Degree Of Olfactory Dysfunction Research Articles

Prevalence and Magnitude of Olfactory Dysfunction in Allergic Rhinitis.

Although allergic rhinitis (AR) can negatively impact the ability to smell, the degree to which this occurs is not clear and prevalence estimates vary among studies. This study had 4 main objectives: (1) To estimate the prevalence and the degree of olfactory dysfunction in AR patients; (2) To compare olfactory perception between AR patients with different persistence and severity of symptoms and determine if olfactory testing may aid in differentiating among Allergic Rhinitis and its Impact on Asthma (ARIA) groups; (3) To determine whether allergic reactions to different allergens differentially impact olfactory function, and (4) Verify possible changes in the olfactory epithelium (OE) caused by AR. One hundred thirty-three patients with AR and one hundred controls were tested. The main outcome was the score in University of Pennsylvania Smell Identification Test (UPSIT®). The OE was examined using immunofluorescence markers for neuronal activity, apoptosis, oxidative stress, signal transduction, eosinophils, and epithelial thickness. Prevalence of olfactory dysfunction in the AR patients was higher (AR: 42.9% vs controls: 9%, P < .001). No difference was found either between intermittent and persistent disease cases (P = .58) or between cases with mild and those with moderate/severe symptomatology (P = .33). Lower olfactory capacity was not associated with the reaction to more (P = .48) or diverse types of allergens (Ps > .05). Although not significant, patients with AR had a greater amount of eosinophilia and a lower amount of cAMP (cyclic adenosine monophosphate) in the OE. The study highlights a higher prevalence of olfactory dysfunction in AR patients compared to controls, but olfactory testing may not effectively differentiate AR severity or allergen sensitivities. Although trends suggest potential pathophysiological changes in the OE of AR patients, further research is needed to validate these findings.

Assessment of olfactory and gustatory functions in COVID-19 patients

BackgroundOlfactory and gustatory disorders are common problems encountered during the COVID-19 pandemic with a significant impact on the patient’s quality of life: The aim of this study was to assess the olfactory and gustatory functions in COVID-19 patients with correlation between them and clinical and laboratory markers. This was a cross-sectional study conducted on 63 subjects recruited from the COVID-19 clinics at Police Authority and Menoufia University hospitals. The patients were assessed using history taking, anterior rhinoscopy, endoscopic examination, computed tomography, and polymerase chain reaction (PCR) test. Olfactory functions were assessed using the alcohol threshold test. Gustatory functions were assessed using the three-drop method. The olfactory and gustatory functions were correlated with age, gender, and laboratory parameters. Also, the recovery of smell and taste disorders was correlated with our assessed laboratory markers.ResultsThe prevalence of olfactory dysfunction among study participants was 41 patients (65%) of the participants including 12 patients (19.1%) having mild hyposmia, 10 patients (15.8%) having moderate hyposmia, 9 patients (14.3%) having severe hyposmia, and 10 patients (15.8%) having complete anosmia. The prevalence of gustatory dysfunction among study participants was 24 patients (38.1%). Age, gender, and laboratory parameters did not show any statistically significant difference between those who experienced olfactory dysfunction or gustatory dysfunction and those who did not. However, there was a significant positive correlation between the total leucocytic count, serum level of CRP, and serum level of D-dimer and the degree of olfactory dysfunction (0.049, 0.03, and 0.02, respectively). There was a nonsignificant correlation between recovery of olfactory and gustatory dysfunction and laboratory markers.ConclusionOlfactory and gustatory dysfunction are established clinical presentations among COVID-19-positive patients. The laboratory markers had no correlation with the incidence of these dysfunctions or their recovery. However, TLC, serum CRP, and serum D-dimer had a significant positive correlation with the severity of olfactory dysfunction.

Sociodemographic Characteristics and Comorbidities of Patients With Long COVID and Persistent Olfactory Dysfunction

