Recovery rates of persistent post-COVID-19 olfactory dysfunction using psychophysical assessment: A longitudinal cohort study.

Objectives: Persistent olfactory dysfunction (OD) following loss of smell associated with SARS-CoV-2 infection is a major feature of long COVID. Perspectives on the prevalence of persistent OD predominantly rely on self-reported olfactory function. Few studies have tracked longitudinal rates of recovery using psychophysical assessment among patients presenting for evaluation of persistent OD beyond a window of acute recovery. Data anchored in standardized testing methods are needed to counsel patients who fail to acutely regain their sense of smell. This study aims to quantify the degree of persistent OD in post-COVID-19 patients who experience subjective and psychophysical OD. Methods: We grouped participants presenting for OD evaluation into cohorts based on both subjective and psychophysical olfactory status at a baseline assessment and assessed their olfactory abilities with a visual analogue scale and the Sniffin' Sticks extended test at baseline and 1-year time points. Participants had confirmed a history of COVID-19 by lab evaluation or clinical diagnosis if lab evaluation was not available. Results: Baseline olfactory evaluation was completed by 122 participants, 53 of whom completed the 1-year follow-up assessment. Among participants presenting with perceived OD, 74.5% had confirmed psychophysical OD at baseline, with 55.1% at 1-year follow-up. Participants had reliable trends in self-rated versus psychophysically tested olfactory function at both time points. The total threshold, discrimination, and identification (TDI) score improved by +3.25 points in the cohort with psychophysical OD (p = 0.0005), with this improvement largely attributable to an increase in median threshold scores (+2.75 points; p = 0.0004). Conclusions: OD persists in a significant number of patients who fail to acutely recovery their sense of smell after COVID-19, with many demonstrating lingering deficits at 1-year. Improvements in threshold, but not discrimination or identification, most significantly mediate improvement of total TDI score at follow-up.

A Subjective Assessment of Chemotherapy Drug-Induced Taste and Smell Alteration in Non-head and Neck Cancer Patients: A Questionnaire-Based Cross-Sectional Study.

OBJECTIVE: This study aimed to evaluate alterations in taste and smell perceptions among non-head and neck cancer patients receiving chemotherapy, aiming to identify factors influencing these changes. METHODS: A cohort of 70 non-head and neck cancer patients undergoing one to four cycles or more than four cycles, over a six-month period, from oncology outpatient clinics was recruited. Participants completed structured taste and smell questionnaires with assistance from interviewers. Demographic data, recurrence history, chemotherapy cycles, drug regimens, and taste and smell perceptions were analyzed using descriptive statistics and chi-square tests. RESULTS: The mean age of participants was 46.5 years, with a predominance of females (81.4%) and breast cancer cases (42.9%). Taste changes were more prevalent (62.9%) than smell changes (32.9%) post chemotherapy, particularly among those on combination drug regimens. Salty taste alterations were the most common (30.0%), followed by sweet taste (22.9%) and sour/bitter tastes (14.3%). Moreover, 38.57% of patients reported experiencing dysgeusia, while 30% noted the occurrence of parosmia post chemotherapy. CONCLUSION: Chemotherapy-induced alterations in taste and smell significantly impact the quality of life and nutritional status of cancer patients. Despite often being overlooked, these changes warrant increased attention in oncological practice to inform treatment decisions and enhance symptom management, particularly in palliative care settings. Further research is needed to explore the implications of chemosensory alterations on patient outcomes and treatment strategies.

Tobacco products and sensory health: An assessment of taste and smell disorders using 2021 NHIS data.

