Biological rhythmicity of nasal airway patency: a re-examination of the 'nasal cycle'

[Definition and illustration of the different types of nasal cycle using long-term rhinometry]

BACKGROUND

A reciprocal swelling of the nasal mucosa is often referred to as the classical nasal cycle; however, reports in the literature suggest a more complex picture. Most of the research on the nasal cycle is based on individual measurements. The long-term rhinometry (LRM) now makes it possible to continuously examine the cyclic swelling of the nasal mucosa over 24 h. The aim of this study was therefore to evaluate the nasal cycle with LRM over 24 h.

MATERIAL AND METHODS

An LRM was performed in 55 rhinologically healthy subjects over 24 h using the portable measuring system Rhino-Move© (Happersberger Otopront; Hohenstein, Germany).

RESULTS

In addition to the expected strictly reciprocal swelling of the nasal mucosa in the sense of the classical nasal cycle, the following cycle types were detected: in-concert type with simultaneous rise and drop of the air flow on both sides of the nose, the one-sided type with significant congestion and decongestion of the mucous membrane only on one side and no detectable changes on the other side of the nose and the non-cycle type without any change in airflow on both sides. Most subjects showed a complex picture with multiple cycle types within the 24 h measurement (mixed nasal cycle). The types often differed during the day and night.

CONCLUSION

This study confirms the assumption that the nasal cycle measured over 24 h is much more complex than often described in the literature. Most subjects showed several of the 5 cycle types described here. The LRM has proven to be an easy to- use and reliable measurement method. The relationship between cycle type and physical activity as well as other factors remains to be investigated.

Re-evaluating the nasal cycle by long-term rhinoflowmetry: most individuals demonstrate a 'mixed' nasal cycle

BACKGROUND

The nasal cycle seems to be more complex than a strictly alternating swelling of the nasal mucosa. Long-term rhinoflowmetry (LRFM) allows continuous investigation of changes in nasal airflow over 24 hours (24h). We evaluated the various types of nasal cycle with LRFM over 24 hours and investigated the influence of age and gender.

METHODS

LRFM was continuously performed over 24h in 55 rhinologically healthy subjects (36 female, 19 male). The LRFM flow curves were examined for phases of the 'classical' 'in-concert' 'one-side' and'no-cycle' cycle types. Subjects were divided into 4 age subgroups (19-29; 30-49; 50-69; >70 years). Correlations of age and gender with the individual cycle forms were analyzed.

RESULTS

85.5% of the subjects presented a 'mixed' nasal cycle within 24h. 'classical' nasal cycle was seen most often (92.7% vs. 'in-concert' 56.4% vs. 'one-sided' 18.2% vs. 'no-cycle' 5.5%). Older age groups significantly more often presented the 'no-cycle' type. A tendency was seen towards a mixed nasal cycle with increasing age. The mixed nasal cycle was significantly more often seen in the female subjects.

CONCLUSIONS

LRFM is an easy-to-use measurement tool. The 'mixed' nasal cycle predominates. However, all 4 different cycle types can be detected, alternating over 24h in each subject. Moreover, the cycle type varies with age.

Air-conditioning characteristics in nasal cavity models exhibiting nasal cycle states

The air-conditioning characteristics in nasal cavity models obtained from two subjects exhibiting different degrees of the nasal cycle states in terms of the airflow partition were investigated using computational fluid dynamics. A constant inspiratory flow rate of approximately 250 mL/s was considered, and the air temperature and relative humidity at the inlet were assumed to be 25 °C and 35%, respectively. The air-conditioning capacities of the congested and decongested sides were assessed by the amounts of epithelial heat and water vapor transferred to the inhaled air through the airway from the nostrils to the end of the septum. The results revealed that the air temperature and relative humidity near the end of the septum, respectively, reached approximately 31.4-32.5 °C and 81.4-88.0% in the decongested sides and 34.0-35.9 °C and 95.3-100% in the congested sides. The differences seen in the air temperatures and relative humidity between the congested and decongested sides were found to be larger in the cavity model that showed a larger degree of reciprocal change in the airflow rate. From a fluid mechanics perspective, while the congested side is in a rest period during the nasal cycle such that a lower amount of airflow is transported through it, this side, in effect, works to provide assistive air-conditioning capacity to the nasal cavity and aids when insufficiently conditioned airflow passes through the decongested side so that the inhaled air merging after the septum can approach the alveolar condition favorably through the nasopharynx.

The Influence of Circadian Timing on Olfactory Sensitivity

Olfactory sensitivity has traditionally been viewed as a trait that varies according to individual differences but is not expected to change with one's momentary state. Recent research has begun to challenge this position and time of day has been shown to alter detection levels. Links between obesity and the timing of food intake further raise the issue of whether odor detection may vary as a function of circadian processes. To investigate this question, 37 (21 male) adolescents (M age = 13.7 years) took part in a 28-h forced desynchrony (FD) protocol with 17.5 h awake and 10.5 h of sleep, for 7 FD cycles. Odor threshold was measured using Sniffin' Sticks 6 times for each FD cycle (total threshold tests = 42). Circadian phase was determined by intrinsic period derived from dim light melatonin onsets. Odor threshold showed a significant effect of circadian phase, with lowest threshold occurring on average slightly after the onset of melatonin production, or about 1.5○ (approximately 21:08 h). Considerable individual variability was observed, however, peak olfactory acuity never occurred between 80.5○ and 197.5○ (~02:22-10:10 h). These data are the first to show that odor threshold is differentially and consistently influenced by circadian timing, and is not a stable trait. Potential biological relevance for connections between circadian phase and olfactory sensitivity are discussed.

Effects of Posture on the Nasal Cycle

The effects of posture on the nasal cycle were studied in 26 normal subjects whose spontaneous nasal cycle had been confirmed before the experiment. Nasal resistance was measured by anterior rhinomanometry with nozzles. With 14 subjects, the changes in nasal resistance were observed consecutively on changing from sitting to supine and from supine to sitting. Six reversals of the cyclic phase occurred in 56 postural changes (reversal rare: 10.7%). The reversal occurred once per 2.9 hours. By contrast, with 12 subjects, 27 reversals were induced in 60 postural changes (reversal rate: 45%), on changing from one lateral recumbent position to the other. The reversal occurred once per 27 minutes. Lateral recumbency tends to switch the phase of the cycle and affects its duration.

