Olfactory mucosal findings in patients with persistent anosmia after endoscopic sinus surgery

Olfactory dysfunction in chronic rhinosinusitis: insights into the underlying mechanisms and treatments

INTRODUCTION

Olfactory dysfunction (OD) is a typical symptom of chronic rhinosinusitis (CRS), which adversely affects the patient's quality of life and results in mood depression. Studies investigating the impairment of olfactory epithelium (OE) have indicated that inflammation-induced cell damage and dysfunction in OE plays a vital role in the development of OD. Consequently, glucocorticoids and biologics are beneficial in the management of OD in CRS patients. However, the mechanisms underlying OE impairment in CRS patients have not been fully elucidated.

AREAS COVERED

This review focuses on mechanisms underlying inflammation-induced cell impairment in OE of CRS patients. Additionally, the methods used for detection of olfaction and both currently available and potentially new clinical treatments for OD are reviewed.

EXPERT OPINION

Chronic inflammation in OE impairs not only olfactory sensory neurons but also non-neuronal cells that are responsible for regeneration and support for neurons. The current treatment for OD in CRS is mainly aimed at attenuating and preventing inflammation. Strategies for use of combinations of these therapies may achieve greater efficacy in restoration of the damaged OE and consequently better management of OD.

Olfactory Change Pattern After Endoscopic Sinus Surgery in Chronic Rhinosinusitis Patients

Background Chronic rhinosinusitis (CRS) is a chronic inflammation of the sinonasal mucosa that is clinically associated with sinus pressure, nasal congestion, rhinorrhea, and a decreased sense of smell that lasts more than 12 weeks. Endoscopic sinus surgery (ESS) for medically refractory CRS is mainly undergone to improve sinus function and access to topical medicinal treatments. However, olfactory changes after ESS can be unpredictable. Aim The current study aimed to assess olfactory change patterns after endoscopic sinus surgery in patients with chronic rhinosinusitis. Methods A record-based retrospective study was conducted in Aseer Central Hospital (ACH) ear, nose, and throat outpatient (ENT OPD) department and Khamis Mushayt General Hospital from August 15, 2021, to December 15, 2021. Data were collected using pre-structured data extraction sheet to avoid errors. Data extracted and collected included patients' biodemographic data, CRS-associated symptoms, and endoscopic surgery-related data, including duration since surgery, presurgical medications, and duration of surgery. Also, postsurgical complications were extracted, especially olfactory complications. Results A total of 168 patients with chronic rhinosinusitis (CRS) and who had undergone endoscopic sinus surgery in the Aseer region were included. Patient ages ranged from 10 to 61 years, with a mean age of 39.8 ± 12.4 years old. Regarding the associated symptoms and complaints of the study patients, 110 (65.5%) complained of sinusitis, and 86 (51.2%) had allergic RS. The postsurgical complications of patients with CRS who had undergone endoscopic sinus surgery were olfactory dysfunction (OD) in 32 (19%), no complications in 115 (68.55%), and other nonspecific complications, such as headache, drowsiness, nose dryness, and bleeding, in 21 (12.55%). Also, 71 (42.3%) reported that they hardly perceive the fragrance in perfumeries. Conclusion In conclusion, olfactory impairment is a frequent clinical presentation in patients with CRS. In this study, olfactory dysfunction was improved, except among nearly one out of each five patients after ESS. Olfactory dysfunction was more among patients who had undergone recent surgery and those with chronic rhinosinusitis with nasal polyps (CRSwNP). Also, among patients who reported no complications, olfactory function did not return to normal in most patients as they hardly perceive fragrance.

International consensus statement on allergy and rhinology: Olfaction

BACKGROUND

The literature regarding clinical olfaction, olfactory loss, and olfactory dysfunction has expanded rapidly over the past two decades, with an exponential rise in the past year. There is substantial variability in the quality of this literature and a need to consolidate and critically review the evidence. It is with that aim that we have gathered experts from around the world to produce this International Consensus on Allergy and Rhinology: Olfaction (ICAR:O).

METHODS

Using previously described methodology, specific topics were developed relating to olfaction. Each topic was assigned a literature review, evidence-based review, or evidence-based review with recommendations format as dictated by available evidence and scope within the ICAR:O document. Following iterative reviews of each topic, the ICAR:O document was integrated and reviewed by all authors for final consensus.