Determining the characteristics, type, and severity of olfactory dysfunction in patients with long COVID is important for the prognosis and potential treatment of the affected population. To describe the sociodemographic and clinical features of patients with long COVID who develop persistent olfactory dysfunction. This cross-sectional study, conducted at a rehabilitation center at a public university in the Amazon region of Brazil between September 9, 2020, and October 20, 2021, comprised 219 patients with long COVID and self-reported neurologic symptoms. Of these 219 patients, 139 received a diagnosis of chronic olfactory dysfunction, as confirmed by the Connecticut Chemosensory Clinical Research Center (CCCRC) test. Clinical diagnosis of long COVID. Electronic case report forms were prepared for the collection of sociodemographic and clinical data. Patients' sense of smell was evaluated via a CCCRC test, and the association of olfactory dysfunction with aspects of daily life was recorded using a questionnaire. Of the 219 patients included in the study, 164 (74.9%) were women, 194 (88.6%) were between 18 and 59 years of age (mean [SD] age, 43.2 [12.9] years), 206 (94.1%) had more than 9 years of education, and 115 (52.5%) had a monthly income of up to US $192.00. In the study group, 139 patients (63.5%) had some degree of olfactory dysfunction, whereas 80 patients (36.5%) had normosmia. Patients with olfactory dysfunction had a significantly longer duration of long COVID symptoms than those in the normosmia group (mean [SD], 242.7 [101.9] vs 221.0 [97.5] days; P = .01). Among patients with anosmia, there was a significant association between olfactory dysfunction and daily activities, especially in terms of impairment in hazard detection (21 of 31 patients [67.7%]), personal hygiene (21 of 31 patients [67.7%]), and food intake (21 of 31 patients [67.7%]). Univariable logistic regression analyses found that ageusia symptoms were associated with the occurrence of olfactory dysfunction (odds ratio [OR], 11.14 [95% CI, 4.76-26.07]; P < .001), whereas headache (OR, 0.41 [95% CI, 0.22-0.76]; P < .001) and sleep disorders (OR, 0.48 [95% CI, 0.26-0.92]; P = .02) showed an inverse association with the occurrence of olfactory dysfunction. Olfactory dysfunction is one of the most important long-term neurologic symptoms of COVID-19, with the highest prevalence seen among women, adults, and outpatients. Patients with olfactory dysfunction may experience persistent severe hyposmia or anosmia more than 1 year from the onset of symptoms, suggesting the possibility of the condition becoming a permanent sequela.

Clinical, Prognostic, and Predictive Value of Olfactory Dysfunction for COVID-19: A Prospective Controlled Study.

To evaluate the effect of olfactory dysfunction on the course and severity of COVID-19 and its prognostic and predictive significance for COVID-19. Prospective case-control study. Ondokuz Mayıs University School of Medicine. Reverse transcription polymerase chain reaction (PCR)-positive patients, patients with COVID-19-related symptoms who had a negative PCR result, and healthy controls were included in the study. Clinicodemographic characteristics, inflammatory markers, and computed tomography stages were recorded. Disease progression and intensive care unit admission were registered. The visual analog scale (0, worst; 10, best) was used to evaluate subjective olfactory, taste, and nasal breathing ability, and the Sniffin' Sticks identification (SS-ID) test was used for psychophysical olfactory assessment. Mean SS-ID scores were significantly lower in the positive group (8.77) than in the negative (10.43) and healthy control (12.17) groups. VAS-smell scores were significantly lower and anosmia was more prevalent in PCR-positive patients (P < .01). SS-ID and VAS-smell scores were significantly correlated (r = 0.681, P < .001). The inflammatory parameters, pulmonary infiltration stage, disease progression, and ICU admission were not associated with SS-ID scores. A cutoff SS-ID score <9 resulted in 55.56% sensitivity in predicting COVID-19 positivity, and a cutoff VAS-smell score <8 yielded 72.22% sensitivity. Olfactory dysfunction was detected objectively and subjectively in the PCR-positive group, and no difference was found in terms of taste function and nasal breathing. The severity and prognosis of COVID-19 are not exclusively dependent on olfactory dysfunction. The degree of olfactory dysfunction can be useful in predicting PCR positivity.

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Enigmatic Neural Pathways: Potentiating Viral Neuroinvasion Into the CNS.

Outcomes of olfaction in patients with empty nose syndrome after submucosal implantation

BackgroundOlfactory dysfunction, such as hyposmia, is a significant symptom of empty nose syndrome (ENS). The efficacy of surgical intervention in olfaction improvements for ENS has not been investigated extensively. ObjectiveThe aim of this study was to evaluate changes in olfaction after surgical treatment for ENS. MethodsThis prospective cohort study at a tertiary medical center enrolled patients with ENS indicated for surgical treatment between June 2015 and June 2019. The Sniffin’ Sticks 12-items odor identification test (SS-12) and subjective olfaction rating were completed by patients before and after surgery to assess olfaction. ResultsA total of 40 patients completed the survey both before and after surgical treatment. Prior to surgery, 25% of the patients had olfactory dysfunction detected by SS-12, whereas 80% of the patients reported a reduction in olfactory function by subjective rating. The degree of olfactory dysfunction by both assessments significantly improved following surgery. The age was a significant predictor of postoperative improvement. ConclusionSurgical treatment is helpful in improving olfaction in patients with ENS who commonly suffer from olfactory dysfunction. Younger patients may benefit more from surgical intervention in aspect of olfaction.

