Nonallergic Rhinopathy: A Comprehensive Review of Classification, Diagnosis, and Treatment

Chronic nonallergic rhinitis syndromes encompass various conditions, of which vasomotor rhinitis is the most common form, representing approximately 80% of patients, also referred to as nonallergic rhinopathy (NAR), nasal hyperreactivity, neurogenic rhinitis, or idiopathic rhinitis. Expert panels have recommended replacing vasomotor rhinitis terminology because it is more descriptive of this condition that is characterized by symptoms triggered by chemical irritants and weather changes through chemosensors, mechanosensors, thermosensors, and/or osmosensors activated through different transient receptor potential calcium ion channels. Elucidating the specific role of transient receptor potential vanilloid 1, triggered by capsaicin, has been an important advancement in better understanding the pathophysiology of NAR because it has now been shown that downregulation of transient receptor potential vanilloid 1 receptors by several therapeutic compounds provides symptomatic relief for this condition. The classification of NAR is further complicated by its association with allergic rhinitis referred to as mixed rhinitis, which involves both immunoglobulin E-mediated and neurogenic mechanistic pathways. Comorbidities associated with NAR, including rhinosinusitis, headaches, asthma, chronic cough, and sleep disturbances, underscore the need for comprehensive management. Treatment options for NAR include environmental interventions, pharmacotherapy, and in refractory cases, surgical options, emphasizing the need for a tailored approach for each patient. Thus, it is extremely important to accurately diagnose NAR because inappropriate therapies lead to poor clinical outcomes and unnecessary health care and economic burdens for these patients. This review provides a comprehensive overview of NAR subtypes, focusing on classification, diagnosis, and treatment approaches for NAR.

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.

High Flow Nasal Cannula Therapy in the Emergency Department: Main Benefits in Adults, Pediatric Population and against COVID-19: A Narrative Review

This review aims to summarize the literature’s main results about high flow nasal cannula therapy (HFNC) HFNC benefits in the Emergency Department (ED) in adults and pediatrics, including new Coronavirus Disease (COVID-19). HFNC has recently been established as the usual treatment in the ED to provide oxygen support. Its use has been generalized due to its advantages over traditional oxygen therapy devices, including decreased nasopharyngeal resistance, washing out of the nasopharyngeal dead space, generation of positive pressure, increasing alveolar recruitment, easy adaptation due to the humidification of the airways, increased fraction of inspired oxygen and improved mucociliary clearance. A wide range of pathologies has been studied to evaluate the potential benefits of HFNC; some examples are heart failure, pneumonia, chronic pulmonary obstructive disease, asthma, and bronchiolitis. The regular use of this oxygen treatment is not established yet due to the literature’s controversial results. However, several authors suggest that it could be useful in several pathologies that generate acute respiratory failure. Consequently, the COVID-19 irruption has generated the question of HFNC as a safety and effective treatment. Our results suggested that HFNC seems to be a useful tool in the ED, especially in patients affected by acute hypoxemic respiratory failure, acute heart failure, pneumonia, bronchiolitis, asthma and acute respiratory distress syndrome in patients affected by COVID-19. Its benefits in hypercapnic respiratory failure are more discussed, being only observed benefits in patients with mild-moderate disease. These results are based in clinical as well as cost-effectiveness outcomes. Future studies with largest populations are required to confirm these results as well as establish a practical guideline to use this device.

The Distinguishing Clinical Features of Nonallergic Rhinitis Patients

Background

Not all rhinitis patients are affected by an immunoglobulin E (IgE)-mediated inflammatory process. Skin and serum allergy assessments are limited in their ability to define local allergic rhinitis (LAR). Thus, patients with negative systemic allergy assessments comprise a mix of those who truly have nonallergic rhinitis (NAR) and patients with LAR.

Objective

To determine the clinical characteristics of patients with NAR.

Methods

A cross-sectional study was performed on consecutive adults with rhinitis symptoms who underwent turbinate surgery. NAR patients were defined by excluding allergy using both systemic (serum-specific IgE and/or skin prick test) and local (inferior turbinate tissue-specific IgE) tests. Allergic rhinitis (AR) patients were defined by any positive systemic or local test toward aeroallergens. The clinical characteristics studied included allergic comorbidities (asthma, eczema, allergic conjunctivitis), inhalant allergen triggers (dust, pollen, animal dander), and environmental triggers (Cincinnati Irritant Index [CII]).

