Olfactory function assessment of migraine patients by using the Sniffin' sticks test: A clinical study.

OBJECTIVE: This as a cross-sectional controlled clinical study. We hypothesis that the olfactory functions in migraine patients may differ from the healthy controls. In this study, we evaluated the olfactory functions by using a Sniffin' Sticks test battery, which is a reliable and semi quantitative test to evaluate for olfactory dysfunction. METHODS: Patients above 18 years of age who had migraine received a definitive diagnosis of migraine from experienced headache specialists based on the criteria of The International Classification of Headache Disorders-3 were included. Odor threshold, discrimination, and identification parameters were assessed using the "Sniffin' Sticks" test. RESULTS: One-hundred and one migraine patients (age [mean ± SD], 36.9 ± 10.4 years; range, 18-60 years) and sixty healthy volunteers (age 34.5 ± 13.2 years, range 18-65 years) participated in our study. The median odor threshold score [percentiles 25th-75th] was 8.3 [6.5-9.8] for the migraine group during attack free period and 4.5[3.6-6.0] for the control group. It was found that the migraine group had a median odor discrimination score of 10.0 [10.0-13.0] and the control group 12.0 [11.0-13.0]. These differences were statistically significant (p < 0.001 and p = 0.032 respectively). The median odor discrimination and identification scores were statistically significant higher for the participants with higher educational level group than in those of lower educational group (p < 0.0001). The median odor discrimination and identification scores of those without allodynia (12.0 [10.0-14.0] and 13.0 [10.0-13.0] respectively) were higher than that of those with allodynia (11.0 [9.0-12.0] and 11.0 [10.0-13.0] respectively) (p = 0.037 and p = 0.034 respectively). CONCLUSIONS: We found that the odor thresholds, discrimination and identification scores of the migraine group demonstrate differences from those of the healthy group and in relation to allodynia.

Assessment of the Olfactory Function in Patients With Idiopathic Intracranial Hypertension Using the Sniffin' Sticks Test: A Case-Control Study.

OBJECTIVE: Despite the lack of recognition in clinical practice, there is increasing evidence that patients with idiopathic intracranial hypertension may suffer from hyposmia. The current case-control study aims to evaluate olfactory dysfunction in a large series of patients with idiopathic intracranial hypertension. METHODS: All subjects, 44 idiopathic intracranial hypertension patients and 57 healthy controls, underwent olfactory function assessment using standardized "Sniffin' Sticks" test at a tertiary referral center of a university hospital. Threshold, discrimination, identification, and total threshold-discrimination-identification scores have been determined and analyzed statistically. RESULTS: Idiopathic intracranial hypertension patients had significantly lower threshold (6.5 [3.69] vs 8 [1.88], P < .001, 95% CI [-2.250, -0.750]) and threshold-discrimination-identification scores (29.75 [5.56] vs 32.5 [5.25], P = .003, 95% CI [-4.250, -0.750]). Twenty-five patients (57%) were diagnosed with hyposmia. Test scores of patients with active idiopathic intracranial hypertension (n = 18) were not statistically different from patients with inactive disease (n = 26), except for discrimination score (14 [2.50] vs 11 [2.25], P = .005, 95% CI [-3.000, -1.000]). Although idiopathic intracranial hypertension patients with a cerebrospinal fluid opening pressure of ≥330 mmH2 O had lower test scores, the difference was significant only for total threshold-discrimination-identification scores (28.5 [5.50] vs 30.5 [4.38], P = .044, 95% CI [0.750, 5.500]). Multiple regression analysis revealed that test scores were related to disease activity, cerebrospinal fluid opening pressure, papilledema, headache, and medication. CONCLUSION: Our clinical study revealed significant olfactory dysfunction in patients with idiopathic intracranial hypertension compared with healthy controls. Future research should employ larger samples to search for usability of olfactory testing in clinical management of patients with idiopathic intracranial hypertension.