Olfactory Dysfunction in COVID-19 Patients: Prevalence and Prognosis for Recovering Sense of Smell.

While olfactory dysfunction associated with coronavirus disease 2019 (COVID-19) has attracted considerable interest, few studies have tracked outcomes at serial time points or beyond 2 weeks. Furthermore, data are conflicting regarding whether COVID-19 severity correlates with degree of olfactory dysfunction. This prospective case-control study analyzed prevalence and severity of subjective loss of smell in outpatients (n = 23) and inpatients (n = 20) with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection vs healthy controls (n = 25). Olfactory dysfunction was reported more commonly in COVID-19 patients than in healthy controls (P < .001), and outpatients paradoxically reported loss of smell more commonly than inpatients (P = .02). Headaches were present in 52% of patients with olfactory dysfunction. Anosmia or hyposmia persisted beyond 5 days but most of the patients recovered by 30 days, suggesting favorable prognosis for olfaction. Differences between inpatients and outpatients are potentially reflective of timeline of olfactory symptoms and contextual factors, underscoring the importance of corroborative objective testing, coupled with careful tracking of temporal relationships.

A data science-based analysis of seasonal patterns in outpatient presentations due to olfactory dysfunction.

Changes in human olfactory function throughout the year appear to be a common perception due to the seasonal oscillations in some etiologies associated with olfactory loss. However, longitudinal data from large cohorts were rarely analysed for temporal patterns of human olfaction apart from oscillations in specific etiologies of olfactory loss. Temporal patterns in the presentation of patients with olfactory disorders to a single centre were investigated as part of a cohort study. The time series analysis performed utilized a power spectrum analysis and an autoregressive integrated moving average (ARIMA) model in order to demonstrate repetitive fluctuations or trends in the monthly number of patients reporting from January 1999 to December 2017. The analyses additionally addressed temporal changes in the causes to which the olfactory disorder was attributed and in the degree of olfactory loss. A cohort of 7,014 patients was included. Descriptive analysis showed that the presentation of olfactory disorders had seasonal variation, high in March, without a trend. Power spectrum analysis showed a general seasonality of the numbers of patients, without further pattern in the causes or the degree of olfactory dysfunction. The yearly periodicity in patient presentations at a specialized smell and taste clinic, was not readily attributable to seasonally changing medical causes of olfactory loss such as viral infections. This suggests that in addition to exploring the seasonality of olfactory etiologies, the changes in human olfactory acuity merit further assessments in longitudinal studies.

Olfactory anosognosia is a predictor of cognitive decline and dementia conversion in Parkinson's disease.

Parkinson's disease (PD) patients are often unaware of olfactory deficits despite having hyposmia from the early stages. We aimed to evaluate whether olfactory anosognosia is a predictor of cognitive decline in PD. In this retrospective cohort study, we recruited 77 PD patients who underwent both olfactory and neuropsychological tests and were followed-up for over 5years. Based on the degree of olfactory dysfunction and awareness of its presence, patients were classified as normosmic patients (Normosmia group, n = 15), hyposmic patients without olfactory anosognosia (Hyposmia-OA-, n = 40), or hyposmic patients with olfactory anosognosia (Hyposmia-OA+, n = 22). We compared the rates of cognitive decline using linear mixed model and dementia conversion using a survival analysis among the groups. A higher proportion of patients in the Hyposmia-OA+ group had mild cognitive impairment at baseline (77.3%) and dementia converter at follow-up (50.0%). The Hyposmia-OA+ group exhibited a faster decline in frontal executive and global cognitive function than did the Normosmia and Hyposmia-OA- groups. A Kaplan-Meier analysis demonstrated that the conversion rate to dementia was significantly higher in the Hyposmia-OA+ group than in the Normosmia (P = 0.007) and Hyposmia-OA- (P = 0.038) groups. A Cox regression analysis showed that olfactory anosognosia remained a significant predictor of time to develop dementia in the Hyposmia-OA+ group compared to the Normosmia group (adjusted hazard ratio 3.30; 95% confidence interval 1.10-8.21). This study suggests that olfactory anosognosia is a predictor of cognitive decline and dementia conversion in PD.

Olfactory evaluation in obstructive sleep apnoea patients.