Long-Term Rhinoflowmetry: A New Method for Functional Rhinologic Diagnostics

Background

With current functional diagnostic tools in rhinology (rhinomanometry, rhinoresistometry, and acoustic rhinometry) long-term assessment of nasal function is difficult to acquire. Usually, only the situation at the time of examination is evaluated. Therefore, temporary nasal complaints of the nasal cycle are difficult to assess. It was the aim of this work to create a diagnostic tool to measure nasal flow over a long time period under physiological and everyday life conditions. We term the method long-term rhinoflowmetry (LRFM).

Methods

A portable device recording nasal airflow over a time period up to 72 hours was developed. Kinetic pressure fluctuations during respiration as a measure for the flow were registered over time and relative airflow was calculated. A summary of diagnostic results is given in six exemplary patients.

Results

Classic nasal cycles could be recorded in detail with durations ranging from 90 minutes to 10 hours. The manifestation of nighttime nasal obstruction as well as a case of paradoxical nasal obstruction were objectified. LRFM enables the assessment of time, duration, and extent of temporary nasal obstruction.

Conclusion

LRFM enables an assessment of temporary nasal obstruction as well as physiological and pathological fluctuations in the nasal cycle. Especially in cases in which traditional rhinological diagnostic tools are unsatisfying, the enhanced diagnostic quality of LRFM appears to be a promising supplement to the currently available rhinological monitoring methods.

Airflow and the Nasal Cycle: Nasal Patency Fluctuations after Laryngectomy

A periodic fluctuation in nasal patency or “nasal cycle” is observed in the majority of adults but has not hitherto been demonstrated in individuals after diversion of nasal airflow. Acoustic rhinometry, a highly sensitive technique which does not require airflow, provided the opportunity to evaluate this situation in patients who had undergone laryngectomy. We examined 21 postoperative individuals (mean postoperative time 4 years) and 14 control subjects matched for age (including 2 patients prelaryngectomy). Acoustic rhinometry was performed serially over 3–8 hours to determine minimum cross-sectional area and nasal cavity volume as indices of nasal patency. Fluctuations in nasal patency were observed in all laryngectomees and controls. These were classified as classical (reciprocal alternating), in concert (parallel) or irregular. The distribution of the control and laryngectomy subjects between the cycle categories was not statistically significant (Fisher's exact test: P > 0.05). The mean periodicity of the cycle was similar in the two groups (controls: 180 minutes, laryngectomees: 176 minutes), but the mean amplitude was significantly less in the laryngectomy group (68 versus 96 cm3; P < 0.07 Mann-Whitney U test). The nasal cycle can continue after cessation of airflow, but it is diminished in amplitude. Therefore, afferent input from nasal airflow receptors may continue to play a role in modulating the cycle's periodicity and amplitude, but are not responsible for generating the underlying cycle phenomenon.

Asymmetric expression level of clock genes in left vs. right nasal mucosa in humans with and without allergies and in rats: Circadian characteristics and possible contribution to nasal cycle

Numerous peripheral tissues possess self-sustaining daily biologic rhythms that are regulated at the molecular level by clock genes such as PER1, PER2, CLOCK, and BMAL1. Physiological function of nasal mucosa exhibits rhythmic variability to a day-night environmental cycle. Nevertheless, little is known of the expression and distribution pattern of clock genes in nasal mucosa. The present study investigates the expression level and distribution pattern of PER1, PER2, CLOCK, and BMAL1 genes in nasal mucosa of healthy controls, allergic rhinitis patients, and normal rats. In human and rat nasal mucosa, the levels of these genes are asymmetrically expressed in nasal mucosa derived from right and left cavities in normal controls, allergic patients, and rat. In human nasal mucosa, the expression levels of these genes were higher in the decongested side than the congested mucosa. In rat nasal mucosa, these clock genes are expressed in a rhythmic circadian manner under the regular light/dark cycles. The expression levels of MUC5AC, a key mucin genes produced in superficial epithelium, are higher in decongested side than that congested side in human nasal mucosa. In rat nasal mucosa, MUC5AC levels showed a circadian rhythm which was associated with different expression levels in nasal mucosa derived from the right and left nasal cavities. Taken together with these results, the present study shows that the clock genes such as PER1, PER2, CLOCK, and BMAL1 are present in human and rat nasal mucosa, and suggest that these clock genes may control the pathophysiological function of nasal mucosa as circadian oscillators and affect the maintenance of the nasal cycle.

Is there any relationship between right and left hand dominance and right and left nasal airflow dominance?

BACKGROUND

Left- or right-handedness is a common human trait, and it has been previously reported that human nasal airflow dominance correlates with hand dominance. Any relationship between hand dominance and nasal airflow dominance would be unusual. This study aimed to measure nasal airflow and look for any relationship to handedness.

METHODS

The modified Glatzel mirror was used to record the dominant nasal passage at 15-minute intervals over a 6-hour period in 29 healthy participants consisting of 15 left-handers and 14 right-handers.

RESULTS

In left-handers, the percentage of time that the left nasal passage was dominant ranged from 0 to 100 per cent. In right-handers, the percentage of time that the right nasal passage was dominant ranged from 4.2 to 95.8 per cent. No correlation between nasal airflow dominance and hand dominance was identified.

CONCLUSION

The results do not support the hypothesis that nasal airflow and handedness are related.

Interpretation of Nasal Swab Measurements Following Suspected Releases of Actinide Aerosols

For radionuclides such as plutonium and americium, detection of removable activity in the nose (i.e., nasal swab measurements) are frequently used to determine whether follow-up bioassay measurements are warranted following a potential intake. For this paper, the authors analyzed 429 nasal swab measurements taken following incidents or suspicious circumstances (such as an air monitor alarming) at Los Alamos National Laboratory (LANL) for which the dose was later evaluated using in vitro bioassay. Nasal swab measurements were found to be very poor predictors of dose and should not be used as such in the field. However, nasal swab measurements can be indicative of whether a reliably detectable committed effective dose (CED) occurred. About 14% of nasal swab measurements between 1.25 and 16.7 Bq corresponded to CEDs greater than 1 mSv, so in general, positive nasal swabs always indicate that follow-up bioassay should be performed (positive nasal swabs less than 1.25 Bq are considered separately). This probability increased significantly for nasal swabs greater than 16.7 Bq. Only about 3% of nasal swabs with no detectable activity (NDA) corresponded to reliably detectable CEDs. A nasal swab with NDA is therefore necessary, but not sufficient, to negate the need for a follow-up bioassay if it was collected following other workplace indicators of a potential intake.

