xRead - Olfactory Disorders (September 2023)

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378

INTERNATIONAL CONSENSUS ON OLFACTION

TABLE VII.7a (Continued) Study Year LOE

Study design

Study groups

Clinical end point

Conclusions High exposure to phenol was the main risk factor for anosmia Exposure to phenol may be associated with self-reported olfactory impairment Exposure to vapors, urinary levels of manganese, 2 thioxothiazolidine 4-carboxylic acid, 2-aminothiazo line-4-carboxylic acid, 2,4 dichlorophenol, and serum lead levels were all implicated in smell disturbance In comparison with office workers, the prevalence of OD was higher in the four occupational groups

Noel

2017

4

Cross-sectional, population based

3594 respondents fromthe 2011–2012 NHANESand

Frequency of

et al 333

self-reported smell disorders

PST

3708 respondents fromthe

2013–2014 NHANES

Lee

OF was evaluated

2018

4

Cross-sectional

Exposed workers (n = 296) in the automobile repair, printing, shoemaking, and plating industries Nonexposed office workers (n = 99)

et al 346

using the Korean SS-ID (8 odors)

LOE = level of evidence; NHANES = National Health and Nutrition Examination Survey; NSHAP = National Social Life, Health, and Aging Project; OB = olfactory bulb; OD = olfactory dysfunction; ODT = odor detection threshold; OF = olfactory function; PEA = phenylethyl alcohol; SS-ID = Sniffin’ Sticks identification only; SS-T = Sniffin’ Sticks threshold only; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; UPSIT R = University of Pennsylvania Smell Identification Test.

E Related to medications Numerous medications from a broad range of therapeutic classes have been associated with changes in OF. Despite the commonality of medication-related changes in olfac tion, there is a paucity of research on both the impli cated medications and underlying pathophysiology of OD. The lack of such data are both caused by the wide range of incidence of medication-related olfactory changes, and also because the patient population that most commonly experiences medication-related changes in olfaction often has many risk factors for baseline OD including advanced age, medical comorbidities, and polypharmacy. 358,359 Addi tionally, the complexity of the olfactory system further complicates this mechanistic investigation, as many of the hundreds of receptors and interacting molecular signaling pathways that make up the olfactory system are potential targets of an exponential number of indiscriminate drug interactions. 360

Ambient air pollution may also impact OF by contact ing the OE, translocating to the OB and migrating to the olfactory cortex causing direct damage of the tissue or inducing local inflammation. 347 In older US adults, exposure to nitrogen dioxide was associated with OD. 348 Residents of cities exposed to severe air pollution have OD demonstrated by worse smell scores than those liv ing in nonpolluted regions. Moreover, the OB showed endothelial hyperplasia and neuronal accumulation of particles. 349 The available evidence shows that the association of multiple environmental, toxin, and work factors are related to olfaction impairment; however, no direct causal ity can be concluded. Toxin exposure, environmental pollution, and exposure to particulate matter is associated with smell disorders. Aggregate grade of evidence : C (Level 4: 30 studies).