Results

There were 154 participants (41.79 ± 14.78 years, 37.7% female). NAR patients (11.7%) were older (49.33 ± 15.99 vs 40.78 ± 14.38 years, P = .02), had less self-reported asthma (5.6% vs 36.3%, P < .01) and house dust inhalant trigger (38.9 vs 65.2%, P = .03) compared to AR patients. The CII score was similar for NAR and AR (31.06 ± 28.88 vs 35.49 ± 24.70, P = .61).

Conclusion

Patients who were older, without asthma, and lacked an inhalant allergy trigger were more likely to have true NAR. Environmental triggers are not distinguishing features of NAR. This may be used as a guide to identify rhinitis patients whose symptoms are truly nonallergic etiology compared to those with falsely negative systemic allergy assessment but may still need management for LAR.

Response to Nonallergenic Irritants in Children With Allergic and Nonallergic Rhinitis

Purpose

Nonallergenic irritants can aggravate the symptoms of rhinitis. We investigated the clinical responses of children with allergic rhinitis (AR) and nonallergic rhinitis (NAR) to nonallergenic irritants, and identified factors associated with these responses.

Methods

Children with chronic rhinitis (n=208) were classified as having AR or NAR based on the presence of aeroallergen-specific IgE. Healthy controls (n=24) were recruited for comparison. The Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines were used to classify patients, and their irritant score (0-21 points) and current symptom score (5-35 points) were measured. Subjects with irritant scores ≥3 and <3 were classified as having irritant and nonirritant rhinitis, respectively.

Results

The mean age of enrolled subjects was 6.8 years (range: 1.8-16.0 years). The AR and NAR groups had similar irritant scores (P=0.394) and proportions of subjects with irritant scores ≥3 (P=0.105). Irritant score correlated positively with symptom score (P=0.005), and the proportion of subjects with irritant scores ≥3 was greater in children with moderate-severe rhinitis than in those with mild rhinitis (P=0.046). Multiple logistic regression analysis indicated that the presence of atopic eczema increased the risk for sensitivity to a nonallergenic irritant (aOR=2.928, 95% CI 1.567-5.473, P=0.001).

Conclusions

Response to a nonallergenic irritant was useful for gauging the severity of rhinitis, but not for differentiating AR from NAR. AR and NAR patients with atopic eczema may increase nasal sensitivity to nonallergenic irritants.

Nonallergic Rhinitis: Environmental Determinants

"Nonallergic rhinitis" (NAR) is defined by intermittent or persistent nasal symptoms without evidence of immunoglobulin E-mediated sensitization to relevant aeroallergens. The largest subgroup is idiopathic, and is characterized by nasal hyperreactivity to nonspecific environmental triggers, including temperature, humidity, and chemical exposures. As nonspecific nasal hyperreactivity is often found in the absence of mucosal inflammation, some clinicians refer to this condition as "nonallergic rhinopathy." Irritant rhinitis, can arise de novo after high-level and/or prolonged exposure to airborne irritant chemicals. We review the range of environmentally induced nonallergic nasal symptoms and signs, and explore issues of pathophysiology unique to environmental chemical exposures.

Nonallergic Rhinitis: Mechanism of Action

Nonallergic rhinitis is a common disease that affects many Americans. It is characterized by nasal symptoms of congestion and rhinorrhea without evidence of allergic sensitization. The pathophysiology of the disease has not been studied extensively. In the following article, the author concentrates on summarizing the available information related to cellular inflammation and neurogenic mechanisms in patients with nonallergic rhinitis. The author also explores nasal reactivity to various stimuli in these patients.

Nasal provocation test using allergen extract versus cold dry air provocation test: which and when?

BACKGROUND

Nasal provocation tests (NPTs) are useful for evaluation of patients with allergic rhinitis. The cold dry air (CDA) provocation test is useful for evaluation of patients with nonspecific nasal hyperreactivity (NHR). This study aimed to determine whether the NPT or CDA provocation would be more useful for patients with different clinical pictures.

METHODS

We evaluated changes in nasal symptoms (visual analog scale [VAS]) and acoustic parameters after NPT or CDA provocation in healthy volunteers (group A, n = 27), patients with allergic rhinitis (group B, n = 20), and subjects with nonallergic rhinitis (group C, n = 26). According to their subjective cold hyperresponsiveness (SCH), we compared changes in VAS and acoustic parameters after each protocol. The correlation between results of the skin-prick test (SPT) and changes in VAS after each protocol was analyzed. Finally, we performed an analysis of correlation between NPT and CDA provocation.

