Correlations between gustatory, trigeminal, and olfactory functions and nasal airflow

PURPOSE

To determine the relationship of chemosensory screening and nasal airflow tests among the same set of participants, and to determine other factors that are related to the outcomes of these tests.

METHODS

Participants had no chemosensory complaints. Structured medical history was taken. Participants underwent 5 screening tests: q-sticks (orthonasal olfaction), q-powders (retronasal olfaction), trigeminal lateralization test, taste sprays, and peak nasal inspiratory flow (PNIF). Ratings of smell/taste ability and nasal airflow were obtained using visual analogue scales (VAS). Composite sinusitis symptoms and significance of olfaction questionnaire scores were also determined.

RESULTS

Four hundred participants were included in the study, 156 men, 244 women; aged 18-82 years (mean: 46). The q-powders and taste spray scores were weakly positively correlated with all the other chemosensory tests and PNIF. However, chemosensory test scores were not correlated with VAS, composite sinusitis symptoms, and significance of olfaction questionnaire scores. Various tests showed significant decrease starting at specific ages (in years, PNIF and trigeminal lateralization: 40, q-powders: 60, and q-sticks: 70).

CONCLUSION

Chemosensory screening tests and self-rated chemosensory function showed no correlation in participants without chemosensory complaints. In addition, gustatory function appeared to be correlated with olfactory and trigeminal function but also with nasal airflow, and nasal airflow was related not only to olfactory but also to trigeminal and taste function. Over all, the results suggest that chemosensory functions (orthonasal olfactory, trigeminal, retronasal olfactory, gustatory) and nasal airflow are correlated with each other, which we propose may be possibly mediated, at least in part, through central nervous system interactions.

Breathing during sleep

The depth, rate, and regularity of breathing change following transition from wakefulness to sleep. Interactions between sleep and breathing involve direct effects of the central mechanisms that generate sleep states exerted at multiple respiratory regulatory sites, such as the central respiratory pattern generator, respiratory premotor pathways, and motoneurons that innervate the respiratory pump and upper airway muscles, as well as effects secondary to sleep-related changes in metabolism. This chapter discusses respiratory effects of sleep as they occur under physiologic conditions. Breathing and central respiratory neuronal activities during nonrapid eye movement (NREM) sleep and REM sleep are characterized in relation to activity of central wake-active and sleep-active neurons. Consideration is given to the obstructive sleep apnea syndrome because in this common disorder, state-dependent control of upper airway patency by upper airway muscles attains high significance and recurrent arousals from sleep are triggered by hypercapnic and hypoxic episodes. Selected clinical trials are discussed in which pharmacological interventions targeted transmission in noradrenergic, serotonergic, cholinergic, and other state-dependent pathways identified as mediators of ventilatory changes during sleep. Central pathways for arousals elicited by chemical stimulation of breathing are given special attention for their important role in sleep loss and fragmentation in sleep-related respiratory disorders.

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.

Chronic intermittent hypoxia alters main olfactory bulb activity and olfaction

Olfactory dysfunction is commonly observed in patients with obstructive sleep apnea (OSA), which is related to chronic intermittent hypoxia (CIH). OSA patients exhibit alterations in discrimination, identification and odor detection threshold. These olfactory functions strongly rely on neuronal processing within the main olfactory bulb (MOB). However, a direct evaluation of the effects of controlled CIH on olfaction and MOB network activity has not been performed. Here, we used electrophysiological field recordings in vivo to evaluate the effects of 21-day-long CIH on MOB network activity and its response to odors. In addition, we assessed animals´ olfaction with the buried food and habituation/dishabituation tests. We found that mice exposed to CIH show alterations in MOB spontaneous activity in vivo, consisting of a reduction in beta and gamma frequency bands power along with an increase in the theta band power. Likewise, the MOB was less responsive to odor stimulation, since the proportional increase of the power of its population activity in response to four different odorants was smaller than the one observed in control animals. These CIH-induced MOB functional alterations correlate with a reduction in the ability to detect, habituate and discriminate olfactory stimuli. Our findings indicate that CIH generates alterations in the MOB neural network, which could be involved in the olfactory deterioration in patients with OSA.

Palatal Sensory Function Worsens in Untreated Snorers but not in CPAP-Treated Patients With Sleep Apnea, Indicating Vibration-Induced Nervous Lesions

BACKGROUND

Signs of both motor and sensory nervous lesions have previously been shown in the upper airway of patients with OSA and habitual snorers. Snoring per se may damage all upper airway neurons over time, thereby causing progression to manifest sleep apnea. To test this hypothesis, nonsnoring subjects, untreated snorers, and CPAP-treated patients underwent repeated sensory testing of the soft palate in a prospective long-term study.