RESULTS

The ICAR:O document reviews nearly 100 separate topics within the realm of olfaction, including diagnosis, epidemiology, disease burden, diagnosis, testing, etiology, treatment, and associated pathologies.

CONCLUSION

This critical review of the existing clinical olfaction literature provides much needed insight and clarity into the evaluation, diagnosis, and treatment of patients with olfactory dysfunction, while also clearly delineating gaps in our knowledge and evidence base that we should investigate further.

Biopsy of the olfactory epithelium from the superior nasal septum: is it possible to obtain neurons without damaging olfaction?

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Olfactory biopsies from the superior part of the nasal septum did not significantly affect smell capacity.

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These biopsies obtain high rates of olfactory neurons.

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The described procedure also provides olfactory epithelium proper for morphological analysis.

Introduction

Olfactory epithelium biopsy has been useful for studying diverse otorhinolaryngological and neurological diseases, including the potential to better understand the pathophysiology behind COVID-19 olfactory manifestations. However, the safety and efficacy of the technique for obtaining human olfactory epithelium are still not fully established.

Objective

This study aimed to determine the safety and efficacy of harvesting olfactory epithelium cells, nerve bundles, and olfactory epithelium proper for morphological analysis from the superior nasal septum.

Methods

During nasal surgery, 22 individuals without olfactory complaints underwent olfactory epithelium biopsies from the superior nasal septum. The efficacy of obtaining olfactory epithelium, verification of intact olfactory epithelium and the presence of nerve bundles in biopsies were assessed using immunofluorescence. Safety for the olfactory function was tested psychophysically using both unilateral and bilateral tests before and 1 month after the operative procedure.

Results

Olfactory epithelium was found in 59.1% of the subjects. Of the samples, 50% were of the quality necessary for morphological characterization and 90.9% had nerve bundles. There was no difference in the psychophysical scores obtained in the bilateral olfactory test (University of Pennsylvania Smell Identification Test [UPSIT®]) between means before biopsy: 32.3 vs. postoperative: 32.5, p = 0.81. Also, no significant decrease occurred in unilateral testing (mean unilateral test scores 6 vs. 6.2, p = 0.46). None out of the 56 different odorant identification significantly diminished (p > 0.05).

Conclusion

The technique depicted for olfactory epithelium biopsy is highly effective in obtaining neuronal olfactory tissue, but it has moderate efficacy in achieving samples useful for morphological analysis. Olfactory sensitivity remained intact.

Olfaction in Juvenile Nasopharyngeal Angiofibroma: The first study

BACKGROUND

To study the pattern of olfactory dysfunction/recovery in juvenile nasopharyngeal angiofibroma (JNA).

METHODS

Olfactory assessment was undertaken in 30 patients (category1) both pre- & post-operatively and in another 18 (category 2) only postoperative. All patients underwent transpalatal excision and variables of interest included age, radiological stage/parameters & tumor size.

RESULTS

Objective olfactory dysfunction was seen in 60% while involvement of olfactory strip was suggested in 50%. Despite some marginal trends only noted between size/age with change of olfaction, Pearson's correlation test did not reveal any significance amongst multiple variables. However a better recovery of olfaction following surgery was evident in Category-2 where Chi-Square test (p < 0.05) significantly revealed this to be a function of postoperative duration. This regenerative course in JNA suggests an optimum period of 4 years for full recovery after surgery.

CONCLUSION

In this first study of olfaction in JNA many new trends have been appreciated. In general, deteriorations of olfaction were seen due to 'vascular-concussion' effect in early postoperative phase where post-surgical clearance of airway showed minimal effect in terms of improvement. The hypervascularity of olfactory epithelium with possible hormonal effects may be responsible for the unique pattern of olfactory function and recovery in JNA.

Diseases of the nasal cavity

Despite garnering minimal attention from the medical community overall, olfaction is indisputably critical in the manner in which we as humans interact with our surrounding environment. As the initial anatomical structure in the olfactory pathway, the nasal airway plays a crucial role in the transmission and perception of olfactory stimuli. The goal of this chapter is to provide a comprehensive overview of olfactory disturbances as it pertains to the sinonasal airway. This comprises an in-depth discussion of clinically relevant nasal olfactory anatomy and physiology, classification systems of olfactory disturbance, as well as the various etiologies and pathophysiologic mechanisms giving rise to this important disease entity. A systematic clinical approach to the diagnosis and clinical workup of olfactory disturbances is also provided in addition to an extensive review of the medical and surgical therapeutic modalities currently available.

