Loss of Olfactory Function-Early Indicator for Covid-19, Other Viral Infections and Neurodegenerative Disorders

The loss of the senses of smell (anosmia) and taste (ageusia) are rather common disorders, affecting up to 20% of the adult population. Yet, this condition has not received the attention it deserves, most probably because per se such a disorder is not life threatening. However, loss of olfactory function significantly reduces the quality of life of the affected patients, leading to dislike in food and insufficient, exaggerated or unbalanced food intake, unintentional exposure to toxins such as household gas, social isolation, depression, and an overall insecurity. Not only is olfactory dysfunction rather prevalent in the healthy population, it is, in many instances, also a correlate or an early indicator of a panoply of diseases. Importantly, olfactory dysfunction is linked to the two most prominent neurodegenerative disorders, Parkinson's disease and Alzheimer's disease. Anosmia and hyposmia (reduced sense of smell) affect a majority of patients years before the onset of cognitive or motor symptoms, establishing olfactory dysfunction as early biomarker that can enable earlier diagnosis and preventative treatments. In the current health crisis caused by SARS-CoV2, anosmia and dysgeusia as early-onset symptoms in virus-positive patients may prove to be highly relevant and crucial for pre-symptomatic Covid-19 detection from a public health perspective, preceding by days the more classical respiratory tract symptoms such as cough, tightness of the chest or fever. Thus, the olfactory system seems to be at the frontline of pathologic assault, be it through pathogens or insults that can lead to or at least associate with neurodegeneration. The aim of this review is to assemble current knowledge from different medical fields that all share a common denominator, olfactory/gustatory dysfunction, and to distill overarching etiologies and disease progression mechanisms.

Involvement of Differentially Expressed microRNAs in the PEGylated Liposome Encapsulated 188Rhenium-Mediated Suppression of Orthotopic Hypopharyngeal Tumor

Hypopharyngeal cancer (HPC) accounts for the lowest survival rate among all types of head and neck cancers (HNSCC). However, the therapeutic approach for HPC still needs to be investigated. In this study, a theranostic ¹⁸⁸Re-liposome was prepared to treat orthotopic HPC tumors and analyze the deregulated microRNA expressive profiles. The therapeutic efficacy of ¹⁸⁸Re-liposome on HPC tumors was evaluated using bioluminescent imaging followed by next generation sequencing (NGS) analysis, in order to address the deregulated microRNAs and associated signaling pathways. The differentially expressed microRNAs were also confirmed using clinical HNSCC samples and clinical information from The Cancer Genome Atlas (TCGA) database. Repeated doses of ¹⁸⁸Re-liposome were administrated to tumor-bearing mice, and the tumor growth was apparently suppressed after treatment. For NGS analysis, 13 and 9 microRNAs were respectively up-regulated and down-regulated when the cutoffs of fold change were set to 5. Additionally, miR-206-3p and miR-142-5p represented the highest fold of up-regulation and down-regulation by ¹⁸⁸Re-liposome, respectively. According to Differentially Expressed MiRNAs in human Cancers (dbDEMC) analysis, most of ¹⁸⁸Re-liposome up-regulated microRNAs were categorized as tumor suppressors, while down-regulated microRNAs were oncogenic. The KEGG pathway analysis showed that cancer-related pathways and olfactory and taste transduction accounted for the top pathways affected by ¹⁸⁸Re-liposome. ¹⁸⁸Re-liposome down-regulated microRNAs, including miR-143, miR-6723, miR-944, and miR-136 were associated with lower survival rates at a high expressive level. ¹⁸⁸Re-liposome could suppress the HPC tumors in vivo, and the therapeutic efficacy was associated with the deregulation of microRNAs that could be considered as a prognostic factor.

A multidimensional cohort study of late toxicity after intensity modulated radiotherapy for sinonasal cancer

PURPOSE

To evaluate the occurrence of late toxicity after curatively intended intensity modulated radiotherapy (IMRT) for sinonasal cancer and assess dose-response associations.

