The effects of nasal anaesthesia upon nasal sensation of airflow

Impact of the Location of Nasal Septal Deviation on the Nasal Airflow and Air Conditioning Characteristics

The location of nasal septal deviation (NSD) directly impacts nasal physiology. The objective is to examine, using computational fluid dynamics (CFD), the difference in the airflow and air conditioning characteristics according to the location of NSD. Twenty patients with septal deviation were divided into two: 10 caudal septal deviation (CSD) and 10 posterior septal deviation (PSD). Physiological variables were compared and numerical models for nasal cavity were created with CT scans. Cases with CSD had distinctive features including restricted airflow partition, larger nasal resistance, and decreased surface heat flux in the more obstructed side (MOS), and lower humidity and air temperature in the lesser obstructed side (LOS). Physiological differences were observed according to the location of septal deviation, CSD cases exhibit significantly more asymmetric airflow characteristics and air conditioning capacity between LOS and MOS.

Trigeminal Function in Sino-Nasal Health and Disease

The upper airway (nasal passages, paranasal sinuses, pharynx, and glottis) provides the sentinel portion of the human respiratory tract, with the combined senses of olfaction (cranial nerve I) and trigeminal sensation (cranial nerve V) signaling the quality of inspired air. Trigeminal function also complements the sense of taste (in turn mediated by cranial nerves VII, IX and X), and participates in the genesis of taste aversions. The ability of trigeminal stimulation in the upper aero-digestive tract to trigger a variety of respiratory and behavioral reflexes has long been recognized. In this context, the last three decades has seen a proliferation of observations at a molecular level regarding the mechanisms of olfaction, irritation, and gustation. Concurrently, an ever-widening network of physiological interactions between olfaction, taste, and trigeminal function has been uncovered. The objective of this review is to summarize the relatively recent expansion of research in this sub-field of sensory science, and to explore the clinical and therapeutic implications thereof.

Improvements in airflow characteristics and effect on the NOSE score after septoturbinoplasty: A computational fluid dynamics analysis

Septoturbinoplasty is a surgical procedure that can improve nasal congestion symptoms in patients with nasal septal deviation and inferior turbinate hypertrophy. However, it is unclear which physical domains of nasal airflow after septoturbinoplasty are related to symptomatic improvement. This work employs computational fluid dynamics modeling to identify the physical variables and domains associated with symptomatic improvement. Sixteen numerical models were generated using eight patients' pre- and postoperative computed tomography scans. Changes in unilateral nasal resistance, surface heat flux, relative humidity, and air temperature and their correlations with improvement in the Nasal Obstruction Symptom Evaluation (NOSE) score were analyzed. The NOSE score significantly improved after septoturbinoplasty, from 14.4 ± 3.6 to 4.0 ± 4.2 (p < 0.001). The surgery not only increased the airflow partition on the more obstructed side (MOS) from 31.6 ± 9.6 to 41.9 ± 4.7% (p = 0.043), but also reduced the unilateral nasal resistance in the MOS from 0.200 ± 0.095 to 0.066 ± 0.055 Pa/(mL·s) (p = 0.004). Improvement in the NOSE score correlated significantly with the reduction in unilateral nasal resistance in the preoperative MOS (r = 0.81). Also, improvement in the NOSE score correlated better with the increase in surface heat flux in the preoperative MOS region from the nasal valve to the choanae (r = 0.87) than in the vestibule area (r = 0.63). Therefore, unilateral nasal resistance and mucous cooling in the preoperative MOS can explain the perceived improvement in symptoms after septoturbinoplasty. Moreover, the physical domain between the nasal valve and the choanae might be more relevant to patient-reported patency than the vestibule area.

Assessing the ability of children and parents to rate their nasal patency. A cross sectional study

OBJECTIVE

Nasal obstruction is a common complaint in pediatric otolaryngology. There are several concerns about how nasal obstruction should be measured. This debate is even more important in children, as they can experience difficulties in being sensitive to their symptoms or even expressing them. In this research we aim to explore the ability of children (and their parents) to assess their nasal obstruction.

PARTICIPANTS

AND METHODS: An observational cross-sectional study was performed. Four cohorts of children were consecutively selected from a third level referral Hospital. Cohort A (children suffering solely turbinate enlargement), B (adenoid enlargement only), and C (adenoid and turbinate enlargement), while cohort D were healthy controls. Children and parents were asked to rate nasal patency through a Likert scale from 0 (no patency, complete obstruction of the nose) to 10 (complete patency, it is easy to breathe through the nose). All participants underwent rhinomanometry. Results of nasal resistance were relativized according to pediatric reference values per each age subgroup.