METHODS

Cold detection threshold (CDT) testing at the soft palate and lip with a thermode and nocturnal respiratory recordings were performed in 2008 to 2009 with retesting 6 to 7 years later.

RESULTS

In 25 untreated snorers, palatal CDT worsened from a median (25th-75th percentile range) 4.2°C (3.2-5.9) to 11.0°C (7.0-17.4) (P < .001). The apnea-hypopnea index increased from a median 7.0 to 14.0 events/h (P < .05). There was no significant correlation between changes in CDT and the apnea-hypopnea index. In 21 nonsnoring control subjects, palatal CDT increased from a median 3.2°C to 5.6°C (P < .005). In 19 CPAP-treated patients, palatal CDT did not significantly change; eight patients had improved values. CDTs worsened significantly more in the snorers group than in the control subjects (P < .05) and the CPAP-treated patients (P < .001). There was no significant difference between control subjects and CPAP-treated patients.

CONCLUSIONS

CDT worsened considerably over time in untreated snorers, significantly more than in nonsnoring control subjects and CPAP-treated patients. Untreated snorers therefore risk developing poor sensitivity in the upper airway. In contrast, efficient treatment of OSA seems to protect the sensory innervation, as the CPAP-treated group maintained their sensitivity to cold and, in some cases, the sensitivity even improved.

The impact of obstructive apnea sleep syndrome on chemical function

OBJECTIVE/HYPOTHESIS

To investigate the impact of obstructive sleep apnea syndrome (OSAS) on the olfactory and gustatory functions, and the potential mechanisms affecting olfactory and gustatory functions.

MATERIALS AND METHODS

A total of 120 men between the ages of 41 and 70 (mean age (SD) = 56 ± 7.5) were divided into three groups according to polysomnography results: snoring group, mild to moderate OSAS group, and severe OSAS group. Olfactory and gustatory functions were evaluated by the Sniffin' Sticks test and the triple-drop method, respectively. Otorhinolaryngologic examination, as well as sleep and quality of life questionnaires, were completed by all subjects one day before or after polysomnography.

RESULTS

There was a significant difference in odor thresholds (THR), odor discrimination (OD), odor identification (OI), thresholds-discrimination-identification (TDI) (p < 0.001, p < 0.001, p = 0.003, p < 0.001), and total taste score (p = 0.004, p = 0.021, p = 0.006) in all three groups. Of the subjects in the OSAS group, 43 (54%) exhibited olfactory dysfunction, including 18 subjects (45%) in the mild to moderate group and 25 subjects (63%) in the severe group. Significant negative correlations were found between all olfactory parameters and polysomnography parameters. Furthermore, a negative correlation was present between the total taste scores and the apnea-hypopnea index (AHI).

CONCLUSION

Men with OSAS exhibited impairment in olfactory and gustatory functions. Significant correlations were found between AHI and olfactory parameters, as well as between AHI and total taste scores.

Effects of morphine on respiratory load detection, load magnitude perception, and tactile sensation in obstructive sleep apnea

Pharyngeal and respiratory sensation is impaired in obstructive sleep apnea (OSA). Opioids may further diminish respiratory sensation. Thus protective pharyngeal neuromuscular and arousal responses to airway occlusion that rely on respiratory sensation could be impaired with opioids to worsen OSA severity. However, little is known about the effects of opioids on upper airway and respiratory sensation in people with OSA. This study was designed to determine the effects of 40 mg of MS-Contin on tactile sensation, respiratory load detection, and respiratory magnitude perception in people with OSA during wakefulness. A double-blind, randomized, crossover design (1 wk washout) was used. Twenty-one men with untreated OSA (apnea/hypopnea index = 26 ± 17 events/h) recruited from a larger clinical study completed the protocol. Tactile sensation using von Frey filaments on the back of the hand, internal mucosa of the cheek, uvula, and posterior pharyngeal wall were not different between placebo and morphine [e.g., median (interquartile range) posterior wall = 0.16 (0.16, 0.4) vs. 0.4 (0.14, 1.8) g, P = 0.261]. Similarly, compared with placebo, morphine did not alter respiratory load detection thresholds for nadir mask pressure detected = −2.05 (−3.37, −1.55) vs. −2.19 (−3.36, −1.41) cmH2O, P = 0.767], or respiratory load magnitude perception [mean ± SD Borg scores during a 5 resistive load (range: 5–126 cmH2O·l−1·s−1) protocol = 4.5 ± 1.6 vs. 4.2 ± 1.2, P = 0.347] but did reduce minute ventilation during quiet breathing (11.4 ± 3.3 vs. 10.7 ± 2.6 l/min, P < 0.01). These findings indicate that 40 mg of MS-Contin does not systematically impair tactile or respiratory sensation in men with mild to moderate, untreated OSA. This suggests that altered respiratory sensation to acute mechanical stimuli is not likely to be a mechanism that contributes to worsening of OSA with a moderate dose of morphine.