INTRODUCTION: This study aims to assess the relationship between use of tobacco products and taste and smell disorders. METHODS: A secondary dataset analysis of cross-sectional data from the National Health Interview Survey (NHIS) 2021 survey cycle, a nationally representative annual cross-sectional interview of non-institutionalized US civilians, was used. Participants' senses of smell and taste are assessed using self-reported questions. Participants were categorized into five groups based on their tobacco use: non-tobacco users; cigarettes only; e-cigarettes only; cigar, pipe, or smokeless tobacco; and poly-tobacco product users. Disorders were defined as any self-reported difficulty in smelling, tasting, or reporting unpleasant odors or persistent tastes. Weighting procedures were used to estimate the national prevalence of taste, smell, and other disorders, stratified by tobacco products used. Adjusted logistic regression models were used to determine the association between tobacco products used and taste or smell compared to non-tobacco users. RESULTS: A total of 40.2 million US adults reported experiencing smell or taste disorders. Nearly one in 10 adults reported a taste disorder (9.8%), and 13.4% indicated a smell disorder. The prevalence of taste or smell disorder was higher among females (17.5%), Hispanics (19.5%), individuals identified as 'other' racial minorities (21.1%), and lower income groups (21%). Compared to non-tobacco users, the highest odds of experiencing smell or taste disorders were among poly-tobacco product users (adjusted odds ratio, AOR=1.44; 95% CI: 1.31-1.58), followed by e-cigarette-only users (AOR=1.38; 95% CI: 1.02-1.87), cigarette-only smokers (AOR=1.17; 95% CI: 1.04-1.32), and users of cigars, pipes, or smokeless tobacco (AOR=1.15; 1.00; and 1.33; respectively). CONCLUSIONS: Tobacco product use was associated with an increased risk of smell and taste disorders. The rising use of e-cigarettes among adolescents and young adults is particularly concerning given the limited understanding of the sensory effects of e-cigarettes and their growing popularity among younger populations. The study findings highlight the need for interventions aimed at reducing tobacco use of all kinds.

Patient Experience and Preferences for the Assessment of Olfaction: The Patient International Clinical Assessment of Smell Survey.

INTRODUCTION: Olfactory dysfunction (OD) is common and carries significant personal and societal burden of disease. Accurate assessment of olfaction is required for good clinical care and affords patients insight into their condition. However, the accuracy of assessment varies with technique used, and there is presently little standardisation of clinical practice. We therefore aimed to determine experience of and preferences for olfactory assessment in healthcare-seeking adults. METHODS: An anonymous patient co-produced survey was developed in collaboration with a UK-based OD charity. Distribution was via their social media patient forum. "Healthcare seeking" adults (i.e., who had undergone olfactory assessment by a healthcare professional [any care level/speciality] or may do so in the future) were included. RESULTS: 576 people (88.5% female, mean 46 years) responded. Hyposmia, parosmia, and retronasal OD were most frequently reported. 55.2% had been assessed by a healthcare professional - GP most commonly, followed by ENT. Importantly, only 15.6% and 16.9% of respondents had undergone systematic assessment with smell tests or symptom questionnaires, respectively. Most respondents had not undergone imaging. Mean satisfaction was higher in those seen by ENT. Interestingly, respondents prioritise orthonasal odour identification over other forms of smell test. Unfortunately, many felt that healthcare professionals (across specialities) were dismissive towards OD and lacked appropriate knowledge of both its pathophysiology and effects. We propose simple steps that can be taken to improve olfactory assessment, including education and establishment of robust referral networks. CONCLUSION: We hope these results and supporting practical recommendations will inform future service planning, funding allocation and research, as well as better aligning patient and clinician priorities.

Extraction of Essential Oils from Lavandula × intermedia 'Margaret Roberts' Using Steam Distillation, Hydrodistillation, and Cellulase-Assisted Hydrodistillation: Experimentation and Cost Analysis.

Lavender oil is an important essential oil with many applications. The purpose of this study was to compare different methods of essential oil extraction to determine which method would be the most effective and profitable for commercial-scale production from Lavandula × intermedia ('Margret Roberts') flowers and leaves. The lavender from this variety flowers year-round, providing an extended production season compared to some other lavender varieties. Steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were used to extract oil. The average extraction times for steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were 57-, 51-, and 49 min, respectively, and the average energy consumption was 15.0-, 13.4-, and 30.8 kJ/g, respectively. Cellulase-assisted hydrodistillation produced the best quality oils, with a lower camphor content and a sweeter, more pleasant smell, while steam-distilled oils had the highest camphor content, as well as a more plant-like smell. Factors affecting scale-up (surface area of cut plants, equipment loading times, energy efficiencies, safety, mixing) have been discussed, while a basic cost analysis of theoretical large-scale processes showed that hydrodistillation and cellulase-assisted hydrodistillation would be the most and least profitable methods, respectively. Overall, hydrodistillation is recommended as the best method for commercial lavender oil production.

