xRead - Olfactory Disorders (September 2023)

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INTERNATIONAL CONSENSUS ON OLFACTION

TABLE IX-23 Section evidence summary: Treatment of other underlying autoimmune diseases

Study design Study groups

Clinical end point Relationship between

Study

Year 2013

LOE Disease

Conclusions

OR gene clusters close to major histocompatibil ity complex Olfactory system

Perricone et al 1499

4

Autoimmunity SLE Review Articles about autoimmunity and smell

autoimmune diseases and OF

Strous

2006

4

Autoimmune disorders

Review Articles about

Olfaction and

et al 1500

autoimmunity and smell

immune system

has a strong link with immune system

Shoenfeld et al 439

2009

2b

SLE

Cohort

100 participants, 50 SLE

SS-TDI

OF decreased in patients with SLE OF decreased in patients with

Bombini et al 976

2018

2b

SLE systemic sclerosis

Cohort and review

366 participants,

SS-TDI

143 SLE patients

SLEand systemic syclerosis

Stone

2012

2b

IgG4-related disease Cohort and review

Review

Mechanism of disease

Multiple immune mediated mechanisms contribute to the inflammatory

et al 1501

processes of IgG4-related disease

Yagi

2016

4

IgG4-related disease Case series 25 patients with IgG4-related disease

T&T olfactometer OD is an important manifestation of IgG4-related disease and may be reversible

Nakanishi et al 1502

Takano

Case series 44 patients with

T&T olfactometer OD may be

2011

4

Mikulicz disease (also an IgG4 disease)

et al 448

Mikulicz disease

associated with infiltration of nasal mucosa by IgG4-positive

plasmacytes in Mikulicz disease LOE = level of evidence; OD = olfactory dysfunction; OF = olfactory function; OR = olfactory receptor; SLE = systemic lupus erythematosus; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; T&T = Toyoda and Takagi.

Patients with many causes of OD such as postinfec tious, posttraumatic, sinonasal, and idiopathic causes were included in this study. Vitamin B treatment, which was noted to be ineffective in the first 2 months, was found to be an effective treatment method when extended to 6 months; however, with such a heterogeneous patient population, enrollment of patients as early as 1 month post-smell loss, with no control or placebo, no definitive conclusion can be made. While discussing the olfactory effects of B vitamins, thiamine, pyridoxine (B6), and methylcobalamin (B12), it is absolutely necessary to consider homocysteine. Homo cysteine, an amino acid synthesized from the amino acid

methionine, has a key role in vitamin B metabolism. If there is an increase of homocysteine in the body, vitamin B deficiency is likely present. In addition, homocysteine lev els increase with age and with increasing oxidation in the body, so homocysteine may be a cause of OD, both directly and indirectly via secondary vitamin B deficiency. 1515 While examining the effects of vitamins and minerals on OF, their mutual interactions and metabolism should not be overlooked, and, in addition, various common muta tions (such as methyltetrafolate reductase enzyme muta tion) will cause differences in homocysteine metabolism and subsequent changes in vitamin B metabolism. 1516