RESULTS

After NPT, group B showed a larger change in VAS for rhinorrhea, sneezing, and itching (p < 0.01). After CDA challenge, the change in VAS for nasal obstruction was larger in group C (p < 0.05). Changes in acoustic parameters were larger in groups B and C after NPT (p < 0.01). After CDA challenge, the SCH(+) group (n = 49) showed a larger decrease of acoustic parameters than the SCH(-) group (n = 24; p < 0.01). Significant correlation was observed between the size of SPT and degree of change in VAS after NPT. No significant correlation was observed between NPT and CDA.

CONCLUSION

CDA could be an adjunct tool for evaluating NHR in patients with self-reported SCH.

Subjective cold hyper-responsiveness grade reflects age- and duration-related increase of nonspecific nasal hyperreactivity

OBJECTIVE

We evaluated the effect of patients' age and duration of allergic rhinitis on nonspecific nasal hyper-reactivity (NHR) using cold dry air (CDA) provocation.

METHODS

In 156 patients of various ages with allergic rhinitis and different symptom duration, we evaluated the change of symptoms, the subjective cold hyper-responsiveness (SCH) grade, the change of acoustic parameters such as total nasal volume (TNV) and minimal cross-sectional area (MCA), and the amount of rhinorrhea before and after CDA provocation.

RESULTS

Patients in different age or duration groups did not show significant differences in the change of each nasal symptom. SCH grade 2 or 3 was more frequently observed in patients older than 30 years (p=0.018). There was a significant correlation between the age of the patients and the SCH grade (R=0.184, p=0.022). Patients with >10 years of duration reported higher SCH grade (p=0.022). There was a significant correlation between the duration of disease and SCH grade (R=0.284, p<0.001). However, there were no significant differences in the change of TNV and MCA, and the amount of rhinorrhea after CDA provocation between different age and duration groups.

CONCLUSION

SCH grade reflects the age- and duration-related increase of NHR. Further studies to elucidate the pathophysiologic mechanisms are needed in the future.

Usefulness of the subjective cold hyperresponsiveness scale as evaluated by cold dry air provocation

BACKGROUND

There is still no study about the correlation between the symptom score and the reactivity to cold dry air (CDA). The authors developed a subjective cold hyperresponsiveness (SCH) scale for CDA and we evaluated its usefulness by comparing the changes of the symptom score and the acoustic parameters between different SCH groups and analyzing the correlation between the SCH scale and other parameters.

METHODS

One hundred fifty-two patients were classified according to their SCH scale. The symptom score by the visual analog scale (VAS), the total nasal volume (TNV), and the minimal cross-sectional area (MCA) by acoustic rhinometry were obtained before and after CDA provocation. Changes of these values were compared between groups and an analysis was performed for the correlation between SCH scale and change of the VAS, TNV, or MCA.

RESULTS

The patients with SCH grade 2 or 3 had a greater change of the VAS scores for nasal obstruction and rhinorrhea. The patients with SCH grade 2 or 3 had a greater change of the TNV (grade 0, 26.1 ± 17.2%; grade 1, 33.3 ± 26.5%, versus grade 2, 44.2 ± 30.0%; grade 3, 61.6 ± 40.0%; p < 0.05) and MCA (grade 0, 23.0 ± 25.3%; grade 1, 35.7 ± 51.1%, versus grade 2, 61.2 ± 72.4%; grade 3, 80.5 ± 56.4%; p < 0.05). Significant correlation existed between the SCH scale and changes in the TNV or MCA.

CONCLUSION

We developed the SCH scale and proved its usefulness for evaluating nonspecific hyperreactivity.

Short-time cold dry air exposure: a useful diagnostic tool for nasal hyperresponsiveness

OBJECTIVES/HYPOTHESIS

Demonstration of nasal hyperreactivity (NHR) in allergic and nonallergic rhinitis remains a diagnostic challenge because of the lack of a clinically attractive protocol with high sensitivity and specificity. Our aim was to evaluate the feasibility of a shortened cold dry air (CDA) provocation protocol for the diagnosis of NHR in patients with allergic rhinitis (AR) and idiopathic rhinitis (IR).

STUDY DESIGN

Twelve AR patients, 12 IR patients, and 12 controls were exposed to air at -10°C and <10% humidity for 15 minutes.

METHODS

Nasal symptoms were subjectively evaluated by visual analogue scale (VAS), and nasal obstruction was objectively measured by peak nasal inspiratory flow (PNIF) before and after CDA exposure. NHR was defined as a drop in PNIF larger than 20% from baseline upon CDA challenge.

