Supraglottic Botulinum Toxin Improves Symptoms in Patients with Laryngeal Sensory Dysfunction Manifesting as Abnormal Throat Sensation and/or Chronic Refractory Cough.

Daniel Novakovic,Duy Duong Nguyen,Catherine Madill,Meet Sheth,Thomas Stewart,Antonia Chacon,Katrina Sandham

doi:10.3390/jcm10235486

Abstract

Laryngeal sensory dysfunction (LSD) encompasses disorders of the vagal sensory pathways. Common manifestations include chronic refractory cough (CRC) and abnormal throat sensation (ATS). This study examined clinical characteristics and treatment outcomes of LSD using a novel approach of laryngeal supraglottic Onabotulinum toxin Type A injection (BTX). This was a retrospective review of clinical data and treatment outcomes of supraglottic BTX in patients with LSD. Between November 2019 and May 2021, 14 patients underwent 25 injection cycles of supraglottic BTX for treatment of symptoms related to LSD, including ATS and CRC. Primary outcome measures included the Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ), Cough Severity Index (CSI), Reflux Symptom Index (RSI), and Voice Handicap Index-10 (VHI-10) at baseline and within three months of treatment. Pre- and post-treatment data were compared using a linear mixed model. After supraglottic BTX, LHQ scores improved by 2.6. RSI and CSI improved by 8.0 and 5.0, respectively. VHI-10 did not change as a result of treatment. Short-term response to SLN block was significantly associated with longer term response to BTX treatment. These findings suggest that LSD presents clinically as ATS and CRC along with other upper airway symptoms. Supraglottic BTX injection is a safe and effective technique in the treatment of symptoms of LSD.

Highlights

The larynx is innervated by branches of the vagus nerve with complex coordination of afferent and efferent pathways in the brainstem required for optimal physiological functioning [1,2]
The aims of the study were to: (1) describe the clinical characteristics of Laryngeal sensory dysfunction (LSD) in a cohort of patients referred for chronic refractory cough (CRC) and abnormal throat sensation (ATS); (2) describe a new treatment of supraglottic laryngeal botulinum toxin in the symptomatic management of laryngeal sensory dysfunction; (3) evaluate the efficacy of using botulinum toxin A in treatment of a pilot group of patients presenting with different phenotypes associated with laryngeal sensory dysfunction including CRC and ATS
The exact role of the dysfunctional sensory pathway in those conditions has not been confirmed by experimental evidence

Summary

Introduction

The larynx is innervated by branches of the vagus nerve with complex coordination of afferent (sensory) and efferent (motor) pathways in the brainstem required for optimal physiological functioning [1,2]. Several phenotypes related to hyperfunctional vagal sensation have been described manifesting in the larynx sharing similar features [3] These include chronic refractory cough (CRC) [4], various forms of inducible laryngeal obstruction including recurrent laryngospasm, paradoxical vocal fold movement [5,6] and irritable larynx syndrome [7], globus pharyngeus [3] and laryngeal sensory neuropathy [8] with various proposed etiologies. We prefer to use the umbrella term laryngeal sensory dysfunction [3] which recognizes the role of abnormal laryngeal afferent sensory pathways in these conditions which may be affected at one or more levels (peripheral receptors, afferent vagal fibers, central pathways), and which present with abnormal/altered laryngeal sensation, without attribution to a specific underlying pathological process or cause. Accurate evaluation of laryngeal dysfunction and hypersensitivity would allow for accurate diagnosis and effective treatment [9]

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