Sonographic evaluation of the vagus nerves: Protocol, reference values, and side-to-side differences
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Updated: Feb 20, 2026

Nerve Ultrasound Protocol to Detect Dysimmune Neuropathies
Published on: October 7, 2021
Johann Otto Pelz1, Elena Belau1, Philipp Henn1
1Department of Neurology, Leipzig University Hospital, Liebigstrasse 20, 04103 Leipzig, Germany.
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).
Results:
Mean VN CSA was significantly larger on the right side (proximal ML: 2.7 ± 0.6 mm2 vs. 2.1 ± 0.5 mm2 ; distal ML: 2.6 ± 0.6 mm2 vs. 1.9 ± 0.4 mm2 ). 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.
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