracts

Rationale: Vagus nerve stimulation (VNS) was approved by the Japan Ministry of Health, Labor and Welfare in 2010. The Japan Neurosurgical Society, the Japan Epilepsy Society, and the Japanese Society for Epilepsy Surgery created the VNS Committee in order to verify and approve neurosurgeons and epileptologists to perform VNS for patients with medically refractory epilepsy. There is a strict regulation in our country in terms of privileges and a guideline to perform VNS. As an example, neurosurgeons who are responsible to perform VNS implantation, they must have the dual certificate by the Japan Neurosurgical Society and the Japan Epilepsy Society. Then the VNS Committee requests neurosurgeons to attend the training session before they perform VNS implantation in practice. Although some neurosurgeons are very familiar with anatomy of the cervical region, others do not have enough experience to expose the neck even if they take the training session. ENT surgeons know anatomy of the neck very well. However, ENT surgeons are not allowed to carry out those implantations in Japan. Therefore it is essential to demonstrate and share the technique and pitfalls in VNS implantation.Methods: The most important thing in the beginning is positioning of patients. The neck should be well extended to make the vagus nerve exposed more easily. We normally introduce a microscope from the skin incision instead of surgical loupes. Then we dissect along the inner surface of the sternocleidomastoid muscle. The vagus nerve is usually found between the carotid artery and the internal jugular vein surrounded by the carotid sheath, sometimes deep in the sheath. That causes exposure of the vagus nerve more complicated. However, exposure by a microscope makes the operative field bloodless and clean, because a microscope shows small and tiny vessels more clearly for preservation. After the vagus nerve is well dissected from the carotid sheath, helical electrodes are placed around the vagus nerve under the microscopic magnification. Skin incision for a generator is normally placed anteriorly to the axilla. Insertion of a generator is occasionally under the major pectoralis muscle especially in small children for cosmetic reasons.Results: We have carried out 65 cases of VNS implantations since we started the treatment in December 2010. A procedure usually takes an hour and a half from skin incision through closing. Sixty-one out of 65 cases did not show any perioperative complications. We had two cases of vocal cord paralysis (3%) and two cases of cough and hoarseness (3%) that gave some influences in QOL. These complications were temporary and there was no permanent morbidity. Surgical site infection did not happen in these consecutive cases.Conclusions: VNS implantation is safe and does not make any serious or permanent morbidities even for children as well as chronic treatment by VNS itself. Then VNS should be recommended when cranial surgery is not indicated after full evaluation including video-EEG monitoring and imaging studies.