Specific patterns of laryngeal electromyography during wakefulness are associated to sleep disordered breathing and nocturnal stridor in multiple system atrophy E. Alfonsi a, * , M. Terzaghi b , G. Cosentino c , C. Tassorelli a , R. Manni b , N. Pozzi d , R. De Icco a , G. Bertino e , M. Todisco a , E. Alvisi a , M. Fresia a , C. Pacchetti d , R. Zangaglia d , P. Prunetti a , A. Moglia a a Spinal and Brainstem Reflexes Laboratory, C. Mondino National Neurological Institute, University of Pavia, Pavia, Italy b Sleep Disorders Center, C. Mondino National Neurological Institute, University of Pavia, Pavia, Italy c Department of Experimental Biomedicine and Clinical Neurosciences (BioNec), University of Palermo, Palermo, Italy d Parkinson's Disease Center, C. Mondino National Neurological Institute, University of Pavia, Pavia, Italy e Department of Otorhinolaryngology, IRCCS Policlinico San Matteo Foundation, University of Pavia, Pavia, Italy article info Article history: Received 10 May 2016 Received in revised form 5 July 2016 Accepted 28 July 2016 Keywords: Multiple system atrophy Laryngeal electromyography Laryngoscopy Sleep disordered breathing Nocturnal stridor abstract Background: Nocturnal stridor and respiratory abnormalities are important features of multiple system atrophy (MSA) with relevance to patient survival, and they are detected and evaluated mainly through video-polysomnography (video-PSG). Diurnal laryngoscopy seems to yield abnormal findings only in the presence of significant vocal cord (VC) dysfunction. Aim: To assess whether specific electrophysiological patterns of diurnal EMG of VC muscles may indicate nocturnal stridor or respiratory dysfunctions in MSA patients. Materials and methods: Seventeen patients with probable MSA were examined. A full-night video-PSG to collect standard breathing parameters (apnea/hypopnea index, mean HbSAO 2 , oxygen desaturation in- dex, total sleep time with HbSaO 2 below 90%) was performed in all the patients. Laryngoscopy and EMG investigation of adductor (thyroarytenoid-TA) and abductor (posterior cricoarytenoid-PCA) muscles of the VCs were also performed. Results: Both the laryngeal EMG abnormalities (based on MUAP analysis and kinesiologic EMG investi- gation of VC muscles) and the laryngoscopic alterations correlated with video-PSG respiratory abnor- malities. Specific patterns of EMG findings were consistently found in MSA subjects with nocturnal stridor detected at PSG. In particular, the following EMG findings were related to the severity of breathing abnormalities and the presence of stridor on video-PSG: neurogenic pattern on MUAP analysis of the PCA, paradoxical activation of the TA during inspiration and tonic EMG activity of the TA during quiet breathing. Conclusions: Electromyographic/kinesiologic investigation of VC muscles during wakefulness provides additional information on the pathophysiology of the respiratory abnormalities in MSA patients that could be useful for guiding the choice of the best appropriate treatment and care. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Multiple system atrophy (MSA) is a disorder consisting of diffuse heterogeneous alterations in various structures of the central ner- vous system (extrapyramidal, pyramidal and cerebellar) combined with autonomic nervous system dysfunction and possible impair- ments, of varying severity, of the peripheral nervous system [1e3]. Abnormalities of vocal cord (VC) motion and of respiration are major clinical features of MSA [1e6]. In most patients, these ab- normalities are observed during sleep and can result in serious and potentially fatal events [4e7]. Stridor is detectable in about 19% of MSA patients [3]. It typically occurs during sleep, and rarely during wakefulness [3,5,8,9]. The pathophysiological mechanism of stridor * Corresponding author.Via Mondino 2, 27100, Pavia (PV), Italy. E-mail address: enrico.alfonsi@mondino.it (E. Alfonsi). Contents lists available at ScienceDirect Parkinsonism and Related Disorders journal homepage: www.elsevier.com/locate/parkreldis http://dx.doi.org/10.1016/j.parkreldis.2016.07.017 1353-8020/© 2016 Elsevier Ltd. All rights reserved. Parkinsonism and Related Disorders 31 (2016) 104e109