xRead - Olfactory Disorders (September 2023)

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590

INTERNATIONAL CONSENSUS ON OLFACTION

TABLE IX.26 (Continued) Author Year

LOE Study design

Study groups

Clinical end point

Conclusions

NA

Head down and forward position demonstrated distribution of drops toOC

Raghavan and Logan 1530

2000 5

Cadaveric

Observed

distribution of nasal drops in cadaveric specimens in head back, head downand forward, lateral head low, and lying head back positions

Mori

2016

4

Observational

Population: 13 healthy volunteers

Applied drops while lying on side with head tilted and the chin turned upward

Nasal drops reached the OC in 96% and 75% of decongested patients and patients without decongestion, respectively No significant difference in the delivery of irrigation to the OC

et al 1531

Kidwai

2017

5

Cadaveric

Population: 4

240-mL irrigation bottle in head over sink position in unoperated and postmiddle turbinate resection

et al 1532

cadaver heads

before and after middle turbinate resection ( P = 0.340) FESS = functional endoscopic sinus surgery; LOE = level of evidence; OC = olfactory cleft; OE = olfactory epithelium; NA = not available; NS = nasal spray.

patients with olfactory loss where patients smelled four odors twice daily for 12 weeks. The odors selected in this initial study were based on the odor prism and were initially chosen somewhat arbitrarily, but do represent dif ferent categories of smell. This method is now consid ered classic OT (COT), including smells from categories of floral (rose), fruity (lemon), resinous (eucalyptus), and aromatic (clove) groups. 1539 There has been a significant amount of interest and research into this treatment modal ity since that initial study. This review identified 22 studies examining OT for olfactory loss (three meta-analyses, two systematic reviews, four RCTs, four prospective random ized trials, two prospective pseudorandomized studies, and seven prospective cohort studies) (Table IX-29). Benefit with OT has been reported in patients with PTOD, PIOD, and IOD, as well as with OD related to PD and aging. While all studies report some benefit for OT regardless of etiology, the benefit appears to be greatest for patients with PIOD. Liu et al 1540 performed a retrospective pooled analysis of eight previously published studies. They found an adjusted odds ratio of 0.29 for PTOD and 0.18 for IOD versus PIOD. Patients with PIOD have an odds ratio of 2.77 of achieving a minimum clinically important dif ference (MCID) on olfactory testing versus control. 250 A shorter duration of olfactory loss has also been associated with greater recovery with OT in several studies. 374,1346,1541 Haehner et al 1486 found, in a prospective cohort study with

COT for 12 weeks, in patients with PD an improvement on TDI and on threshold for the four scents used for train ing. Last, Lamira et al 1542 found that OT in adults with age-related olfactory loss (mean age, 66 years) showed a clinically significant improvement in olfaction in 44% of patients who completed the study, but the investigation had a dropout rate of 45%. Two systematic reviews con cluded that improvement is primarily in the discrimina tion and identification realms. 1484,1543 Most studies have performed OT using four different odors, with the majority using the COT technique, but the odors used do not appear to have a significant effect on outcome. 1539,250 Patel et al 1544 reported that OT with nonstandardized concentrations of commercially available essential oils was as effective as prior studies using pure odorants, achieving an MCID in 32% of patients (ver sus 10% of controls). Altundag et al 1545 noted incremental improvement in olfactory recovery in patients with PIOD when using three different sets of four odors for training versus COT for 36 weeks. Conversely, Saatci et al 1546 com pared the modified OT method with an OT ball containing the same odors as in COT but found greater improvement with the OT ball. Oleszkiewicz et al 1547 used three differ ent training regimens (COT, four scent mixtures, and three sets of four odors) in patients with IOD or PIOD. All groups exhibited an improvement in TDI scores, but there was no difference between groups. Jiang et al 1548 compared the use