Nasal airflow and brain activity: is there a link?

BACKGROUND

Over the past few decades, evidence has emerged suggesting that nasal airflow asymmetry and brain asymmetry are linked. The nose exhibits asymmetrical airflow, with the dominant airflow alternating from one nasal passage to the other over a period of hours. Some authors have suggested a correlation between cerebral hemisphere dominance and nostril dominance. Others have proposed an association between rhythmic fluctuations in nasal airflow and corresponding fluctuations in cerebral hemisphere activity. Based on ancient yoga breathing techniques, newer evidence suggests that altering nasal airflow can influence brain activity, with reports of improved cognitive function caused by unilateral forced nostril breathing. It seems that a nasal airflow stimulus may have an activating effect on the brain, as it has also been shown to trigger seizure activity in epileptic patients.

OBJECTIVES

This article explores these theories in detail, reviews the evidence, and presents new models linking nasal airflow and brain activity.

A model for the central control of airflow patterns within the human nasal cycle

BACKGROUND

The nasal cycle exhibits mainly reciprocal changes in nasal airflow that may be controlled from centres in the hypothalamus and brainstem. This study aims to gather new knowledge about the nasal cycle to help develop a control model.

METHOD

Right and left nasal airflow was measured in healthy human subjects by rhinomanometry. This was performed over 7-hour periods on 2 study days separated by approximately 1 week. The correlation coefficient for nasal airflow was calculated for day 1 and day 2.

RESULTS

Thirty subjects (mean age, 22.7 years) completed the study. The correlation coefficient for nasal airflow varied between r = 0.97 with in-phase changes in airflow and r = -0.89 with reciprocal changes in airflow. The majority of r values were negative, indicating reciprocal changes in airflow (50 out of 60). There was a tendency for r values to become more negative between day 1 and day 2 (p < 0.001).

CONCLUSION

A control model involving a hypothalamic centre and two brainstem half centres is proposed to explain both the in-phase and reciprocal changes in airflow associated with the nasal cycle.

Swelling of Erectile Nasal Tissue Induced by Human Sexual Pheromone

Most chemically mediated sexual communication in humans remains uncharacterized. Yet the study of sexual communication is decisive for understanding sexual behavior and evolutive mechanisms in our species. Here we provide the evidence to consider 4,16-androstadien-3-one (AND) as a man's sexual pheromone. Our experiment provides support for the physiological effect of AND on nasal airway resistance (Rna) in women, as assessed by anterior rhinomanometry. We found that AND administration increased the area of turbinate during the ovulatory phase, resulting in an increase of Rna. Thus, we discovered that minute amounts of AND, acting through neuroendocrine brain control, regulate Rna and consequently affect the sexual physiology and behavior. Fascinatingly, this finding provides the evidence of the preservation of chemosexual communication in humans, which it has been largely neglected due to its unconscious perception and concealed nature. Therefore, chemical communication is a plesiomorphic evolutive phenomenon in humans.

Assessment of nasal parameters in determination of olfactory dysfunction in Parkinson's disease

OBJECTIVES

To assess nasal cycle, nasal mucosal pH and mucociliary clearance time in patients with Parkinson's disease and healthy control subjects.

METHODS

Patients with idiopathic Parkinson's disease and healthy control subjects were recruited. Presence of the nasal cycle, nasal mucosa pH and mucociliary clearance time were investigated in all participants.

RESULTS

The study included 27 patients and 24 control subjects. The nasal cycle was present in significantly fewer patients than controls. Nasal pH and mucociliary clearance time were significantly higher in patients than in controls.

CONCLUSIONS

Parkinson's disease is associated with alterations in nasal cycle, nasal mucosa pH and mucociliary clearance time. Measurements of these nasal parameters may be useful for the early diagnosis of autonomic and olfactory dysfunction in Parkinson's disease.

Physiology and pathophysiology of respiratory mucosa of the nose and the paranasal sinuses

In this review, anatomy and physiology of the respiratory mucosa of nose and paranasal sinuses are summarized under the aspect of its clinical significance. Basics of endonasal cleaning including mucociliary clearance and nasal reflexes, as well as defence mechanisms are explained. Physiological wound healing, aspects of endonasal topical medical therapy and typical diagnostic procedures to evaluate the respiratory functions are presented. Finally, the pathophysiologies of different subtypes of non-allergic rhinitis are outlined together with treatment recommendations.

An odor is not worth a thousand words: from multidimensional odors to unidimensional odor objects

Olfaction is often referred to as a multidimensional sense. It is multidimensional in that approximately 1000 different receptor types, each tuned to particular odor aspects, together contribute to the olfactory percept. In humans, however, this percept is nearly unidimensional. Humans can detect and discriminate countless odorants, but can identify few by name. The one thing humans can and do invariably say about an odor is whether it is pleasant or not. We argue that this hedonic determination is the key function of olfaction. Thus, the boundaries of an odor object are determined by its pleasantness, which--unlike something material and more like an emotion--remains poorly delineated with words.

Does inhaling menthol affect nasal patency or cough?

OBJECTIVE

There is widespread use of menthol in over-the-counter medications, despite scant information on any beneficial effects. Our aim was to assess the effect of menthol on nasal air flow, perception of nasal patency and cough challenge testing.

MATERIALS AND METHODS

Subjects comprised 42 healthy children aged 10 and 11 in a school setting. We used a single-blind pseudo-randomized cross-over trial to compare the effect of an inhalation of either menthol or placebo(eucalyptus oil). Baseline and post-intervention measurements were made on each of 2 consecutive days. Main outcome measures were (i) nasal expiratory and inspiratory flows and volumes, measured by spirometer, (ii) perception of nasal patency, assessed with a visual analogue scale (VAS), and (iii) the number of coughs in response to nebulized citric acid.

