Recovery Of Olfactory Function Research Articles

A prospective study of the effect of functional endoscopic sinus surgery on the recovery of olfactory function in patients with chronic rhinosinusitis with nasal polyposis

Objective:To investigate the efficacy of functional endoscopic sinus surgery（FESS） in the treatment of olfactory dysfunction in patients with chronic rhinosinusitis with nasal polyps （CRSwNP） , at the same time, it provides an evidence for the prognosis evaluation of olfaction and the clinical application of oERPs to evaluate the plasticity of olfaction cortex. Methods:From October 2021 to October 2022, 45 patients with CRSwNP who underwent FESS nine-step standardized treatment in our department were recruited as the research subjects, divided into 22 patients with eosinophilic CRSwNP（ECRS）and 23 patients with non-eosinophilic CRSwNP（nECRS）. VAS-olfactory dysfunction （VAS-OD） score, SNOT-22 olfactory score, Sniffin' Sticks test and oERPs collection and processing were performed before the operation. All items were evaluated again 3 months after the operation. Results:VAS-OD and SNOT-22 olfactory score were significantly lower in all CRSwNP patients after the operation than those before the operation[F（1, 43） =357.429, P<0.001; F（1, 43） =185.657, P<0.001], the scores of T, D, I and TDI scores in Sniffin' Sticks test were significantly higher than those before the operation[F（1, 43） =126.302, P<0.001; F（1, 43） =311.301, P<0.001; F（1, 43） =131.401, P<0.001; F（1, 43） =295.885, P<0.001]; The decrease of VAS-OD and SNOT-22 olfactory score in the ECRS group was smaller than that in the nECRS group[F（1, 43） =4.825, P=0.033; F（1, 43） =9.916, P=0.003], T, D and TDI scores were significantly lower in nECRS group than those in nECRS group[F（1, 43） =6.719, P=0.013; F（1, 43） =4.890, P=0.032; F（1, 43） =4.469, P=0.040]; There was a positive correlation between preoperative eosinophil-to-lymphocyte ratio（ELR） and SNOT-22 olfactory score and how much it changes（r=0.455, P=0.002; r=-0.414, P=0.005）, a negative correlation between T, TDI score and how much they change respectively（r=-0.431, P=0.003; r=-0.385, P=0.009; r=-0.383, P=0.010; r=-0.316, P=0.035）. The latency of P3 was significantly shorter after operation than that before operation in all CRSwNP patients[F（1, 14） =24.840, P<0.001], however, the amplitude has no significant surgical effect. Conclusion:FESS could significantly improve the olfactory function of CRSwNP patients, while changes in plasticity may occur in the olfactory cortex. In addition, the preoperative peripheral blood eosinophil granulocyte level can predict the postoperative olfactory improvement.

COVID-19 Induced Enantiopathy to Hyperosmia (P6-10.005)

<h3>Objective:</h3> Pathophysiology behind reduced olfactory ability in hyperosmic individuals. <h3>Background:</h3> COVID-19 infection as an enantiopathy to hyperosmia has not been described. <h3>Design/Methods:</h3> A 63 year-right-handed male presented with hyperosmia of 150% of normal whereby aromas appeared distorted and disgusting. Shortly, he tested positive for COVID-19 which led to a resolution of his hyperosmia. Alcohol Sniff Test scores fluctuated between zero and three (anosmia). Gradually, his smell improved from 80% and 100% of normal. However, post COVID-19 infection, it returned to 130% of normal. <h3>Results:</h3> Neurological abnormalities: Olfactory Testing: Odor Discrimination Memory Test: Total 7/12 (hyposmia). Bilateral Olfactory Threshold Testing to Phenylethyl Alcohol: 3 (hyposmia). Taste Threshold and Suprathreshold Testing: Mild hypogeusia to Sucrose. Ageusia to Hydrochloric acid, urea and propothiocarbamide. Olfactometer Identification Testing: Left nostril: 10 (anosmia), Right nostril: 8 (anosmia). <h3>Conclusions:</h3> The mechanism whereby COVID-19 acts to reduce olfactory ability in normosmic individuals has been postulated as viral involvement of olfactory nerve at olfactory bulb (Lechien, 2020), pathology of sustentacular cells (Zhang, 2021), olfactory receptor site destruction (Xu, 2022) vasculopathy/arteriopathy of cranial nerve or central connections of olfactory nerve (Parry, 2020) or inflammatory response induced destruction of lamina propria and olfactory nerve apoptosis (Lechien, 2020). The same may have incited a reduced olfaction in hyperosmic individuals-such may be under grouped as understanding the pathophysiology of this subject’s hyperosmia. Perceived hyperosmia is often objectively hyposmic: pathology of inhibiting the inhibitory olfactory discharges that result in enhancement of perceived odor (Kalita, 2022). Elimination of hyperosmia reduces functionality of remaining normosmic neurons which then became relatively hyposmic, but were perceived as normal due to lack of the inhibitory factors. Recovery of hyperosmia upon recovery of olfactory function from COVID-19 would be consistent with such a postulation. Of those with preexisting chemosensory dysfunction, query as to impact of COVID-19 on remaining sensory function is warranted. <b>Disclosure:</b> Mrs. Kalita has nothing to disclose. Miss Birwatkar has nothing to disclose. Dr. Hirsch has nothing to disclose.

