Treatment strategies for postviral olfactory dysfunction: A systematic review

Traditional Chinese medicine for post-viral olfactory dysfunction: A systematic review

Background

Post-viral olfactory dysfunction (PVOD) is the common symptoms of long COVID, lacking of effective treatments. Traditional Chinese medicine (TCM) is claimed to be effective in treating olfactory dysfunction, but the evidence has not yet been critically appraised. We conducted a systematic review to evaluate the effectiveness and safety of TCM for PVOD.

Methods

We searched eight databases to identified clinical controlled studies about TCM for PVOD. The Cochrane risk of bias tools and GRADE were used to evaluate the quality of evidence. Risk ratio (RR), mean differences (MD), and 95 % confidence interval (CI), were used for effect estimation and RevMan 5.4.1 was used for data analysis.

Results

Six randomized controlled trials (RCTs) (545 participants), two non-randomized controlled trials (non-RCTs) (112 participants), and one retrospective cohort study (30 participants) were included. The overall quality of included studies was low. Acupuncture (n = 8) and acupoint injection (n = 3) were the mainly used TCM therapies. Five RCTs showed a better effect in TCM group. Four trials used acupuncture, and three trials used acupoint injection. The results of two non-RCTs and one cohort study were not statistically significant. Two trials reported mild to moderate adverse events (pain and brief syncope caused by acupuncture or acupoint injection).

Conclusions

Limited evidence focus on acupuncture and acupoint injection for PVOD and suggests that acupuncture and acupoint injection may be effective in improving PVOD. More well-designed trials should focus on acupuncture to confirm the benefit.

Protocol registration

The protocol of this review was registered at PROSPERO: CRD42022366776.

The efficacy of olfactory training in improving olfactory function: a meta-analysis

PURPOSE

Study the efficacy of olfactory training in smell recovery.

METHODS

An extensive search was performed through different databases in order to find articles analyzing the efficacy of olfactory training as a treatment for olfactory dysfunction. Methodological quality of primary studies within the final sample was assessed following PRISMA guidelines. Standardized mean differences in pre-post olfactory training groups, and also in experimental-control and pre-follow up if possible, were computed by Hedges' g effect size statistic. Each effect size was weighted by its inverse variance.

RESULTS

Final sample was composed of 36 articles (45 pre-post effect sizes). Contrasts were performed separately for odor identification, odor discrimination, odor threshold and general olfactory function. Moderate to large and heterogeneous effect was obtained for olfactory function (g = 0.755, k = 45, SE = 0.093, CI 95% = [0.572, 0.937]), different moderators had a significant effects, such as, training duration, age and anosmia diagnosis.

CONCLUSION

Olfactory training was found to have a positive and significant effect on rehabilitating the olfactory function.

Olfactory dysfunction and the role of stem cells in the regeneration of olfactory neurons

The prevalence of COVID-19 has drawn increasing attention to olfactory dysfunction among researchers. Olfactory dysfunction manifests in various clinical types, influenced by numerous pathogenic factors. Despite this diversity, the underlying pathogenesis remains largely elusive, contributing to a lack of standardized treatment approaches. However, the potential regeneration of olfactory neurons within the nasal cavity presents a promising avenue for addressing olfactory dysfunction effectively. Our review aims to delve into the current research landscape and treatment modalities concerning olfactory dysfunction, emphasizing etiology, pathogenesis, clinical interventions, and the role of stem cells in regenerating olfactory nerves. Through this comprehensive examination, we aim to provide valuable insights into understanding the onset, progression, and treatment of olfactory dysfunction diseases.

Persistent COVID-19 parosmia and olfactory loss post olfactory training: randomized clinical trial comparing central and peripheral-acting therapeutics

PURPOSE

Although COVID-19 anosmia is often transient, patients with persistent olfactory dysfunction (pOD) can experience refractory parosmia and diminished smell. This study evaluated four putative therapies for parosmia in patients with chronic COVID-19 olfactory impairment.