Office Procedures for Quantitative Assessment of Olfactory Function

Background

Despite the importance of the sense of smell for establishing the flavor of foods and beverages, as well as protecting against environmental dangers, this primary sensory system is commonly ignored by the rhinologist.

Methods

In this article basic issues related to practical measurement of olfactory function in the clinic are described and examples of the application of the two most common paradigms for such measurement—odor identification and detection–are presented. A listing is made of the 27 olfactory tests currently used clinically, along with their strengths and weaknesses. A brief review of common nasosinus-related disorders for which quantitative olfactory testing has been performed is provided.

Results

Although many psychophysical tests are available for quantifying olfactory loss, it is apparent that a number are limited in terms of practicality, sensitivity, and reliability. In general, sensitivity and reliability are positively correlated with test length. Given the strengths of the more reliable forced-choice pyschophysical tests and the limitations of electrophysiological tests, the common distinction between “subjective” and “objective” tests is misleading and should not be used. Complete recovery of olfactory function, as measured quantitatively, rarely follows surgical or medical interventions in patients with rhinosinusitis.

Conclusion

Given the availability of practical clinical olfactory tests, the modern rhinologist can easily quantify cranial nerve (CN) I function. The application of such tests has led to a new understanding of the effects of nasal disease on olfactory function. Except in cases of total or near-total nasal obstruction, olfactory and airway patency measures usually are unrelated, in accord with the concept that rhinosinusitis primarily influences olfactory function by apoptotic pathological changes within the olfactory neuroepithelium.

Gross Olfaction Before and After Laparoscopic Gastric Bypass

BACKGROUND

Obesity leads to olfaction alterations, and this can further impact food choices, appetite, and nutritional status. Bariatric procedures induce weight loss and change in taste and smell perception, but more information is needed, especially using objective olfaction tests.

METHODS

A prospective study was conducted during 6 months, with candidates to laparoscopic gastric bypass at a single institution. A preoperative nasofibroscopy and gross smell identification test (The Pocket Smell Test ®) were performed in those meeting the inclusion criteria. After 6 months, a new test was performed, and the primary objective was to determine if there was an improvement in the olfaction score. Weight loss and comorbidities improvement were also analyzed.

RESULTS

From the 30 patients with morbid obesity enrolled, 21 met the inclusion criteria and ENT evaluation. At baseline, 42.8% of patients scored 3 points, 53.3% scored 2 points, and 4.7% scored 1 point. After 6 months, there was a -81.1% of change. Seventeen patients scored 3 points (p = 0.002 vs initial) and two scored 2 points (p = 0.006 vs initial). There were no patients with less than 2 points. Weight and comorbidities had a significant improvement as well.

CONCLUSION

Laparoscopic gastric bypass improves the olfaction scores of the Pocket Smell Test in morbidly obese patients 6 months after their procedure. More complex tests can be used in candidates to bariatric surgery if low scores are detected initially. Other causes of olfaction dysfunctions should be determined if there is no improvement after weight loss.

Olfactory loss in chronic rhinosinusitis is associated with neuronal activation of c-Jun N-terminal kinase

BACKGROUND

Olfactory inflammation in chronic rhinosinusitis (CRS) is associated with cytokines that may result in the death of olfactory sensory neurons. The principal signaling molecules involved in the apoptotic pathway are c-Jun N-terminal kinases (JNK). Although the JNK pathway has emerged as a key player in programmed cell death in neuroinflammation, its specific role in CRS-associated olfactory loss has not been thoroughly investigated.

METHODS

JNK activation was studied in human tissue samples from 9 control and 11 CRS patients by immunohistochemical staining for phosphorylated c-Jun. A mouse model of inducible olfactory cytokine expression was used to experimentally control inflammation and assess JNK activation over time.

RESULTS

In patients with CRS, activation of c-Jun is significantly increased relative to non-CRS control subjects, and there is an associated loss of sensory neurons. In the olfactory inflammation mouse model, prolonged induction of inflammation results in elevation of c-Jun expression and neuronal apoptosis.

CONCLUSION

Activation of neuronal JNK is a feature of chronic olfactory inflammation that is associated with neuronal apoptosis. Given that inhibition of JNK activity is neuroprotective in other settings, antagonism of this pathway may have therapeutic potential in the management of inflammatory olfactory loss or other disorders linked to olfactory neuronal apoptosis.