Olfactory dysfunction in type II diabetes: Therapeutic options and lessons learned from other etiologies – A scoping review

IntroductionOlfactory dysfunction (OD) is highly prevalent amongst type 2 diabetes mellitus (DM2) patients and has many associated health risks. For example, OD can lead to poor nutrition, safety issues related to diminished hazard detection, and increased mortality rates. While limited research exists about therapeutics for DM2-associated OD, recovery of olfactory function is better studied in other pathologic states. The objectives of this scoping review are to synthesize the existing data on interventions for DM2-associated OD and present the evidence for therapies that have been utilized for non-DM2-associated causes of OD. Additionally, the potential therapeutic opportunities for patients with DM2 are explored. MethodsA scoping review was conducted with a medical librarian to identify studies investigating treatments of DM2-related OD. 6 databases were searched (Embase, CINAHL, the Cochrane Library, Google Scholar, OVID Medline, and Web of Science). Studies were eligible if the primary discussion involved treatment of olfactory deficits in the context of DM2. All publication dates were included, and studies published in languages other than English were excluded. Results3631 articles were identified; 3 articles met inclusion criteria and underwent full text review. Hyperbaric oxygen (HBO), the DPP-4 inhibitor Linagliptin and the GLP-1 agonists Exenatide and Liraglutide are the only therapeutics that have been used in the context of DM2. Only HBO and GLP-1 agonists produced statistically significant improvements in olfactory identification. The literature regarding non-DM2-associated OD supports interventions such as olfactory training, dietary supplements, and intranasal insulin. Specifically, olfactory training was very effective in many contexts such as post-viral and traumatic OD while being affordable and non-invasive. ConclusionThis scoping review of olfactory rehabilitation options for DM2-induced OD demonstrates a paucity of prospective investigations of plausible therapeutics. Additionally, treatments for OD related to non-DM2-associated etiologies, such as olfactory training, are well-studied, efficacious, and should be investigated in the context of DM2. Future investigation has the potential to enhance the quality of clinical intervention for OD and improve short- and long-term outcomes for DM2 patients.

YAP signaling in horizontal basal cells promotes the regeneration of olfactory epithelium after injury.

SummaryThe horizontal basal cells (HBCs) of olfactory epithelium (OE) serve as reservoirs for stem cells during OE regeneration, through proliferation and differentiation, which is important in recovery of olfactory function. However, the molecular mechanism of regulation of HBC proliferation and differentiation after injury remains unclear. Here, we found that yes-associated protein (YAP) was upregulated and activated in HBCs after OE injury. Deletion of YAP in HBCs led to impairment in OE regeneration and functional recovery of olfaction after injury. Mechanically, YAP was activated by S1P/S1PR2 signaling, thereby promoting the proliferation of HBCs and OE regeneration after injury. Finally, activation of YAP signaling enhanced the proliferation of HBCs and improved functional recovery of olfaction after OE injury or in Alzheimer's disease model mice. Taken together, these results reveal an S1P/S1PR2/YAP pathway in OE regeneration in response to injury, providing a promising therapeutic strategy for OE injury.