METHODS

After screening nasal endoscopy, 85 patients (49 female, 58%) with pOD and treatment-refractory parosmia were randomized to: (1) ultramicronized palmitoylethanolamide and luteolin + olfactory training (OT) (umPEALUT group, n = 17), (2) alpha-lipoic acid + OT (ALA group, n = 21), (3) umPEALUT + ALA + OT (combination group, n = 28), or 4) olfactory training (OT) alone (control group, n = 23). Olfactory function was assessed at baseline (T0) and 6 months (T1) using a parosmia questionnaire and Sniffin' Sticks test of odor threshold, detection, and identification (TDI). Analyses included one-way ANOVA for numeric data and Chi-Square analyses for nominal data on parosmia.

RESULTS

The umPEALUT group had the largest improvement in TDI scores (21.8 ± 9.4 to 29.7 ± 7.5) followed by the combination group (19.6 ± 6.29 to 27.5 ± 2.7), both p < 0.01. The control and ALA groups had no significant change. Patients in the combination and umPEALUT groups had significantly improved TDI scores compared to ALA and control groups (p < 0.001). Rates of parosmia resolution after 6 months were reported at 96% for combination, 65% for control, 53% for umPEALUT and 29% for ALA (p < 0.001). All treatment regimens were well-tolerated.

CONCLUSIONS

umPEALUT and OT, with or without ALA, was associated with improvement in TDI scores and parosmia, whereas OT alone or OT with ALA were associated with little benefit.

Olfactory immune response to SARS-CoV-2

Numerous pathogens can infect the olfactory tract, yet the pandemic caused by SARS-CoV-2 has strongly emphasized the importance of the olfactory mucosa as an immune barrier. Situated in the nasal passages, the olfactory mucosa is directly exposed to the environment to sense airborne odorants; however, this also means it can serve as a direct route of entry from the outside world into the brain. As a result, olfactotropic infections can have serious consequences, including dysfunction of the olfactory system, CNS invasion, dissemination to the lower respiratory tract, and transmission between individuals. Recent research has shown that a distinctive immune response is needed to protect this neuronal and mucosal tissue. A better understanding of innate, adaptive, and structural immune barriers in the olfactory mucosa is needed to develop effective therapeutics and vaccines against olfactotropic microbes such as SARS-CoV-2. Here, we summarize the ramifications of SARS-CoV-2 infection of the olfactory mucosa, review the subsequent immune response, and discuss important areas of future research for olfactory immunity to infectious disease.

Integrating the patient's voice into the research agenda for treatment of chemosensory disorders

World-wide some 658 million people were infected with coronavirus disease 2019 (COVID-19) and millions suffer from chemosensory impairment associated with long COVID. Current treatments for taste and smell disorders are limited. Involving patients has the potential to catalyze the dynamic exchange and development of new ideas and approaches to facilitate biomedical research and therapeutics. We assessed patients' perceptions of the efficacy of treatments for chemosensory impairment using an online questionnaire completed by 5,815 people in the US Logistic regression determined variables predictive of reported treatment efficacy for patients aged 18 to 24, 25 to 39, 40 to 60, and 60+ yrs. who were treated with nasal steroids, oral steroids, zinc, nasal rinse, smell training, theophylline, platelet-rich plasma, and Omega 3. The most consistent predictor was age, with the majority of those 40 to 60 and 60+ reporting that nasal steroids, oral steroids, zinc, nasal rinse, and smell training were only slightly effective or not effective at all. Many of these treatment strategies target regeneration and immune response, processes compromised by age. Only those under 40 reported more than slight efficacy of steroids or smell training. Findings emphasize the need to include patients of all ages in clinical trials. Older adults with olfactory impairment are at increased risk for Alzheimer's disease (AD). We speculate that olfactory impairment associated with long COVID introduces the potential for a significant rise in AD. Long COVID-associated chemosensory impairment increases the urgency for translational and clinical research on novel treatment strategies. Suggestions for high-priority areas for epidemiological, basic, and clinical research on chemosensory impairment follow.