Combined assessment by transcranial sonography and Sniffin' Sticks test has a similar diagnostic accuracy compared to brain SPECT for Parkinson's disease diagnosis.

OBJECTIVES: This study aimed to investigate the accuracy of TCS combined with the Sniffin' sticks olfactory test (SST-16) for differentiation between idiopathic PD patients and healthy controls compared to that of 99 mTc-TRODAT-1 SPECT (TRODAT). METHODS: A cross-sectional study included PD patients diagnosed in accordance with United Kingdom PD Society Brain Bank criteria and a control group of age and sex- matched healthy subjects. All patients were examined by a movement disorder specialist and underwent brain SPECT using TRODAT, TCS examination and SST-16 test. Receiver Operating Characteristic (ROC) curves were used to calculate cut-off points for TCS, striatal TRODAT binding potentials and SST-16. The area under the ROC curve determined the diagnostic accuracy of the method. RESULTS: Twenty patients with PD (13 males and 7 females) and nine healthy subjects were included. Median age of PD onset was 56.5 years with median disease duration of 5 years. A larger substantia nigra (SN) echogenic area was observed in the PD group (p = 0.013). SN echogenic area cut-off point of 0.22 cm2 was obtained from a ROC curve for PD diagnosis. Considering this cut-off point, TCS diagnostic accuracy was estimated at 79.2% for PD diagnosis. The cut-off value of 0.90 for striatal TRODAT binding was associated with 99% diagnostic accuracy for the diagnosis of PD. SST-16 values equal or less than 9 points showed an 85.8% diagnostic accuracy for PD diagnosis. Combination of both SST-16 and TCS improved the diagnostic accuracy to 95% for PD diagnosis. CONCLUSION: Combined SST-16 and TCS assessment was indicated as accurate for distinguishing PD patients from healthy controls. The diagnostic accuracy of TCS combined with SST-16 for differentiation between idiopathic PD patients and healthy controls is similar to that of SPECT TRODAT.

Assessment of olfactory fluctuations in a clinical context.

PURPOSE: The aim of the study was to investigate whether olfactory fluctuations (OF) are pronounced in patients with sinonasal olfactory dysfunction (OD). METHODS: The retrospective investigation included patients aged 18 years or older, who consulted a tertiary referral center for olfactory loss. Patients with normal smell function were excluded. Patients answered a structured questionnaire about their olfactory symptoms, with specific questions related to the presence of OF and its average frequency, amplitude, duration, time since most recent OF, and associated symptoms of self-reported OF. Patients also underwent clinical evaluation including a structured medical history and physical examination including nasal endoscopy. In addition, we assessed orthonasal olfactory function using Sniffin' Sticks, and gustatory function using "taste sprays". RESULTS: Participants included 131 men and 205 women (n = 336), aged 18 to 86 years (mean 50, SD 16). Patient-reported fluctuations occurred most frequently in sinonasal (38%), idiopathic (29%), and postviral (29%) OD. Amplitude of OF was highest in postviral OD (p = 0.009). Average frequency, duration, and the time since the most recent fluctuation were not significantly different between groups (all p's > 0.42). Odor discrimination (p = 0.002) and identification (p = 0.017) scores were higher among those individuals with OF. CONCLUSION: Amplitude of OF may help distinguish postviral from other causes of OD, especially in patients presenting with equivocal symptoms of sinonasal disease.

Assessment and Scientific Progresses in the Analysis of Olfactory Evoked Potentials.

