Assessment of Change in Palatal Sensation in Obstructive Sleep Apnea Patients by Using Two-Point Palatal Discrimination

Lack of association of impaired upper airway sensation with the presence or absence of obstructive sleep apnoea or chronic rhinosinusitis in World Trade Center responders

OBJECTIVE

Examine sensory function of the upper airway in four groups of subjects recruited from the World Trade Centre General Responder Cohort (WTCGRC), with/without obstructive sleep apnoea (OSA), and with/without chronic rhinosinusitis (CRS).

METHODS

Upper airway sensory function was determined using 2-point discrimination (2-PD) and vibration threshold (VT) in 163 WTCGRC subjects with both OSA and CRS (cases), OSA or CRS alone and without OSA or CRS (controls). Presence of OSA was determined from clinical sleep studies or home sleep testing. Presence of CRS was determined by nasal symptom questionnaire. The relationship between the presence of OSA and CRS and upper airway sensory impairment was assessed using linear regression analysis with each of 2PD and VT sensory threshold values as the dependent variable; OSA, CRS and their interaction were the independent variables. Age, gender and body mass index were covariates in the statistical model. The primary analysis was comparison of OSA+CRS versus controls (no OSA and no CRS) evaluated by linear contrasts.

RESULTS

There were no differences in 2-PD or VT in those with OSA+CRS, OSA and CRS alone or controls. However, both 2-PD and VT were significantly higher in the WTCGRC controls compared with values seen in historical controls using the same methodology (median 2-PD 13.0; CI (11.0 to 13.5) vs 10.5; CI (8 to 11); VT: mean±SEM (9.3±0.6 vs 2.2±0.1)).

CONCLUSION

While no differences were found in upper airway sensation between cases of OSA and CRS versus controls in the WTGRC population, there was evidence of impaired upper airway sensation in the WTGRC overall.

Sensorimotor nerve lesion of upper airway in patients with obstructive sleep apnea

The pathogenesis of obstructive sleep apnea (OSA) remains controversial. The role of anatomic stenosis is indisputable, and neural regulation of the upper airway remains to be elucidated. The upper airway maintains patency through the upper airway reflex. Lesions in any link of the reflex can increase the collapsibility of the upper airway. In this study, we investigated sensorimotor nerve lesions and their possible relationship with OSA. Tissue samples were obtained from the pharyngopalatine arch in 47 patients with OSA and 45 control participants to examine changes in the expression levels of myelin basic protein (MBP) and agrin through immunohistochemistry and western blotting. Downregulation of MBP in the mucosa reflects myelinated degeneration of mucosal sensory nerve axons, whereas upregulation of agrin in the neuromuscular junction reflects synaptic regeneration following denervation. The two neural factors correlate significantly with polysomnographic parameters, such as the apnea hypopnea index and lowest oxygen saturation. Our findings suggest that sensorimotor nerve damage in the upper airway of patients with OSA may be associated closely with the mechanism of OSA.

Characteristics of pharyngeal paraesthesia symptoms in patients with obstructive sleep apnoea

PURPOSE

This study aimed to investigate pharyngeal paraesthesia symptoms in patients with obstructive sleep apnoea (OSA).

MATERIAL AND METHODS

Patients with snoring and suspected OSA as well as age-matched controls were recruited. All participants underwent nocturnal polysomnography (PSG) and pharyngeal paraesthesia assessment using the Glasgow-Edinburgh throat scale (GETS). The incidence and severity of pharyngeal paraesthesia symptoms were compared between the groups.

RESULTS

A total of 280 patients who snored or were suspected of having OSA and 35 healthy, age-matched controls were recruited. The total pharyngeal paraesthesia symptom score was significantly higher in the OSA group than in the healthy group (12 [5, 23] vs. 3 [0, 9]; p < 0.001). The most frequent pharyngeal paraesthesia symptoms in the snore patients were Q7 (catarrh down the throat) and Q3 (discomfort/irritation in the throat), which are related to the irritability of the throat. The incidence of Q7 (OSA, 58% vs. controls, 14%; χ² = 23.66; p < 0.001), Q3 (OSA, 46% vs. controls, 3%; χ² = 23.07; p < 0.001), Q1 (feeling of something stuck in the throat; OSA, 33% vs. controls, 6%; χ² = 11.00; p = 0.001), Q6 (swelling in the throat; OSA, 31% vs. controls, 0%; χ² = 14.53; p < 0.001), Q9 (want to swallow all the time; OSA, 20% vs. controls, 6%; χ² = 6.28; p = 0.012), Q5 (throat closing off; OSA, 24% vs. controls, 6%; χ² = 6.16; p = 0.013), and Q2 (pain in the throat; OSA, 23% vs. controls, 6%; χ² = 5.32; p = 0.021) was significantly higher in the OSA group than in the controls CONCLUSIONS: Patients with obstructive sleep apnoea have higher pharyngeal paraesthesia symptoms scores and tend to have irritated throats compared to healthy controls.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03506178.

Quantitative Evaluation of the Function of the Sensory Nerve Fibers of the Palate in Patients With Obstructive Sleep Apnea

STUDY OBJECTIVES

To quantitatively evaluate the functional integrity of sensory nerve fibers of the palate in patients with obstructive sleep apnea (OSA) using the Neurometer system.

METHODS

A total of 32 patients with OSA and 18 healthy control patients were included in the study. All participants were selected based on medical history, physical examination, and nocturnal polysomnography (PSG) and divided into two groups. The palatal sensory status of participants was examined with a Neurometer current perception threshold (CPT) system. The system was used to deliver an electrical stimulus at three different frequencies (2,000 Hz, 250 Hz, and 5 Hz) by an investigator blinded to the PSG results.