METHODS

Patients treated with IMRT in 2008-2016 were included. Cross sectional examinations of toxicity from the optic pathway, the brain, the pituitary gland and the nose were performed along with quality of life - (QoL) and dose-response analyses.

RESULTS

Twenty-seven patients were enrolled; median age was 67 years (range 47-83). Five patients (19%) had radiation-related ocular toxicity. The risk of visual acuity impairment increased with increasing dose (grade 2 odds ration (OR) 1.12, p = 0.01; grade 3 OR 1.14, p = 0.02) and dose constraint violations (grade 2, OR = 21, p < 0.01; grade 3, OR = 41, p < 0.01). Six patients (22%) exhibited evidence of radiation-related hypopituitarism, but no dose-response association was detected. Seventeen patients (63%) had impaired olfactory function. The risk of olfactory impairment increased with higher stage (OR = 3.32, p = 0.03). Three patients (11%) had structural abnormalities in irradiated areas of the brain, and impaired cognitive function was present in 17 patients (63%). Cognitive, physical, role functioning as well as fatigue and insomnia were affected the most in QOL analyses. Fifteen patients (56%) had grade 2 radiation-related impairment in at least one organ. Grade 3 toxicity was only present in patients with toxicities in >3 organs and in patients initially treated for T4 tumours. Three patients (11%) had radiation-related impaired function in all examined OARs.

CONCLUSION

Late toxicity after radiotherapy was substantial in all examined organs, with dose-response associations between visual acuity impairment and the optic nerve. The results have led to changed praxis for follow-up examinations in Denmark.

Prospective assessment of gustatory function after radiotherapy for head and neck cancers

BACKGROUND

Taste disorders are major causes of morbidity in patients undergoing head and neck irradiation. We quantitatively assessed the gustatory function of patients with head and neck cancers who underwent radiotherapy using recently developed standardised tools for measuring taste.

METHODS

Twenty patients undergoing head and neck irradiation responded to a specific questionnaire and were assessed by olfactory and gustatory function tests. To assess changes over time, testing was performed before, immediately after, and at 2- and 4-week intervals following the start of radiotherapy. Concurrently, patients were evaluated for xerostomia from radiotherapy.

RESULTS

A decrease in the taste recognition threshold was observed in the second week after the beginning of radiotherapy. The taste detection threshold improved within the 14th-18th week. Most affected patients demonstrated that their gustatory function primarily decreased independent of the olfactory function. Disturbances in taste were exponentially worsened beyond an accumulated dose of 30 Gy and involved all tastants. According to a multivariate analysis, radiation-induced taste impairment was not influenced by the degree of xerostomia. However, there was an association between the dose of irradiation and the severity of taste disturbance.

CONCLUSIONS

In this preliminary study, we found that the taste function was worse 2 weeks after the start of radiotherapy and returned to pretreatment levels within 4.5 months. Taste disturbances were exponentially worse beyond an accumulated dose of 20 Gy. Taste dysfunction after radiotherapy was not influenced by the degree of xerostomia, whereas only the dose of irradiation was associated with the severity of taste dysfunction.

Toxic exposures and the senses of taste and smell

This review addresses the adverse influences of neurotoxic exposures on the ability to smell and taste. These chemical senses largely determine the flavor of foods and beverages, impact food intake, and ultimately nutrition, and provide a warning for spoiled or poisonous food, leaking natural gas, smoke, airborne pollutants, and other hazards. Hence, toxicants that damage these senses have a significant impact on everyday function. As noted in detail, a large number of toxicants encountered in urban and industrial air pollution, including smoke, solvents, metals, and particulate matter can alter the ability to smell. Their influence on taste, i.e., sweet, sour, bitter, salty, and savory (umami) sensations, is not well documented. Given the rather direct exposure of olfactory receptors to the outside environment, olfaction is particularly vulnerable to damage from toxicants. Some toxicants, such as nanoparticles, have the potential to damage not only the olfactory receptor cells, but also the central nervous system structures by their entrance into the brain through the olfactory mucosa.

