Aesthesiometer-Based Testing for Laryngopharyngeal Hyposensitivity

OBJECTIVES/HYPOTHESIS

To develop a method for threshold estimation of the laryngeal adductor reflex (LAR) response using Cheung-Bearelly monofilaments.

STUDY DESIGN

Cross-sectional.

METHODS

Twenty-two healthy adults (12 men, 10 women) were tested for LAR response outcome using 30 mm 5-0 and 4-0 nylon monofilaments. Tactile stimuli were delivered to the aryepiglottic (AE) fold and medial pyriform sinus (MPS). Dichotomous classifier features and performance (area under the curve (AUC)), the LAR response outcome agreement and disagreement matrix, and test-retest reliability were examined. From those data, a test protocol that would minimize patient burden to estimate the LAR triggering threshold was formulated.

RESULTS

Classifier performance of 5-0 monofilament stimulation of the AE fold (sensitivity = 0.63, specificity = 0.63, PPV = 0.74, NPV = 0.25) and MPS (sensitivity = 0.45, specificity = 0.77, PPV = 0.74, NPV = 0.23,) was slightly below that of 4-0 monofilament stimulation of the AE fold (sensitivity = 0.82, specificity = 0.50, PPV = 0.82, NPV = 0.50) and MPS (sensitivity = 0.84, specificity = 0.64, PPV = 0.90, NPV = 0.56), based on AUC. LAR response outcome agreement for 5-0 and 4-0 stimulations was high (93%) for 5-0 positive response, but low (29%) for 5-0 negative response. Aesthesiometer test-retest reliability for LAR response outcome was excellent (Cronbach's alpha = 0.97).

CONCLUSIONS

Threshold estimation of the LAR response may be operationalized by adopting a decision tree protocol. For negative LAR response to initial 5-0 monofilament stimulation and positive response to subsequent 4-0 monofilament stimulation, the higher threshold is confirmed. Positive LAR response to 5-0 or 4-0 monofilament stimulation is expected in over 90% of asymptomatic adults. Negative LAR response to 4-0 monofilament stimulation identifies patients at risk for laryngopharyngeal hyposensitivity.

LEVEL OF EVIDENCE

3b Laryngoscope, 2021.

Novel Adaptation of a Validated Tactile Aesthesiometer to Evaluate Laryngopharyngeal Sensation

OBJECTIVES

To evaluate laryngopharyngeal sensation at specific subsites using a novel adaptation of a buckling force aesthesiometer for delivery of calibrated tactile stimuli.

STUDY DESIGN

Cross-sectional.

METHODS

Twenty-two healthy adults (12 men, 10 women) were tested for responses to tactile forces, using 30-mm 6-0, 5-0, and 4-0 nylon monofilaments to map sensation of the aryepiglottic (AE) fold, lateral pyriform sinus (PS), and medial PS bilaterally. The outcome measures were the laryngeal adductor reflex (LAR) and patient reported rating of perceptual strength.

RESULTS

Rates of triggered LAR response grew monotonically with increasing tactile force at a mean (SD) stimulus duration of 663 (164) msec across all three subsites. The AE fold and medial PS had similar profiles and were the most responsive, while the lateral PS was the least responsive. Low force (6-0) response rate was ≤14% for all subsites. High force (4-0) response rate was 91% for AE fold and medial PS, and 23% for lateral PS. The perceptual strength gradient was in the lateral to medial trajectory.

CONCLUSION

Normative data for LAR response rates to low, medium, and high stimulation forces will be useful to assess sensory dysfunction in a variety of laryngopharyngeal disorders, including aspiration, dysphagia, chronic cough, and spasmodic dysphonia. In turn, that information will guide the creation of innovative treatments. LAR response profiles to low and high force stimuli will inform the development of screening tools to diagnose laryngopharyngeal hypersensitivity and hyposensitivity conditions.

LEVEL OF EVIDENCE

3b Laryngoscope, 131:1324-1331, 2021.

Dissociable Contributions of Precuneus and Cerebellum to Subjective and Objective Neuropathy in HIV

Neuropathy, typically diagnosed by the presence of either symptoms or signs of peripheral nerve dysfunction, remains a frequently reported complication in the antiretroviral (ART)-treated HIV population. This study was conducted in 109 healthy controls and 57 HIV-infected individuals to investigate CNS regions associated with neuropathy. An index of objective neuropathy was computed based on 4 measures: deep tendon ankle reflex, vibration sense (great toes), position sense (great toes), and 2-point discrimination (feet). Subjective neuropathy (self-report of pain, aching, or burning; pins and needles; or numbness in legs or feet) was also evaluated. Structural MRI data were available for 126/166 cases. The HIV relative to the healthy control group was impaired on all 4 signs of neuropathy. Within the HIV group, an objective neuropathy index of 1 (bilateral impairment on 1 measure) or 2 (bilateral impairment on at least 2/4 measures) was associated with older age and a smaller volume of the cerebellar vermis. Moderate to severe symptoms of neuropathy were associated with more depressive symptoms, reduced quality of life, and a smaller volume of the parietal precuneus. This study is consistent with the recent contention that ART-treated HIV-related neuropathy has a CNS component. Distinguishing subjective symptoms from objective signs of neuropathy allowed for a dissociation between the precuneus, a brain region involved in conscious information processing and the vermis, involved in fine tuning of limb movements. Graphical Abstract In HIV patients, objective signs of neuropathy correlated with smaller cerebellar vermis (red) volumes whereas subjective symptoms of neuropathy were associated with smaller precuneus (blue) volumes.