Effect of any form of steroids in comparison with that of other medications on the duration of olfactory dysfunction in patients with COVID-19: A systematic review of randomized trials and quasi-experimental studies

BACKGROUND

The life quality of about two-thirds of patients with COVID-19 is affected by related olfactory dysfunctions. The negative impact of olfactory dysfunction ranged from the decreased pleasure of eating to impaired quality of life. This research aimed to provide a comprehensive understanding of the effects of corticosteroid treatments by comparing that to other currently available treatments and interventions.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist's 27-point checklist was used to conduct this review. PubMed (Public/Publisher MEDLINE), PubMed Central and EMBASE (Excerpta Medica Database) databases were conveniently selected and Boolean search commands were used for a comprehensive literature search. Five core search terms were "effects of treatments", " COVID-19-related olfactory dysfunction", "corticosteroids", "treatments" and "interventions". The reporting qualities of the included studies were appraised using JBI (Joanna Briggs Institute) appraisal tools. The characteristics of the 21 experimental studies with a total sample (of 130,550) were aggregated using frequencies and percentages and presented descriptively. The main interventions and their effects on the duration of the COVID-19-related olfactory dysfunction were narratively analyzed.

RESULTS

Among patients with COVID-19, the normal functions of the olfactory lobe were about 23 days earlier to gain with the treatments of fluticasone and triamcinolone acetonide nasal spray compared with that of mometasone furoate nasal spray and oral corticosteroid. The smell loss duration was reduced by fluticasone and triamcinolone acetonide nasal spray 9 days earlier than the inflawell syrup and 16 days earlier than the lavender syrup. The nasal spray of corticosteroids ended the COVID-19-related smell loss symptoms 2 days earlier than the zinc supplementation, about 47 days earlier than carbamazepine treatment and was more effective than palmitoylethanolamide (PEA) and luteolin and omega-3 supplementations and olfactory training. Treatment with oral corticosteroid plus olfactory training significantly improved Threshold, Discrimination and Identification (TDI) scores compared with olfactory training alone. A full dose of the COVID-19 vaccination was not uncertain to reduce the COVID-19-related smell loss duration.

CONCLUSION

Corticosteroid treatment is effective in reducing the duration of COVID-19-related smell loss and olfactory training, the basic, essential and effective intervention, should be used as a combination therapy.

Olfactory Dysfunction following COVID-19 and the Potential Benefits of Olfactory Training

COVID-19 is associated with a common symptom of olfactory dysfunction, which may persist even after the infection is resolved. Olfactory training (OT) has emerged as the most effective intervention for post-viral olfactory dysfunction. OT involves daily exposure of the olfactory system to various odors. The current study aims to explore olfactory dysfunction following COVID-19 and the potential benefits of olfactory training.

METHODS

This is a cross-sectional study conducted among adults aged 18-60 living in Alahssa, Saudi Arabia. An online questionnaire containing an informed consent form and a survey to collect demographic data, vaccination status, level of loss of smell and taste, and the level of awareness about olfactory training (OT) was distributed among all participants who agreed to participate in this study.

RESULTS

The study included 524 participants and presented their baseline characteristics, including age, gender, COVID-19 infection status, and complaints. Most patients were female (66.0%), and 46.2% had previously been infected with COVID-19. About 54.8% of participants reported chemosensory dysfunction, while 286 had olfactory dysfunction. Of those, 29.8% had anosmia, 16.8% had hyposmia, and 8.0% had parosmia. Results suggest that being fully or partially vaccinated may offer some protection against olfactory dysfunction compared to being unvaccinated. Adherence to olfactory training was associated with improvement in the sense of smell.

CONCLUSIONS

The study highlights the importance of awareness and adherence to olfactory training, which may improve the sense of smell in individuals with chemosensory dysfunction. The findings of this study can inform public health policies and interventions aimed at reducing the burden of olfactory dysfunction associated with COVID-19 vaccination.

