Knowledge of Anatomical Relationships of the Vagus Nerve with Internal Jugular Vein and Common Carotid Artery in the Neck Necessary for Vagus Nerve Stimulation (VNS) Surgery

Abstract

A precise understanding of the anatomy is essential to perform vagus nerve stimulation VNS therapy for refractory epilepsy. We evaluated the anatomical relationships of the cervical vagus nerve with the carotid artery and jugular vein on the basis of findings during VNS surgery. We investigated the anatomical relationships among the vagus nerve VN , common carotid artery CCA , and internal jugular vein IJV in 73 patients who underwent VNS surgery at our hospital from December 2010 to January 2015, classified the position of the VN into 5 categories, and studied the frequency of each category. The position of the VN was medial to the IJV and ventral to the CCA type 1 in 8 patients 10.9 , medial to the IJV and lateral to the CCA type 2 in 4 5.5 , dorsomedial to the IJV and ventral to the CCA type 3 in 51 70 , dorsomedial to the IJV and lateral to the CCA type 4 in 7 9.5 , and dorsal to the CCA type 5 in 3 4.1. This report is the first to propose a classification of the anatomical relationships of the VN with the CCA and IJV based on intraoperative findings. According to this classification, the difficulty of VNS surgery increases with advances of the type. Type 3 was the most frequent, and types 2 and 5 were rare. Understanding the variation in the position of the cervical vagus nerve is considered to contribute to safer surgical manipulations in VNS surgery.

Vagus Nerve Visualization Using Fused Images of 3D-CT Angiography and MRI as Preoperative Evaluation for Vagus Nerve Stimulation

“…The ultrasonographical study demonstrated that vagus nerve variation is seen in 5.5% of 326 cases, and the vagus nerve runs dorsal to the CCA after it changes the course in 1.2% of cases [ 5 ]. Regarding the VNS, a previous study reported that the anatomical relationships between the vagus nerve and the blood vessels, including the IJV and the CCA, are classified into five patterns [ 3 ]. Accordingly, a type in which the vagus nerve is located dorsal to the CCA was seen in 4.1% of 73 cases.…”

“…Moreover, 3D-CTA requires radiation exposure, which can be the biggest disadvantage of this technique. Because previous studies indicated that the vagus nerve location was detectable by ultrasonography [ 3 , 5 , 6 , 7 ], it may be considered to be enough to visualize its location. However, clinical examination of cervical ultrasonography by radiographers is usually not intended to detect the vagus nerve location or clarify the anatomical relationships around the nerve.…”

“…The head was fixed in median and vertex-down positions so that neck muscles, such as a sternocleidomastoid muscle, were not loosened. The neck skin on the left side was linearly incised with 30–35 mm long at the cricoid cartilage level not to involve the cardiac branches of the vagus nerve [ 3 , 4 ]. The platysma muscle was transversely cut after the skin incision.…”

“…Detecting the vagus nerve is occasionally difficult in some cases because of its anatomical variations although its surgical procedure is not so complicated. A previous study regarding the VNS reported the anatomical relationship between the vagus nerve and major blood vessels, such as the internal jugular vein (IVJ) and common carotid artery (CCA) [ 3 ]. Additionally, the location of the vagus nerve is classified into five patterns, and the most difficult pattern from the point of surgical manipulations is the pattern in which the vagus nerve is located dorsal to the CCA due to the deep surgical field and difficulty in vagus nerve detection.…”

“…To our best knowledge, there is an only VNS study reported on detecting vagus nerve location preoperatively using cervical ultrasonography [ 3 ]. The present study fused the images of the neck magnetic resonance imaging (MRI) and the three-dimensional computed tomography angiography (3D-CTA) for IVJ and CCA around the neck, successfully visualized the vagus nerve location preoperatively, and reports the usefulness for detecting the vagus nerve location for VNS.…”