RESULTS

There was no effect of menthol on any of the spirometric measurements. Following menthol, there was a significant increase in the perception of nasal patency (mean difference in log VAS (menthol-placebo) = -0.207, 95%CI -0.329, -0.085). The cough count after menthol inhalation was reduced when compared to baseline but the change was not different from that after placebo (mean difference in cough count (menthol-placebo) = -1.71, 95%CI -4.11, 0.69).

CONCLUSION

Menthol has no effect on objective measures of flow but significantly increases the perception of nasal patency. It may not be possible to extrapolate these findings to younger children and those with rhinitis. Extending the study of menthol to these groups, including investigations of the efficacy and safety profiles, will provide further valuable evidence for its common use.

Study of nasal cycles in children by acoustic rhinometry

BACKGROUND

Studies concerning nasal cycle physiology in children are still rare, and controversies exist about its existence. This study was ascertained to evaluate the dynamic behavior of inferior turbinates in children by acoustic rhinometry.

METHODS

Sixteen volunteer patients, aged 2-11 years old (mean, 6.25 years), were evaluated between April and July 2003. The patients submitted to periodic acoustic rhinometry, with triplicate measurements (each 30 minutes) for 3 hours.

RESULTS

All evaluated children presented nasal cycles, with five children presenting a classic pattern (31.25%), three children presenting a concert pattern (18.75%), and eight children presenting an irregular pattern (50%).

CONCLUSION

This study suggests that children present nasal cycles, as well as adults. Nevertheless, the most prevalent pattern in children was the irregular pattern, whereas in adults the most frequently detected is the classic pattern.

The sniff is part of the olfactory percept

In this review, we use data obtained primarily from humans to argue that sniffs are not merely a stimulus carrier but are rather a central component of the olfactory percept. We argue that sniffs 1) are necessary for the olfactory percept, 2) affect odorant intensity perception and identity perception, 3) drive activity in olfactory cortex, 4) are rapidly modulated in an odorant-dependent fashion by a dedicated olfactomotor system, and 5) are sufficient to generate an olfactory percept of some sort even in the absence of odor.

Nostril dominance: differences in nasal airflow and preferred handedness

Because there appears to be a general propensity among many people to have a consistency in the sidedness of their lateral preferences, the purpose of the present study was to determine if this consistency extends to the airflow through the individual nostrils as well. To test for this, hot wire anemometers measured the airflow in each nostril at 15-minute intervals for 6 continuous hours in 11 right-handed and 9 left-handed adult males. Participants also provided self-reports of which nostril appeared to have the greater airflow. The airflow measurements supported the hypothesis of a handedness by nostril interaction, in that left-handers more often experienced greater airflow in their left nostrils whereas right-handers showed the opposite pattern. Self-reports were not an especially reliable measure of nasal patency. In most subjects the same nostril was not always the more open one. This left/right shifting of the more patent nostril is termed the nasal cycle. This study also provides the first data comparing the nasal cycle patterns of left-handers and right-handers.

Bilateral nasal allergen provocation monitored with acoustic rhinometry. Assessment of both nasal passages and the side reacting with greater congestion: relation to the nasal cycle

BACKGROUND

The effect of bilateral nasal provocation on nasal mucosa measured with the use of acoustic rhinometry (AR) can be assessed for both nasal passages or for the side responding with greater congestion. Assessment of changes in nasal congestion during the nasal provocation test (NPT) can be affected by the nasal cycle (NC). The aim of this study was to find out the most accurate method to evaluate changes observed during bilateral nasal provocation.

METHODS

Cross-sectional areas (CSA) at the level of inferior nasal turbinate (CSA-2) were recorded by AR in 26 volunteers with allergic rhinitis during the NC for 5-7 h and subsequently during NPT. The risk of spontaneous total and unilateral CSA-2 decrease was established. Sensitivity of the NPT assessment for the total CSA-2 and for the side responding with greater congestion was evaluated at chosen thresholds. These thresholds were selected in a way that the risk levels of spontaneous decrease of unilateral and total CSA-2 were equal.

RESULTS

The assessment of the total CSA-2 was found to be more sensitive than the assessment of the side responding with greater congestion. The highest sensitivity and specificity of the test was achieved by using a combination of both assessments. Optimum thresholds of the CSA-2 decrease for assessment at 15 min after provocation, with this method, were 27% and 40% for the side responding with greater congestion and for the total CSA-2, respectively.

CONCLUSIONS

Recognition of the risk of spontaneous unilateral and total CSA-2 decreases enables introduction of combined assessment of bilateral NPT. This assessment seems to be the most accurate method for evaluation of the test results.

Reliability of acoustic rhinometry

In recent years increasing evidence has been provided on frequent simultaneous coexistence of inflammatory diseases and allergies in upper and lower airways. To achieve a good standard of measurement of upper airways, an objective method should be used. A total of 48 nasal cavities with nasal stuffiness associated with chronic sinusitis were measured with acoustic rhinometry (AR) and High-resolution computer tomography volumetry (HRCTV). Comparison of volumes and minimum cross-sectional areas measured with these methods was performed. The volumes measured from the nostril with both methods were the anterior (0-10 mm), middle (11-40 mm) and posterior (41-70 mm) volumes. The AR cross-sectional area curve was analysed based on two minimal notches corresponding to local minimal areas. A series of 1-mm coronal CT images without intervening gaps were made and analysed based on two minimal voxel values, which were later converted to cross-sectional areas corresponding to local, minimum cross-sectional areas (MCA). Furthermore, the distances of these 2 MCAs from the nostril were also measured. Strong statistically significant (P < 0.05) correlations were found between AR and computer tomography volumetry (CTV) volumes in the anterior (r = 0.83) and middle (r = 0.77) parts of the nasal cavity. In the posterior part of the nasal cavity a statistically significant (P < 0.05) correlation was also found (r = 0.62). Good agreements between the AR and CTV volumes in the anterior and middle parts of the nasal cavities were confirmed with Bland-Altman plots. Correlations among the MCAs were weaker (r = 0.59 and r = 0.55). Our results suggest that the reliability of AR appears sufficient for clinical and scientific use in the nasal cavities. Reliability is very good in the anterior and middle parts of the nasal cavities, while strong conclusions based on evaluation of the posterior part should be avoided due to decreasing accuracy.