The human sense of smell is important for many vital functions, but with the current state of the art, there is a lack of objective and non-invasive methods for smell disorder diagnostics. In recent years, increasing attention is being paid to olfactory event-related potentials (OERPs) of the brain, as a viable tool for the objective assessment of olfactory dysfunctions. The aim of this review is to describe the main features of OERPs signals, the most widely used recording and processing techniques, and the scientific progress and relevance in the use of OERPs in many important application fields. In particular, the innovative role of OERPs is exploited in olfactory disorders that can influence emotions and personality or can be potential indicators of the onset or progression of neurological disorders. For all these reasons, this review presents and analyzes the latest scientific results and future challenges in the use of OERPs signals as an attractive solution for the objective monitoring technique of olfactory disorders.

Assessment of Smell and Taste Disturbances among COVID-19 Convalescent Patients: A Cross-Sectional Study in Armenia.

BACKGROUND AND OBJECTIVES: Neurological manifestations of Coronavirus Disease 2019 (COVID-19) such as olfactory and gustatory disturbance have been reported among convalescent COVID-19 patients. However, scientific data on the prevalence of smell and taste disturbance are lacking. Therefore, we present findings on the degree of smell and taste disturbances among the Armenian population. METHODS: Study participants were randomly recruited and then categorized into two groups based on their course of the disease. A cross-sectional study was performed to assess participants' sensitivity to smell triggered by the olfactory and the trigeminal nerves; their ability to differentiate between various odors; and to evaluate their gustatory perception. RESULTS: The smell test revealed that the degree of olfactory nerve disturbance was different by 30.7% in those participants of the early group as compared to those of the late group, and the degree of trigeminal nerve disturbance was different by 71.3% in the early group as compared to the late group. A variation of the differentiating ability among the participants of the early and late groups was detected. Gustatory disturbances for all flavors were also found to be different in both the groups. A moderate positive correlation (0.51) was found between the overall sensitivity of smell and the ability to differentiate between various odors as cumulatively stimulated by both the olfactory and trigeminal nerves. Also, a moderate positive correlation (0.33) was found between headache and smell sensitivity through the olfactory nerve and a high negative correlation (-0.71) was found between headache and smell sensitivity through the trigeminal nerve. CONCLUSION: Pathological changes in the olfactory and trigeminal perceptive abilities caused disturbances in smell sensation, with the trigeminal nerve being more affected. The capacity to differentiate fragrances did not improve with time and the disturbance severity of bitter taste perception was higher among the study participants.

Subjective assessment of taste and smell disfunction in patients with COVID-19 in Paraguay / Evaluación subjetiva de las alteraciones del sentido del gusto y del olfato en pacientes con COVID-19 en Paraguay

The alteration of the senses of taste and smell in relation to COVID-19 is a widely known phenomenon; however, this alteration has not been exhaustively characterized in the international literature. The following study is proposed with the aim of describing the alterations in the senses of taste and smell in relation to COVID-19 by means of their subjective evaluation. The nature of the study is observational, descriptive and cross-sectional, and was applied to patients who sought medical attention via remote consultations carried out on virtual platforms of the Service of Otorhinolaryngology and Head and Neck Surgery of the Clínicas Hospital, San Lorenzo, between the months of March and October of 2021. We included 440 patients aged 31.3 ± 9.9 years (18 to 60 years), 308 (70%) female, 388 (88%) from urban areas, with evidence of infection by SARS-CoV-2 by RT-PCR in 260 (59%), predominantly without comorbidities 232 (53%), with fever as the most frequently reported symptom 352 (80%), treated more frequently with NSAIDs 208 (47%) and/or Paracetamol 216 (49%). Both taste and smell alterations in patients who have had COVID-19 have been shown to appear more frequently 1 to 7 days after the onset of symptoms (207 for smell, 184 for taste), occurring more frequently with a total decrease of both senses (anosmia 302 and ageusia 216), recovering completely in most cases (214 and 216) and within a period of 1 to 4 weeks (140 and 130).