Olfactory dysfunction and its measurement in the clinic

The sense of smell is largely taken for granted by laypersons and medical professionals alike. Indeed, its role in determining the flavor of foods and beverages, as well as in warning of, or protecting against, environmental hazards, often goes unrecognized. This is exemplified, in part, by the fact that most patients presenting to medical clinics with "taste" problems are typically subjected to complex brain imaging and gastroenterological tests without the sense of smell even being tested or considered as a basis of the problem. Aside from frank deficiencies in sweet, sour, bitter, salty and savory (umami) sensations, "taste" disorders most commonly reflect inadequate stimulation of the olfactory receptors via the retronasal route; i.e., from volatiles passing to the receptors from the oral cavity through the nasal pharynx. This article describes the two most common procedures for measuring the sense of smell in the clinic and provides examples of the application of these tests to diseases and other disorders frequently associated with smell loss. Basic issues related to olfactory testing and evaluation are addressed. It is pointed out that smell loss, particularly in later life, can be a harbinger for not only a range of neurodegenerative diseases, but can be a prognostic indicator of early mortality.

Olfaction in Endoscopic Sinus and Skull Base Surgery

Olfactory dysfunction is a common complaint for patients with chronic rhinosinusitis, because smell loss decreases a patient's quality of life. Smell loss is caused by obstruction from polyps, nasal discharge, and mucosal edema, as well as inflammatory changes within the olfactory epithelium. Addressing olfaction before endoscopic sinus and skull base surgery is important in order to set postoperative expectations, because an improvement in smell is difficult to predict. Several commercially available olfactory testing measures are available and can easily be administered in clinic. During surgery, careful dissection within the olfactory cleft is recommended in order to optimize postoperative olfactory function.

Olfactory neuroepithelium in the superior and middle turbinates: which is the optimal biopsy site?

Introduction: Olfactory neuroepithelium (ON) biopsy has several therapeutic applications for both disorders of olfaction and neurodegenerative diseases. Successful collection of ON is still anything but routine due to a dearth of studies on the distribution of ON in the superior and middle turbinates.

Aim: To determine the location in which ON is most likely to be present in endoscopically removed cadaver superior and middle turbinates as well as the influences of gender, age, and naris side on the presence of ON and the extent to which it is present.

Methods: We conducted a prospective anatomical study. The superior and middle turbinates on both sides endoscopically removed from 25 fresh cadavers (less than 12 h post-mortem). The turbinates were halved into anterior and posterior segments for a total of 200 specimens, which were analyzed after hematoxylin and eosin and immunohistochemical staining. Hematoxylin and eosin-stained slides were subjected to blind examination by 3 independent pathologists, and the presence of ON was graded on a 5-point scale from 0 to 4. Kappa measurement was used to determine the agreement between pairs of observers.

Results: ON was present in 82.9% of superior turbinate samples and in 17.1% of middle turbinate samples. Immunohistochemistry detected ON in superior turbinates only by S-100 staining and only in 15 fragments. Gender, age, and naris side had no statistically significant effects on the presence of ON.

Conclusion: When biopsying ON, the posterior portion of the superior turbinate should be targeted whenever possible because it has the highest concentration of ON among the nasal structures.

Olfactory function and quality of life following microscopic endonasal transsphenoidal pituitary surgery

Olfactory outcomes as well as oronasal postoperative complications of transsphenoidal pituitary surgery have not been well studied. The objective of this study was to investigate nasal symptoms including olfactory function as well as quality of life following transsphenoidal pituitary surgery. The study is designed as a prospective cohort study set in a single tertiary hospital. A total of 53 patients with pituitary adenomas were included. All patients underwent pituitary surgery with the right-sided endonasal transsphenoidal approach. Outcomes were assessed with the Chinese version of the Medical Outcomes Study Short Form-36 (SF-36) to survey patient health, the Chinese version of the 22-item Sinonasal Outcome Test (SNOT-22), and a Toyota and Takagi (T&T) olfactometer. Assessments were carried out before surgery and at 1 week, and 1 and 4 months after surgery. The overall SF-36 scores were significantly lower, but the SNOT-22 scores were higher at 1 week and 1 month postoperatively compared with baseline (all P < 0.001). The results of T&T olfactometer testing showed that there was a significant decline in the ability to detect odors postoperatively, even at 4 months. Multivariate linear regression analysis showed that lower education level, partial tumor removal, and longer duration of surgery were independent risk factors for a higher SNOT-22 score at 1 week after surgery. The findings show that microscopic endonasal transsphenoidal pituitary surgery impairs olfactory function in most patients for at least 4 months after surgery.

