Ultrasound of the normal vagus nerve cross-sectional area in the carotid sheath

Abstract

The aim of this article is to utilize ultrasound to evaluate the normal cross-sectional area (CSA)of the vagus nerve (VN) in the carotid sheath. This study included 86 VNs in 43 healthy subjects (15 men, 28 women); mean age 42.1 years and mean body mass index 26.2 kg/m2. For each subject, the bilateral VNs were identified by US at the anterolateral neck within the common carotid sheaths. One radiologist obtained 3 separate CSA measurements for each of the bilateral VNs with complete transducer removal between each measurement. Additionally, for each participant, demographic information of age and gender as well as body mass index, weight, and height were documented. The mean CSA of the right VN in the carotid sheath was 2.1 and 1.9 mm2 for the left VN. The right VN CSA was significantly larger than the left VN (P < .012). No statistically significant correlation was noted in relation to height, weight, and age. We believe that the reference values for the normal CSA of the VN obtained in our study, could help in the sonographic evaluation of VN enlargement, as it relates to the diagnosis of various diseases affecting the VN.

Figure 1.

Short-axis (transverse) ultrasound images of the left vagus nerve (A) in relation to the left CCA, the SCM, the IJV, and the left thyroid lobe with (B) measurement by the tracer method. CCA = internal jugular vein, IJV = internal jugular vein, SCM = sternocleidomastoid muscle.