NEW & NOTEWORTHY Forty milligrams of MS-Contin does not alter upper airway tactile sensation, respiratory load detection thresholds, or respiratory load magnitude perception in people with obstructive sleep apnea but does decrease breathing compared with placebo during wakefulness. Despite increasing concerns of harm with opioids, the current findings suggest that impaired respiratory sensation to acute mechanical stimuli with this dose of MS-Contin is unlikely to be a direct mechanism contributing to worsening sleep apnea severity in people with mild-to-moderate disease.

Submental Ultrasonographic Parameters among Patients with Obstructive Sleep Apnea

Objective

This study aimed to determine the value of submental ultrasonography (US) parameters for diagnostic workup among patients with obstructive sleep apnea (OSA) and to determine whether there is a correlation between US findings and the severity of OSA.

Study Design

Cross-sectional analysis.

Setting

Tertiary education hospital.

Subjects and Methods

The study included 147 patients with suspected OSA who underwent submental US to evaluate various parameters following overnight polysomnography. US findings were compared with the apnea-hypopnea index and other parameters.

Results

All US parameters, except for subcutaneous tissue thickness, were significantly different among patients with OSA. Of note, distance between lingual arteries (DLA), geniohyoid muscle thickness (GMT), and lateral parapharyngeal wall thickness (LPWT) were significantly greater in the patients with severe OSA than those with mild and moderate OSA ( P < .001). GMT had the strongest correlation with OSA ( r = 0.419, P < .001); LPWT and DLA also had high correlation coefficient values ( r = 0.343, P < .001, and r = 0.342, P < .001, respectively). Stepwise regression analysis showed that GMT (beta = 0.243, P = 0.004), LPWT (beta = 0.236, P = 0.004), and DLA (beta = 0.204, P = 0.008) were the most significant factors for predicting the severity of OSA according to the apnea-hypopnea index.

Conclusion

Submental US can be used to determine whether there is a correlation between US findings and severity of OSA. GMT could be considered a novel parameter for determining the severity of OSA.

Tonsillectomy with Uvulopalatopharyngoplasty in Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a very common disorder (prevalence 2-7% in women, 7-14% in men). It impairs the quality of life and increases mortality. Conservative treatment with continuous positive airway pressure is highly effective, but patient compliance is variable. Surgical treatments are controversial, as only a few are supported by evidence from controlled clinical trials.

METHODS

Adult patients with OSA, CPAP intolerance, and oropharyngeal obstruction were included in the trial. All underwent polysomnography (PSG) and were randomly allotted to one of two groups. Patients in the treatment group underwent tonsillectomy with uvulopalatopharyngoplasty (TE-UPPP) within one month. All patients had a follow-up PSG at three months, and all PSGs were evaluated in blinded fashion. The primary outcome variable was the apneahypopnea index (AHI) as determined by PSG. Other outcome variables were subjective symptoms (daytime sleepiness, quality of life), complications, and patient satisfaction.

RESULTS

42 patents were included in the trial (23 in the treatment group, 19 in the control group). The baseline AHI was 35.7 ± 19.4/hr in the control group and 33.7 ± 14.6/hr in the treatment group. The corresponding figures at 3 months were 28.6 ± 19.4/hr in the control group and 15.4 ± 14.1/hr in the treatment group (p = 0.036). The intervention also led to significant improvement in daytime sleepiness and in snoring, according to the patients' and their bed partners' assessment. 97% of the patients who underwent surgery were satisfied with the outcome. 65% of them needed no further treatment for OSA.

CONCLUSION

TE-UPPP significantly improved apnea/hypopnea, daytime sleepiness, and snoring compared to control (i.e., no) treatment. It is a safe and effective treatment for OSA..