xRead - Olfactory Disorders (September 2023)

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INTERNATIONAL CONSENSUS ON OLFACTION

C. Use of validated quantitative smell tests . . . 500 Types of olfactory tests employed clinically . . . 500 Suprathreshold olfactory tests . . . . . . . . . . 524 Odor identification tests . . . . . . . . . . . 524 Odor discrimination tests . . . . . . . . . . 524 Odormemorytests. . . . . . . . . . . . . . 525 Odor intensity rating tests . . . . . . . . . . 525 Tests of basal odor sensitivity . . . . . . . . . . 525 Odor threshold tests . . . . . . . . . . . . . 525 Signal Detection Tests . . . . . . . . . . . . 526 Reliability of Olfactory Test Measures . . . . . . 527 Relationships Among Nominally Different Types ofOlfactoryTests . . . . . . . . . . . . . . 527 Unilateral or Bilateral Testing?. . . . . . . . . . 527 General Recommendations . . . . . . . . . . . 527 D. Use of validated survey QOL testing . . . . . 538 E. Measurement of cytokine/mucin levels . . . 539 F. Electro-olfactogram . . . . . . . . . . . . . 539 G. Role of bloodwork/lab values . . . . . . . . 541 H. Specific evaluation and workup for phantosmia ................. 542 IX. MANAGEMENT................ 542 A. Prognosis and spontaneous recovery . . . . 542 B. Treatment of posttraumatic loss . . . . . . . 546 C. Treatment of underlying sinonasal inflammatory etiologies . . . . . . . . . . . 547 1. Medical treatment for CRS or AR-related olfactoryloss. . . . . . . . . . . . . . 547 2. Surgical treatment for CRS or AR-related olfactoryloss. . . . . . . . . . . . . . 567 D. Treatment of intracranial, neurotransmitter, neurodegenerative diseases . . . . . . . . . 569 E. Treatment of other underlying systemic diseasestates................. 573 Treatment of OD related to endocrine and metabolic diseases . . . . . . . . . . . 577 Treatment of OD related to autoimmune diseases................ 577 Treatment of OD related to mineral and vitamin deficiency . . . . . . . . . . . 579 F. If no underlying disease state to correct . . . 586 1. Treatment with corticosteroids . . . . . . 586 2. Olfactory training. . . . . . . . . . . . . 588 3. Intranasal sodium citrate . . . . . . . . . 597 4. Vitamins and supplements . . . . . . . . 599 5. Minocycline ............... 605 6. Theophylline............... 606 7. Intranasal insulin . . . . . . . . . . . . . 609 8. Platelet-rich plasma . . . . . . . . . . . 611 G. Phantosmia/Parosmia Treatment . . . . . . 613 1. Medical treatment options . . . . . . . . 613 2. Surgical treatment options . . . . . . . . 613 X. SPECIAL CONSIDERATIONS . . . . . . . . . 614

A. Delay in initiating treatment may be detrimental to potential recovery . . . . . . 614 B. Multiple-hit hypothesis . . . . . . . . . . . 614 C. Inherent predisposition of cranial nerve dysfunction when exposed to viruses . . . . 615 D. Discussion of protective and supportive measures................... 615 1. Control of environmental and food-related risks.................. 615 2. Nutritional monitoring . . . . . . . . . . 615 3. Counseling or therapy for psychologic effects................. 616 XI. SUMMARY OF KNOWLEDGE GAPS AND RESEARCH OPPORTUNITIES . . . . . . . . . 616 A. Etiology................... 616 1. Better delineate cause—many patients still characterized as idiopathic . . . . . . 616 2. Relative susceptibility and underlying mechanisms.............. 617 B. Clinical Assessment . . . . . . . . . . . . . 617 1. How culture and literacy affect some psychophysical test results. . . . . . . 617 C. Management................. 619 1. Identify predictors of response to current and future therapeutic options . . . . 619 2. A “cure” for all olfactory disorders . . . . 619 3. Increase public awareness of this disorder and its many implications . . . . . . . 619 ORCID........................ 620 REFERENCES.................... 620 INTRODUCTION The field of olfaction is a relatively young one. Detailed knowledge of the mechanisms of the olfactory system were only discovered in the second half of the 21st century, with Richard Axel and Linda Buck awarded the 2004 Nobel Prize for their landmark description of odorant receptors and the organization of the olfactory epithelium (OE), olfactory bulb (OB), and olfactory cortex. 1 An explosion of investigation followed in both the basic science research realm as well as clinical study, steadily growing in num ber of publications and complexity of study design over the 2 decades that have followed, peaking within the past year as the COVID-19 pandemic brought loss of smell and taste to the forefront of international importance and recognition. 2,3 In the many decades before Axel and Buck’s publica tion, articles listed in PubMed under “olfaction” totaled less than 5000. In the decade that followed, publications matched this number and over the next decade continued to accelerate until, in the decade between 2011 and 2021, I