Effectiveness and safety of PRP on persistent olfactory dysfunction related to COVID-19

Treatment of COVID-19 Associated Olfactory Dysfunction: A Systematic Review

PURPOSE OF REVIEW

COVID -19 associated olfactory dysfunction is widespread, yet effective treatment strategies remain unclear. This article aims to provide a comprehensive systematic review of therapeutic approaches and offers evidence-based recommendations for their clinical application.

RECENT FINDINGS

A living Cochrane review, with rigorous inclusion criteria, has so far included 2 studies with a low certainty of evidence. In this systematic review we list clinical data of 36 randomised controlled trials (RCTs) and non-randomised studies published between Jan 1, 2020 and Nov 19, 2023 regarding treatment options for COVID-19 associated olfactory dysfunction. Nine treatment groups were analysed, including olfactory training, local and systemic corticosteroids, platelet-rich plasma (PRP), calcium chelators, vitamin supplements including palmitoylethanolamide with luteolin, insulin, gabapentin and cerebrolysin. Primary objective was the effect of the studied treatments on the delta olfactory function score (OFS) for objective/psychophysical testing. Treatments such as PRP and calcium chelators demonstrated significant improvements on OFS, whereas olfactory training and corticosteroids did not show notable efficacy for COVID-19 associated olfactory dysfunction.

Polyunsaturated Fatty Acids as Potential Treatments for COVID-19-Induced Anosmia

Some individuals with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) experience anosmia, or loss of smell. Although the prevalence of anosmia has decreased with the emergence of the Omicron variant, it remains a significant concern. This review examines the potential role of polyunsaturated fatty acids (PUFAs), particularly omega-3 PUFAs, in treating COVID-19-induced anosmia by focusing on the underlying mechanisms of the condition. Omega-3 PUFAs are known for their anti-inflammatory, neuroprotective, and neurotransmission-enhancing properties, which could potentially aid in olfactory recovery. However, study findings are inconsistent. For instance, a placebo-controlled randomized clinical trial found no significant effect of omega-3 PUFA supplementation on olfactory recovery in patients with COVID-19-induced anosmia. These mixed results highlight the limitations of existing research, including small sample sizes, lack of placebo controls, short follow-up periods, and combined treatments. Therefore, more rigorous, large-scale studies are urgently needed to definitively assess the therapeutic potential of omega-3 PUFAs for olfactory dysfunction. Further research is also crucial to explore the broader role of PUFAs in managing viral infections and promoting sensory recovery.

Short-term efficacy of platelet-rich plasma in the treatment of persistent olfactory dysfunction: systematic review and meta-analysis

PURPOSE

To assess the short-term effects of topical platelet-rich plasma (PRP) injection on persistent refractory olfactory dysfunction.

METHODS

A comprehensive literature search of the PubMed, SCOPUS, EMBASE, Web of Science, Google Scholar, and Cochrane databases was conducted for articles up to November 2023. The search focused on studies that compared the amelioration of olfactory dysfunction between a topical PRP treatment cohort and a control group (receiving either placebo or no treatment), along with pre- and post-treatment comparisons. Subgroup analysis of the evaluation of olfactory function was also performed.

RESULTS

The improvement in olfactory scores 1-3 months post-treatment (standardized mean difference = 1.5354 [95% confidence interval: 0.7992; 2.2716], I2 = 83.8%) was greater in the treatment group than in the control group. In the treatment group, PRP increased the threshold, discrimination, and identification (TDI) score for Sniffin' Sticks by > 5.5 (minimum clinically significant difference; mean difference = 6.1789 [3.9788; 8.3789], I2 = 0.0%), indicating clinically significant improvement based on verified examinations. The rate of significant improvement among patients was 0.6683 [0.5833; 0.7436] after treatment. All TDI subdomains were significantly and similarly improved after treatment.

CONCLUSION

This meta-analysis suggests that injection of PRP into the olfactory fissure or surrounding mucosal areas is an effective treatment for persistent refractory olfactory dysfunction in the short term.

