Aesthesiometer-Based Testing for Laryngopharyngeal Hyposensitivity

Laryngeal Hyposensitivity in Obstructive Sleep Apnea

INTRODUCTION

Impaired laryngopharyngeal sensation has been implicated in obstructive sleep apnea (OSA) and may play an important pathophysiological role. We evaluated sensory function in OSA by examining the laryngeal adductor reflex (LAR) response rate and temporal profile to tactile stimulation.

METHODS

Laryngeal sensation testing was performed in awake adults with and without diagnosed OSA by stimulating the medial aryepiglottic fold or arytenoid using 30-mm 5-0 and 4-0 nylon Cheung-Bearelly monofilaments. Video analysis by two independent reviewers evaluated for the presence of the LAR in response to satisfactory stimuli and LAR latency to vocal fold adduction.

RESULTS

Twenty-six OSA and 12 control subjects were tested with 270 satisfactory stimuli. The mean full LAR response rate to 4-0 stimulation was 38.3% in OSA vs 86.9% in control subjects (p <0.001) and to 5-0 stimulation was 27% in OSA vs 63.9% in control subjects (p  <0.001). The mean LAR latency to vocal fold closure in OSA was 123.7 ms (SD 35.8) vs 156.4 ms (SD 44.3) in control (p = 0.04) subjects. OSA LAR latency was positively correlated with the apnea-hypopnea index (r = 0.30; p = 0.008).

CONCLUSION

The OSA group exhibited reduced LAR response rates and shortened LAR latency, where latency was correlated with disease severity. Laryngeal hyposensitivity was affirmed and changes to LAR sensorimotor temporal dynamics were revealed. These pathophysiological alterations to the LAR may be accounted for by decreased somatosensory receptor sensitivity, increased sympathetic tone, and reorganized brain stem function in OSA.

LEVEL OF EVIDENCE

3 Laryngoscope, 134:3856-3861, 2024.

Assessment of Laryngeal Sensory Function using a Tactile Aesthesiometer in Healthy Adults

INTRODUCTION

Laryngeal sensory function in healthy adults was assessed through the delivery of tactile stimuli using Cheung-Bearelly monofilaments.

METHODS

37 healthy adults were recruited with 340 tactile stimuli analyzed. Four calibrated tactile stimuli were delivered to three laryngeal sites: false vocal fold (FVF), aryepiglottic fold (AEF), and lateral pyriform sinus (LPS). Primary outcome was the elicitation of laryngeal adductor reflex (LAR). Secondary outcomes were gag, patient-reported laryngeal sensation (PRLS), and perceptual strength. Analysis was performed with mixed effects logistic regression modeling.

RESULTS

Positive LAR was observed in 35.7%, 70.2%, and 91.2% of stimuli at LPS, AEF, and FVF respectively. LAR rates were significantly associated with laryngopharyngeal subsite (p < 0.001), tactile force (p = 0.001), age (p = 0.022) and sex (p = 0.022). LAR, gag, PRLS, and perceptual strength significantly increased as a more medial laryngeal subsite was stimulated and as stimulus force increased. Each of the ten years of age increase was associated with 19% reduction in odds of LAR (aOR = 0.81, 95% CI [0.68, 0.97]; p = 0.022). Male gender was associated with a 55% reduction in odds of LAR (aOR = 0.45, 95% CI [0.23, 0.89]; p = 0.022).

CONCLUSION

LAR elicitation capability decreases in the male gender, aging, and a more lateral subsite. This study provides insight into the pathophysiology of hypo- and hyper-sensitive laryngeal disorders and is paramount to making accurate diagnostic assessments and finding novel treatment options for various laryngological disorders. Laryngoscope, 133:2525-2532, 2023.