La alteración de los sentidos del gusto y del olfato en relación con el COVID-19 es un fenómeno ampliamente conocido, sin embargo, esta alteración no ha sido caracterizada de forma exhaustiva en la literatura internacional. Se plantea el siguiente estudio con el objetivo de describir las alteraciones del sentido del gusto y del olfato en relación con el COVID-19 a través de la evaluación subjetiva del mismo. El mismo es observacional, descriptivo, de corte transversal, aplicado a pacientes que consultaron a través de teleconsultas realizadas sobre plataformas virtuales de la Cátedra y Servicio de Otorrinolaringología y Cirugía de Cabeza y Cuello del Hospital de Clínicas, de San Lorenzo, durante los meses de marzo a octubre del 2021. Fueron incluidos 440 pacientes de 31,3 ± 9,9 años (18 a 60 años), 308 (70%) de sexo femenino, 388 (88%) provenientes de zona urbana, con evidencia de infección por SARS-CoV-2 por RT-PCR en 260 (59%), predominantemente sin comorbilidades 232 (53%), con fiebre como síntoma asociado al COVID-19 más frecuentemente reportado 352 (80%), tratados más frecuentemente con AINES 208 (47%) y/o Paracetamol 216 (49%). Tanto la alteración del gusto como del olfato en pacientes que han cursado con COVID-19 ha demostrado ser aparecer más frecuentemente en 1 a 7 días del inicio del cuadro (207 para el olfato. 184 para el gusto), cursando más frecuentemente con disminución total de ambos sentidos (anosmia 302 y ageusia 216), recuperándose más frecuentemente de forma total (214 y 216) y en un plazo de 1 a 4 semanas (140 y 130).

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.

Long-Term Subjective and Objective Assessment of Smell and Taste in COVID-19.

Among the first clinical symptoms of the SARS-CoV-2 infection is olfactory−gustatory deficit; this continues for weeks and, in some cases, can be persistent. We prospectively evaluated 162 patients affected by COVID-19 using a visual analogue scale (VAS) for nasal and olfactory−gustatory symptoms. Patients were checked after 7, 14, 21, 28, 90, and 180 days. A total of 118 patients (72.8%) reported an olfactory VAS < 7 at baseline (group B), and 44 (27.2%) reported anosmia (VAS ≥ 7) (group A) and underwent the Brief Smell Identification Test (B-SIT) and Burghart Taste Strips (BTS) to quantify the deficit objectively and repeated the tests to confirm the sense recovery. Group A patients showed B-SIT anosmia and hyposmia in 44.2% and 55.8% of cases, respectively. A total of 88.6% of group A patients reported ageusia with VAS ≥ 7, and BTS confirmed 81.8% of ageusia and 18.2% of hypogeusia. VAS smell recovery was recorded starting from 14 days, with normalization at 28 days. The 28-day B-SIT score showed normosmia in 90.6% of group A patients. The mean time for full recovery (VAS = 0) was shorter in group B (22.9 days) than in group A (31.9 days). Chemosensory deficit is frequently the first symptom in patients with COVID-19, and, in most cases, recovery occurs after four weeks.

The digital scent device as a new concept for olfactory assessment.

BACKGROUND: There are major challenges in olfactory measurements in clinical practice; therefore, a handheld digital scent device (DSD; Noar MultiScent 20) was developed as a tablet with an integrated storage system for odors. The DSD is a self-administered, handheld device that controls the duration of odor release to the nasal cavity through a touchscreen digital interface with automatic database generation. In this study we aimed to determine the feasibility of this DSD as an olfactory assessment test. METHODS: We recruited 180 participants (age [mean ± standard deviation], 34.58 ± 9.71 years; 114 women and 66 men) to participate in smell tests using both the DSD and the 40-item Smell Identification Test (SIT-40), which contained the same type and order of odors and the same multiple-choice answers. The scores were compared and evaluated for correlation between the tests, and test-retest reliability was calculated. RESULTS: The DSD test scores were higher than the SIT-40 scores (median [interquartile range], 32 [5.0] vs 31 [7.0]; p = 0.005). The completion time was less for the DSD test than for the SIT-40 (12.5 [5.0] vs 16 [6.0] minutes; p < 0.001). The tests were strongly correlated (Spearman rho = 0.74; p < 0.001) and exhibited a high level of agreement (Bland-Altman regression coefficient = 0.672; p = 0.003). The DSD test-retest reliability coefficient was 0.820. CONCLUSION: The DSD is feasible as an olfactory assessment test. The digitalization of olfactory assessment combined with data science may enable new research perspectives in the field of olfaction.