Evaluation of olfactory dysfunction persistence after COVID-19: a prospective study.

Alterations of the olfactory function in patients affected by COVID-19 often have an early onset and a variable duration ranging from a few weeks to months. The aim of this study was to evaluate olfactory dysfunction persistence after recovery from COVID-19, and potential related clinical-demographic conditions. A total of 76 patients recovered from COVID-19 from at least 20 days with olfactory dysfunction during the infection were included in the study. For the subjective evaluation of olfactory function, a visual analogic scale (VAS) was used. The objective evaluation was performed with the use of the Sniffin' Sticks test. Objective assessment of olfactory function revealed that 48 (63.16%) patients were found to be normosmic (TDI ≥ 30.5), 26 (34.21%) were hyposmic (TDI from 30.5 to 16.5) and two (2.63%) were anosmic (TDI ≤ 16.5) at the time of the evaluation. These results did not show a significant difference between subjective and objective tests (p = 0.45). Most patients recovered their sense of smell within the first two months after recovery while a portion (22.2%) still experienced olfactory alterations 4-6 months after SARS-CoV-2 infection. Patients who had not recovered their sense of smell had a significantly longer period of SARS-CoV-2 positivity compared to patients that fully recovered (36.07 ± 7.78 days vs. 29 ± 7.89 days; p = 0.04). Our results suggest that the duration of the infection negatively correlates with the recovery of olfactory function.

Efficacy of Platelet-Rich Plasma as an Adjuvant Therapy to Endoscopic Sinus Surgery in Anosmia Patients with Sinonasal Polyposis: A Randomized Controlled Clinical Trial.

Background: Treatment of patients with anosmia is a major therapeutic challenge. The present study evaluated the efficacy of platelet-rich plasma (PRP) in the treatment of anosmia in patients with sinonasal polyposis. Methods:In the present clinical trial, atotal of 48 patients with sinonasal polyposis with theIran Smell Identification Test (I-SIT) score of <6 who completed the medical treatment and were observed 3 months after the sinus surgery were included and randomly divided in to 2groups. After endoscopic sinus surgery, the intranasal injection of 1 mL PRP and normal saline was performed in the olfactory region in the intervention and control groups, respectively. Odor function was assessed using the I-SIT at the baseline and at the end of the studyby an independent samples ttest. Results: Based on the findings of the present study, the I-SIT improved in both groups during the follow-up, as it reached from 2.63 ± 2.63 to 5.85 ± 2.46 after oral steroid administration and 18.93 ± 1.14 after surgery in the intervention group and from the baseline of 2.10 ± 2.83 to 5.62 ± 2.99 after receiving standard medical treatment and 18.43 ± 1.36in the control groupafter surgery. Although this improvement was significant in both groups in either time interval (all with p<0.001), there was no significant difference between the 2groups in terms of changes in the I-SIT score (p=0.802). Conclusion: According to the current study, PRP injection showed no short-term effect on the recovery of olfactory function in patients with sinonasal polyposis.

Effects of Age on Recovery of Olfactory Function After Endoscopic Sinus Surgery and Related Risk Factors.

To study the effects of age on the olfactory function recovery of chronic rhinosinusitis patients after endoscopic sinus surgery and related risk factors. A total of 176 chronic rhinosinusitis (CRS) patients enrolled from February 2017 to October 2019 were divided into child, youth, middle-aged, and elderly groups. Their baseline data, T&T olfactory test score, visual analogue scale (VAS) olfactory score, sinus computed tomography (CT) Lund-Mackay score, and Lund-Kennedy score were compared. Based on postoperative olfactory function, they were divided into good and poor improvement groups. Complication with nasal polyps, allergic rhinitis history, and sinus surgery history had significant differences among patients of different ages (P < .05). Three months after surgery, T&T olfactory, VAS olfactory, Lund-Mackay, and Lund-Kennedy scores all rose with increasing age, with significant differences between any 2 groups (P < .05). The improvement of postoperative olfactory function became poorer with aging (P < .05). T&T and VAS olfactory scores had significant positive correlations with Lund-Mackay and Lund-Kennedy scores (P < .001). Age, preoperative Lund-Mackay and Lund-Kennedy scores, complication with nasal polyps, allergic rhinitis history, sinus surgery history, and postoperative complications were risk factors for the poor improvement of postoperative olfactory function. Doctor-directed treatment was a protective factor for good improvement. The improvement of olfactory function of CRS patients after endoscopic sinus surgery declines with aging. Age, preoperative Lund-Mackay and Lund-Kennedy scores, complication with nasal polyps, allergic rhinitis history, sinus surgery history, and postoperative complications are risk factors for the poor improvement of postoperative olfactory function. Doctor-directed treatment is a protective factor for good improvement.