Post-traumatic olfactory dysfunction: a scoping review of assessment and rehabilitation approaches

Post-traumatic Olfactory Dysfunction (PTOD) consists of a complete or partial loss of olfactory function that may occur after a traumatic brain injury (TBI). PTOD may be linked to some neuropsychiatric features, such as social, cognitive and executive dysfunction, as well as behavioral symptoms, especially when TBI involves the orbito-frontal cortex. The diagnosis of PTOD is based on medical history and clinical data and it is supported by psychometric tests (i.e., subjective tools) as well as electrophysiological and neuroimaging measures (i.e., objective methods). The assessment methods allow monitoring the changes in olfactory function over time and help to establish the right therapeutic and rehabilitative approach. In this context, the use of the olfactory training (OT), which is a non-pharmacological and non-invasive treatment option, could promote olfactory function through top-down (central) and bottom-up (peripheral) processes. To better manage patients with TBI, PTOD should be detected early and properly treated using the various therapeutic rehabilitative possibilities, both conventional and advanced, also taking into consideration the emerging neuromodulation approach.

Food-related experiences and behavioral responses among people affected by chemosensory dysfunctions following COVID-19: A scoping review

A category of symptoms that became characteristic early in the first wave of the coronavirus disease 2019 (COVID-19) pandemic was chemosensory dysfunctions (alterations of smell and taste). Such symptoms substantially affect food and eating-cornerstones for both nutrition-related health outcomes and for quality of life. Based on this, this scoping review aimed to map out existing scientific literature on food-related experiences and related behavioral responses among people affected by chemosensory dysfunctions following COVID-19. A librarian-supported search of PsycInfo, PubMed, and Scopus for publications written in English (2020 to April 26, 2022) was conducted. Two authors searched for and screened publications and three others extracted and collated data. These are reported following the Preferred Reporting Items of Systematic reviews and Meta-Analyses extension for Scoping Reviews. Of 1169 hits, 9 publications were included in the review. The results are thematized as "Psychological and social aspects" and "Nutritional aspects," each with the subsections "Experiences" and "Behavioral responses." A great variety of food-related problems, nutritional and mental health effects, and implications for social life are identified. People affected by chemosensory dysfunctions following COVID-19 suffer, as evident both in stories from qualitative studies and in measurements of quality of life. The results impact all professions who are and may come to be involved in treating these patients, such as nurses, physicians, dietitians, and psychologists. With more knowledge about the dysfunctions' manifestation, duration, and impact on everyday life, multiprofessional teams need to collaborate in supporting patients medically, psychosocially, and nutritionally.

SMART Pharmacists Serving the New Needs of the Post-COVID Patients, Leaving No-One Behind

This study aims to demonstrate the improvements in clinical symptoms in patients with post-COVID syndrome after a community pharmacy-based intervention in Serbia. The Pharmaceutical Chamber of Serbia ("Chamber") invited pharmacists to deliver post-COVID patient care counselling, supported by the SMART Pharmacist Program, offering education and guidance. Present symptoms, duration and patient self-reported severity of symptoms on a scale of 1-5 on the first visit were recorded. After the counselling and proposed self-medication treatment, the time of the follow-up visit and the severity of the recorded symptoms were also recorded. The prospective data collection lasted from December 2021 to September 2022. In total, 871 patients with post-COVID symptoms were included in the study, served by 53 pharmacists. The most frequently reported post-COVID symptoms coincided with the literature, mostly related to the respiratory system (51.2%), immunity status (32.2%), fatigue and exhaustion (30.7%), skin, hair and nails (27.4%) and cognitive functions (27.9%). A total of 26.5% of patients were referred to their family physician (general practitioner), and 69.5% returned to the pharmacist for a follow-up visit. On the first visit, the median severity of patients' symptoms was three, while on the second visit it dropped to one. The pharmacists' intervention led to a significant improvement in the post-COVID patients' condition.