[Determination of the prevalence of postcovid syndrome and assessment of the effectiveness of the drug Cortexin in the treatment of neurological disorders in patients with postcovid syndrome. Results of the multicenter clinical and epidemiological observational program CORTEX]. / Opredelenie rasprostranennosti postkovidnogo sindroma i otsenka effektivnosti preparata Korteksin v terapii nevrologicheskikh narushenii u patsientov s postkovidnym sindromom. Rezul'taty mnogotsentrovoi nablyudatel'noi programmy KORTEKS.

OBJECTIVE: To study the prevalence of clinical manifestations of postcoid syndrome in patients at an outpatient neurological appointment, to evaluate the effectiveness of therapy regimens using Cortexin at doses of 10 mg and 20 mg IM for 10 days. MATERIALS AND METHODS: 674 neurologists from all regions of the Russian Federation, Azerbaijan, Kyrgyzstan and Kazakhstan took part in the study. A total of 979 COVID-19 patients were recruited. The average age is 54.6±0.45 years. The duration of the transferred SARS-CoV-2 days and from 1 month or more 12. 3 visits were carried out: 1 on the day of treatment (assessment of complaints, analysis of scale indicators, prescription of the drug Cortexin in doses of 10-20 mg/m for 10 days). 2 (telephone survey) visit for 10-14 days, 3 visit - for 30 days at the reception. The condition was assessed using the Asthenia Assessment Scale (MFI-20), the Brief Mental Status Assessment Scale (MMSE questionnaire), the Schulte test, and the Subjective Treatment Quality Assessment Scale. RESULTS: The daily proportion of patients with complaints after a previous coronavirus infection was 30% in the total structure of neurological admission. The most common complaints: fatigue, general weakness, decreased memory and concentration, dizziness, sleep disturbance, irritability, aggression, shortness of breath, pain syndromes, excessive sweating, anosmia, hyposmia, perverted taste of paresthesia, hair loss, blurred vision, unstable blood pressure, tachycardia, allergic reactions, menstrual irregularities, erectile dysfunction, apathy, panic attacks, suicidal thoughts, depression, refusal to eat meat. CONCLUSION: There was no significant correlation of clinical symptoms with the severity of COVID-19, the percentage of lung tissue damage, and different periods of postcovid syndrome. The clinical efficacy of the drug Cortexin in dosages of 10 and 20 mg for the correction of cognitive and asthenic disorders has been proven. Revealed anti-anxiety, antidepressant and anxiolytic activity of Cortexin is more pronounced when using a dosage of 20 mg.

Assessment of Taste Function.

Taste disorders, impacting well-being and physical health, can be caused by many etiologies including the use of medication. Recently, taste disturbance is also considered as one of the predominant symptoms of COVID-19 although its pathogenesis requires further research. Localized taste disorders may be overlooked considering that whole-mouth taste perception is insured through several mechanisms. Individuals often fail to discern taste from flavor, and interviews/surveys are insufficient to properly assess taste function. Hence, various taste assessment methods have been developed. Among them, psychophysical methods are most widely applied in a clinical context. Less-biased electrophysiological, imaging, or morphological methods are used to a much lesser degree. Overall, more research is needed in the field of taste.

Clinical assessment of olfactory function.

Approximately 5% of the general population is affected by functional anosmia with approximately additional 15% exhibiting decreased olfactory function. Many of these individuals ask for help. Because the subjective rating of olfactory function is biased, assessment of olfactory function is important. Olfactory measurements are needed for patient counseling and the tracking of changes in the sense of smell over time. The present review provides an overview of frequently used psychophysical tests for olfactory function, discusses differences between threshold and suprathreshold aspects of olfactory function, and gives examples on how to apply psychophysical tests.

Impact of olfactory dysfunction on quality of life in coronavirus disease 2019 patients: a systematic review.