Reorganizing brain structure through olfactory training in post-traumatic smell impairment: An MRI study

Purpose and backgroundPost-traumatic olfactory dysfunction (PTOD), mostly caused by head injury, is thought to be associated with changes in the structure and function of the brain olfactory processing areas. Training and repeated exposure to odorants lead to enhanced olfactory capability. This study investigated the effects of a 16-weeks olfactory training (OT) on olfactory function and brain structure. MethodsTwenty-five patients with PTOD were randomly divided in three groups: (1) 9 control patients who did not receive any training, (2) 9 patients underwent classical OT by 4 fixed odors, and (3) 7 patients underwent modified OT coming across 4 sets of 4 different odors sequentially. Before and after the training period, all patients performed olfactory function tests and structural magnetic resonance imaging (MRI). Sniffin’ Sticks test was used to assess olfactory function. MRI data were analyzed using voxel-based morphometry and surface-based morphometry. ResultsBoth trained groups showed a considerable recovery of olfactory function, especially in odor identification. MRI data analysis revealed that the classical OT leads to increases in cortical thickness/density of several brain regions, including the right superior and middle frontal gyrus, and bilateral cerebellums. In addition, the modified OT yielded a lower extent of cortical measures in the right orbital frontal cortex and right insular. Following modified OT, a positive correlation was observed between the odor identification and the right orbital frontal cortex. ConclusionBoth olfactory training methods can improve olfactory function and that the improvement is associated with changes in the structure of olfactory processing areas of the brain.

Recovery Over Time and Prognostic Factors in Treated Patients with Post-Infectious Olfactory Dysfunction: A Retrospective Study.

The aims of the present study were to clarify the time-course of olfactory recovery and the prognostic factors in PIOD patients treated with Toki-shakuyaku-san (TSS). A retrospective cohort study of patients with PIOD was conducted by reviewing patients' medical records. This study included patients who received TSS or a combination of TSS and zinc sulfate. Olfactory function was examined by T&T olfactometer at each 3-monthly follow-up visit. Patients with normal and mild olfactory dysfunction were excluded. Gender, age, treatment, duration of disease until the first visit and olfactory function scores of the T&T olfactometer at the first visit were analyzed as candidate clinical predictors of recovery. A total of 82 PIOD patients with ages ranging from 16 to 79 years were included. The mean duration of follow-up was 14.5 months (range 3-45 months). The number of patients with olfactory recovery increased for 24 months and the cumulative recovery rate was 77.3%. In about 60% of patients, olfactory recovery occurred within 6 months. Multivariate analysis showed that younger age (<65 years) and residual olfactory function were significantly associated with good olfactory recovery. We revealed recovery rates over time in patients with PIOD. The recovery of olfactory function often occurred during the early period (≤6 months). However, the number of patients with olfactory recovery increased for a long-term of 24 months after the first visit. Residual olfactory function and younger age were prognostic factors exactly. TSS may be a useful therapeutic agent for patients with PIOD. We believe that these results provide important information that is useful for counseling patients with PIOD.

Recovery of Olfactory Function After Excitotoxic Lesion of the Olfactory Bulbs Is Associated with Increases in Bulbar SIRT1 and SIRT4 Expressions.