RESULTS

Nasal CDA exposure induced nasal obstruction in AR and IR patients but not in controls. The VAS for nasal obstruction increased significantly in IR patients (post-CDA: 9.1 cm [6.9, 9.7] vs. pre-CDA: 5.5 cm [5.0, 8.9], P = .004) as well as in AR patients (post-CDA: 5.0 cm [1.3, 6.6] vs. pre-CDA: 0.8 cm [0.0, 1.7], P = .001). PNIF values showed a significant decrease in the AR (post-CDA: 50.0 L/min [37.5, 97.5] vs. pre-CDA: 95.0 L/min [52.5, 127.5], P = .002) and IR (post-CDA: 75.0 L/min [47.5, 102.5] vs. pre-CDA: 100.0 L/min [67.5, 130.0], P = .002) group after CDA provocation, which was not observed in the controls (P = 1.000). The sensitivity and specificity of CDA provocation for diagnosis of NHR were 66.7% and 100%, respectively, for both IR and AR. In contrast to nasal obstruction, rhinorrhea and sneezing were not induced by CDA exposure.

CONCLUSIONS

This study demonstrates that a short nasal CDA exposure is a reliable method for the diagnosis of NHR in rhinitis patients, with a high sensitivity and specificity.

Use of cold dry air provocation with acoustic rhinometry in detecting nonspecific nasal hyperreactivity

BACKGROUND

Cold dry air provocation is useful for evaluating nonspecific nasal hyperreactivity. However, there is no research on nasal volume and dimensions after cold dry air provocation. In this respect, acoustic rhinometry is a useful tool in objectively assessing nasal cavity volume and dimension. The goal of this study was to evaluate nonspecific hyperreactivity using cold dry air provocation with acoustic rhinometry.

METHODS

Cold dry air provocation with acoustic rhinometry was performed on 21 healthy volunteers (group A), 24 patients with allergic rhinitis (group B), and 32 patients with nonallergic rhinitis (group C). The change in symptoms using a visual analog scale (VAS), amount of rhinorrhea, and change of total nasal volume (TNV) and minimal cross-sectional area (MCA) were measured in all three groups.

RESULTS

The two patient groups showed greater change in nasal symptoms (VAS, 2.0 +/- 2.3 in group C versus 0.9 +/- 1.8 in group A), more rhinorrhea (0.4 +/- 0.7 g in group B and 0.3 +/- 0.3 g in group C versus 0.1 +/- 0.1 g in group A), and greater change in total nasal volume (TNV) and MCA. The patient group with history of nonspecific hyperreactivity showed more rhinorrhea (0.5 +/- 0.7 g versus 0.1 +/- 0.2 g) and greater change in TNV and MCA (TNV, 56.8 +/- 39.5% versus 18.0 +/- 17.0%; MCA, 86.6 +/- 81.0% versus 11.5 +/- 9.7%).

CONCLUSION

Cold dry air provocation with acoustic rhinometry could be a useful adjunct tool for detecting nonspecific hyperreactivity.

Diagnostic Criteria of Nonspecific Hyperreactivity Using Cold Dry Air Provocation With Acoustic Rhinometry

Objective. The authors aimed to (1) compare symptom changes in patients with or without nonspecific hyperreactivity, (2) compare changes in total nasal volume (TNV) and minimal cross-sectional area (MCA) using acoustic rhinometry after cold dry air (CDA) challenge, and (3) set the diagnostic criteria using receiver operating characteristic (ROC) curve analysis.

Study Design. Prospective pilot.

Setting. Academic tertiary rhinologic practice.

Subjects and Methods. CDA provocation was performed on 45 patients with self-reported hypersensitivity to cold dry air (group A) and to 53 patients without such hypersensitivity (group B). Symptoms (as measured by visual analog scale [VAS]), TNV, and MCA were checked before and after provocation.

Results. The changes in nasal obstruction (1.8 ± 2.1 vs 0.0 ± 2.3) and rhinorrhea (0.8 ± 2.1 vs −0.5 ± 2.3) were significantly greater in group A ( P < .01 in each case). There were no significant differences between groups in VAS scores for sneezing and itching. From the ROC curve, the authors set the diagnostic criterion as “TNSS (total nasal symptom score) change larger than 1.5,” and its sensitivity and specificity were 75.6% and 86.8%, respectively. The criteria “TNV decrease larger than 19.5%” and “MCA change larger than 15.0%” had higher sensitivity and specificity (TNV: 84.4% sensitivity and 77.4% specificity; MCA: 93.3% sensitivity and 77.4% specificity).

Conclusions. The authors were able to propose diagnostic criteria of nonspecific hyperreactivity using a CDA provocation test with acoustic rhinometry. These results are also helpful for understanding the pathophysiologic mechanisms of nonspecific hyperreactivity.