Long-term olfactory loss post-COVID-19: Pathobiology and potential therapeutic strategies

An acute loss of smell emerged as a striking symptom present in roughly half of the people infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus in the early phases of the COVID-19 pandemic. In most COVID-19 patients, olfaction recovers over the course of a few weeks. However, a lasting partial or complete loss of smell, often associated with distorted olfactory perceptions termed parosmia, has emerged as a widespread problem impacting at least 5%-10% of those who experience anosmia due to COVID-19. Our inability to offer effective therapies to this hyposmic or anosmic population, comprising millions of patients, highlights an enormous unmet need for the medical system. Here, we summarize the current understanding of the pathobiology causing acute olfactory loss due to SARS-CoV-2 infection, focusing on how the virus interacts with the peripheral olfactory system, a major site of viral infection. We also explore the problem of long-COVID olfactory dysfunction, which may accompany other persistent systemic disorders collectively termed postacute sequelae of COVID-19. Specifically, we discuss an emerging model focused on unresolved immune cell activity driving ongoing dysfunction. Finally, we review current and future therapeutic approaches aimed at restoring olfactory function.

Injection of Platelet Rich Plasma in the Olfactory Cleft for COVID-19 Patients With Persistent Olfactory Dysfunction: Description of the Technique

In this paper, we described technique of platelet rich plasma injection into the olfactory cleft in a 22-year-old female with 24-month post-COVID-19 anosmia. The technique starts with the blood extraction and the isolation of PRP through a 10-min centrifugation. The supernatant was injected in nasal regions after a local anesthesia through a 0° rigid optic. Several points of .2-.5 mL were performed in the nasal septum in regard of the head of the middle turbine and in the head of the middle turbine in both sides. The baseline threshold, discrimination, and identification scores were 1, 8, and 0, and the Olfactory Disorder Questionnaire score was 51, respectively. The injection of PRP in olfactory cleft was done without complication and mild pain. The patient perception of recovery of smell sense occurred at 3-week post-injection. From this time, the smell sense progressively improved to the 2-month consultation. At 2-month post-injection, the TDI scores reached 16, 16, and 16 (48), while the Olfactory Disorder Questionnaire was 73. The injection of PRP into the olfactory cleft appears to be a safe and easiness new approach that may improve the recovery of smell sense. Future controlled studies are needed.

Platelet-Rich Plasma (PRP) in the Treatment of Long COVID Olfactory Disorders: A Comprehensive Review

Background: Long COVID has brought numerous challenges to healthcare, with olfactory dysfunction (OD) being a particularly distressing outcome for many patients. The persistent loss of smell significantly diminishes the affected individual's quality of life. Recent attention has been drawn to the potential of platelet-rich plasma (PRP) therapy as a treatment for OD. This comprehensive review aims to evaluate the effectiveness of PRP therapy in ameliorating OD, especially when associated with long-term COVID-19. Methods: We executed a comprehensive search of the literature, encompassing clinical trials and observational studies that utilized PRP in treating OD limited to COVID-19. We retrieved and comprehensively discussed data such as design, participant demographics, and reported outcomes, focusing on the efficacy and safety of PRP therapy for OD in COVID-19 patients. Results: Our comprehensive analysis interestingly found promising perspectives for PRP in OD following COVID-19 infection. The collective data indicate that PRP therapy contributed to a significant improvement in olfactory function after COVID-19 infection. Conclusions: The evidence amassed suggests that PRP is a promising and safe therapeutic option for OD, including cases attributable to Long COVID-19. The observed uniform enhancement of olfactory function in patients receiving PRP highlights the necessity for well-designed, controlled trials. Such studies would help to refine treatment protocols and more definitively ascertain the efficacy of PRP in a broader, more varied patient cohort.

Effect of intranasal administration of concentrated growth factors on regeneration of the olfactory epithelium in an olfactory dysfunction-induced rat model

OBJECTIVE

The development of treatments that promote the regenerative capacity of the olfactory epithelium (OE) is desirable. This study aimed to evaluate the effects of intranasal administration of concentrated growth factors (CGFs) in a rat model of olfactory dysfunction.

STUDY DESIGN

Animal study.

METHODS

Nineteen male rats were used. Fourteen olfactory dysfunction models were created by intraperitoneal administration of 3-methylindole. We randomly divided the rats from the olfactory dysfunction model after 1 week into the CGF or saline group; CGFs were administered to seven animals and saline to seven animals. Behavioral assessments using the avoidance test were conducted until day 28 after CGF/saline administration. On day 28, histological evaluation was conducted to determine olfactory epithelial thickness and the olfactory marker protein (OMP)-positive cell count. Five animals were intraperitoneally injected with saline as the control group.