[Evidence map on post-acute COVID-19 sequelae and rehabilitation: Update as of July 2022Mapa de evidencia sobre las secuelas y la rehabilitación tras la COVID-19 aguda: versión actualizada en julio del 2022]

Objective

To update the evidence map on the effects of interventions for post-acute COVID-19 rehabilitation.

Method

The search scope was defined according to the population (patients with symptomatic COVID-19 and post-acute COVID sequelae), the context (interventions for rehabilitation), and the type of study (systematic reviews, rapid reviews, scoping reviews or overviews of reviews). Following a search in PubMed and the Virtual Health Library, two independent authors selected the articles for review. The map was updated on July 27, 2022, using the same procedures employed in the initial review.

Results

The initial evidence map included 22 studies (four systematic reviews, four rapid reviews, four reviews of case reports, one scoping review, and nine systematic review protocols). In the present update, an additional 10 studies were included. The analysis revealed four groups of interventions (multimodal, therapeutic, complementary, and pharmacological) and seven groups of outcomes (pathological conditions, diseases/respiratory disorders, pain, physiological and metabolic markers, mental health/quality of life, sensory function, and mortality), totaling 166 associations between interventions and outcomes. The highest number of associations was observed for complementary therapies (n = 94). Among the outcomes, the highest number of associations was observed for physiological and metabolic markers, pathological conditions, and mental health/quality of life (44, 41, and 35 associations respectively).

Conclusions

The map update involved the analysis of 69 associations, most notably exercise (isolated, multicomponent, or multimodal intervention), with 23 positive and four potentially positive effects) and pharmacologic and complementary therapies for sensorial functions (15 associations). The high number of systematic review protocols indicates that the literature is still incipient.

The Effect of Traditional Chinese Medicine on Postviral Olfactory Dysfunction: A Systematic Review and Meta-Analysis

Objective

The aim of this study is to evaluate the efficacy and safety of traditional Chinese medicine (TCM) for postviral olfactory dysfunction (PVOD).

Methods

PubMed, EMBASE, Cochrane Central Register of Controlled Trials, China Network Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), Chinese Biomedical and Medical (CBM) Database, and Wanfang Database were electronically searched from their inception to July 25, 2022. Two authors independently performed study selection, data extraction, and quality assessment to ensure systematic quality evaluation. Randomized controlled trials (RCTs) comparing TCM with olfactory training and/or drug therapy (OTDT) were included. The outcomes were the effective rate, QOD-P, TDI score, UPSIT score, and adverse effects. Cochrane RoB was the guideline used to evaluate the methodological quality of the included trials. RevMan 5.3 software was used for statistical analysis.

Results

A total of 6 RCTs involving 467 patients with PVOD were selected. Compared with OTDT, TCM plus OTDT decreased QOD-P (MD = -1.73, 95% CI (-2.40, -1.06), P < 0.0001) but did not increase the effective rate (T&T) (RR = 1.28, 95% CI (0.86, 1.90), P=0.22, I ² = 61%). Compared with no treatment, TCM seemed to increase the treatment success rate (UPSIT) (RR = 3.17, 95% CI (1.78, 5.65), P < 0.0001, I ² = 0%), but there was no statistically significant difference in improving the UPSIT score (MD = 3.44, 95% CI (-1.36, 8.24), P=0.16). Compared with drug therapy, TCM plus drug therapy appeared to increase the effective rate (ΔVAS) (RR = 2.36, 95% CI (1.41, 3.94), I ² = 0%), but there was no statistically significant difference in improving the TDI score (MD = 2.10, 95% CI (-1.99, 6.19), P=0.31). No significant differences in adverse reactions were reported between TCM and OTDT.

Conclusion

TCM may be an effective treatment for PVOD. With a lack of high-quality RCTs, further large-scale and high-quality RCTs are still warranted.