RESULTS

146 participants were included. Cohort A (54), B (40), C (28), D (24). There is a poor but significant correlation between parents' assessment and nasal resistance (rho = -0.28; p = 0.004). In children, there is no significant correlation with nasal resistance (rho = -0.14; p = 0.17). Stratified by severity, only children (and their parents) with good nasal breathing demonstrated good correlation values with the visual analogue score (VAS). Stratified by age, the correlation is only significant for parents of children older than 12 years old.

CONCLUSIONS

This study has demonstrated a good ability to rate nasal patency by healthy children and their parents, but a poor ability for children suffering from impaired nasal breathing. We suggest combining subjective assessment of nasal patency with objective measurements such as rhinomanometry in children.

Sensation of Nasal Obstruction Compared to Rhinomanometry in Patients Referred for Septoplasty and in Patients with Chronic Rhinitis

Correlation between active anterior rhinomanometry and subjective sensation of nasal obstruction was studied in three groups of patients. Group A included patients with marked septal deviation causing high nasal resistance. Group B represented cases where there was minor septal deviation, but normal resistance. Group C consisted of cases with chronic rhinitis causing nasal stuffiness, but normal septum and normal decongestion resistance. The patient's response as to the more obstructed side of the nose was correlated with the rhinomanometrically recorded less patent nostril. The results show that the correlation was good in Group A, but did not exist in the other groups. The reason for this is that, when the side difference of resistance between the two nasal cavities was less than 60–70%, it was very difficult for the patient to estimate the more obstructed side. This was especially the case in Group C, where mucosal swelling often changes sides. The conclusion is that patients’ capability to detect a minor side difference is poorer than rhinomanometry's. Furthermore, if rhinomanometry and subjective sensation do not agree, the reason may be that the patient's nasal complaint is dominated by the mucosal disease, rather than by a structural deformity and therefore, treatment other than surgery may be preferred.

Comparison of the Relative Abilities of Acoustic Rhinometry, Rhinomanometry, and the Visual Analogue Scale in Detecting Change in the Nasal Cavity in a Healthy Adult Population

The relative abilities of acoustic rhinometry, rhinomanometry, and subjective sensation of nasal patency, as recorded using a Visual Analogue Scale (VAS), were compared in a group of 51 healthy volunteers. All three methods were able to detect a change following the application of a nasal decongestant. A 27.5% change in minimum cross sectional area, a 13.29% change in nasal resistance, and a 30.7% change in the sensation of nasal patency was observed. No correlation was demonstrated between either acoustic rhinometry or rhinomanometry and subjective sensation, and only a weak correlation was found between acoustic rhinometry and rhinomanometry.

The physiological mechanism for sensing nasal airflow: a literature review

BACKGROUND

Nasal obstruction is a common otolaryngologic complaint, yet the mechanism of sensing airflow is not commonly understood. The objective of this work was to review current knowledge on the physiological mechanism for sensing nasal airflow.

METHODS

Current literature pertaining to nasal sensation to airflow was retrieved using PubMed and Google Scholar searches.

RESULTS

The primary physiological mechanism that produces the sensation of ample nasal airflow is activation of trigeminal cool thermoreceptors, specifically transient receptor potential melastatin family member 8 (TRPM8), by nasal mucosal cooling. The dynamic change in temperature is ultimately sensed. Nasal mucosal cooling is a result of conductive heat loss, driven by temperature gradient, and evaporative heat loss, driven by humidity gradient. The perception of ample nasal airflow is dependent on the overall nasal surface area stimulated by mucosal cooling, which is mainly governed by air flow patterns. Cool thermoreceptors in the nasal mucosa are connected to the respiratory centers and consequently can alter respiration patterns. Mechanoreceptors do not seem to play a role in sensing nasal airflow. Computational fluid dynamics (CFD) modeling could be a valuable objective tool in evaluating patients with nasal congestion.

CONCLUSION

Understanding the physiological mechanism of how the nose senses airflow can aid in diagnosing the cause behind patient symptoms, which allows physicians to provide better treatment options for patients.

