Ultrasound Detection of Vagus Nerve Atrophy in Bulbar Amyotrophic Lateral Sclerosis

BACKGROUND AND PURPOSE Neuromuscular ultrasound in amyotrophic lateral sclerosis (ALS) is of increasing interest. As bulbar symptoms are commonly developed by most ALS patients during disease, the aim of our study was to find possible sonographic changes of vagus nerve size in bulbar affected ALS patients. METHODS We investigated 24 ALS patients and 19 controls without neuromuscular disorders. In ALS patients, bulbar affection was documented clinically (eg, dysarthria, dysphagia, and fasciculations) or subclinically using ultrasound and electromyography of bulbar muscles. Vagus nerve ultrasound was performed in all participants bilaterally at the level of the thyroid gland. RESULTS The cross-sectional area (CSA) of the vagus nerve in bulbar affected ALS patients (mean CSA right/left 1.9 +/- .7 mm(2)/1.8 +/- .6 mm(2)) was significantly reduced on both sides compared to controls (mean CSA right/left 2.2 +/- .6 mm(2)/2.0 +/- .3 mm(2)) - right:P= .0387, left:P= .0386. Receiver operating characteristic curve analysis of the vagus nerve CSA yielded a sensitivity of 66.7% and a specificity of 63.2% (cutoff value 1.85 mm(2)). Vagus nerve CSA did not correlate significantly with age in controls (right:P= .45, left:P= .66). In controls and ALS patients, there was no significant difference of vagus nerve CSA between the right and left sides (controls:P= .43; patients:P= .86). CONCLUSION Our study demonstrates vagus nerve atrophy in bulbar affected ALS patients. Further studies are warranted investigating the relevance of our finding for monitoring disease progression in ALS.