2018 Section 6 - Laryngology, Voice Disorders, and Bronchoesophalogy

Reprinted by permission of Respirology. 2013; 18(6):948-956.

ORIGINAL ARTICLE

Laryngeal sensory dysfunction in laryngeal hypersensitivity syndrome

A NNE E. VERTIGAN, 1,3,4 S ARAH L. BONE 3,4 AND P ETER G. GIBSON 1,2,4,5

1 Priority Centre for Asthma and Respiratory Diseases, School of Medicine and Public Health, The University of Newcastle, 2 Department of Respiratory and Sleep Medicine, 3 Speech Pathology Department, 4 Hunter Medical Research Institute, Newcastle, and 5 Woolcock Institute of Medical Research, Sydney, Australia

ABSTRACT Background and objective: Diseases associated with laryngeal dysfunction include chronic refractory cough (CRC), paradoxical vocal fold movement (PVFM), muscle tension dysphonia (MTD) and globus pharyngeus. We hypothesized the presence of a common sensory laryngeal dysfunction, the ‘laryngeal hypersensitivity’ syndrome, in these conditions. The aim of the study was to compare symptoms and sensory function in patients with CRC, PVFM,MTD and globus. Methods: The 103 participants included healthy con- trols ( n = 13) and four case groups: CRC ( n = 33), PVFM ( n = 28), globus pharyngeus ( n = 11) and MTD ( n = 18). Participants completed self-report questionnaires: Symptom Frequency and Severity Scale, Voice Handi- cap Index and the Laryngeal Paraesthesia Question- naire; and quantitative sensory testing: capsaicin cough reflex sensitivity, hypertonic saline challenge, the timed swallow test, acoustic voice testing, cough frequency monitor and a voice stress test. Results: All case groups reported a high-symptom burden in comparison to controls. The case groups showed a similar pattern of symptoms, with impair- ment in each of the cough, respiration, vocal and upper airway symptom domains. Objective testing revealed significant sensory impairment in the case groups compared to controls and also showed an overlap in sensory dysfunction between the four case groups. Fur- thermore, there was cross-sensory stimulation of symptoms whereby stimulation of a particular response resulted in symptoms in another domain. Conclusions: These discrete clinical laryngeal syn- dromes display considerable overlap in their clinical features and a common sensory dysfunction, support- ing the ‘laryngeal hypersensitivity’ hypothesis. Recon- ceptualizing functional laryngeal disorders as a formof laryngeal hypersensitivity syndrome provides an alter- native approach to management of these perplexing conditions. Correspondence: Anne Vertigan, John Hunter Hospital, Locked Bag 1 Hunter Region Mail Centre, NSW 2310, Australia. Email: anne.vertigan@hnehealth.nsw.gov.au Received 18 November 2012; invited to revise 20 December 2012, 24 January 2013; revised 10 January 2013, 11 February 2013; accepted 11 February 2013 (Associate Editor: Graham Hall).

SUMMARY AT A GLANCE Laryngeal sensory function is impaired in patients with chronic cough, paradoxical vocal fold move- ment, globus pharyngeus and muscle tension dys- phonia. This study is the first to quantify sensory dysfunction and identify the extent of overlap between the conditions. It provides a hypothesis for development of further treatments for these conditions.

Key words: cough, dysphonia, globus, laryngeal hypersensi- tivity, paraesthesia.

INTRODUCTION Several well-defined clinical syndromes that involve laryngeal dysfunction include chronic refractory cough (CRC), globus pharyngeus (globus), paradoxi- cal vocal fold movement (PVFM) and muscle tension dysphonia (MTD). These syndromes present to clini- cians as discrete and unrelated abnormalities of dif- ferent aspects of laryngeal motor function, that is, cough, breathing and phonation. However, they have overlapping symptomatology, 1 and the symptoms are not limited to the domains of cough, respiration and phonation. These conditions also respond similarly to multifactorial behavioural treatment involving edu- cation, environmental modification and specific laryngeal exercises to address the symptoms and motor components of the disorder. 2 It is possible that these observations indicate a common mechanistic pathway such as laryngeal hypersensitivity in these disorders of laryngeal dys- function. Laryngeal hypersensitivity has been pro- posed as a common feature of neuropathic laryngeal dysfunction 3,4 prompting the description of the irrita- ble larynx syndrome . Similarities were identified between the laryngeal irritability in chronic cough and neural irritability in trigeminal neuralgia and other neuropathic pain syndromes, and it was pro- posed that the cough was a manifestation of a sensory

© 2013 The Authors Respirology © 2013 Asian Pacific Society of Respirology

Respirology (2013) 18 , 948–956 doi: 10.1111/resp.12103

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