RESULTS

There were no significant differences in the CPT values of the hard palate between the patients with OSA and control patients at any of the three stimulation frequencies. The differences in the CPT values of the soft palate between these groups failed to show any statistical significance at 250 Hz and 5 Hz. However, the patients with OSA showed significantly higher CPT values of the soft palate at 2,000 Hz than the age-matched healthy control patients (256.56 ± 129.34 versus 372.13 ± 152.06; P = .009).

CONCLUSIONS

Our study revealed an impairment of 2,000 Hz-related sensory nerve function of the soft palate among patients with OSA. The CPT test could be a useful tool for the quantitative and selective assessment of the sensory nerve function in patients with OSA. Additional research is required to evaluate the different types of sensory nerve dysfunctions among such patients.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Title: The Effects of Nasal Airflow on Upper Airway Dilator Muscles During Sleep; Identifier: NCT03506178; URL: https://clinicaltrials.gov/ct2/show/NCT03506178.

CITATION

An Y, Li Y, Chang W, Gao F, Ding X, Xu W, Han D. Quantitative evaluation of the function of the sensory nerve fibers of the palate in patients with obstructive sleep apnea. J Clin Sleep Med. 2019;15(9):1347-1353.

Investigation of smell and taste function in patients with obstructive sleep apnoea syndrome

Objective

This study investigated the relationship between disease severity and taste and smell functions in patients with obstructive sleep apnoea syndrome.

Methods

A total of 65 patients with recurrent upper airway obstruction during sleep were included. Participants were divided into four groups according to apnoea-hypopnoea index, obtained on polysomnography. Smell and taste tests were performed on these patients.

Results

A significant difference was observed between the smell thresholds of the groups for the identification test (p = 0.016). In the taste test, significant differences were observed between the groups in terms of sweet, sour, salty and bitter taste test thresholds (p = 0.029, p = 0.0005, p = 0.001 and p = 0.017, respectively).

Conclusion

As sleep apnoea severity increased (according to the apnoea-hypopnoea index) in obstructive sleep apnoea syndrome patients, the taste and smell thresholds decreased due to the effect of neuropathy and inflammation in the upper respiratory tract.

Neuromuscular function of the soft palate and uvula in snoring and obstructive sleep apnea: A systematic review

OBJECTIVE

A collapsible upper airway is a common cause of obstructive sleep apnea. The exact pathophysiology leading to a more collapsible airway is not well understood. A progressive neuropathy of the soft palate and pharyngeal dilators may be associated with the progression of snoring to OSA. The purpose of this study is to systematically review the international literature investigating the neurophysiologic changes in the soft palate and uvula that contribute to progression from snoring to OSA.

METHODS

PubMed/MEDLINE and 4 other databases were systematically searched through July 4, 2017. Eligibility: (1) Patients: controls, snoring or OSA patients (2) Intervention: neuromuscular evaluation of the palate and/or uvula (3) Comparison: differences between controls, snoring and OSA patients (4) Outcomes: neuromuscular outcomes (5) Study design: Peer reviewed publications of any design.

RESULTS

845 studies were screened, 76 were downloaded in full text form and thirty-one studies met criteria. Histological studies of the soft palate demonstrated diffuse inflammatory changes, muscular changes consistent with neuropathy, and neural aberrancies. Sensory testing studies provided heterogeneous outcomes though the majority favored neuronal dysfunction. Studies have consistently demonstrated that increasing severity of snoring and sleep apnea is associated with worsening sensory nerve function of the palate in association with atrophic histological changes to the nerves and muscle fibers of the soft palate and uvula.

CONCLUSIONS

Recent evidence highlighted in this systematic review implicates the role of neurogenic pathology underlying the loss of soft palate and/or uvular tone in the progression of snoring to sleep apnea.

A retrospective study: does upper airway morphology differ between non-positional and positional obstructive sleep apnea?

Objective

The objective of this study was to explore the differences in upper airway morphology between positional (POSA) and non-positional (NPOSA) obstructive sleep apnea.

Methods

This retrospective study enrolled 75 patients (45 NPOSA and 30 POSA) who underwent polysomnography (PSG) and computed tomography (CT). The differences in, and relationships of, the PSG values and CT data between POSA and NPOSA were analyzed.

Results

Significant (p < 0.05) differences between the two groups were found in the apnea/hypopnea index (AHI), lateral-AHI (L-AHI), soft palate length (SPL), cross-sectional palatopharyngeal area, and the coronal diameter (CD) of the palatopharyngeal area at the narrowest part of the glossopharynx, which were all higher in POSA, except for SPL, AHI, and L-AHI. L-AHI was correlated with the cross-sectional area (r =  − 0.306, p = 0.008) and CD (r =  − 0.398, p < 0.001) of the palatopharyngeal area, the cross-sectional area (r =  − 0.241, p = 0.038) and CD (r =  − 0.297, p = 0.010) of the narrowest level of the glossopharynx, the CD of the glossopharynx (r = 0.284, p = 0.013), body mass index (BMI, r = 0.273, p = 0.018), SPL (r = 0.284, p = 0.014), and vallecula-tip of tongue (r = 0.250, p = 0.030). The SPL and CD at the narrowest part of the glossopharynx were included in the simplified screening model.

Conclusions

In NPOSA, the CD of the upper airway was smaller, and the soft palate was longer, than in POSA. These differences may play significant roles in explaining the main differences between NPOSA and POSA.