OBJECTIVE: To outline the impact on quality of life in coronavirus disease 2019 patients with olfactory dysfunction. METHODS: Five databases were searched for articles referring to the impact on quality of life in coronavirus disease 2019 patients with olfactory dysfunction. The search was conducted for the period from November 2019 to April 2021. The search was conducted over one month (May 2021). RESULTS: Four studies that met the objective were included. Altogether, there were 1045 patients. Various questionnaires were used to assess quality of life. Overall, the quality of life deficit affected 67.7 per cent of patients. Quality of life domains investigated include overall quality of life (four studies), food and taste dysfunction (two studies), mental health (two studies), cognitive function (one study), functional outcome (one study) and safety domains (one study). CONCLUSION: Quality of life deficit was reported to be 67.7 per cent among coronavirus disease 2019 patients with olfactory dysfunction. The high prevalence of persistent olfactory dysfunction prompts more serious research, as the long-standing consequences of olfactory dysfunction are detrimental.

Assessment of patient recognition of coronavirus disease 2019 (COVID-19)-associated olfactory loss and recovery: a longitudinal study.

BACKGROUND: The clinical course of coronavirus disease 2019 (COVID-19) olfactory dysfunction remains poorly characterized, often limited by self-reported measures. Given the logistical challenges of psychophysical testing, understanding the longitudinal relationship between self-reported and quantitative measures can help accurately identify patients with persistent olfactory dysfunction. This study aimed to longitudinally correlate measured and subjective olfactory function in COVID-19 subjects. METHODS: A prospective, longitudinal study evaluating subjective and measured olfaction was conducted on ambulatory COVID-19 subjects. Olfaction scores were obtained using a visual analogue scale (VAS) (0 = anosmia, 10 = normosmia) and the validated 12-item Brief Smell Identification Test (BSIT). Weekly testing was performed until recovery (BSIT ≥ 9/12 and/or VAS = 10/10) or study completion. RESULTS: Eighty-six polymerase chain reaction (PCR)-positive COVID-19 subjects were recruited ≤3 days from diagnosis and 52 completed longitudinal testing. Among those with self-reported smell loss at recruitment, similar levels (75.8%) of objective (BSIT ≥ 9/12) and subjective recovery were obtained using a VAS cutoff ≥8, yet only 30.3% reported complete subjective recovery (VAS = 10). Median times to objective and complete subjective olfactory recovery were 12 ± 2.3 and 24 ± 3.5 days, respectively. Although both measures showed chemosensory improvement, the distributions of objective and full subjective olfactory recovery differed significantly (log rank test χ2 = 6.46, degrees of freedom [df] = 1, p = 0.011). Overall correlation between BSIT and VAS scores was moderate to strong across longitudinal follow-up (rs = 0.41-0.65). CONCLUSION: Self-reported and psychophysically measured COVID-19 olfactory dysfunction improve at similar levels and are moderately correlated longitudinally, yet there is a significant delay in complete subjective recovery. Psychophysical testing in conjunction with qualitative assessments may be considered for counseling and follow-up of patients with COVID-19 smell loss.

Assessment of olfactory information in the human brain using 7-Tesla functional magnetic resonance imaging.

Olfaction could prove to be an early marker of neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. To use olfaction for disease diagnosis, elucidating the standard olfactory functions in healthy humans is necessary. However, the olfactory function in the human brain is less frequently assessed because of methodological difficulties associated with olfactory-related cerebral areas. Using ultra-high fields (UHF), functional magnetic resonance imaging (fMRI) with high spatial resolution and sensitivity may allow for the measurement of activation in the cerebral areas. This study aimed to apply 7-Tesla fMRI to assess olfactory function in the human brain by exposing individuals to four different odorants for 8 s. We found that olfactory stimulation mainly activated the piriform and orbitofrontal cortex in addition to the amygdala. Among these regions, univariate fMRI analysis indicated that subjective odor intensity significantly correlated with the averaged fMRI signals in the piriform cortex but not with subjective hedonic tone in any region. In contrast, multivariate fMRI analysis showed that subjective hedonic tone could be discriminated from the fMRI response patterns in the posterior orbitofrontal cortex. Thus, the piriform cortex is mainly associated with subjective odor intensity, whereas the posterior orbitofrontal cortex are involved in the discrimination of the subjective hedonic tone of the odorant. UHF-fMRI may be useful for assessing olfactory function in the human brain.