Assessment of Nasal Cycle by Acoustic Rhinometry and Rhinomanometry

OBJECTIVE: We sought to investigate the pattern, duration, and amplitude of nasal cycle and its response to nasal decongestant.

STUDY DESIGN AND SETTING: Ten adult volunteers attended 2 sessions (with and without nasal spray of 0.1% xylometazoline) for consecutive examinations by rhinomanometry and acoustic rhinometry every 10 minutes over 6 hours.

RESULTS: A spontaneous fluctuation in nasal minimum cross-sectional area, volume, and nasal resistances (inspiration and expiration) could be observed in every consecutive measurement. A significant negative correlation ( r = −0.33 to −0.70, P < 0.05) between both nasal passages was shown in 5 subjects by rhinomanometry and in 2 subjects by acoustic rhinometry but was not detectable after nasal spray with 0.1% xylometazoline.

CONCLUSION: A spontaneous fluctuation in nasal patency can be documented every 10 minutes with irregular pattern, frequency, and amplitude. Classic nasal cycle is not a universal phenomenon, which can be abolished by the application of decongestant.

Investigating the nasal cycle using endoscopy, rhinoresistometry, and acoustic rhinometry

OBJECTIVES

Cyclic congestion and decongestion in the two nasal cavities is seen in connection with the respiratory function of the nose. The turbulent behavior of nasal airflow is a prerequisite for adequate contact of inspired air particles with the mucosa. The aim of this study was to gain insight into this turbulent behavior of nasal airflow during the nasal cycle.

METHODS

The nasal cycle in 10 healthy human subjects was investigated using endoscopic imaging, rhinoresistometry, and acoustic rhinometry every 20 minutes over a time period of up to 15 hours. The following parameters were recorded for each nasal cavity: airflow resistance, hydraulic diameter, friction coefficient lambda as an indicator for the wall configuration triggering turbulence, transition from laminar to turbulent flow, and the minimal cross-sectional areas.

RESULTS

In addition to the known cyclic change of flow resistance and nasal width, a periodic change in the turbulence behavior was observed. In the resting phase, mainly laminar flow was found. During the working phase, the onset of turbulence occurred already at low flow velocities. The increase of turbulence during the working phase is caused by the increase in cross-sectional area in the anterior cavum due to decongestion of the mucosa of the head of the inferior turbinate and the septal tuberculum.

CONCLUSIONS

Rhinoresistometry and acoustic rhinometry complement each other. The combination of the two methods provides insight into the functional changes during the nasal cycle and into nasal physiology in general. The authors therefore advocate a combination of the two methods for functional evaluation of the nasal airway.

Lateralization of brain activation to imagination and smell of odors using functional magnetic resonance imaging (fMRI): left hemispheric localization of pleasant and right hemispheric localization of unpleasant odors

PURPOSE

Our goal was to use functional MRI (fMRI) of brain to reveal activation in each cerebral hemisphere in response to imagination and smell of odors.

METHOD

FMRI brain scans were obtained in 24 normal subjects using multislice fast low angle shot (FLASH) MRI in response to imagination of banana and peppermint odors and in response to smell of corresponding odors of amyl acetate and menthone, respectively, and of pyridine. Three coronal sections selected from anterior to posterior brain regions were used. Similar studies were obtained in two patients with hyposmia using FLASH MRI and in one patient with hyposmia using echo planar imaging (EPI) both before and after theophylline treatment that returned smell function to or toward normal in each patient and in two patients with birhinal phantosmia (persistent foul odor) and global phantogeusia (persistent foul taste) with FLASH and EPI fMRI before and after treatment with neuroleptic drugs that inhibited their phantosmia and phantogeusia. Activation images were derived using correlation analysis. Ratios of hemispheric areas of brain activation to total hemispheric brain areas were calculated for FLASH fMRI, and numerical counts of pixel clusters in each hemisphere were made for EPI studies. Total pixel cluster counts in localized regions of each hemispheric section were also obtained.

RESULTS

In normal subjects, activation generally occurred in left (L) > right (R) brain hemisphere in response to banana and peppermint odor imagination and to smell of corresponding odors of amyl acetate and menthone. Whereas there were no overall hemispheric differences for pyridine odor, activation in men was R > L hemisphere. Although absolute activation in both L and R hemispheres in response to banana odor imagination and amyl acetate smell was men > women, the ratio of L to R activation was women > men. In hyposmic patients studied by FLASH fMRI, activation to banana odor imagination and amyl acetate smell was L > R hemisphere both before and after theophylline treatment. In the hyposmic patient studied with EPI before theophylline treatment, activation to banana and peppermint odor imagination and to amyl acetate, menthone, and pyridine smell was R > L hemisphere; after theophylline treatment restored normal smell function, activation shifted completely with banana and peppermint odor imagination and amyl acetate and menthone smell to L > R hemisphere, consistent with responses in normal subjects. However, this shift also occurred for pyridine smell, which is opposite to responses in normal control subjects. In patients with phantosmia and phantogeusia, activation to phantosmia and phantogeusia before treatment was R > L hemisphere; after treatment inhibited phantosmia and phantogeusia, activation shifted with a slight L > R hemispheric lateralization. Localization of all lateralized responses indicated that anterior frontal and temporal cortices were brain regions most involved with imagination and smell of odors and with phantosmia and phantogeusia presence.

CONCLUSION

Imagination and smell of odors perceived as pleasant generally activated the dominant or L > R brain hemisphere. Smell of odors perceived as unpleasant and unpleasant phantosmia and phantogeusia generally activated the contralateral or R > L brain hemisphere. With remission of phantosmia and phantogeusia, hemispheric activation was not only inhibited, but also there was a slight shift to L > R hemispheric predominance. Predominant L > R hemispheric differences in brain activation in normal subjects occurred in the order amyl acetate > menthone > pyridine, consistent with the hypothesis that pleasant odors are more appreciated in L hemisphere and unpleasant odors more in R hemisphere. Anterior frontal and temporal cortex regions previously found activated by imagination and smell of odors and phantosmia and phantogeusia perception accounted for most hemispheric differences.