Abnormal Laryngopharyngeal Sensation in Adductor Laryngeal Dystonia Compared to Healthy Controls

BACKGROUND/OBJECTIVES

Laryngeal sensory abnormality has been implicated as a component of adductor laryngeal dystonia (AdLD). The study objective was to assess laryngopharyngeal sensation in AdLD utilizing a calibrated, tactile aesthesiometer to deliver differential stimuli to lateral pyriform sinus (LPS), aryepiglottic fold (AEF), and false vocal fold (FVF).

METHODS

Patients with known Botox-responsive AdLD underwent sensory testing using a previously-validated methodology involving calibrated tactile stimuli (6-0, 5-0, 4.5-0, 4-0 nylon monofilaments). Laryngeal adductor reflex (LAR) and participant-rated perceptual strength of stimulI were evaluated. Responses were compared to normative controls (n = 33). Two-samples, Mann-Whitney and Fisher exact tests compared mean strength ratings and LAR between AdLD and control groups. Mixed-effects logistic regression and linear models assessed association of filament size, stimulus site, age, sex, and LD status on LAR and perceptual strength rating respectively.

RESULTS

Thirteen AdLD patients (nine women, mean age 60+/-15 years) completed testing. Average LAR response rates were higher amongst all filament sizes in AdLD versus controls at LPS (56.3% vs. 35.7%) and AEF (96.1% vs. 70.2%) with comparable rates at FVF (90.2% vs. 91.7%). AdLD had 3.3 times the odds of observed LAR compared to controls (p = 0.005), but differences in subjective detection of stimuli, perceptual strength ratings, and cough/gag rates were insignificant on multivariate modeling (p > 0.05).

CONCLUSIONS

This is the first study to objectively assess laryngopharyngeal sensation in AdLD. Findings demonstrated increased laryngopharyngeal sensation in AdLD compared to controls. The identification of increased laryngeal hypersensitivity in these patients may improve understanding of AdLD pathophysiology and identify future targets for intervention.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:2271-2278, 2023.

An Ex Vivo Investigation of Tactile Aesthesiometer Force in Laryngopharyngeal Sensory Testing

BACKGROUND/OBJECTIVE

Cheung-Bearelly aesthesiometers can deliver buckling-force stimuli to the laryngopharynx and objectively evaluate sensation. Ambiguity surrounds the transformation of stimuli in the laryngopharyngeal environment. This study aims to evaluate the effect of aesthesiometer size, saliva, successive compressions, and angles of tissue contact on stimulus force delivered.

METHODS

An ex vivo stimulus delivery device was constructed to measure the buckling force of aesthesiometers. Dry and saliva-saturated aesthesiometers (6-0, 5-0, 4.5-0, and 4-0) were each compressed six times on cadaveric buccal mucosa on an electronic balance. The force for each compression was recorded at 0, 15, 30, 45, and 60° from the vertical plane. 240 compressions were analyzed utilizing a mixed-effects statistical model.

RESULTS

The mean force delivered by the 6-0, 5-0, 4.5-0, and 4-0 aesthesiometers were 0.017, 0.082, 0.120, and 0.268 g respectively (p < 0.001). Mean force significantly reduced for the 4-0 aesthesiometer at 30° (p = 0.003) and 60° (p = 0.001). Force decreased by the 4th compression for the 5-0 aesthesiometer (p = 0.004) and after one compression for the 4.5-0 (p = 0.004) and 4-0 (p < 0.001) aesthesiometer. By the 4th compression, the 4.5-0 aesthesiometer was indistinguishable (p > 0.05) from the 5-0 aesthesiometer. The effect of saliva was insignificant (p = 0.83).

CONCLUSION

Aesthesiometers can deliver discrete buckling-force stimuli to evaluate laryngopharynx sensory function. Up to 60° (15° for 4-0 aesthesiometer) deviation from orthogonal tissue contact and salivary forces do not significantly alter force delivered. 4.5-0 aesthesiometers should be exchanged after three compressions. For all other aesthesiometers, force reduction after six compressions is likely clinically insignificant given current laryngopharyngeal sensory testing protocols.

LEVEL OF EVIDENCE

N/A Ex Vivo Laboratory Design Laryngoscope, 2022.