title: The "vagal ansa": a source of complication in vagus nerve stimulation.
abstract: A 16-year-old boy underwent vagus nerve stimulation for treatment-resistant multifocal epilepsy. During intraoperative system diagnostics, vigorous contraction of the ipsilateral sternomastoid muscle was observed. On re-exploration, a thin nerve fiber passing from the vagus to the sternomastoid was found hooked up in the upper electrode. Detailed inspection revealed an abnormal course of the superior root of the ansa cervicalis, which descended down as a single nerve trunk with the vagus and separated to join the inferior root. The authors discuss the variation in the course of the ansa cervicalis and how this could be a reason for postoperative neck muscle contractions.
authors.affiliation: Division of Neurosurgery, Department of Surgery, University of British Columbia and BC Children's Hospital; and.
authors.forename: Chittur Viswanathan
authors.initials: CV
authors.lastname: Gopalakrishnan
authors.forename: John R W
authors.initials: JR
authors.lastname: Kestle
authors.forename: Mary B
authors.initials: MB
authors.lastname: Connolly
mesh_terms: D000293:Adolescent; D004567:Electrodes, Implanted; D004827:Epilepsy / Q000473:pathology / Q000628:therapy; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal; D009333:Neck; D009412:Nerve Fibers; D011184:Postoperative Period; D034941:Upper Extremity / Q000294:innervation*; D014630:Vagus Nerve / Q000033:anatomy & histology / Q000502:physiology; D055536:Vagus Nerve Stimulation / Q000295:instrumentation
keywords: VNS = vagus nerve stimulation; ansa cervicalis; complication; epilepsy; peripheral nerve; vagus nerve stimulation; variation