Platelet-rich plasma injection in the olfactory clefts of COVID-19 patients with long-term olfactory dysfunction

OBJECTIVE

To investigate safety, feasibility, and effectiveness of platelet-rich plasma (PRP) injection into the olfactory clefts of COVID-19 patients with persistent olfactory dysfunction (OD).

METHODS

From March 2022 to July 2022, COVID-19 patients with persistent OD were consecutively recruited to benefit from PRP injection into the olfactory clefts. Patient pain, annoyance, time of procedure, and adverse events were evaluated. Olfactory function was evaluated at baseline and 2-month post-injection with the olfactory disorder questionnaire (ODQ) and threshold, discrimination, and identification (TDI) test.

RESULTS

Eighty-seven patients with anosmia (N = 30), hyposmia (N = 40), or parosmia (N = 17) with a mean OD duration of 15.7 months completed the evaluations. The PRP injection was successfully performed in all patients with a mean procedure time of 18.4 ± 3.4 min. The adverse events included transient epistaxis (N = 31), parosmia related to xylocaine spray (N = 10), and vasovagal episode (N = 2). The injection procedure was evaluated as somewhat or moderately painful by 41 (47%) and 22 (25%) patients, respectively. Thirty-seven patients were assessed after 2 months post-injection. The mean ODQ and TDI scores significantly improved from baseline to 2-month post-injection (p < 0.01). The olfactory improvement occurred after a mean of 3.6 ± 1.9 weeks.

CONCLUSION

The injection of PRP into the olfactory clefts is safe and associated with adequate patient-reported outcomes. The findings of this preliminary study suggest possible efficacy on subjective and psychophysical evaluations, but future randomized controlled studies are needed to determine the superiority of PRP injection over placebo.

Insight into the mechanisms of olfactory dysfunction by COVID-19

One of the unique symptoms of COVID-19 is chemosensory dysfunction. Almost three years since the beginning of the pandemic of COVID-19, there have been many studies on the symptoms, progress, and possible causes, and also studies on methods that may facilitate recovery of the senses. Studies have shown that some people recover their senses even within a couple of weeks whereas there are other patients that fail to recover chemosensory functions fully for several months and some never fully recover. Here we summarize the symptoms and the progress, and then review the papers on the causation as well as the treatments that may help facilitate the recovery of the symptoms. Depending on the differences in the levels of severity and the locations where the main pathological venues are, what is most effective in facilitating recovery can vary largely across patients and thus may require individualized strategies for each patient. The goal of this paper is to provide some thoughts on these choices depending on the differences in the causes and severity.

Efficacy and safety of acupuncture in the treatment of the sequela of olfactory disorders after infection with COVID-19: A protocol for systematic review and meta analysis

BACKGROUND

From the end of 2019 to now, coronavirus disease 2019 (COVID-19) has put enormous strain on the world's health systems. As a characteristic sign of COVID-19 patient, olfactory dysfunction (OD) poses considerable problems for patients. In China, acupuncture has been widely used to treat OD caused by COVID-19, but there is still a lack of evidence-based medical evaluation. This study was designed to evaluate the effectiveness and safety of acupuncture for the treatment of COVID-19 OD.

METHODS

According to the retrieval strategies, randomized controlled trials on the acupuncture for COVID-19 OD were obtained from Cochrane Central Register of Controlled Trials, Embase, PubMed, Web of Science, the Chinese National Knowledge Infrastructure, the Chinese Biomedical Literature Database, the Chinese Scientific Journal Database and the Wanfang Database, regardless of publication date, or language. Studies were screened based on inclusion and exclusion criteria, and the Cochrane risk bias assessment tool was used to evaluate the quality of the studies. The meta-analysis was performed using Review Manager (RevMan 5.3) and STATA 14.2 software. Ultimately, the evidentiary grade for the results will be evaluated.

RESULTS

The results of this meta-analysis will be submitted to a peer-reviewed journal for publication.

CONCLUSION

This study will provide up-to-date summary proof for evaluating the effectiveness and safety of acupuncture for COVID-19 OD.