Characteristics of Anal Sphincter Electromyography in Patients with Multiple System Atrophy

Abstract

In this study, the characteristics of external anal sphincter electromyography (EAS-EMG) in patients with multiple system atrophy (MSA) were analyzed, and its value in the diagnosis of MSA was discussed. The data of 23 patients with MSA who underwent EAS-EMG examination between January 2019 and December 2021 were selected to analyze examination data such as the average duration of motor unit potentials (MUPs), average amplitude, satellite potentials, and the percentage of polyphasic waves, and to explore the correlation between the results of EAS-EMG and autonomic dysfunction in patients with MSA based on their data characteristics. The results of data analysis showed that the most common symptoms in 23 patients with MSA were urination and defecation disorders, sleep disorders, and unsteady walking, the most common signs were increased muscle tone, postural hypotension, and ataxia, and the most common autonomic dysfunction was rectal and bladder dysfunction, orthostatic hypotension, and sexual dysfunction. The average duration of MUPs was 11.6 (10.1-13.9) ms, the average amplitude was 885 (683-1198) μV, and the percentage of polyphasic waves was 26.2 (12.5-50.0)%. Patients with satellite potentials had longer disease duration. There were no significant differences in parameters between different types of autonomic dysfunction. The results suggested that abnormal changes in EAS-EMG may indicate an impaired autonomic function in patients with MSA, and this conclusion may not limit to patients with urination and defecation disorders.