Ultrasound evaluation of vagus nerve cross-sectional area in a community-dwelling elderly Japanese cohort

Abstract

Objectives Although the vagus nerve (VN) is easily observed by ultrasonography, few studies have evaluated the cross-sectional area (CSA) of the VN in healthy older individuals from East Asia. In this study, we aimed to report reference values for the CSA of the VN in community-dwelling elderly Japanese individuals and to identify any associated medical history and/or lifestyle factors. Methods The present study included 336 participants aged >= 65 years from a prospective cohort study conducted in Yahaba, Japan from October 2021 to February 2022. The CSA of the VN was measured bilaterally at the level of the thyroid gland by ultrasonography. Univariate and multivariable linear regression analyses were conducted to identify the associations between clinical and background factors and the CSA of the VN on each side. Results In our cohort, the median CSA of the VN was 1.3 mm2 (interquartile range [IQR] 1.1–1.6) on the right side and 1.2 mm2 (IQR 1.0–1.4) on the left side. Multivariable linear regression analysis showed that history of head injury (β = -0.15, p < .01), history of convulsion (β = 0.19, p < .01), and BMI (β = 0.30, p < .01) were independently associated with the CSA of the VN on the left side. In contrast, there were no independent associations between any of the assessed variables and the CSA on the right side. Conclusion We have reported reference VN CSA values for community-dwelling elderly Japanese individuals. In addition, we showed that the CSA of the VN on the left side was positively associated with a history of convulsive seizure and BMI and inversely associated with a history of head injury.

Vagus Nerve Ultrasonography Helps Distinguish Multiple System Atrophy from Other Parkinsonian Syndromes

“…Sex, age, BMI, DM, and MSA diagnosis were selected as independent factors for multiple regression models. 15 We used images stored on an ultrasound machine to remeasure VN CSA and analyzed inter-and intra-rater reliability using intra-class correlation coefficients (ICC). Statistical significance was set at P < 0.05 (two-tailed) (see Supplementary Methods for further details).…”

“…Demographic information such as sex, age, height, weight, body mass index (BMI), duration of parkinsonism, and various comorbidities, including diabetes mellitus (DM), head injury, epilepsy, atrial fibrillation, constipation, and orthostatic hypotension, all of which have been previously reported to be correlated with VN CSA, 15 were recorded (see Supplementary Methods for definitions).…”

“…VN CSA measurements were classified as “no,” “unilateral,” or “bilateral” atrophy. Sex, age, BMI, DM, and MSA diagnosis were selected as independent factors for multiple regression models 15 …”

“…All patients underwent VN ultrasonography, performed by four experienced technicians blinded to the patient's diagnosis. The VN CSA was measured as in previous studies, 15,18 at the level of the thyroid gland using high-resolution ultrasound (Aplio i700, Canon Medical Systems, Otawara, Japan) and a 12-MHz linear probe. The VN was scanned in the axial view, and the optimal settings for gain, depth, and focus were used for each patient (Fig.…”