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

611

PATEL et al.

TABLE IX-40 Studies investigating medical management of phantosmia Study Year LOE Study design Study groups

Clinical end point Conclusions

No analysis Symptom resolution

Subjective

Majumdar et al 1614

2003 4

Case reports

Sodium valpoate or phenytoin sodium (n = 2)

improvement (at 3.5 years)

Landis

2010 4

Cohort

Observation (n = 44) Subjective

Phantosmia symptoms: disappeared in 14 (32%), improved in 11 (25%), remained the same in 17 (39%), and worsened in 2 (5%) No association with sex or TDI score Phantosmia symptoms: improvement in 9 of 14 patients, all patients with headache resolution also had phantosmia resolution Phantosmia symptoms: transient resolution in 5 of 6 patients for hours to days, 1 of 6 patients improved for 6 weeks Phantosmia returned in all patients Resolution of phantosmia in all patients, include 2 of 5 with haloperidol alone and 3 of 5 with surgery

et al 1313

improvement (at ameanof 6 years)

Coleman et al 910

Subjective

2011 4

Cohort

Topirimate,

improvement (at 30months)

verapamil, nortriptyline, gabapentin (n = 14)

Leopold

2013 4

Cohort

Topical cocaine (n = 6)

Subjective

et al 1615

improvement (at 19months)

Morrissey et al 1613

Subjective

2016 4

Cohort

Haloperidol for 3 months (n = 5) Olfactory mucosa

improvement (at 18 months to 5 years)

excision for failures (n = 3) OT therapy (n = 43)

Liu Presence of phantosmia failed to be associated with clinically relevant improvement in OF LOE = level of evidence; OF = olfactory function; OT = olfactory training; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; TDI = threshold, discrimination, and identification. et al 1618 2020 4 Cohort SS-TDI (at a mean of 26 weeks)

8 Platelet-rich plasma The use of platelet-rich plasma (PRP) as a treatment option for OD has not been well established, but pilot studies have demonstrated safety and potential efficacy. 1602–1604 PRP is an autologous blood product containing supraphysiologic concentrations of platelets with neurotrophic and anti inflammatory effects that have shown promise in neural regeneration in other peripheral neuropathies. 1605–1612 A murine model of anosmia treated with topical PRP demon strated improved OF and decreased olfactory epithelial damage. 1611 Two small human studies used PRP for treat ment of OD with no adverse outcomes including no worsening smell function. 1610,1611 Most recently, a small case series of patients with recalcitrant olfactory loss ( > 6 but < 12 months) showed statistically significant olfac tory improvement at 3 months posttreatment, although the number of patients was extremely limited and there was no control group, so no definite conclusion could be reached. 1610 Although not uniquely targeting patients with

established. One proposed theory is increased cyclic adenosine monophosphate and guanosine monophos phate within the olfactory neuroepithelium secondary to intranasal insulin application. 1601 Use of intranasal insulin to treat OD Aggregate grade of evidence : C (Level 2: one; Level 3: one). Benefit : Modest improvement in threshold. Harm : None currently known. Cost : Procedural cost for placement of intranasal gelfoam. Small cost for intranasal insulin spray and gelfoam. Benefits-harm assessment : Possible benefit in modest olfactory recovery, although evidence is mixed. Value judgments :Unknown. Policy level : No recommendation. Intervention : Further investigation of intranasal insulin for OD is warranted. Limited evidence currently exists.