Objective: to systematically evaluate laryngeal electromyography findings, correlate them to laryngeal movement disorders assessed by a systematic task-protocol performed during FEES and clinical laryngeal symptoms.

Background: Laryngeal dysfunctions have a high prevalence in multiple system atrophy (MSA), its pathophysiological cause however still remains under debate.

Method: Patients with probable or possible MSA underwent laryngeal EMG examination and flexible endoscopic evaluation of swallowing utilizing the MSA-FEES protocol.

Results: 10 MSA-patients (66 [63–71] years; 4women) were included. 5/10 MSA-patients showed clinically overt laryngeal symptoms with inspiratory stridor. However, all patients presented with laryngeal movement disorders during endoscopy. Irregular arytenoid cartilage movements were present in all patients, 8/10 presented with vocal fold motion impairment. One patient exhibited paradoxical vocal fold motion, another one vocal fold fixation. On laryngeal EMG, 9/10 patients showed pathologically increased activity of internal and external laryngeal muscles at rest. All patients showed reduced activity of the posterior cricoarytenoid muscle during inspiration and dystonic co-activation of its antagonizing thyroarytenoid/lateral cricoarytenoid muscle complex. Irregular arytenoid cartilage movements correlated with dystonic innervation the laryngeal muscles. MUP analysis showed normal amplitude and duration.

Conclusion: Our data support dystonic innervation of laryngeal muscles to be the underlying cause of laryngeal movement disorders observed in MSA-patients during endoscopy when performing the MSA-FEES task-protocol.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/laryngeal-electromyography-findings-in-patients-with-multiple-system-atrophy/