VAGUS NERVE IMAGING WITH ULTRASOUND - ANATOMIC AND IN-VIVO VALIDATION

To provide the anatomic basis and demonstrate the reproducibility of u ltrasound studies far the identification of the vagus nerve within its course in the carotid sheath in the neck, cadaveric and in vivo imagi ng studies were conducted. On transverse B-mode images of the neck, th ere is a centrally hypoechoic and peripherally hyperechoic structure b etween the common carotid artery and the jugular vein inside the carot id sheath. This structure was also identified in a fresh, nonpreserved cadaver and was marked with a hypodermic needle by means of a transde rmal approach, Neck dissection was performed leaving the carotid sheat h intact, B-mode imaging yielded detailed anatomic information about t he structures in the carotid sheath, Further dissection showed the vag us nerve us the target of the needle. One hundred consecutive transver se carotid scans were reviewed, and the characteristic echo patterns o f the vagus nerve were identified in 97 instances, A distinct and repr oducible, round, hypoechoic structure was defined adjacent to the comm on carotid artery and jugular vein as the vagus nerve. On the basis of this study, a new, noninvasive, and highly reproducible method to loc ate the vagus nerve in the carotid sheath is introduced. This may lead to further clinical application such as presurgical localization or u ltrasound-guided needle studies, Stimulation of the vagus nerve has be en proposed for seizure therapy, The diagnosis of vagus nerve tumors m ay be improved.