A genetic model of chronic rhinosinusitis-associated olfactory inflammation reveals reversible functional impairment and dramatic neuroepithelial reorganization

Inflammatory sinus and nasal disease is a common cause of human olfactory loss. To explore the mechanisms underlying rhinosinusitis-associated olfactory loss, we have generated a transgenic mouse model of olfactory inflammation, in which tumor necrosis factor alpha (TNF-alpha) expression is induced in a temporally controlled manner specifically within the olfactory epithelium (OE). Like the human disease, TNF-alpha expression leads to a progressive infiltration of inflammatory cells into the OE. Using this model, we have defined specific phases of the pathologic process. An initial loss of sensation without significant disruption is observed, followed by a striking reorganization of the sensory neuroepithelium. An inflamed and disrupted state is sustained chronically by continued induction of cytokine expression. After prolonged maintenance in a deficient state, there is a dramatic recovery of function and a normal histologic appearance when TNF-alpha expression is extinguished. Although obstruction of airflow is also a contributing factor in human rhinosinusitis, this in vivo model demonstrates for the first time that direct effects of inflammation on OE structure and function are important mechanisms of olfactory dysfunction. These features mimic essential aspects of chronic rhinosinusitis-associated olfactory loss, and illuminate underlying cellular and molecular aspects of the disease. This manipulable model also serves as a platform for developing novel therapeutic interventions.

Olfactory function in patients with chronic rhinosinusitis before and after functional endoscopic sinus surgery

BACKGROUND

The olfactory loss in patients with chronic rhinosinusitis has been measured by different methods. However, the results have been variable and it is not clear whether functional endoscopic sinus surgery (FESS) significantly improves olfactory function. This study was performed to evaluate the influences of FESS on olfactory function in patients with chronic rhinosinusitis using three different types of olfactory tests.

METHODS

Seventy patients with chronic rhinosinusitis were administered the University of Pennsylvania Smell Identification Test (UPSIT), a single staircase phenyl ethyl alcohol odor detection threshold test (STT), and a short-term odor memory/discrimination test a day before and 6 months after FESS. A questionnaire inquiring about the patients' self-perception of olfactory function was administered also. Independent ratings of the severity of chronic rhinosinusitis before FESS were established from CT scans.

RESULTS

Fifty-two (74.3%) of the patients reported that their olfactory function was impaired before surgery, and 68.6% of the patients reported impaired olfactory function after surgery, a difference that was not significant. No meaningful changes in any of the olfactory test scores were noted 6 or more months after FESS. Preoperatively, small correlations between CT scores and the symptom scores (r = 0.278; p = 0.024), threshold scores (r = -0.27; p = 0.031), and UPSIT scores (r = -0.36; p = 0.003) were observed.

CONCLUSION

In patients with severe rhinosinusitis, FESS had little impact on the ability to smell, regardless of the method for assessing smell function. Subtle associations between olfactory function and the severity of chronic rhinosinusitis determined by CT were observed, however, preoperatively. The olfactory test measures were correlated with one another both pre- and postoperatively.

Olfactory dysfunction in nasal polyposis: correlation with computed tomography findings

AIMS

This study evaluates if a computed tomography (CT) scan is useful to assess the olfactory loss in sinonasal disease, and if a preoperative CT scan has a predictive value for the long-term outcome regarding olfaction.

METHODS

Thirty-one patients with nasal polyposis were included. Olfactory function was assessed with the 'Sniffin' Sticks' test and subjective perception recorded with a visual analogue scale. CT scans were assessed with the Lund-Mackay system and the Damm nasal segmentation. Patients were retested after endoscopic sinus surgery in a follow-up appointment at least 1 year later.

RESULTS

Disease in the upper meatus and the posterior portion of the middle meatus strongly affects olfactory function. Lund-Mackay scores were significantly correlated with preoperative olfactory test results. Preoperative subjective ratings had a significant correlation only with present disease in the anterior upper meatus. Postoperative results were significantly decreased. Their relative percentage change was correlated only with the preoperative presence of disease in the anterior upper meatus. No correlation was found between the Lund-Mackay score and the postoperative olfactory results.

