Ultrasonography of the Vagus Nerve for ALS Patients: Correlations with Clinical Data and Dysfunction of the Autonomic Nervous System.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the degeneration of both upper and lower motor neurons, leading to the rapid decline of motor function. In recent years, dysfunction of the autonomic nervous system (ANS) has also been increasingly recognized as a contributing factor in various neurodegenerative diseases, including ALS. This study is the second publication from our ALS research cohort at Kaunas Clinics. Our previous work examined ultrasonographic changes in the phrenic nerve as a supplementary diagnostic approach for ALS. In the present study, we investigated ultrasonographic alterations of the vagus nerve within the same ALS cohort, aiming to explore correlations with ANS involvement. We performed high-resolution ultrasonography of the vagus nerve (VN), collected clinical data, conducted heart rate monitoring, and evaluated respiratory function. We prospectively included 32 ALS patients meeting "Gold Coast" criteria and 64 age- and sex-matched control patients. The average onset of ALS was 57.97 ± 9.22 years, and the duration of the disease was15.41 ± 9.04 months. For ALS patients, we found significantly reduced vagus nerve cross-sectional area (CSA) at the level of the carotid artery bifurcation bilaterally compared to controls (right VN 1.86 ± 0.21 vs. 2.07 ± 0.18 mm, < 0.001; left VN 1.69 ± 0.21 vs. 1.87 ± 0.21 mm, < 0.001). Reduced values of the left VN positively correlated with the reduced values of FEV1% and sO. Our findings revealed a significant bilateral reduction in vagus nerve size in ALS patients compared to controls, suggesting that vagal atrophy may serve as a potential marker of autonomic dysfunction in ALS.