Laryngeal Hypersensitivity From the Perspective of Pain Science: An Integrative Review of Empirical Studies on...

Laryngeal hypersensitivity (LHS) is a state of heightened sensorimotor response to stimuli in the upper airway. Although its clinical picture is becoming progressively clearer with recent research progress, specificities about its associated factors and processes remain to be clarified. The aim of this integrative review was to synthesize published empirical data from human studies on LHS, focusing on related factors and pathophysiology.

Integrative review of the literature; Pubmed, EMBASE, and Web of Science.

Keywords associated with the following three main concepts were used to query databases: (1) manifestations potentially associated with an irritable larynx (dysphonia, inducible laryngeal obstruction (ILO), chronic cough, and globus); (2) hypersensitivity; and (3) pathophysiology. Peer-reviewed studies in English providing empirical original research data on the pathophysiology of LHS were included, with no restriction based on study design.

In total, 54 papers met the inclusion criteria. Factors potentially associated with LHS were identified, namely (1) psychological and lifestyle factors, (2) upper airway inflammation and injuries from exogenous/endogenous irritants, infections, or mucosal atrophy, (3) sex hormones, (4) metabolic abnormalities, and (5) aberrant respiratory behavior. Given the parallels between pain-related mechanisms and suggested LHS mechanisms, processes identified as putatively contributing to LHS were categorized in light of the current pain literature. Findings suggest that LHS may stem from a peripheral tissue insult, a neuropathic insult, and/or maladaptive neuroplasticity. Gaps in the literature were identified, in part driven by an uneven repartition of research across the various alleged manifestations of LHS. In fact, a large majority of studies pertained to chronic cough, with very few addressing muscle tension dysphonia, ILO, and globus.

Future research can focus on the potential role of hypersensitivity in manifestations such as muscle tension dysphonia and ILO, and on the development of guidelines to identify the specific underlying factors and mechanisms at play in LHS symptoms.