The effects of endoscopic sinus surgery on the nasal cycle as assessed by acoustic rhinometry

Previous studies have demonstrated that acoustic rhinometry (AR) has a considerable utility in measuring nasal patency and in detecting the nasal cycle. This study was performed in 10 patients with chronic rhinosinusitis who were submitted to endoscopic sinus surgery. AR was used to determine minimum nasal cross-sectional area and volume as the indices of the nasal patency in all patients on the day before the surgery and 3 months postoperatively. We did not find any significant alteration when comparing the pattern of fluctuation, the periodicity, and the amplitude of the nasal cycle demonstrated by patients in the pre and postoperative periods, confirming that this surgery does not have any adverse effect on this physiologic cycle.

Acoustic rhinometry assessment of the nasal cycle in neonates

In this study the nasal cycle in newborns was assessed using acoustic rhinometry with miniprobe (RHIN 2100). Enrolled in the study were 67 newborns aged 2 to 4 days. Each subject was assessed for 3 h, examinations taking place every 30 min. At least six measurements, three from each nostril, were taken at each examination. The miniprobe RHIN 2100 (SR Electronics ApS) was used for evaluation of nasal geometry. The minimal cross-sectional area (MCA) and the total volume of the anterior 45 mm (VOL45) were calculated and used for statistical analysis. The mean volume of MCA and VOL45 in the examined group of children was 0.08 cm3 and 1.19 cm3 respectively. Nasal cycle was assessed by constructing the plots of acoustic rhinometry parameters MCA or VOL45 for time and statistically using Pearson's correlation coefficients. Most of the examined infants (70-85%) showed no significant fluctuations in nasal patency.

Nasal airflow in health and disease

This review examines our present understanding of the physiology, pathophysiology and pharmacology of nasal airflow. The main aim of the review is to discuss the basic scientific and clinical knowledge that is essential for a proper understanding of the usefulness of measurements of nasal airflow in the clinical practice of rhinology. The review concludes with a discussion of the measurement of nasal airflow to assess the efficacy of surgery in the treatment of nasal obstruction. Areas covered by the review include: influence of nasal blood vessels on nasal airflow; nasal valve and control of nasal airflow; autonomic control of nasal airflow; normal nasal airflow; nasal cycle; central control of nasal airflow; effect of changes in posture on nasal airflow; effect of exercise on nasal airflow; effect of hyperventilation and rebreathing on nasal airflow; nasal airflow in animals; cerebral effects of nasal airflow; sensation of nasal airflow; sympathomimetics and sympatholytics; histamine and antihistamines; bradykinin; and corticosteroids.

Nasal cycle in patients with septal deviation: evaluation by acoustic rhinometry

The nasal cycle in patients with septal deviation was studied by acoustic rhinometric techniques. This study included 24 patients with anteriorly located septal deviations (mean age = 23.5), and 26 normal controls (mean age = 24.7). Data of MCA (minimum cross-sectional area) and NV (nasal volume), collected in 20-minute intervals, were plotted for each subject during 8 hours. Twenty of 24 patients (83%) with septal deviation and 20 of 26 normal subjects (77%) showed at least one complete cycle. Duration of the nasal cycle, which ranged from 100 minutes to 400 minutes, had no statistical difference between the septal deviation group (mean duration of 216 minutes) and the normal control group (mean duration of 227 minutes). The degrees of variation of MCA and NV, defined as Degree of Variation of MCA (%) = 100 (MCAmax - MCAmin)/MCAmax, Degree of Variation of NV (%) = 100 (NVmax - NVmin)/NVmax, which represent the percent change of MCA and NV throughout the study, showed no difference between the wide side and the narrow side, or between the septal deviation group and the normal control group. These findings suggest that the nasal cycle is relatively independent of peripheral anatomic factors for its generation. However, the amplitude of changes of MCA was greater in the wide side, and the sum of both MCAs tended to fluctuate in accordance with the fluctuation of MCA of the wide side. Thus, the nasal cycle seemed to be affected by septal deviation.

Effects of nasal-airway volume and body temperature on intranasal chemosensitivity

Interrelations between intranasal detection sensitivity for odor (H2S) and pain (CO2), nasal-airway volume (acoustic rhinometry), and body temperature were studied in young, healthy men across the diurnal cycle. The results showed a weak but statistically significant negative correlation between nasal volume and odor threshold and a weak but positive correlation between body temperature and odor threshold.

Physiological fluctuations in nasal resistance may interfere with nasal monitoring in the nasal provocation test

The physiological fluctuations in nasal flow and resistance in allergic subjects were studied by monitoring 12 subjects with perennial occupational allergic rhinitis with active anterior rhinomanometry (AAR) for 3 h at 15 min intervals. The subjects were then challenged bilaterally with the diluent solution for allergen extracts and the effect was monitored with AAR. In AAR. cellular rubber nose adapters were used. Many physiological fluctuations in nasal patency were observed. Reference intervals were calculated for the changes in flow and resistance at the gradient pressure of 150 pa. For example, a 100% increase in unilateral resistance was found to be significant at the risk level of 5-10% for the observation time of 30-60 min. The corresponding increase for bilateral resistance was close to 70%. Challenge with diluent solution had a negliglible effect on the resistance fluctuation, the reference intervals being close to those for baseline monitoring. In conclusion, rapid changes in nasal flow and resistance in allergic subjects were common, and caution is necessary when interpreting these changes as a positive nasal reaction in the nasal provocation test. In addition, the use of other objective parameters, such as the amount of nasal secretion is recommended.

