xRead - Olfactory Disorders (September 2023)

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382

INTERNATIONAL CONSENSUS ON OLFACTION

TABLE VII.8 (Continued) Study

Year LOE Study design Study groups

Clinical end point SS-ID, SS-D, SS-T Nasal obstruction symptom score

Conclusions

Decrease in odor TDI

Riva

2019 3

Cohort

10 patients undergoing RT for HNC, excluding nasal tumors

et al 383

scores during RT with recovery after 3 months; however, 40% with subjective persistent hyposmia

Riva

2015

3

Cohort

30HCs 30 patients with NPC treated withRTand chemotherapy

SS-ID, SS-D, SS-T Symptom survey

≥ 2 years post-RT,

et al 387

patients exhibited worsened odor

threshold and TDI scores as compared withHCs No difference based on typeofRT OF and OB size were significantly lower in patients following RT as compared with controls

Veyseller et al 390

CCCRC olfactory test Olfactory bulb volume (MRI)

2014 4

Case-control

24 patients with NPC treated withRT ≥ 12 months ago 14HCs

Wang

2015

3

Cohort

41 patients with NPC treated with intensity-modulated RT

UPSIT R TWSNOT-22

One year after

et al 386

completion of IMRT, mild OD still existed

AHSP = Appetite, Hunger and Sensory Perception; CCCRC = Connecticut Chemosensory Clinical Research Center; ERP = event-related potential; HC = healthy control; HNC = head and neck cancer; MRI = magnetic resonance imaging; NPC = nasopharyngeal cancer; OB = olfactory bulb; OD = olfactory dysfunction; OE = olfactory epithelium; OF = olfactory function; RT = radiation therapy; SOIT = Scandinavian Odor-Identification Test; SS-ID = Sniffin’ Sticks identification only; SS-D, Sniffin’ Sticks discrimination only; SS-T = Sniffin’ Sticks thresholds only; TDI = thresholds, discrimination, and identification; TWSNOT-22 = Taiwanese version of the 22-item Sino-Nasal Outcome Test; UPSIT R = University of Pennsylvania Smell Identification Test; VAS = visual analog scale. *Level of evidence (LOE) downgraded because of heterogeneity of results and lack of randomized controlled trials.

jective and objective metrics. 382–384 A systematic review of 23 studies demonstrated impairment in odor detection, discrimination, and identification after RT. 385 Themajor ity of patients in these cohorts were treated for head and neck cancer, although some patients with brain tumors or cutaneous malignancies have been studied as well. Fol lowing the completion of RT, some patients may expe rience a partial or even complete recovery of OF. 382,383 In a study of 70 patients, Bramerson et al 385 demon strated that radiation dosage was significantly related to OD, while age, sex, and concurrent chemotherapy admin istration were not. 385 In a series of 56 patients, Hölscher et al 384 demonstrated that higher radiation doses to the OE were associated with lower odor discrimination scores 2 weeks after initiating RT, but no dose-dependent differ ence was observed for odor identification and threshold scores. 384 Several investigators have demonstrated persistent objective OD over 1 year following the completion of RT. Such studies have utilized a variety of outcome metrics, including the UPSIT R , Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test, SS, and measurement of event-related potentials (ERPs) to assess odor threshold, discrimination, and identification (TDI),

that medication usage of a wide array of both prescription and nonprescription medications may result in deficits of OF. Importantly, for otolaryngologists who routinely use topical tetracaine, lidocaine, and phenylephrine in their offices, although tetracaine and lidocaine do cause a tran sient increase in olfactory threshold during the visit, these medications appear safe and without long-term effect on the olfactory system. 370–372 Multiple medications can have detrimental effects on olfaction. Aggregate grade of evidence : C (Level 2: three studies; Level 3: two studies; Level 4: seven studies; Level 5: two studies). F Postradiation Therapy OD is a potential sequela of radiation therapy (RT) for head and neck tumors, and various mechanisms of injury have been proposed. Several prospective cohort studies have demonstrated that patients treated with RT experi ence impaired olfaction during and immediately follow ing completion of treatment, as measured by both sub