Excitotoxicity consists in a cascade of intracellular events initiated by an excessive release of glutamate and hyperactivation of glutamatergic receptors that is involved in several pathologies, including traumatic brain injury and neurodegenerative diseases such as Parkinson's disease. Both disorders are a common cause of olfactory dysfunction. We previously reported a role for glutamate excitotoxicity in olfactory dysfunction showing an olfactory deficit 1week after lesion and a spontaneous recovery 2weeks after excitotoxicity lesion of the olfactory bulbs (OBs). The olfactory dysfunction recovery was associated with an increase in subventricular zone neurogenesis and an increase in the OB glomerular dopaminergic interneurons. However, the underlying molecular mechanisms involved in the OB dopaminergic differentiation and olfactory recovery are still unknown. To investigate the role of silent information regulator family proteins sirtuins (SIRTs), a family of NAD+-dependent histone deacetylases, on the olfactory function recovery, we examined the OB SIRT (SIRT1, SIRT2, and SIRT4) expressions after OB excitotoxic lesions in rodents. N-methyl-D-aspartate (NMDA) OB administration induced a decrease in the number of correct choices in the discrimination tests 1week after lesions (p < 0.01) and a spontaneous recovery of the olfactory deficit 2weeks after lesions (p < 0.01) associated with an increase in OB SIRT1 and SIRT4 expression. Our results point out for the first time the association between recovery of olfactory function and the increase in bulbar SIRT1 and SIRT4 expression suggesting a role for these SIRTs in the pathophysiology of recovery of loss of smell.

Postinfectious olfactory loss: A retrospective study on 791 patients.

Postinfectious olfactory loss is among the most common causes of olfactory impairment and has substantial negative impact on patients' quality of life. Recovery rates have been shown to spontaneously improve in most of patients, usually within 2 to 3 years. However, existing studies are limited by small sample sizes and short follow-up. We aimed to assess the prognostic factors for recovery in a large sample of 791 patients with postinfectious olfactory disorders. Retrospective cohort. We performed a retrospective analysis of 791 patients with postinfectious olfactory loss. Olfactory functions were assessed using the Sniffin' Sticks test at the first and final visits (mean follow-up = 1.94 years). Smell test scores improved over time. In particular, patient's age and the odor threshold (T), odor discrimination (D), and odor identification (I) (TDI) score at first visit were significant predictors of the extent of change. The percentage of anosmic and hyposmic patients exhibiting clinically significant improvement was 46% and 35%, respectively. This study provides new evidence within the postinfectious olfactory loss literature, shedding light on the prognostic factors and showing that recovery of olfactory function is very frequent, even many years after the infection. 4. Laryngoscope, 128:10-15, 2018.

Effects of isotretinoin on the olfactory function in patients with acne.

BackgroundIsotretinoin is a synthetic analog of vitamin A. Recent studies support a role for retinoic acid in the recovery of olfactory function following injury in mice.ObjectiveThis study aimed at determining the effect of isotretinoin on olfactory function in patients who have acne and are otherwise healthy.MethodsForty-five patients (aged 25-40 years) with acne were included in the study. All patients underwent a rhinological examination. Olfactory function was assessed by the Sniffin' Sticks Test. The test was assessed at baseline and in the third month of isotretinoin treatment.ResultsIsotretinoin improved the performance of patients in the olfactory test. The SST score increased from 8.7±1.09 to 9.5±1.19 (p<0.001), prevalence of hyposmia decreased from 40% to 24% and normosmia increased from 60% to 75% (p=0.059). The percentage of patients whose olfactory function was categorized as "good" increased from 6% to 21.3%. This increase was statistically significant (p<0.05).Study limitationsAbsence of a control group is one of the limitations of this study. Also, we did not evaluate patients with smell test after stopping isotretinoin treatment.ConclusionWe examined the effect of systemic isotretinoin on olfactory function. It can be concluded from the present investigation that isotretinoin therapy improves the sense of smell.

Recovery of Olfactory Function in Postviral Olfactory Dysfunction Patients after Acupuncture Treatment.

Introduction. The aims of this study were to assess the impact of traditional Chinese acupuncture (TCA) in postviral olfactory dysfunction (PVOD) patients who were refractory to standardized treatment and to compare the results with the impact observed in an observation group. Methods. Fifty patients who presented to the outpatient clinic with PVOD and were refractory to standardized treatment were included: 25 were treated with TCA and 25 patients were simply observed. A subjective olfactory test was performed using the University of Pennsylvania Smell Identification Test (UPSIT). The effects of TCA were compared with the results obtained in the observation group. Results. Improved olfactory function was observed in eleven patients treated with TCA compared with four patients in the observation group. This study revealed significantly improved olfactory function outcomes in patients who underwent acupuncture compared with the observation group. No significant differences in olfaction recovery were found according to age, gender, or duration of disease between the two groups; however, hyposmic patients recovered at a higher rate than anosmic patients. Conclusion. TCA may aid the treatment of PVOD patients who are refractory to drugs or other therapies.