Cerebral metabolic changes related to clinical parameters in idiopathic anosmic patients during olfactory stimulation: a pilot investigation

Idiopathic olfactory loss neural consequences have been studied especially by means of magnetic resonance imaging. Since other functional neuroimaging technique findings are lacking in the literature, present study used a validated ¹⁸F-2-fluoro-2-deoxy-D-glucose (FDG) functional positron emission tomography procedure under olfactory stimulation (OS) to assess brain changes in idiopathic anosmic patients (IAPs) in comparison with healthy subjects (HS). A voxel-based analysis between these groups was used to evaluate FDG uptake in the brain and perform a correlation analysis between metabolic responses and the Sniffin' stick test as well as intensity visuo-analogue scores and disease duration (DD). A significant relative decrease of glucose metabolism in the right and left frontal lobes, left insula, right parietal lobe, and left occipital, temporal and parietal lobes was found in IAPs during OS. The same condition resulted in a relative higher glucose metabolism in the right cerebellum in IAPs. Moreover, a negative correlation between DD and FDG uptake in the left temporo-parietal joint was found in IAPs. Such a correlation suggested a possible involvement of this area metabolic decrease in self-consciousness impairment, which is known to affect IAPs. Present preliminary functional results could be of interest to further deepen such neural impairments possibly useful for future perspective in pharmaceutical and rehabilitative protocols.

A systematic review of smell alterations after radiotherapy for head and neck cancer

PURPOSE

To review the current knowledge on radiotherapy associated olfactory dysfunction among head and neck cancer (HNC) patients.

METHODS

A systematic review of RT-related olfactory dysfunction in HNC was performed. Searches were conducted in several databases (Medline, EMBASE, CINAHL, CAB Abstracts, SCOPUS, Proquest Dissertations and Theses, PROSPERO, ALLEBM Reviews - Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED). Publications investigating olfactory dysfunction as an explicit side effect of Radiotherapy (RT, or RT-chemo or RT-monoclonal antibodies) were eligible, no limits were applied.

RESULTS

Two hundred and twenty-nine papers were screened and 23 met inclusion criteria.

CONCLUSIONS

Odor detection, identification and discrimination are olfactory functions impaired after RT for HNC. An RT dose-effect has been calculated for odor identification and odor discrimination. There were no studies of the effect of olfactory dysfunction on weight loss or energy intake among RT-treated HNC patients. To improve our understanding of RT associated olfactory dysfunction among HNC patients, future studies should include a multi-dimensional assessment of olfactory function in a longitudinal design, track other conditions affecting olfaction, assess retronasal olfactory perception, adopt validated self-report tools and explore the impact of olfactory dysfunction on the eating experience of HNC patients.

Olfactory event-related potentials: a new approach for the evaluation of olfaction in nasopharyngeal carcinoma patients treated with chemo-radiotherapy

Objective:

Olfactory dysfunction is a possible side effect of chemo-radiotherapy performed in patients affected by nasopharyngeal carcinoma. Self-rating measurements and olfactory event-related potentials were used and compared in order to evaluate the impact of this treatment on the olfactory system.

Methods:

Nine patients underwent subjective evaluation of olfactory function (using visual analogue scales for olfactory symptoms and quality of life, and a six-item Hyposmia Rating Scale), and a quantitative and objective measurement (olfactory event-related potentials).

Results:

Spearman's rank correlation analyses highlighted significant relationships between the clinical scales and olfactory event-related potentials. Inter-group analyses showed significant differences in the latency and in the amplitude of olfactory event-related potentials between patients and controls.

Conclusion:

Taking into account the small sample size and the lack of pre-treatment assessment, olfactory event-related potentials seemed to allow a more objective diagnosis of unilateral and bilateral olfactory loss. Moreover, olfactory event-related potentials and subjective scales results were concordant.

Squamous cell cancer of the nasal cavity: New insights and implications for diagnosis and treatment

BACKGROUND

Squamous cell carcinoma (SCC) of the nasal cavity is a rare malignancy and often analyzed in heterogeneous studies with other tumors of the nose or the paranasal sinuses. The purpose of this study was to evaluate distinct risk factors, tumor characteristics, outcome predictors, and the prevalence of human papillomavirus (HPV) in SCC of the nasal cavity.