Influence of age on the 'nasal cycle'

The nasal cycle is classicially defined as a side-to-side fluctuation in nasal engorgement and airflow, with period lengths ranging from approximately 1 to 5 hours. This cycle, as well as its variants (e.g., cyclic changes on one side of the nose only), is produced by alterations in autonomic tone of the nasal vasculature and reportedly correlates with a number of ultradian rhythms, including asymmetries in left:right cerebral electroencephalographic (EEG) activity and differential performance on visual/spatial psychological tasks. Since the pacemaker for the nasal cycle is believed to lie within the suprachiasmatic nucleus of the hypothalamus, and this nucleus evidences degeneration in later life, we sought to determine whether the nasal cycle or its variants changes with age. To achieve this end, we used a liquid crystal thermography exhalation monitor to measure relative airflow of the two nasal chambers at 15-minute intervals for 6 hours in 60 people representing four age categories: 18 to 29 years (n=12); 30 to 49 years (n=15); 50 to 69 years (n=13); and 70 to 85 years (n=20). Overall, the proportion of subjects exhibiting the alternating rhythmicity associated with the classic nasal cycle decreased with age. No association was present between nasal cycle parameters and scores on the Mini-Mental State Examination (MMSE). The results suggest that the classic nasal cycle may be a marker for age-related central nervous system changes.

Aging of the normal nose in adults

Like other organs, the nose changes as the body ages. A review of the literature reveals a basic understanding of the aging process in the nose but a paucity of documentation and few organized studies. This study was designed to identify systematically the agerelated changes in the normal, nondiseased adult nose. A nasal-sinus laboratory was created, and a computerized patient database was developed. Four separate investigations were conducted. First, 111 subjects ranging in age from 21 to 94 years of age were studied prospectively using 135 variables. The following data were collected: history, symptoms, physical examination, rhinomanometry, ciliary beat frequency, smell testing, and incentive spirometry. Second, photographs of a separate group of 105 subjects 20 to 86 years of age were studied to ascertain the facial cephalometric changes that occur with aging. Third, a histopathologic examination of the nasal septum was performed in 20 additional subjects to evaluate the cellular changes that accompany aging. Finally, an epidemiologic study analyzing the prevalence of various nasal complaints by age was conducted, based on a review of more than 11,000 patient charts from surgeries and office visits. A number of specific age-related changes in the nose were identified, including an increased likelihood of certain nasal complaints, a pattern of increasing airflow resistance, and a decrease in physical abnormalities in the nasopharynx. The appearance of the nose, as measured by the nasolabial angle and the height/length ratio, was also found to change with age.

Monitoring fluctuations in nasal patency in children: acoustic rhinometry versus rhinohygrometry

Simple rhinohygrometry and passive rhinomanometry studies have suggested that the 'nasal cycle' in children is often different in pattern of that of adults and experimental animals. We aimed to establish whether this assertion was correct, using a reliable and sensitive method, acoustic rhinometry (AR), and to compare results with those of simple rhinohygrometry (RH). Healthy children with no evidence of nasal disease were examined (n = 15; age range three to 10 years; mean age six years). Simultaneous recordings using AR and RH were made on each child every 10-15 minutes over two to four hour periods. Six children underwent nine additional AR studies on separate occasions. 'Classical' reciprocal alternating patterns were evident in 80 per cent (12/15) AR and 53 per cent (8/15) RH studies, 'in concert' patterns in seven per cent (1/15) AR and 20 per cent (3/15) RH studies and 'irregular' patterns in 13 per cent (2/15) AR and 27 per cent (4/15) RH studies. The agreement between the two methods was 47 per cent, with a kappa (kappa) value of -0.17 (poor agreement compared to chance). Agreements between the acoustic rhinometry parameters were 'fair' for all data (kappa = 0.34) and excellent (kappa = 1.0) if irregular patterns were ignored. Repeated studies showed that the pattern of fluctuation varies within any particular individual. The nasal cycle is similar in pattern in children and adults, and acoustic rhinometry is currently the method of choice to further investigate and clarify this phenomenon.

The nasal cycle after deprivation of airflow: a study of laryngectomy patients using acoustic rhinometry

Previous studies of the nasal cycle in laryngectomy patients using rhinomanometric techniques concluded that the cycle was abolished as a result of the cessation of airflow after laryngectomy. This study was performed with 20 postoperative laryngectomy patients (mean time after surgery 4 years, range: 2 weeks to 10 years) and 10 control subjects matched for age and sex (including 2 preoperative patients). Acoustic rhinometry was used to determine minimum nasal cross-sectional area and nasal cavity volume as the indices of nasal patency. Testing was repeated at intervals of 15-30 min over a period of 3-8 h. Fluctuations in nasal patency were observed in all laryngectomees and controls. The fluctuations were classified as 'classical' (reciprocal alternating) in 5 (25%) laryngectomees and 5 (50%) controls. An 'irregular' pattern of fluctuation was seen in 8 (40%) laryngectomees and 2 (20%) controls. An 'in concert' cyclical pattern was seen in 7 (35%) laryngectomees and 3 (30%) controls. This is the first demonstration of retention of the nasal cycle after airflow deprivation. Whilst the cycle may in some instances be modified after operation, it is not abolished. The central generation of the cycle is confirmed, although afferent input from airflow receptors may play a role in modulating the cycle's pattern and amplitude.

The relationship of cortical activation to alternating autonomic activity

It has been proposed that it is possible to selectively activate the cerebral hemispheres, thereby enhancing lateralized cognitive abilities. A proposed method of achieving selective activation is by altering nasal congestion/decongestion (nasal cycle), which is believed to effect a contralateral change in hemispheric activation through the autonomic nervous system (ANS). This hypothesis was tested in 4 right-handed male and 6 right-handed female undergraduate students. Subjects were untrained in specific breathing techniques but were aware of the experimental hypothesis. Four 1 min samples of EEG were recorded in each of 4 experimental conditions in which nasal decongestion was altered by having subjects lie in the lateral recumbent position and occluding the contralateral nare. Cortical activation and laterality were examined using ratios of the low beta (12-18 Hz) and high alpha (10-12 Hz) bandwidths relative to each other and between hemispheres. Repeated measures ANOVAs showed non-significant changes in the alpha and beta bandwidths across the 4 experimental conditions. Although changes in hemispheric activation have been postulated for all subjects, this study does not support such changes in subjects untrained in breathing techniques.