SUMMARYThe sense of smell has a high impact on the quality of life. The aim of the present study was to investigate olfactory dysfunction in patients with obstructive sleep apnoea syndrome (OSAS) and correlate the severity of disease with olfactory dysfunction. The relationships between nasal obstruction, nasal mucociliary cleareance and olfactory tests were also evaluated. Sixty patients with a diagnosis of OSAS were enrolled and underwent olfactory function evaluation. In all patients olfactory performance was tested with the Sniffin’ Sticks method. Mucociliary transport times and anterior rhinomanometry were performed to identify eventual nasal obstruction and deficits in nasal mucociliary clearance. Olfactory dysfunction was present in 22 (36.6%) patients of the study group: of these, hyposmia was present in 19 (86.4%) and anosmia in 3 (13.6%). The mean TDI score in the study group was 30. A strong correlation between the olfactory dysfunction and severity of sleep apnoea measured using the AHI was found. Patients with OSA would seem to have a high incidence of olfactory dysfunction. The degree of olfactory dysfunction appears to be related to the severity of disease. However, other co-factors such as nasal obstruction and reduced mucociliary clearance might also play a role in of the aetiology of this condition.

Head trauma and olfactory function.

Olfactory impairment is a well-established sequela of head injury. The presence and degree of olfactory dysfunction is dependent on severity of head trauma, duration of posttraumatic amnesia, injuries obtained, and as more recently established, age. Deficits in smell can be conductive or neurosensory, contingent on location of injury. The former may be amenable to medical or surgical treatment, whereas the majority of patients with neurosensory deficits will not recover. Many patients will not seek treatment for such deficits until days, weeks, or even months after the traumatic event due to focus on more pressing injuries. Evaluation should start with a comprehensive history and physical exam. Determination of the site of injury can be aided by CT and MRI scanning. Verification of the presence of olfactory deficit, and assessment of its severity requires objective olfactory testing, which can be accomplished with a number of methods. The prognosis of posttraumatic olfactory dysfunction is unfortunate, with approximately only one third improving. Emphasis must be placed on identification of reversible causes, such as nasal bone fractures, septal deviation, or mucosal edema/hematoma. Olfactory loss is often discounted as an annoyance, rather than a major health concern by both patients and many healthcare providers. Patients with olfactory impairment have diminished quality of life, decreased satisfaction with life, and increased risk for personal injury. Paramount to the management of these patients is counseling with regard to adoption of compensatory strategies to avoid safety risks and maximize quality of life. Practicing otolaryngologists should have a thorough understanding of the mechanisms of traumatic olfactory dysfunction in order to effectively diagnose, manage, and counsel affected patients.

Impaired cholinergic transmission in patients with Parkinson's disease and olfactory dysfunction

Olfactory dysfunction represents a frequent and disturbing non-motor manifestation of Parkinson's disease (PD). The pathophysiology of olfactory dysfunction in PD is still poorly understood. Experimental evidence suggests that olfactory impairment could be related to central cholinergic dysfunction. Short latency afferent inhibition (SAI) technique gives the opportunity to test an inhibitory cholinergic circuit in the human cerebral motor cortex. The objective of the study was to assess the cholinergic function, as measured by SAI, in PD patients with different degrees of olfactory dysfunction. We applied SAI technique in 31 patients with PD. These patients also underwent Olfactory Event-Related Potentials (OERPs) studies to objectively evaluate the olfactory system and a battery of neuropsychological tests to assess the cognitive functions. Absent OERPs indicated a severe olfactory dysfunction in 13 subjects. The presence of OERPs with an alteration in latency and/or amplitude can be considered as a borderline condition of slight alteration of smell and was found in other 15 patients. Only 3 patients showed normal OERPs. SAI was significantly reduced in the PD patients with absent OERPs compared with those with present but abnormal OERPs. Neuropsychological examination showed a mild cognitive impairment in 12 out of 13 PD patients with severe olfactory dysfunction, and in 3 out of the 15 patients with borderline olfactory dysfunction. SAI abnormalities and presence of severe olfactory impairment strongly support the hypothesis of cholinergic dysfunction in some patients with PD, who will probably develop a dementia. Longitudinal studies are required to verify whether SAI abnormalities in PD patients with olfactory dysfunction can predict a future severe cognitive decline.

Analysis of Characteristics and Steroid Effects in Olfactory Dysfunction Patients

Background and Objectives: Olfactory dysfunction is a common sensory disorder, but there are currently no standard diagnostics or therapeutic methods. We analyzed the effects of systemic steroid therapy in patients with olfactory dysfunction. Materials and Method: We analyzed patients who visited our ENT department with olfactory dysfunction for 3 years. We reviewed their charts and classified the patients according to age, sex, etiology of olfactory dysfunction, degrees of olfactory dysfunction and the effect of systemic steroid therapy. Results: The mean age was 44.3 years old and there were 50 males and 55 females; 55 patients had inflammatory disease and 50 patients had non-inflammatory disease. The distribution of degrees of olfactory disorder according to cause was not signifi cantly different (p=0.120). In 105 patients, 20% experienced improvements after systemic steroid therapy, and the response of systemic steroid therapy was better among patients with inflammatory causes. In cases of inflammatory disease, there was a larger amount of severe hyposmia patients, and their response to systemic steroid therapy was significant (p =0.015). Patients with mild and moderate hyposmia were more responsive to systemic steroid therapy than patients with severe hyposmia (p=0.382). Conclusion: In cases of hyposmia due to inflammatory disease, systemic steroid therapy with proper operative management may increase therapeutic effects.