CONCLUSIONS

Olfactory dysfunction in nasal polyposis is strongly related to specific obstructed nasal areas. A CT scan has no predictive value for the long-term surgical outcome regarding olfaction.

Diagnosis and management of olfactory disorders: survey of UK-based consultants and literature review

Background:

The diagnosis and management of olfactory disorders is an often neglected topic in otolaryngology. This article evaluates current clinical practice within the United Kingdom, and provides a literature-based review of the diagnosis, management and prognosis of olfactory pathology.

Design:

A questionnaire was sent to consultant and associate specialist members of the British Association of Otolaryngologists and Head and Neck Surgeons. The responses were documented to gain an impression of how olfactory disorders are managed in the United Kingdom. The literature relating to olfactory dysfunction was then evaluated and the findings summarised.

Conclusions:

Management of olfactory pathology varies across the United Kingdom. The literature suggests that chemosensory testing is optimal and that both forced-choice and threshold testing should be applied if objective evaluation is required. Imaging can be of value but the appropriate technique should be used. Olfactory function can recover following head injury, viral infection and chronic sinonasal disease, although varying degrees of dysfunction are likely to persist. There is a role for the use of corticosteroids, particularly when administered systemically. More research is needed to establish the appropriate dose and length of treatment.

Olfactory dysfunction and its measurement in the clinic and workplace

OBJECTIVES

To provide an overview of practical means for quantitatively assessing the sense of smell in both the clinic and workplace. To address basic measurement issues, including those of test sensitivity, specificity, and reliability. To describe and discuss factors that influence olfactory function, including airborne toxins commonly found in industrial settings.

METHODS

Selective review and discussion.

RESULTS

A number of well-validated practical threshold and suprathreshold tests are available for assessing smell function. The reliability, sensitivity, and specificity of such techniques vary, being influenced by such factors as test length and type. Numerous subject factors, including age, sex, health, medications, and exposure to environmental toxins, particularly heavy metals, influence the ability to smell.

CONCLUSIONS

Modern advances in technology, in conjunction with better occupational medicine practices, now make it possible to reliably monitor and limit occupational exposures to hazardous chemicals and their potential adverse influences on the sense of smell. Quantitative olfactory testing is critical to establish the presence or absence of such adverse influences, as well as to (a) detect malingering, (b) establish disability compensation, and (c) monitor function over time.

Basic and clinical aspects of olfaction

Disturbances of olfaction are a common occurrence in many neurological and neurosurgical patients and their correct diagnosis might be helpful in management and enhancement of quality of life. However, olfaction is seldom checked in most neurosurgical units and the "smell bottles" are often either absent or out of date. This chapter reviews systematically recent advances in our understanding of the anatomy, physiology (olfactory coding) and measurement of olfactory function in the human. The causes and symptoms of smell disorders, risk of damage to the olfactory system by various surgical procedures and, finally, the natural history of recovery and treatment of smell disorders, for example after trauma, are discussed.

Olfactory mucosa histological findings in laryngectomees

After total laryngectomy, the patients often report immediate and marked olfactory deficit. The aim of this study was to determine whether hyposmia in laryngectomees reflects olfactory epithelial damage. Ten laryngectomized patients and ten rhinologically normal subjects were subjected to olfactory testing, after which histological examination of biopsied olfactory mucosa was performed. Olfactory testing in laryngectomees revealed a marked reduction in odor perception. Histological examination of olfactory mucosa specimens showed that in laryngectomees some neuroepithelial structural features were comparable with those found in normal subjects. However, additional signs of damage were also observed, consisting mainly of various degrees of epithelial degeneration, above and beyond those that are characteristic of physiological epithelium turnover. These different degenerative features consisted of severe damage to the neuroepithelium, culminating in complete topical loss. Bowman's glands were also observed to be involved in the degenerative process. Laryngectomy-induced hyposmia seems to be correlated with the almost complete loss of nasal airflow due to the disconnection between the upper and lower airways, which prevents odor molecules from reaching the olfactory area, together with degenerative phenomena, which affect the neuroepithelium, and consequent failure in neurosensorial performance.