Perception of better nasal patency correlates with increased mucosal cooling after surgery for nasal obstruction

OBJECTIVES

To (1) quantify mucosal cooling (ie, heat loss) spatially in the nasal passages of nasal airway obstruction (NAO) patients before and after surgery using computational fluid dynamics (CFD) and (2) correlate mucosal cooling with patient-reported symptoms, as measured by the Nasal Obstruction Symptom Evaluation (NOSE) and a visual analog scale (VAS) for sensation of nasal airflow.

STUDY DESIGN

Prospective.

SETTING

Academic tertiary medical center.

SUBJECTS AND METHODS

Computed tomography (CT) scans and NOSE and VAS surveys were obtained from 10 patients before and after surgery to relieve NAO. Three-dimensional models of each patient's nasal anatomy were used to run steady-state CFD simulations of airflow and heat transfer during inspiration. Heat loss across the nasal vestibule and the entire nasal cavity, as well as the surface area of mucosa exposed to heat fluxes >50 W/m(2), were compared pre- and postoperatively.

RESULTS

After surgery, heat loss increased significantly on the preoperative most obstructed side (P < .0002). A larger surface area of nasal mucosa was exposed to heat fluxes >50 W/m(2) after surgery. The best correlation between patient-reported and CFD measures of nasal patency was obtained for NOSE against surface area in which heat fluxes were >50 W/m(2) (Pearson r = -0.76).

CONCLUSION

A significant postoperative increase in mucosal cooling correlates well with patients' perception of better nasal patency after NAO surgery. Computational fluid dynamics-derived heat fluxes may prove to be a valuable predictor of success in NAO surgery.

Nasal cavity size, airway resistance, and subjective sensation after surgically assisted rapid maxillary expansion: a prospective longitudinal study

INTRODUCTION

The aims of this study were to measure changes in nasal minimum cross-sectional area and nasal airway resistance after surgically assisted rapid maxillary expansion and to explore a possible correlation with the subjective sensation of nasal obstruction.

METHODS

Minimum cross-sectional area and nasal airway resistance were measured in 39 consecutive patients treated with surgically assisted rapid maxillary expansion. Subjective nasal obstruction was assessed by a questionnaire at pretreatment and at 3 and 18 months postoperatively.

RESULTS

Subjective nasal obstruction had improved significantly by 3 months postoperatively. Minimum cross-sectional area increased and nasal airway resistance decreased. No correlations were found. In subjects with pretreatment subjective nasal obstruction and initially narrow anterior minimum cross-sectional area, there was a significant correlation between a moderate increase in anterior minimum cross-sectional area and improvement in perceived nasal obstruction. Eighteen months postoperatively, no changes were found from pretreatment values for subjective nasal obstruction, minimal cross-sectional area, or nasal airway resistance, and there were no correlations. Subjects with a sensation of nasal obstruction at treatment start reported a lasting significant subjective improvement.

CONCLUSIONS

The postoperative effects of surgically assisted rapid maxillary expansion did not persist in the long term. No correlation was found between objective and subjective findings. Subjects with pretreatment nasal obstruction, however, reported a lasting sensation of improved nasal function after surgically assisted rapid maxillary expansion.

The role of sensation in subjective and objective evaluation of nasal patency

To assess if sensation of nasal mucosa affect the subjective sensation of nasal patency. This is a case control study with 50 patients, using 2% lignocaine as the active drug and normal saline as the placebo (2 groups of 25 patients each). Each subject had 2 ml of solution sprayed into the test nose. These subjects had no prior nasal symptoms, allergy or surgery. They were evaluated subjectively using Likert scale and objectively by acoustic rhinometry before and after lignocaine or normal saline. The patients in both normal saline and lignocaine groups demonstrated no significant change based upon Likert scale. The study also demonstrated the mean cross sectional area 1 (CSA1), mean cross sectional area 2 (CSA2), with mean Volume 1 and mean Volume 2, these results did not vary significantly in both groups with Acoustic Rhinometry. The analysis thus shows that the use of topical anesthetic spray on nasal mucosa produces no objective effect on nasal resistance or subjective sensation of altered nasal patency. Thus the study concludes that, tactile sensation of nasal mucosa does not play a role in the sensation of nasal obstruction.

Modified Glatzel mirror test reproducibility in the evaluation of nasal patency

The Glatzel Mirror (GM) is used to evaluate nasal patency. Validation studies are not available in the literature. This paper aims to verify the GM test reproducibility and the correlation between the intra-subject condensation area and nasal patency subjective perception.