Recovery of Olfactory Function following Pediatric Traumatic Brain Injury: A Longitudinal Follow-Up

There is increasing evidence that disruption of olfactory function after pediatric traumatic brain injury (TBI) is common. Olfactory dysfunction (OD) has been linked to significant functional implications in areas of health, safety, and quality of life, but longitudinal research investigating olfactory recovery is limited. This study aimed to investigate recovery trajectories for olfaction following pediatric TBI and explore predictors of early and late olfactory outcomes. The olfactory function of 37 children with TBI ages 8-16 years was assessed on average at 1.5, 8.0, and 18.0 months post-injury using the University of Pennsylvania Smell Identification Test. A significant improvement in olfactory performance was seen over time in those with acute OD, however, only 16% of those with the most severe OD showed recovery to normal olfactory function, with the remainder demonstrating ongoing olfactory impairment at the 18 month follow-up. Predictors of early (0-3 month) and late (18 month) olfactory outcomes varied with site of impact, a significant predictor of later olfactory performance. In summary, while there was evidence of recovery of OD over time in pediatric TBI, the majority of children with severe OD did not show any recovery. In light of limited recovery of function for more severely affected children, the importance of appropriate education and implementation of rehabilitation management strategies is highlighted.

Medical treatment of traumatic anosmia.

To study the effects of zinc and steroid in the treatment of traumatic anosmia. A prospective, randomized study. Academic medical center. Patients with a clear history of loss of smell after head injury and whose thresholds were -1 measured by the phenyl ethyl alcohol threshold test were included in this study from January 2010 to May 2013. They were randomly divided into 4 groups. Patients in group 1 were treated with zinc gluconate for a month and high-dose prednisolone with tapering for 2 weeks. Those in group 2 took only zinc gluconate, and those in group 3 took only prednisolone. Patients in group 4 did not take any medicine. All patients were followed up by phenyl ethyl alcohol threshold testing, and magnetic resonance imaging was performed to measure the volume of olfactory bulbs. Thirty-nine patients in group 1, 35 in group 2, 34 in group 3, and 37 in group 4 completed the study. The recovery of olfactory function was observed in 11 patients (28.2%) in group 1, in 9 (25.7%) in group 2, in 4 (11.8%) in group 3, and in 1 (2.7%) in group 4. The recovery rates of olfactory function of groups 1 and 2 were significantly higher than the recovery rate of group 4. The volume of olfactory bulbs was not significantly different between those with and without improved olfactory function. Our results show that zinc gluconate has a promising effect in treating traumatic anosmia.

Effects of Statins on the Recovery of Olfactory Function in a 3-Methylindole–Induced Anosmia Mouse Model

Despite the importance of olfactory function, no effective medications have been identified to treat olfactory disorders. This study was performed to evaluate the functional recovery of olfaction damaged by 3-methylindole (3MI) in a mouse model with hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins). In a randomized placebo-controlled trial, 24 healthy female BALB/c mice (aged 9-10 weeks and weighing 18-20 g each) were randomly allocated to statin-treated or control groups. Olfactory loss was induced by i.p. injections of 3MI. Atorvastatin (10 mg/kg) or normal saline was then administered per os with a gastric tube for 3 weeks. The effects of treatment were evaluated by food-finding tests and Western blot analysis. Both groups showed complete losses of olfactory function 1 week after 3MI injection. Three weeks after 3MI injection, 9 of the 12 mice in the statin-treated group (75%) passed a food-finding test, in which they were able to find the food within 3 minutes, at least two times out of three trials. However, only two mice in the control group (16.6%) passed the food-finding test, and this difference was statistically significant (p = 0.004; chi-square test). The expression level of the olfactory marker protein was also elevated in the statin-treated group (p = 0.030; Wilcoxon rank sum test). Statins are associated with recovery of olfaction after 3MI injection in a mouse model.

