xRead - Olfactory Disorders (September 2023)

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577

PATEL et al.

TABLE IX-18 (Continued) Study

Year LOE Study design

Study groups

Clinical end point Conclusions

BTT VAS

Compared with

Blomqvist et al 1359

2001

2

RCT

CRSwNP (n = 32)with symmetrical nasal airways where each side was randomly assigned to ESS vs no ESS followed by local nasal budesonide All patients received pretreatment with oral prednisolone for 10 days and topical budesonide for 1 month

baseline, both sides improved Compared with medical treatment side, there

was no additional benefit noted with surgery

B-SIT = Brief Smell Identification Test; BTT = Butanol Threshold Test; CRS = chronic rhinosinusitis; CRSsNP = chronic rhinosinusitis without nasal polyps; CRSwNP = chronic rhinosinusitis with nasal polyps; CT = computed tomography; ESS = endoscopic sinus surgery; LOE = level of evidence; MCID = minimum clinically important difference; OD = olfactory dysfunction; OF = olfactory function; QOD-NS = Questionnaire of Olfactory Disorders-Negative Statements; RCT = randomized controlled trial; SNOT-22 = 22-item Sino-Nasal Outcome Test; SS = Sniffin’ Sticks; SS-ID = Sniffin’ Sticks identification only; SS-TDI = Sniffin’ Sticks threshold, discrimination, identification combination; STS = standardized test statistic; UPSIT R = University of Pennsylvania Smell Identification Test; VAS = visual analog scale.

ity is associated with an increase in body weight. 957 Ther apeutically, mixed results have been reported with weight loss surgery. One study of gastric bypass patients demon strated a positive effect on taste but not on olfaction. 1498 In a later similar study, weight loss surgery was able to return olfaction, and taste recovered to normal levels 6 months postprocedure. 976 Treatment of OD related to autoimmune diseases Autoimmune diseases have long been associated with smell loss. 1499,1500 Specifically, patients with Sjögren syn drome and SLE have been found to commonly exhibit olfactory deficits. Schonfeld et al 439 reported that the odor threshold and odor discrimination scores decreased in patients with SLE, and that OD correlated with disease severity and CNS involvement. SLE is a chronic autoim mune disease that requires long-term immunosuppressive therapy and causes neurocognitive damage caused by both the disease and the side effects of the treatments. Bombin et al 403 found that factors such as inflammation and dura tion of illness with SLE, as well as secondary anxiety and depression, usually mandates multidisciplinary evaluation in these patients. Another important cause of olfactory dis orders among autoimmune diseases is IgG4-related dis ease, which has been associated with type 1 autoimmune pancreatitis, chronic sialoadenitis, kidney disease, periaor titis, and dacryoadenitis. 1501 Yagi-Nakanishi et al 1502 found that 52% of these patients had OD. Likewise, OD was found in patients with Mikulicz disease restricted to the salivary glands, which is also thought to be an IgG4-related disease

this area, three main systemic causes emerge: hormonal diseases, autoimmune diseases, and vitamin and mineral deficiencies. Treatment of OD related to endocrine and metabolic diseases Diabetes mellitus (DM) is the most common cause of OD among patients with hormonal diseases. 1490 Several mech anistic hypotheses have been suggested, including elevated hemoglobin A 1c levels, microvascular and macrovascu lar complications, and polyneuropathies. 1490,470 A strong association between OD and increased risk of cognitive impairment has been reported in type 2 DM. 1302,1491 Ingen eral, studies have revealed that type 2 DM with complica tions is associated with OD, while uncomplicated type 1 DM is not. 1492,1493 Therefore, prevention of diabetic com plications plays an important role in the treatment of OD in these patients. Interestingly, hyperbaric oxygen therapy used in the adjuvant treatment of diabetic neuropathy sig nificantly increased OF scores. 1494 Thyroid diseases are also important causes of OD among patients with endocrine diseases, most com monly hyposmia in hypothyroidism. 464 It is thought that the main reason for the development of hyposmia in hypothyroid patients is the role of thyroid hormone in OR maturation. 1495 Thyroid hormone replace ment provides significant olfactory improvement in patients with frank hypothyroidism, as well as subclinical hypothyroidism. 1496,1497 Obesity has recently become associated with metabolic OD and studies have shown that a loss of odor sensitiv