Olfactory bulb volume and olfactory function in patients with multiple sclerosis

Some studies reported olfactory dysfunction in patients with multiple sclerosis (MS). There is no agreement about the most suitable testing method for measuring olfactory function (OF) in MS patients. Recent studies showed that olfactory bulb volume changes with the degree of olfactory dysfunction. We assessed olfactory bulb volume of MS patients with magnetic resonance imaging (MRI) and related it to the OF. Volumetric measurements of the right and left olfactory bulb (OB) were performed by manual segmentation within 36 MS patients. Psychophysical testing of the orthonasal OF was performed using threshold-discrimination-identification (TDI) score in MS patients. Of all MS patients, 44.4% displayed olfactory dysfunction. The TDI score of all 36 MS patients, especially the score of the Identification subtest correlated strongly with neurological scores typical of MS. In patients with a decreased OB volume, there was a positive correlation between volumetry of the OB and OF. OB volumes may provide valuable information about MS patients with olfactory dysfunction. The TDI test and Identification subtest were very sensitive in detecting olfactory dysfunction in MS patients.

Chemosensory specific reduction of trigeminal sensitivity in subjects with olfactory dysfunction

Humans with olfactory loss have been found to exhibit a decreased sensitivity of the chemosensory trigeminal system. It is not clear, whether the reduced trigeminal sensitivity is restricted to the chemosensitive properties of the trigeminal nerve, or whether it reflects a general decrease of trigeminal sensitivity which is also found for cutaneous afferents. To investigate the relationship between cutaneous somatosensory and intranasal chemosensory trigeminal sensitivity, 91 subjects were investigated. Forty-five of them were considered healthy controls, whereas 46 subjects had olfactory dysfunction. Subjects with olfactory dysfunction were found to have higher thresholds for CO 2 than controls indicating lower trigeminal chemosensory sensitivity in subjects with olfactory dysfunction. Both etiology and degree of olfactory dysfunction appeared to have an impact on CO 2 thresholds. In contrast, no such differences were found with regard to detection thresholds for electrical cutaneous stimulation. These results indicate that the decrease of trigeminal sensitivity in subjects with olfactory dysfunction is specific for chemosensory sensations.

Olfactory dysfunction in sinusitis with infiltration of numerous activated eosinophils

Objectives To compare the number of activated eosinophils in the ethmoidal sinus mucosa with the computed tomographic findings and degree of olfactory dysfunction, and study the clinical characteristics of this disease. Material and Methods Ethmoidal sinus mucosal specimens were obtained from 84 patients with bilateral sinusitis accompanied by endoscopic sinus surgery (ESS). The percentage of activated eosinophils identified by staining with EG2 antibody was compared with the nasal symptoms (nasal obstruction, nasal discharge, headache, problems of smell and overall), the CT images and the olfactory dysfunction assessed using the T&T olfactometry kit and the Alinamin ® test. In addition, comparison was made of the endoscopic findings obtained after the ESS and the results of the T&T olfactometry assessment. Results Specimens from 42 patients were classified in the group showing a high percentage of EG2-positive cells, while specimens from 40 patients were classified in the group showing a low percentage of EG2-positive cells. Comparison of the subjective symptoms in these two groups found a statistically significant difference only in relation to “problems of smell”, while comparison of the two groups in terms of the CT scan findings found significant differences only in relation to the anterior and posterior ethmoidal sinuses. In addition, it was found that there was a possibility of manifestation of olfactory dysfunction in the group with a high percentage of EG2-positive cells even when the overall CT score was low. Comparison of the postoperative ethmoidal sinus endoscopic findings and the results using the T&T Olfactometry kit revealed that olfactory dysfunction occurs together with aggravation of the lesions. Conclusions For the diagnosis of sinusitis accompanied by severe infiltration of activated eosinophils, attention should be paid not only to the eosinophil counts in the blood and the tissues, but also to the clinical findings, such as the status of lesions in the ethmoidal sinus as seen in CT scans and the manifestation of olfactory dysfunction.