Methods

This is a prospective study. 25 subjects were evaluated with the GM for five consecutive minutes, every half an hour for 4 hours; every day, beginning in the early afternoon, every Thursday for five consecutive weeks. A visual analogue scale was used to evaluate nasal patency perception in all periods.

Results

The total correlation coefficient (right + left areas) found between the condensation area and the subjective perception was r = 0.04 (p = 0.37). On the left side it was r = 0.08 (p = 0.09) and on the right side r = 0.05 (p = 0.28). The mean unilateral variation coefficient was less than 15% and the total was less than 12%, regardless of the time period interval between test and re-test.

Conclusion

We did not observe any significant correlation between the subjective perception of breathing and the condensation area. Unilateral variability was higher than the total (right + left area) and the test variability was the same between the different time periods of measurements.

Impact of Menthol Inhalation on Nasal Mucosal Temperature and Nasal Patency

Background

Menthol is a natural herbal compound. Its isomer L-menthol presents the characteristic peppermint scent and is also responsible for the cooling sensation when applied to nasal mucosal surfaces because of stimulation of trigeminal cold receptors. The aim of this study was to assess the effect of menthol inhalation on end-inspiratory nasal mucosa temperature and nasal patency.

Methods

Eighteen healthy volunteers with a mean age of 30 years were enrolled in this study. Objective measurements included the septal mucosal temperature within the nasal valve area by using a miniaturized thermocouple as well as active anterior rhinomanometry before and after inhalation of l-menthol vapor. All subjects completed a visual analog scale (VAS; range, 1–10) evaluating nasal patency before and after menthol.

Results

The mean end-inspiratory mucosal temperature ranged from 27.7°C (±4.0) before menthol inhalation to 28.5°C (±3.5) after menthol inhalation. There were no statistically significant differences between the temperature values before and after menthol inhalation (p > 0.05). In addition, no statistically significant differences between the rhinomanometric values before and after menthol inhalation were observed. Sixteen of the 18 subjects reported an improvement of nasal breathing after menthol inhalation by means of the VAS.

Conclusion

Menthol inhalation does not have an effect on nasal mucosal temperature and nasal airflow. The subjective impression of an improved nasal airflow supports the fact that menthol leads to a direct stimulation of cold receptors modulating the cool sensation, entailing the subjective feeling of a clear and wide nose.

A reprodutibilidade do espelho de Glatzel modificado na aferição da permeabilidade nasal

O espelho de Glatzel (EG) é utilizado para a avaliação da permeabilidade nasal. Estudos de validação inexistem na literatura. Este estudo teve por objetivos verificar a reprodutibilidade do EG e a correlação intra-sujeito entre área de condensação e percepção subjetiva de permeabilidade nasal. MÉTODOS: Estudo prospectivo onde 25 sujeitos foram avaliados com o EG por cinco minutos consecutivos; cada meia hora por quatro horas; cada dia no início da tarde, por cinco dias e toda a quinta-feira por cinco semanas consecutivas. Utilizou-se uma escala analógica visual para avaliar a percepção de respiração nos períodos. RESULTADOS: O coeficiente de correlação total (área direita mais esquerda) encontrado entre área de condensação e percepção subjetiva foi de r=0,04 (p=0,37). No lado esquerdo foi de r=0,08 (p=0,09) e no lado direito de r=0,05 (p=0,28). Os coeficientes de variação unilaterais medianos foram menores que 15% e os totais menores que 12%, independente do intervalo de tempo entre teste e re-teste. CONCLUSÃO: Não se evidenciou correlação significativa entre a percepção subjetiva e a área de condensação. A variabilidade unilateral foi maior do que quando considerados os valores totais (direito mais esquerdo) e não houve diferença na variabilidade das medidas de área de condensação nasal nos diferentes momentos do tempo.

Nasal mucosal temperature in relation to nasal airflow as measured by rhinomanometry

BACKGROUND

The aim of this study was to measure in vivo nasal mucosal temperature and assess its relationship to nasal patency.

METHODS

Nasal mucosal temperature of 30 nasal cavities was measured by means of a miniaturized thermocouple within the anterior turbinate area during respiration. Temperature values were compared with corresponding rhinomanometrical data.