RESULTS

The avoidance rate remained decreased until 28 days after CGF/saline administration, and there was no significant difference between the two groups. Olfactory epithelial thicknesses on day 28 were 38.64 ± 3.17 μm and 32.84 ± 4.50 μm in the CGF and saline groups, respectively. OE thickness was significantly thicker in the CGF group than in the saline group (P = 0.013). The numbers of OMP-positive cells were 40.29 ± 9.77/1.0 × 104 μm2 and 31.00 ± 3.69/1.0 × 104 μm2 in the CGF and saline groups, respectively. The number of OMP+ cells in the CGF group was significantly increased compared with that in the saline group (P = 0.009). Both groups showed no improvement compared with the control group (OE thickness: 54.08 ± 3.36 μm; OMP+ cell count: 56.90 ± 9.91/1.0 × 104 μm2).

CONCLUSIONS

The CGF group showed improved olfactory epithelial thickness and OMP-positive cell numbers compared with that in the saline group.

Platelet-Rich Plasma for Patients with Olfactory Dysfunction: Myth or Reality? A Systematic Review

BACKGROUND

With promising outcomes, platelet-rich plasma (PRP) has recently been suggested as a treatment for olfactory dysfunction (OD).

METHODS

Clinical studies utilizing PRP in OD caused by COVID-19, trauma, anesthetic exposure, viral infection, and chronic rhinosinusitis were included in a systematic review.

RESULTS

Ten clinical studies were qualitatively analyzed. Six of these studies used the PRP for OD caused by COVID-19, one on OD after functional endoscopic sinus surgery, and three on post-infectious or post-trauma OD. The population included 531 patients, ranging in age from 15 to 63.

CONCLUSION

The use of PRP may be a risk-free and efficient therapeutic option with very encouraging outcomes. Indeed, it enhances olfactory perception in patients who not only exhibit COVID-19 infection aftereffects, but also in those who have lost their sense of smell due to trauma, rhinosinusitis, rhinitis, or even surgery. To evaluate the PRP's therapeutic benefits in OD patients and to compare the efficacy of different therapeutic protocols with regard to treatment schedules, there is an urgent need for focused controlled trials.

Effectiveness of Platelet-Rich Plasma for COVID-19-Related Olfactory Dysfunction: A Controlled Study

OBJECTIVE

To investigate the effectiveness of platelet-rich plasma (PRP) injection into the olfactory clefts of coronavirus disease 2019 (COVID-19) patients with persistent olfactory dysfunction (OD).

STUDY DESIGN

Controlled study.

SETTING

Multicenter study.

METHODS

From March 2022 to November 2022, COVID-19 patients with persistent OD were recruited from three European hospitals to undergo PRP injections into the olfactory clefts. Olfactory function was evaluated at baseline and 10 weeks postinjection with the Olfactory Disorder Questionnaire (ODQ) and threshold, discrimination, and identification (TDI) test. Data were compared with a control group of untreated patients.

RESULTS

Eighty-one patients who underwent PRP injection and 78 controls were included. Sixty-five PRP patients (80.3%) experienced subjective smell improvement after a mean duration of 3.4 ± 1.9 weeks. The parosmia, life quality statement, and ODQ sub- and total scores significantly decreased from pre- to 10-week postinjection in the PRP group. The TDI sub- and total scores significantly increased 10 weeks postinjection. In controls, the ODQ score did not change over time, while the discrimination, identification, and total TDI scores significantly increase after 10 weeks of follow-up. The 10-week TDI and ODQ scores were significantly better in the PRP group compared with the controls.

CONCLUSION

Patients who underwent PRP injection reported better 10-week subjective and objective smell outcomes than controls. Future randomized-controlled studies using saline injection into the olfactory cleft of controls are needed to determine the superiority of PRP over placebo.

[Persistent olfactory impairment after COVID-19-recommendations of the Working Group on Olfactology and Gustology of the German Society of Oto-rhino-laryngology, Head and Neck Surgery]

This article does not intend to comprehensively review the existing literature on coronavirus disease 2019 (COVID-19)-associated smell disorders, but aims to summarize scientific evidence for otorhinolaryngological practice and provide recommendations for diagnosis and treatment of persistent smell disorders following COVID-19.

Effectiveness of platelet-rich plasma on post-COVID chronic olfactory dysfunction

OBJECTIVE

The aim of this study was to investigate the efficacy of platelet-rich plasma injection on the olfactory cleft of patients with post-COVID olfactory dysfunction lasting over 1 year, who were unresponsive to common treatments.