METHODS

We conducted a retrospective study of 39 patients treated at a single quaternary medical care and cancer center. We analyzed tumor characteristics, HPV status, treatment, and outcome. We present the largest study on SCC of the nasal cavity from a single center.

RESULTS

The majority of patients (70.2%) presented with an early-stage tumor (T1 or T2). Only 1 patient had a single neck metastasis at the time of diagnosis. Four tumors were HPV-positive. Most patients (61.5%) underwent surgical resection without adjuvant treatment, with 12 patients (30.8%) undergoing additional radiotherapy. Three patients were treated with primary radiotherapy or chemoradiotherapy. No patient treated primarily with total rhinectomy developed local tumor recurrence.

CONCLUSION

Local tumor control is crucial, even if it makes radical surgery necessary. Postoperative epithetic treatment enables reliable follow-up examinations. Regional metastases at the time of diagnosis are rare. Neck dissection should therefore be reserved for cases of suspected metastasis. HPV may also play a role in the etiology of SCC of the nasal cavity. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2112-E2117, 2016.

Multidimensional Evaluation of Endogenous and Health Factors Affecting Food Preferences, Taste and Smell Perception

OBJECTIVE

This study, by taking a holistic approach, investigates the relationships between taste, smell sensitivity and food preference with prognostic (endogenous and health) factors including age, gender, genetic taste markers, body mass, cigarette smoking, and number of drugs used.

DESIGN

Cross sectional study.

SETTING

Northern Italy.

PARTICIPANTS

203 healthy subjects (160 women/43 men; mean age: 58.2±19.8 years) were examined.

MEASUREMENTS

Individual taste sensitivity was determined by saccharose, sodium chloride, acetic acid and caffeine solutions and by 6-n-propylthiouracil (PROP) responsiveness test. Olfactory sensitivity has been assessed by «Sniffin' Sticks». Four tag Single nucleotide polymorphisms (SNPs) in regions of interest were genotyped. Factor analysis and multivariate regression were performed for scaling food preferences and screening prognostic factors, respectively.

RESULTS

Increasing age is associated with decreased responsiveness to NaCl (P=0.001), sweet solutions (P=0.044), and smell perception (P<0.001). Concerning the food preferences, elderly like the "vegetables" and "fruits" but dislike "spicy" more than younger. Regarding number of drugs taken, there is a significant negative effect on smell perception (P<0.001). In addition, drugs reduce both the "vegetables foods" score (P=0.002) and the "milk-product foods" score (P=0.027). With respect to Body Mass Index (BMI), only a significant effect was shown, on sweet perception (P=0.006). Variation in taste receptor genes can give rise to differential perception of sweet, acid and bitter tastes. No effect of gender and smoking was observed.

CONCLUSIONS

Our study suggested that age, genetic markers, BMI and drugs use are the factors which affect taste and smell perception and food preferences.

Liposomal treatment of xerostomia, odor, and taste abnormalities in patients with head and neck cancer

BACKGROUND

Smell and taste disorders, sicca symptoms, can be detected in patients with head and neck cancer. The purpose of this study was to assess the utility of local liposomal application in the treatment of patients with head and neck cancers.

METHODS

Ninety-eight patients with head and neck cancer were included in this study. The groups were defined as: group 1 = only surgery; group 2 = surgery + adjuvant radiochemotherapy; and group 3 = primarily radiochemotherapy. All patients had finished cancer treatment and received liposomal sprays for the nose and mouth for 2 months (LipoNasal, LipoSaliva; Optima Pharmaceutical GmbH, Germany) and suffered from taste and smell disorders. We performed tests with "Sniffin' Sticks," "Taste Strips," and a xerostomia questionnaire before and after treatment.

RESULTS

After application of liposomes, patients demonstrated a statistically significant increase in smell and taste, and reduced xerostomia.

CONCLUSION

Our results demonstrate that using nonpharmaceutical liposomal sprays improve smell, taste, and symptoms of xerostomia in patients with head and neck cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1232-E1237, 2016.