RESULTS

The median mucosal temperature ranged from 30.2 degrees C (range, 28.9-31.7 degrees C) after inspiration to 32.2 degrees C (range, 31.0-33.9 degrees C) after expiration. The end-inspiratory (r = -0.85) and end-expiratory mucosal temperature values (r = -0.88) negatively correlated with the rhinomanometrical data.

CONCLUSION

This study supports the fact that there is a negative correlation between nasal mucosal temperature and nasal resistance. Changes in nasal patency seem to influence nasal mucosal temperature. Within this context, nasal thermoreceptors might play an important role concerning the perception of nasal patency.

Olfactory and sensory attributes of the nose

The human nasal cavity contains multiple sensory and olfactory structures. The nasal mucosa with its complex innervation detects the danger substances in the air and stimulates the protective reflexes. Healthy olfactory mucosa allows for appreciation of pleasant aromas and food flavors. The olfactory nerve, in concert with the trigeminal nerve, serves as a main interpreter and modulator of chemosensory information. The anatomy of the olfactory neuroepithelium, which occupies only a small portion of the nasal mucosa, is generally well understood, while the presence and distribution of the sensory/tactile receptors in the mucosa of the nasal cavity is still a subject of controversy. The nasal vestibule, lined with skin, contains receptors that can sense noxious stimuli and air-flow. The sensitivity of the nasal mucosa to air-flow still needs further research. Understanding the distribution of the air-flow receptors could help to guide nasal surgery for obstruction.

Paradoxical sensation of nasal airflow in patients with common cold. Are we measuring the correct modality?

CONCLUSIONS

A paradoxical relationship between objective and subjective measures of nasal obstruction exists in participants not exposed to any treatment. The sensation of nasal obstruction may be due to the amalgamation of many different nasal sensations. Improved methods for measuring nasal sensations are required to further investigate the relationship between objective and subjective measures of nasal obstruction.

OBJECTIVES

In a recent study it was shown that the subjective sensation of nasal patency increased as the nasal passages became objectively more obstructed in patients who received a placebo compared to those who received an oral decongestant. This paradoxical response may be explained as a placebo effect, i.e. patients who received a placebo may have expected to feel less obstructed. The aim of the present study was to investigate this interesting paradox by determining objective and subjective measures of nasal obstruction over time in participants not exposed to any treatment.

MATERIAL AND METHODS

A total of 60 healthy participants with common cold were recruited. Objective and subjective measures of nasal obstruction were recorded at baseline and at 1 and 2 h using posterior rhinomanometry and a visual analogue scale.

RESULTS

Objective measures demonstrated an increase in nasal obstruction over time for both nasal passages considered together and for individual nasal passages. Subjective measures demonstrated a sensation of decreased nasal obstruction over time for both nasal passages considered together and for individual nasal passages.

Menthol: effects on nasal sensation of airflow and the drive to breathe

Menthol, in lozenges, nasal sprays, vapo-rubs, inhalers, and cough syrups, is widely used as a treatment for rhinitis that is associated with acute upper respiratory tract infection and allergy. Menthol as a plant extract has been used in traditional medicine in Asia for the treatment of respiratory diseases for hundreds of years, but it was only introduced to the West as a medicine at the end of the 19th century. With the recent discovery of a menthol receptor on the sensory nerves that modulate the cool sensation, menthol has graduated from the realms of herbal medicine into the field of molecular pharmacology. This review concerns the physiologic and pharmacologic mechanisms that underlie the widespread use of menthol as a treatment for the relief of nasal congestion associated with rhinitis and its effects on the drive to breathe and symptomatic relief of dyspnea.

Perceptual and physiologic effects of histamine challenge on nasal breathing

The purpose of this study is to determine the effect of histamine-induced nasal congestion on nasal airflow and the perception of externally applied resistance to nasal breathing. Nasal cross-sectional area and nasal airflow during free breathing were measured in 15 adult subjects before and after histamine challenge. The threshold for perception of resistance to nasal breathing was determined using a dynamic perturbator device, with both free breathing and controlled nasal air-flow. The average threshold for perception of nasal resistance was 0.383 Pa/cm3/s at baseline. After histamine application, there was a significant decrease in nasal cross-sectional area (p = 0.0001), associated with a decrease in nasal airflow (r = 0.6). The average threshold of perception increased to 1.373 Pa/cm3/s (p < 0.0001). When nasal airflow was controlled at the baseline rate, the threshold of perception improved to 0.638 Pa/cm3/s (p = 0.024). These findings indicate that nasal congestion causes a reduction in both nasal airflow and the perception of resistance to nasal breathing. The ability to detect nasal airway impairment is improved with increased nasal airflow. An improved understanding of the physiology of the subjective perception of nasal patency may lead to innovative methods for the treatment of nasal obstruction.