METHODS

Patients over 18 years of age with post-COVID olfactory dysfunction over 1 year whose complaints did not improve with intranasal steroids and D-panthenol/vitamin A combination nasal sprays with olfactory rehabilitation training for 1 month were prospectively collected and randomized into two groups: intranasal platelet-rich plasma group and control group. At the end of 1 month, Connecticut Chemosensory Clinical Research Center olfaction test scores of smell detection threshold and smell identification test were compared accordingly.

RESULTS

A total of 25 patients were randomized into platelet-rich plasma (n=12) and control (n=13) groups. In the platelet-rich plasma group, the mean smell detection threshold score increased from 5.63 (SD 0.68) to 6.46 (SD 0.45), and the mean smell identification test score increased from 11.42 (SD 1.17) to 15.17 (SD 0.39). In the control group, the mean smell detection threshold score changed from 5.69 (SD 0.66) to 5.77 (SD 0.70), and the mean smell identification test score changed from 11.20 (SD 1.12) to 11.85 (SD 1.57). Post-hoc analysis revealed that similar mean smell detection threshold (mean difference 0.07; p=0.994) and smell identification test (mean difference -0.50; p=0.703) scores were transformed into a significant difference between groups (smell detection threshold mean difference 0.69; p=0.037; smell identification test mean difference 3.32; p<0.001).

CONCLUSION

At the end of the first month, there was a significant improvement in olfactory threshold values in the platelet-rich plasma group compared to the control group. No side effect or adverse event related to platelet-rich plasma injection was observed.

Assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms

Purpose of review

To provide a detailed overview of the assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms.

Recent findings

COVID-19-related olfactory dysfunction can have a detrimental impact to the quality of life of patients. Prior to the COVID-19 pandemic, olfactory and taste disorders were a common but under-rated, under-researched and under-treated sensory loss. The pandemic has exacerbated the current unmet need for accessing good healthcare for patients living with olfactory disorders and other symptoms secondary to COVID-19. This review thus explores the associations that COVID-19 has with psychological, neuropsychiatric, and cognitive symptoms, and provide a framework and rationale for the assessment of patients presenting with COVID-19 olfactory dysfunction.

Summary

Acute COVID-19 infection and long COVID is not solely a disease of the respiratory and vascular systems. These two conditions have strong associations with psychological, neuropsychiatric, and cognitive symptoms. A systematic approach with history taking and examination particularly with nasal endoscopy can determine the impact that this has on the patient. Specific olfactory disorder questionnaires can demonstrate the impact on quality of life, while psychophysical testing can objectively assess and monitor olfaction over time. The role of cross-sectional imaging is not yet described for COVID-19-related olfactory dysfunction. Management options are limited to conservative adjunctive measures, with some medical therapies described.

The use of Platelet rich Plasma in COVID-19 Induced Olfactory Dysfunction: Systematic Review

PURPOSE

Different modalities of treatment have been suggested in the treatment for post COVID-19 olfactory dysfunction (OD). Starting with lifestyle modification, smoking cessation, for example, was shown to improve the symptoms for patients with OD. Intranasal and oral corticosteroids have been described in the literature for the treatment of OD. In this review, we are looking at a novel intervention using platelet-rich plasma injection into the nasal cleft for treatment of post COVID-19 infection olfactory dysfunction.

METHODS

A literature search was done using the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) 2020 Guidelines, the databases of PMC, Medline, CINAHL, Wiley online library were searched from their year of inception until February 2023. Search terms were used and included a combination of the following keywords; "platelet-rich plasma", "platelet rich plasma", "PRP", "Anosmia", "olfactory dysfunction" and "COVID".

RESULTS

The four studies in this review included a total of 238 adult patients who presented with olfactory dysfunction. The studies were heterogenic in terms of follow up period which was not long enough through all the included studies. Additionally, different protocol of injecting was seen in different studies.

CONCLUSION

Injecting PRP for treatment of COVID-19 induced olfactory dysfunction is a safe technique with what seems like promising initial results with low complication rate. However, there are not enough studies assessing its effectiveness compared to other treatment modalities. Further randomized controlled trials with shared protocol are needed to establish further understanding of its role in treatment of COVID-19 induced OD.

