The Role of Vocal Fold Bowing on Cough and Swallowing Dysfunction in Progressive Supranuclear Palsy

Abstract

Objectives: Progressive supranuclear palsy (PSP) is a neurodegenerative disease which results in cough and swallowing dysfunction and aspiration pneumonia. Relationships among vocal fold atrophy, cough, and swallowing have been identified in related diseases, but remain unknown in PSP. This study examined: 1) the prevalence of vocal fold bowing in PSP, and 2) the influence of vocal fold bowing on cough and swallowing in PSP.Study Design: Prospective Cohort Study. Methods: Twenty-three participants with PSP completed instrumental assessments of cough and swallowing. Vocal fold bowing (BI) and swallowing safety (PAS) was assessed using flexible laryngoscopy. Measures of cough effectiveness were obtained using spirometry. Statistical analyses were used to determine the frequency of mild-moderate (BI > 0) and severe (BI > 12.2) bowing, and to assess the influence of BI on PAS and cough effectiveness in PSP.Results: Fifty-two percent (n = 12) of participants exhibited severe bowing while 48% (n = 11) exhibited mild-to-moderate bowing. Voluntary cough peak expiratory flow rate (P = .01), as well as reflex (P = .02) and voluntary (P = .005) cough volume acceleration were lower for participants with severe BI when compared to mild-to-moderate BI. However, BI did not influence PAS (P > .05).Conclusions: Findings from this study suggest that vocal fold bowing is highly prevalent in PSP and associated with reduced reflex and voluntary cough effectiveness. These findings provide insight into the pathophysiology of compromised airway protection in this patient population. Future studies should examine vocal fold atrophy as a treatment target for behavioral and medical intervention in PSP.

Best Practices in the Clinical Management of Progressive Supranuclear Palsy and Corticobasal Syndrome: A Consensus Statement of the CurePSP Centers of Care

“…These permit fluids or chewed food to drop into the pharynx and are associated with prolonged mealtimes, fatigue, oral cavity residue, nasal regurgitation, wet-sounding vocal quality, coughing, throatclearing, and choking during oral intake. Increased vocal cord bowing caused by muscular atrophy was recently identified as a deficit in PSP that impairs cough efficiency and leads to aspiration (160). On the other hand, "piecemeal deglutition" (excessive lingual gestures causing multiple swallows required to clear a single bolus) is characteristic of CBS patients as assessed by Modified Barium Swallow (MBS) testing (161).…”

Changes in Cough Airflow and Acoustics After Injection Laryngoplasty

“…Ruddy et al noted improved CVA in their case series of three patients undergoing injection laryngoplasty 19 . Enver et al found a significant decrease in cough effectiveness in patients with vocal fold bowing and progressive supranuclear palsy, with both decreased PEFR and CVA as measured with pneumotachometry 25 . Also using a pneumotachometer, Murty et al compared cough airflow in subjects with unilateral vocal fold paralysis to that of age and sex‐matched controls and noted a statistically significant increase in PEFRT and no change in PEFR in subjects with paralysis 26 .…”

“…19 Enver et al found a significant decrease in cough effectiveness in patients with vocal fold bowing and progressive supranuclear palsy, with both decreased PEFR and CVA as measured with pneumotachometry. 25 Also using a pneumotachometer, Murty et al compared cough airflow in subjects with unilateral vocal fold paralysis to that of age and sex-matched controls and noted a statistically significant increase in PEFRT and no change in PEFR in subjects with paralysis. 26 Patients with laryngectomy have been noted to have reduced CVA compared to age-matched controls, indicating a possible role for the functional larynx in ensuring cough effectiveness.…”

“…41 Following these early investigations, interest in laryngeal activity during cough waned in the otolaryngology literature. In addition to the notable publications previously mentioned, [17][18][19][20]25,26,28 Sant'Ambrogio et al studied the pattern of discharge of the posterior cricoarytenoid (PCA), cricothyroid (CT), thyroarytenoid (TA), and arytenoideus transversus (AR) muscles during cough using electromyography in anesthetized dogs, finding that the PCA and CT are activated during the inspiratory phase whereas the laryngeal adductors (TA and AR) are recruited during the compressive phase. 42 More recently, Britton et al used rigid and flexible laryngoscopy to examine the TVF during voluntary cough and establish normative data related to TVF movement during cough in young healthy adults.…”

“…Degree of glottic insufficiency could have been estimated by acoustic and aerodynamic measures of breathiness, the volume of injectable used or quantification of vocal fold bowing on laryngoscopy frames. 25 Also, we did not analyze our data according to the different injectable materials used, though we recognize that injectable varying viscoelastic properties may affect the physiology of cough generation in different ways. Second, respiratory muscle strength and pulmonary function, which affect cough strength and may vary in the individual subject over time, were not measured and may confound some of the cough airflow measurements.…”