Nasal receptors responding to cold and l-menthol airflow in the guinea pig

The aim of this study was to demonstrate the presence of nasal 'cold' receptors, through recordings of action potentials from the ethmoidal nerve (EN), in guinea pigs and to characterize their responsiveness to l-menthol and capsaicin. Constant flows (400 ml/min) of room air (20 degrees C), warm air (45 degrees C), room air containing l-menthol, and cold air (-5 degrees C) were directed into the nasal cavity in the inspiratory direction via a nasopharyngeal catheter in the anesthetized guinea pigs breathing spontaneously through a tracheostomy. The ethmoidal afferent activity was increased by cold air, and to a greater extent by l-menthol but hardly by warm air. After topical anesthesia of the nasal cavity with 2% lidocaine, cold air and l-menthol no longer stimulated the EN. L-menthol noticeably stimulated the EN even after repeated capsaicin instillation into the nose, but these values were lower than those following the l-menthol stimulus before the 1st capsaicin treatment. These results suggest that the ethmoidal nerve in guinea pigs has cold-sensitive receptors which consist of both small myelinated fibers and C-fiber endings.

Menthol and related cooling compounds

Menthol and related cooling compounds such as 'coolant agent 10', are widely used in products ranging from common cold medications to toothpastes, confectionery, cosmetics and pesticides. The review brings together a range of information on production and chemistry of menthol, and its metabolism, mechanism of action, structure-activity relationships, pharmacology and toxicology. In particular, the coolant action and carminative actions of menthol are discussed in terms of actions on calcium conductance in sensory nerves and smooth muscle. The actions of menthol on the nose, respiratory reflexes, oral cavity, skin and gastrointestinal tract are reviewed.

The role of mucosal receptors in the nasal sensation of airflow

50 subjects were admitted into a randomized double-blind placebo controlled cross-over trial with 4% lignocaine as the active drug and normal saline as the placebo. Each subject had 2 ml of solution sprayed into each nasal cavity and all subjects had both sprays but on different occasions. The order in which the sprays were administered was randomized. The subjective sensation of nasal airflow was measured using a visual analogue scale before and after the spray. These measurements were made under conditions of the same airflow rate, which was monitored throughout the experiment using a reprogrammed NR6 rhinomanometer. Objective nasal patency was measured as peak nasal inspiratory flow rate. It was found that the nasal sensation of airflow decreased slightly after both lignocaine (difference between medians 5.0; 95% confidence interval -2.91 to 6.11) and normal saline (difference between medians 6.0; 95% confidence interval -1.02 to 7.21). Nonparametric analysis of variance showed this difference to be non-significant (P = 0.73). In addition there was no significant change in objective nasal patency. The results suggest that nerve endings in the nasal mucosa play no part in sensing nasal airflow during respiration.

Trigeminal nasal receptors related to respiration and to various stimuli in cats

In twenty adult cats of either sex under nembutal anaesthesia, we aimed at delineating the sensitive territory of trigeminal nerves innervating the nasal mucosa. The different trigeminal nerves (anterior ethmoidal, posterior nasal and infraorbital nerves) were dissected in the orbit. Activity of these nerves was recorded during spontaneous nasal and tracheal breathing and in response to various stimuli: mechanical (manual probing and air jets) and irritants (ammonia vapours). Multiple and unitary activity recorded in nerve filaments enabled a classification of the receptors on the basis of their discharge pattern as rapidly-, intermediately- or slowly adapting receptors, and as drive or non-drive nasal receptors depending on whether or not the respiratory modulation was preserved during tracheal breathing.

The effect of L-menthol stimulation of the major palatine nerve on nasal patency

Objective and subjective measurements of nasal patency were made before and after L-menthol stimulation of the palatal mucosa (supplied with the trigeminal nerve) in 15 normal adult subjects. The stimulation exerted indirect effect on the nasal cavity in that all subjects mentioned a cold sensation in their nose and a sensation of increased nasal patency, but no influence on nasal resistance to airflow was detected.