Post-COVID-19 Anosmia and Therapies: Stay Tuned for New Drugs to Sniff Out

Background: Anosmia is defined as the complete absence of olfactory function, which can be caused by a variety of causes, with upper respiratory tract infections being among the most frequent causes. Anosmia due to SARS-CoV-2 infection has attracted attention given its main role in symptomatology and the social impact of the pandemic. Methods: We conducted systematic research in a clinicaltrials.gov database to evaluate all active clinical trials worldwide regarding drug therapies in adult patients for anosmia following SARS-CoV-2 infection with the intention of identifying the nearby prospects to treat Anosmia. We use the following search terms: "Anosmia" AND "COVID-19" OR "SARS-CoV-2" OR "2019 novel coronavirus". Results: We found 18 active clinical trials that met our criteria: one phase 1, one phase 1-2, five phases 2, two phases 2-3, three phases 3, and six phases 4 studies were identified. The drug therapies that appear more effective and promising are PEA-LUT and Cerebrolysin. The other interesting drugs are 13-cis-retinoic acid plus aerosolized Vitamin D, dexamethasone, and corticosteroid nasal irrigation. Conclusions: COVID-19 has allowed us to highlight how much anosmia is an important and debilitating symptom for patients and, above all, to direct research to find a therapy aimed at curing the symptom, whether it derives from SARS-CoV-2 infection or other infections of the upper airways. Some of these therapies are very promising and are almost at the end of experimentation. They also provide hope in this field, which not addressed until recently.

Autologous Platelet and Extracellular Vesicle-Rich Plasma as Therapeutic Fluid: A Review

The preparation of autologous platelet and extracellular vesicle-rich plasma (PVRP) has been explored in many medical fields with the aim to benefit from its healing potential. In parallel, efforts are being invested to understand the function and dynamics of PVRP that is complex in its composition and interactions. Some clinical evidence reveals beneficial effects of PVRP, while some report that there were no effects. To optimize the preparation methods, functions and mechanisms of PVRP, its constituents should be better understood. With the intention to promote further studies of autologous therapeutic PVRP, we performed a review on some topics regarding PVRP composition, harvesting, assessment and preservation, and also on clinical experience following PVRP application in humans and animals. Besides the acknowledged actions of platelets, leukocytes and different molecules, we focus on extracellular vesicles that were found abundant in PVRP.

Therapies for COVID-19-Related Persistent Olfactory Disorders: One of the Good Fruits of the Pandemic

At the beginning of 2021, the scientific community realized the burden of COVID-19-related persistent olfactory disorders (ODs). The percentage of those infected with COVID-19 who developed severe and persistent ODs [1-3] with devastating effects on their quality of life was 5 to 40% [4,5].

Use of platelet-rich plasma for COVID-19-related olfactory loss: a randomized controlled trial

INTRODUCTION

The current study evaluated the use of platelet-rich plasma (PRP), an autologous blood product with supraphysiologic concentrations of growth factors, in the treatment of prolonged coronavirus disease 2019 (COVID-19)-related smell loss.

METHODS

This multi-institutional, randomized controlled trial recruited patients with COVID-19 who had objectively measured smell loss (University of Pennsylvania Smell Identification Test [UPSIT] ≤ 33) between 6 and 12 months. Patients were randomized to three intranasal injections of either PRP or sterile saline into their olfactory clefts. The primary outcome measure was change in Sniffin' Sticks score (threshold, discrimination, and identification [TDI]) from baseline. The secondary end point measures included responder rate (achievement of a clinically significant improvement, ≥5.5 points TDI), change in individual TDI olfaction scores, and change in subjective olfaction via a visual analog scale.

RESULTS

A total of 35 patients were recruited and 26 completed the study. PRP treatment resulted in a 3.67-point (95% CI: 0.05-7.29, p = 0.047) greater improvement in olfaction compared with the placebo group at 3 months and a higher response rate (57.1% vs 8.3%, odds ratio 12.5 [95% exact bootstrap confidence interval, 2.2-116.7]). There was a greater improvement in smell discrimination following PRP treatment compared with placebo but no difference in smell identification or threshold. There was no difference in subjective scores between PRP and placebo. No adverse effects were reported.

CONCLUSION

Olfactory function following COVID-19 can improve spontaneously after 6 months and can improve to a greater extent with PRP injection. These data build on the promise of PRP to be a safe potential treatment option for patients with COVID-19-related smell loss, and larger-powered studies will help further assess its efficacy.