The nasal cycle in patients with autonomic nervous disturbance

The nasal cycle is thought to be controlled by the autonomic nervous system. In this study, we measured nasal airflow resistance in patients with lesions of the autonomic nerves that supply the nasal mucosa. We examined 20 patients with facial palsy as examples of parasympathetic disturbance, five with Horner's syndrome as examples of sympathetic disturbance, and one with acute pandysautonomia. The nasal cycle was observed in 13 patients with facial palsy and four patients with Horner's syndrome. The nasal cycle was also observed in one patient with acute pandysautonomia and disturbance of the sympathetic-parasympathetic nerves. Our results indicate that disturbance of the parasympathetic and sympathetic nerves has little influence on the nasal cycle.

Developmental changes in nasal airflow patterns

Airflow through each nasal passage was measured every 10 min throughout a 5-h period in 48 subjects whose ages ranged from 3 to 17 years. The data were subjected to statistical techniques that characterize and quantify periodicities in a time series. Such analyses revealed that for the majority of children younger than 7 years of age, the airflow through the two nostrils changed either randomly (50%) or in parallel (31%). Between the ages of 7 and 10 years, however, the distribution of airflow patterns characteristic of adults emerged, such that the incidence of reciprocity increased to 63%, and the incidence of random and parallel patterns decreased to 31% and 6%, respectively. A similar distribution was evidenced in the 11- to 17-year-old subjects (56% reciprocal, 38% random, 6% parallel). Although the total airflow through the nose also increased with age, the increased inspiratory flow rates could not account for the developmental changes evidenced in airflow patterns.

Limbic autonomic arousal: its physiological classification and review of the literature

The object of this article is to present a novel physiological classification of Limbic-Autonomic (LA) arousal on the basis of human physiological data, specifically the oro-nasal breathing patterns in man. It is proposed that the multidimensional LA arousal can be classified into five grades: Grade I: Non-nasal (NN) or oral breathing with bilateral nasal congestion, and nonactive behavior, Grade II: Left Nasal (LN) breathing and quiet behavior, Grade III: Right Nasal (RN) breathing and active behavior, Grade IV: Bilateral Nasal (BN) breathing and very active behavior, and Grade V: Oral and Bilateral Nasal (ON) breathing with maximal behavioral activation. The data from polygraphic electroencephalographic recordings from five healthy volunteers, before, during and after exercise are presented in support of this physiological classification of LA arousal. On the basis of Limbic-Autonomic asymmetry a novel concept of "Visceral Dominance" is also proposed.

Normal nasal airway resistance in noses of different sizes and shapes

Measurement of nasal airway resistance is becoming a common clinical technique. Accurate definition of the normal range of airflow is critical for maximal usefulness of this technique. Since typical nasal size and shape vary greatly with ethnic background, different norms for different ethnic groups may be appropriate. Nasal airway flow and resistance and external nasal size and shape were measured in 130 asymptomatic subjects (52 black, 56 white, and 22 Hispanic). Nasal length, width, columellar length, and nasolabial angle were similar for whites and Hispanics, but both groups differed significantly from blacks--even when changes attributable to biologic aging were factored out. In spite of these differences, there was no significant difference in any nasal airflow or resistance parameter among groups, suggesting that currently used airflow and resistance standards are valid for these three different ethnic groups.

Right-nostril advantage for discrimination of odors

Olfactory discrimination was tested with eight pairs of odors presented to each nostril of each subject. Ninety-nine subjects were tested; there were equal numbers of left- and right-handers, as well as both sexes. Detection thresholds for phenylethyl alcohol were measured separately in each nostril using a forced-choice staircase procedure. In addition, a verbal dichotic listening test known to be sensitive to language lateralization was administered. Results indicated that discrimination performance was significantly better when the stimuli were presented to the right nostril than when they were presented to the left, but no differences between the nostrils in detection thresholds were found. The right-nostril advantage did not vary as a function of sex or handedness, and did not bear any relation to language lateralization as measured via dichotic listening. The asymmetry for olfactory discrimination replicates an earlier study and is interpreted in terms of a possible specialization of function within the right cerebral hemisphere.

Nasal mucosal temperature and the effect of acute infective rhinitis

Nasal mucosal temperature was measured in 71 healthy subjects with an electronic thermometer. No correlation was found between the nasal mucosal temperature and age or sex. An increased mucosal temperature was found in patients with acute rhinitis, an effect which is supposed to assist in the defence system against microorganisms. When measuring nasal mucosal temperature over a 7-h period at the same time as nasal airway resistance, there was no correlation between these factors, indicating that the temperature is independent of the state of the capacitance vessels.

Reciprocity versus rhythmicity in spontaneous alternations of nasal airflow

Active anterior rhinomanometry was used to observe nasal airflow in five men and four women (ages 18-30). Measurements were obtained for each nasal passage every 5 min throughout an uninterrupted 8-hr session. Facial skin temperature from the left and right side of the face was recorded simultaneously from thermocouples. Observations were made during the months of May and June; subjects were allowed to maintain their routine diurnally active schedules prior to observation. Airflow in the two passages showed a significant negative correlation (i.e. was reciprocal) in 44% of subjects (N = 9). Autocorrelation and spectral analysis of the airflow data found evidence of periodicity in 39% of individual nostrils and 56% of subjects. Mean estimated period was 4.5 +/- 1.0 hr (range 3.5-6.0 hr). Only 22% of subjects showed statistical evidence of periodicity in both nostrils (i.e. a "nasal cycle"). Left- and right-side facial skin temperatures changed in parallel rather than reciprocally, but showed evidence of periodicity in 50% of hemifacial time series (56% of subjects), with an estimated period of 3.8 +/- 1.0 hr (range 2.3-5.0).

Sex, handedness and side of nose modulate human odor perception

Multidimensional scaling was used to analyze odor similarity judgments obtained by monorhinic (single nostril) stimulation from normal subjects (N = 52), equally partitioned by sex and handedness. Neither sex nor handedness nor side of nose appeared to alter the position of stimuli on a two-dimensional map of odor similarity. However, women produced significantly more consistent maps than men. This result was not due to differential utilization of axes in the multidimensional perceptual space, nor to differences in verbal labeling. Left versus right nostril asymmetries were significantly greater in dextrals.