Chest

Chest

Volume 146, Issue 5, November 2014, Pages 1294-1299
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Original Research Signs and Symptoms of Chest Diseases
Decreased Cough Sensitivity and Aspiration in Parkinson Disease

https://doi.org/10.1378/chest.14-0066Get rights and content

BACKGROUND

Aspiration pneumonia is a leading cause of death in people with Parkinson disease (PD). The pathogenesis of these infections is largely attributed to the presence of dysphagia with silent aspiration or aspiration without an appropriate cough response. The goal of this study was to test reflex cough thresholds and associated urge-to-cough (UTC) ratings in participants with PD with and without dysphagia.

METHODS

Twenty participants with PD were recruited for this study. They completed a capsaicin challenge with three randomized blocks of 0, 50, 100, and 200 μM capsaicin and rated their UTC by modified Borg scale. The concentration of capsaicin that elicited a two-cough response, total number of coughs, and sensitivity of the participant to the cough stimulus (UTC) were measured. The dysphagia severity of participants with PD was identified with the penetration-aspiration scale.

RESULTS

Most participants with PD did not have a consistent two-cough response to 200 μM capsaicin. UTC ratings and total number of coughs produced at 200 μM capsaicin were significantly influenced by dysphagia severity but not by general PD severity, age, or disease duration. Increasing levels of dysphagia severity resulted in significantly blunted cough sensitivity (UTC).

CONCLUSIONS

UTC ratings may be important in understanding the mechanism underlying morbidity related to aspiration pneumonia in people with PD and dysphagia. Further understanding of decreased UTC in people with PD and dysphagia will be essential for the development of strategies and treatments to address airway protection deficits in this population.

Section snippets

Materials and Methods

This prospective study included 20 participants with mild to moderate PD. Participants were recruited from the University of Florida Center for Movement Disorders and Neurorestoration by consecutive referral to speech-language pathology over a 3-month period. Fellowship-trained movement disorders neurologists diagnosed PD using UK brain bank criteria.14 This study received ethical approval by the University of Florida Institutional Review Board (188-2012). All participants provided written

Results

Twenty participants (14 men), aged 49 to 81 years (average, 68 years) completed this study. Disease severity spanned from H&Y stage II to IV with Unified Parkinson's Disease Rating Scale on medication scores between 9 and 48 (average, 24.4). Disease severity was not significantly associated with swallowing dysfunction (P-A score) (r s = 0.091,P= .704). None of the participants had a history of aspiration pneumonia. Demographic information is included inTable 1.

Discussion

Aspiration pneumonia is a leading cause of death in PD,1, 2, 3and although the pathogenesis of this infection is not completely understood, it is likely attributable to dysphagia and concomitant dystussia. Although our current clinical management focuses on rehabilitation of dysphagia with relative disregard for concomitant dystussia, our understanding of airway protection is evolving to include a continuum of behaviors serving to prevent (swallowing) and eject material from the airway

Conclusions

The results of this study add to the body of literature, suggesting that various components of the cough behavior are impaired in people with PD, particularly in those with dysphagia. This study highlights the idea that the absent cough response in people with silent aspiration should not be considered as solely secondary to increased cough thresholds; it may also be due to a reduced UTC in response to a specific stimulus. Therefore, a reduced awareness of the presence of a tussigenic stimulus

Acknowledgments

Author contributions:M. S. T. had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. M. S. T. contributed to the study concept and design; obtaining of funding; data acquisition, analysis, and interpretation; statistical analysis, and drafting and revision of the manuscript; A. E. B. contributed to the data acquisition, analysis, and interpretation and drafting and revision of the manuscript; M. S. O. and P.

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    Part of this article has been presented in abstract form at the Annual Meeting of the International Society for the Advancement of Respiratory Psychophysiology, September 27-29, 2013, Leuven, Belgium.

    FUNDING/SUPPORT:This work was funded in part by a National Institutes of Health (National Center for Advancing Translational Sciences) Clinical and Translational Science Award through the University of Florida [UL1TR000064 and KL2TR000065 to Dr Troche].

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

    originally published Online First June 26, 2014.

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    Copyright © 2014 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.