Olfactory changes at threshold and suprathreshold levels following septoplasty with partial inferior turbinectomy

Partial inferior turbinectomy with septoplasty is routinely carried out for airway obstruction. However, its effects on the sense of smell have not been systematically evaluated. The aim of this prospective study was to evaluate the influence of septoplasty with partial inferior turbinectomy on threshold and suprathreshold olfactory acuity. The subjects were 30 patients undergoing septoplasty including partial inferior turbinectomy. Olfactory function was determined by the "Sniffin' Sticks," which allow the assessment of odor thresholds, odor discrimination, and odor identification. The patients rated both olfactory function and nasal airflow using visual analog scales. Nasal airflow was measured by anterior rhinomanometry. Multivariate analyses of variance for repeated measures were used to analyze the results before and after surgery (mean interval, 9.1 weeks). After operation, 87% of the patients had increased airflow, 80% had improved olfactory function in terms of odor identification, and in 70% odor discrimination was found to be improved - but only 54% had improved olfactory function in terms of odor thresholds. Surgery increased ratings of nasal airflow in 93%, and those of olfactory function in 77% (p < .001). Similarly, bilateral inspiratory nasal flow increased (p < .001) and olfactory function was improved (p < .001) after surgical treatment. However, this increase was most pronounced for suprathreshold tests, while it was moderate for odor thresholds (interaction "surgery" x "olfactory test," p = .001). The present investigation suggests that septoplasty in combination with inferior turbinectomy has a beneficial effect on olfaction, mainly on suprathreshold olfactory functions. This effect may be partly due to interactions between the increased perception of nasal airflow and cognitive factors involved in olfactory sensitivity. According to the present results and data from the literature, a moderate decrease of olfactory function appears to occur in as many as 20% of patients. However, anosmia seems to be an extremely rare complication of septoplasty and partial turbinectomy.

The superior turbinate as a source of functional human olfactory receptor neurons

OBJECTIVES

The function of human olfactory receptor neurons (ORNs) remains incompletely understood, in part because of the difficulty of obtaining viable olfactory tissue for study. During endoscopic sphenoidotomy, a portion of the superior turbinate is often removed to achieve wide and safe access to the sphenoid sinus. The purpose of this study was to determine whether functional olfactory mucosa could be obtained from such superior turbinate tissue.

STUDY DESIGN/METHODS

Superior turbinate tissue was resected from 4 patients undergoing transnasal endoscopic approaches to the sphenoid sinus. The gross appearance of the turbinate mucosa was normal at the time of surgery. The specimens were placed directly into cold cell culture media and transferred to the laboratory. A portion of the mucosa was fixed and embedded for histology and immunohistochemistry. The remaining tissue was enzymatically dissociated, and the resulting cell suspension was either prepared for immediate calcium imaging or placed into cell culture. Cultured ORNs underwent calcium imaging after several weeks to assess their ability to respond to odorants.

RESULTS

Histologic analysis of superior turbinate tissue revealed the presence of patchy olfactory neuroepithelium staining positive for olfactory marker protein. Acutely dissociated ORNs were capable of generating calcium responses to odorant mixtures. ORNs could be maintained in mixed culture and retained their ability to respond to odorants.

CONCLUSIONS

Superior turbinate tissue removed during endoscopic sphenoidotomy can provide a valuable source of human olfactory neuroepithelium for functional or histologic study. Superior turbinate tissue yields stem cells and immature neurons capable of differentiating into ORNs that retain many of their functional characteristics even after growth in culture.

Olfaction and its alteration by nasal obstruction, rhinitis, and rhinosinusitis

The sense of smell has been largely ignored by otorhinolaryngologists, even though 1) its medical stewardship falls within their specialty's purview, 2) olfactory dysfunction is not uncommon in the general population, and 3) disorders of olfaction have significant quality of life, nutritional, and safety consequences. This report provides a succinct overview of the major intranasal neural systems present in humans (namely, cranial nerves O, I, and V, and the nonfunctional accessory [vomeronasal] organ system), along with a summary of notable findings resulting from the application of modern olfactory tests to patient populations, emphasizing diseases of the nose. Such tests have led to the discovery of significant influences of age, gender, smoking, toxic exposure, and genetics on the ability to smell. Within the field of otorhinolaryngology, they have revealed that 1) surgical and medical interventions in patients with rhinosinusitis do not, on average, lead to complete recovery of olfactory function, despite common beliefs to the contrary, and 2) associations are generally lacking between measures of airway patency and olfactory function in such cases. These findings have thrown into question the dogma that olfactory loss in rhinosinusitis is attributable primarily to blockage of airflow to the receptors and have led to histopathological studies demonstrating significant olfactory epithelial compromise in sinonasal syndromes.