Sonographic evaluation of the vagus nerves: Protocol, reference values, and side‐to‐side differences

INTRODUCTION: Reported sonographic reference values for the vagus nerves (VNs) vary greatly. We aimed to generate reference values in a large cohort and examine intrarater, interrater, and across-ultrasound systems agreement. METHODS: The VNs of 60 healthy subjects were examined by 2 sonographers and with 2 ultrasound systems. Cross-sectional areas (CSAs) of each VN were assessed at the level of the carotid sinus [proximal measurement level (ML)] and thyroid gland (distal ML). VN CSA decreased with increasing age. There were good intrarater, interrater, and across-ultrasound systems agreements. DISCUSSION: The right VN CSA is significantly larger than the left. These side- and age-specific reference values for the VN may be useful for future studies. Muscle Nerve 57: 766-771, 2018.