Effects of traditional Chinese acupuncture in post-viral olfactory dysfunction

Objective To date, recovery of olfactory function after viral infection of the upper airway cannot be achieved reliably with pharmacotherapy. The aim of this study was to evaluate the effects of traditional Chinese acupuncture (TCA) on olfactory function in patients with persistent post-viral olfactory dysfunction (PVOD). Study Design Historical cohort study. Setting University Medical Center, Department of Otorhinolaryngology. Subjects and Methods A total of 15 patients presenting to the outpatient clinic with PVOD were treated by TCA in 10 weekly, 30-minute sessions. Subjective olfactometry was performed with the Sniffin' Sticks test set. Treatment success was defined as an increase in Sniffin' Sticks test scores of at least six points. The effects of TCA, obtained with the χ 2 test, were compared with those of matched pairs suffering from PVOD who had been treated with vitamin B complex over 12 weeks. Results Eight patients treated with TCA had improved olfactory function compared with two treated with vitamin B complex. χ 2 test revealed a significantly better outcome in olfactory function in patients undergoing acupuncture compared with patients receiving vitamin B complex ( P = 0.02). Conclusion TCA possibly offers a new therapeutic regimen for post-viral dysosmia. More research in a larger case series is needed before a clearer picture will emerge.

Transplantation of Neural Stem Cells in Anosmic Mice

ObjectivesTreating olfactory dysfunction is a challenge for physicians. One of the therapeutic options could be transplantation of stem cells. In this study, neural stem cells were transplanted into anosmic mice.MethodsNeural stem cells were generated from the olfactory bulb of green fluorescent protein (GFP)-transgenic C57BL6 mice. Anosmia were induced by injection of intraperitoneal 3-methylindole. The neural stem cells were transplanted transnasally on the next day. The olfactory function was evaluated by a food-finding test once a week. The olfactory neuroepithelium was harvested for histologic examination and protein analysis at 4 weeks.ResultsTwenty-five percent (6/24) of the control mice that were not transplanted with neural stem cells survived at 4 weeks while 67% (8/12) of the transplanted mice survived (P=0.029). The food finding test showed that the transplanted mice resumed finding food at 3 weeks while the control mice resumed finding food at 4 weeks. GFP-positive cells were observed in the olfactory neuroepithelium of the transplanted mice. Western blotting revealed that the olfactory marker protein expression was significantly lower in the control mice than that in the transplanted mice.ConclusionThis study demonstrated that improvement of mouse survival was achieved and recovery of olfactory function was promoted by transnasal transplantation of neural stem cells in the anosmic mouse model. These results indicate that stem cells might be one of the future modalities for treating olfactory impairment.

A tale of two etiologies: Loss and recovery of olfactory function

A tale of two etiologies: Loss and recovery of olfactory function

Recovery of Olfactory Function Following Closed Head Injury or Infections of the Upper Respiratory Tract

To investigate the outcome of olfactory function in patients with olfactory loss following infections of the upper respiratory tract (post-URTI) or head trauma. Retrospective patient-based study. Smell and Taste Outpatient Clinic at a university hospital. A total of 361 patients (228 women, 133 men) were included. Olfactory function was assessed using the "Sniffin' Sticks" test battery, which result in a threshold, discrimination, and identification score. The mean interval between first and last visit was 14 months. In comparing the overall threshold, discrimination, and identification scores between the last and first visit, olfactory function improved in 26% of the patients whereas it decreased in 6%. The cause of olfactory impairment had a significant effect on the recovery rate of olfactory function. Within the post-URTI group (n = 262), 32% of the patients improved, but in the posttraumatic group (n = 99) only 10% improved. In patients with post-URTI olfactory loss, a negative correlation was found between age and recovery of olfactory function. In general, the factor "sex" had no significant effect on recovery of smell function. To our knowledge, the series of patients presented herein is the largest in the literature to date in which standardized testing methods were used to assess the progression of impaired olfaction. It showed that the rate of improvement of olfactory function was significantly higher in patients with post-URTI dysosmia compared with patients with posttraumatic dysosmia. During an observation period of approximately 1 year, more than 30% of patients with post-URTI olfactory loss experienced improvement, whereas only 10% of patients with posttraumatic olfactory loss experienced improvement. Furthermore, age plays a significant role in the recovery of olfactory function.