xRead - Olfactory Disorders (September 2023)

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546

INTERNATIONAL CONSENSUS ON OLFACTION

TABLE IX.1 (Continued)

Clinical end point

Study

Year 2018

LOE Study design Study groups

Conclusions

791 postviral patients

ΔSS-TDI

Age and severity were important prognostic factors.

Cavazzana et al 252

4*

Retrospective

cohort (mean 1.94 years)

Ogawa

2020 2*

Retrospective

82 patients with PVOD

ΔT&T

77% of patients showed recovery, with 60% recovering within 6 months Lower age and more residual function, but not sex, lead to higher recovery rates

et al 1326

cohort (0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 36, 39, and 42months)

olfactometer

Δ = change; AR = allergic rhinitis; BTT = Butanol Threshold Test; csERP = chemosensory functions with event-related potential; ID = identification; NA = not available; OBV = olfactory bulb volume; OD = olfactory dysfunction; OE = olfactory epithelium; OT = olfactory training; PTOD = posttraumatic olfactory dysfunction; PVOD = postviral olfactory dysfunction; RCT = randomized controlled trial; RS = rhinosinusitis; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; T&T = Toyoda and Takagi; UPSIT R = University of Pennsylvania Smell Identification Test; VAS = visual analog scale. *Ranked down a level of evidence (LOE) because of methodological concerns.

Early intervention strategies to mitigate chronic OD is recommended. Intervention : There is a need for well-designed studies examining the spontaneous course of resolution in patients with OD, and there is evidence that intervening early for patients with loss of smell is helpful for accelerating recov ery. Research protocols for therapeutics should balance the restriction of patients most likely to recover to avoid con founding results (eg, restrict to at least 6 months loss) ver sus the likelihood of being able to help more patients early in the time course of loss and seeing a treatment effect (eg, restrict to loss no longer than 1 year). B Treatment of posttraumatic loss While spontaneous recovery has been observed follow ing some cases of posttraumatic olfactory loss, 1337 several studies have investigated treatment with medications. One study reported that spontaneous improvement rate was only 10% on average after 23 months of observation. 1328 Kampo medicines (Japanese herbal medicine), zinc or vita min preparations, topical or systemic steroids, and adeno sine triphosphate have been used to treat PTOD. Some recent reports indicate that OT is also effective in recov eringOF. 1346 From Kampo medicine, Toki-shakuyaku-san (TSS) treatment improved OF in 42% of patients with PTOD. 1347 In another study, seven patients with PTOD were treated with kamikihito. In this study, one patient recovered, five patients improved, and one patient showed no change. 1348 For zinc, although a prior double-blind, crossover study of 106 patients found no statistically significant effects on either taste or smell after 3 to 4 months of treatment, 1349 a recent prospective randomized study compared the effi cacy of four treatments: zinc gluconate, prednisolone, zinc

with prednisolone, and no medication in 145 patients with traumatic anosmia and concluded that zinc gluconate has a promising effect for treating traumatic anosmia. 1350 In another study, 95 patients with PTOD were treated with either zinc sulfate only, combination of zinc sulfate and the “usual” therapy (topical corticosteroids and systemic vitamin B complex), or the usual therapy. Patients who were administered zinc sulfate demonstrated significantly higher improvement rates than those who received the usual therapy. 450 Another study reported that 22 patients with PTOD were treated with zinc sulfate, TSS, and vita minB 12 complex, and five patients were cured, five patients improved, 10 patients showed no change, and two patients showed an exacerbation of symptoms. 1351 For steroids, some case studies have reported the efficacy of topical or systemic steroids. A total of 108 patients with PTOD were treated with topical steroids, and the improvement rate was 25%. 1325 In another study, 12 patients with PTOD were treated with topical betametha sone, with only one of 12 patients showing an improve ment in the olfactory test score. Five patients were also treated with topical dexamethasone, and three of the five patients showed an improvement. 1352 . In another study, 116 patients with PTOD were treated with systemic pred nisolone (60 mg/day for 3 days, tapered every 3 days for 15 days), and the olfactory threshold improved in 19 patients. 1353 Patients with PTOD were treated with top ical betamethasone and the improvement rate was 29%. In this report, the improvement rate between patients who were administered steroids and those administered TSS was compared, but no significant differences were observed. 1347 For vitamin A, in a double-blinded, placebo-controlled study, a dose of 10,000 IU/day was administered to 52 patients with olfactory loss, including 19 patients with posttraumatic olfactory loss, for 3 months. No significant