xRead - Olfactory Disorders (September 2023)

20426984, 2022, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/alr.22929, Wiley Online Library on [04/09/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

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PATEL et al.

was 1 in 3 of the treatment group as compared with none in the control group. In a prospective observational study, the duration of effect subjectively reported by patients was 3hours. 1559 The subsequent study by Whitcroft et al 1558 that looked specifically at PIOD showed an effect on combined threshold and identification scores, but not separately. 1558 The method of application differed among the four stud ies. In the Dresden studies, sodium citrate was applied with an intranasal “squirt device,” with patients lying supine throughout, with their neck extended and head back over the edge of the examination bed ( ≈ 35 ◦ to 40 ◦ below the horizontal) for 30 to 60 seconds. In the RCT by Philpott et al, the sodium citrate was applied using a repur posed co-phenylcaine bottle and nasal applicator with the patients in an upright position. In the original study by Panagiotopoulos et al, 1559 patients were instructed to self administer the sodium citrate using a 2.5-mL syringe in the “head down and forward” position and then to stay there for 1 minute. Sodium citrate has shown some potential, especially in patients with PIOD, but further studies are needed to con firm benefit in a well-designed RCT with an appropriate placebo arm, outcome measures, and longer-term follow up. Duration of improvement after one application appears to be short-lived. Use of sodium citrate to treat OD Aggregate grade of evidence : B (Level 2: two studies; Level 3: two studies). Benefit : May improve olfactory performance for short duration (up to 2 to 3 hours), but replication of this result has varied. Harm : Short-term side effects (up to 30 minutes after application): local irritation of nasal and oropharyngeal mucosa. Cost : May include the following: Direct: $16 USD for 500 g of sodium citrate will provide treatment for several months. Indirect: Time for daily therapy; could perhaps be used three times per day in conjunction with mealtimes but fur ther evidence is needed. Benefits-harm assessment : Minimal risk of short term side effects versus low cost and potential for improve ments to be discussed between clinician and patient. Those with PIOD may be the best group to select. No data on long term use to advise on any potential longer-term harm. Value judgments : Although the existing data provide promise for transient improvement, this treatment needs evidence around long-term benefits and delivery. If effi cacy can be proven and replicated, it is a low-cost, low-risk option to offer patients. Policy level :Option. Intervention : Topical sodium citrate can be considered an option for patients presenting with PIOD for short-term

improvement. Clinicians may need to provide a delivery device such as a mucosal atomizer to apply the solution.

4 Vitamins and supplements a. Omega-3

Omega-3 long-chain polyunsaturated fatty acids are inte gral to lipid metabolism and play an important role in diet and physiology. In addition, they are critical in nor mal brain function and structure, with additional anti inflammatory and antioxidant properties. In animal mod els, rats fed a diet deficient in docosahexaenoic acid (DHA), an omega-3 fatty acid, made significantly more errors in a series of olfactory-cued tasks. 1560 Further more, omega-3 supplementation has been suggested to be protective against other neurologic insults and degen erative processes, such as Alzheimer or diabetic sensori motor polyneuropathy, both known pathologies that are associated with OD, as noted in prior sections. 1561,1562 Finally, accelerated functional recovery after peripheral nerve injury was detected among mice transgenically overexpressing omega-3 long-chain polyunsaturated fatty acids. 1563 There is one prospective RCT examining OF after endo scopic sellar and parasellar tumor resection with omega-3 supplementation. 1564 The 46 patients randomized to 1000 mg of omega-3 supplementation, twice a day, plus saline irrigation postoperatively had significantly less olfactory loss on the UPSIT R at 3 and 6 months postoperatively compared with the 41 who performed saline irrigations alone. While the magnitude of the immediate postopera tive olfactory defect was not quantified, this study provides evidence supporting the potential role of omega-3 long chain polyunsaturated fatty acids in the treatment of post operative OD. Future research is needed to characterize the role of omega-3 supplementation in other causes of olfac tory loss. A population-based cohort of 667 Australians found that older adults with the highest consumption of nuts and fish, sources of omega-3 fatty acids, had reduced odds of olfactory impairment. 1565 (Table IX-31) Omega-3 supplementation is a therapeutic option in the setting of postoperative olfactory loss, with the potential to improve the course of OD from other inflammatory causes. Addi tional study is needed to evaluate appropriate treatment protocols and the impact of omega-3 long-chain polyun saturated fatty acids on other forms of OD. Use of omega-3 for treatment of OD Aggregate grade of evidence : B (Level 1b: one study; Level 3: two studies). Benefit : Protection against olfactory loss after endo scopic skull base surgery as well as potentially protective for other causes of smell loss, eg, in an aging population.