A New Method for Assessment of Retronasal Olfactory Function.

OBJECTIVES/HYPOTHESIS: The aim of the study was to develop a test for the assessment of retronasal olfaction in healthy participants and patients with olfactory disorders using "tasteless" powders. STUDY DESIGN: Prospective case-control series. METHODS: A total of 150 participants (110 women, 40 men, mean age = 40 ± 16 years) were recruited for this study; 100 were healthy controls and 50 were patients with olfactory loss due to infections of the upper respiratory tract (n = 25), idiopathic causes (n = 12), sinonasal disease (n = 7), and head trauma (n = 6). Orthonasal olfactory function was evaluated using the Sniffin' Sticks test battery, and retronasal olfaction was evaluated using powders lacking distinctive tastes administered to the oral cavity. To establish test-retest reliability, healthy participants had their orthonasal and retronasal function tested twice. RESULTS: The validity analyses revealed that the selected 16 stimuli differentiated between normosmic participants and patients with olfactory loss, and that retronasal and orthonasal olfaction were highly correlated. CONCLUSIONS: The results of the present study indicate that patients with olfactory loss and controls can be clearly separated using a reliable test of retronasal olfaction based on 16 retronasal stimuli. LEVEL OF EVIDENCE: 2b Laryngoscope, 131:E324-E330, 2021.

Tract-based spatial statistics of the olfactory brain in patients with multiple sclerosis.

PURPOSE: To investigate diffusion tensor abnormalities, e.g. fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD), in olfactory structures of multiple sclerosis (MS) patients using diffusion tensor imaging (DTI). METHODS: Institutional review board-approved prospective study on 30 MS patients and 12 healthy controls investigated with MRI including DTI. Central olfactory structures were labelled on each patient's and healthy contro''s DTI volume. The diffusion tensor was determined in the central olfactory structures in MS patients. Tract-based spatial statistics (TBSS) was used to quantify the streamlines outgoing from the olfactory structures and to quantify changes in FA, MD, and RD within olfactory structures. These brain changes were correlated with olfactory function measured as TDI (Threshold, Discrimination, Identification) scores in patients and compared to our own reference group of 30 healthy volunteers. RESULTS: Central olfactory structures in the MNI (Montreal Neurological Institute) data volume comprise 4808 voxels (4808 mm(3)). TFCE (Threshold-free cluster enhancement) and cluster analysis of patients identified a total of 127 voxels in one cluster with a significantly decreased FA (p<0.05) and none for MD and RD within olfactory structures compared to healthy controls. The correlation with the age-normalised Identification subscore of the TDI score increased the significant number of voxels with decreased FA to 208 voxels, with increased MD to 370 and with increased RD 364 voxels at the same region. CONCLUSION: The decrease in FA and increase of MD and RD correlate with the degree of identification impairment of olfactory function in MS patients and clusters of abnormalities were identified on a MNI data volume.

Treatment of chronic rhinosinusitis with pressure-pulsed corticosteroid inhalation.

Chronic rhinosinusitis may cause olfactory dysfunction and affects quality of life in patients. In a prospective study we investigated the effect of topical application of corticosteroids through pressure-pulsed inhalation as treatment option of chronic rhinosinusitis with olfactory disorder. Patients with sinonasal olfactory disorder according to the European Position Paper on Rhinosinusitis and Nasal Polyps (EP3OS) were allocated to the new nasal inhalation therapy or a systemic corticosteroid therapy, each receiving a corticosteroid course of 12 days. 18 patients received topical corticosteroid pressure-pulsed inhalation (AMSA, Schumacher, Dausenau) and 15 systemic corticosteroid. Olfactory function was measured before and after treatment using the Threshold Discrimination Identification score (TDI score) and visual analogue scales. Lund Mackay score (LMS) was measured before starting treatment. Olfactory function (OF) increased from 17.5 ± 6.4 to 21 ± 7.9 TDI points (p < 0.0005) after 2 months. OF decreased again to 19.5 ± 6.0 after 6 months (p = 0.007). OF increased from 17.0 ± 8.9 to 22.0 ± 9.5 points (p = 0.002) with systemic treatment after 2 months. In the follow-up period of 6 months, the mean TDI score dropped to 20.0 ± 9.2 points (p = 0.01). There was no correlation between LMS and TDI. Treatment of chronic rhinosinusitis with pressure-pulsed inhalation was demonstrated to be effective. Multicenter investigations with large participant numbers are needed.

Olfactory function in patients with multiple sclerosis: a diffusion tensor imaging study.

BACKGROUND: Previous research has shown that multiple sclerosis (MS) patients can develop olfactory disturbances. OBJECTIVE: The purpose of our study was to investigate how olfactory function in MS patients correlates with cerebral magnetic resonance imaging (MRI) including diffusion tensor imaging (DTI). METHODS: Olfactory performance was tested in 30 MS patients and 30 controls to determine odour threshold (T), odour discrimination (D), and odour identification (I) summarised in the TDI score. The lesion load (number and total volume of lesions) was measured on proton-density (PD)- and T2-weighted images of the olfactory brain and the total brain. Fractional anisotropy (FA) of the lesions and the surrounding normal-appearing brain tissue (NABT) was quantified using DTI. RESULTS: The median FA of white matter lesions was 0.29 and was on average 11.1% lower than in the surrounding NABT. The normalised TDI score and the normalised I subscore were significantly poorer in the MS group compared to controls (p<0.0001), while the T and D subscores were similar in both groups. The median FA of lesions in the olfactory brain correlated inversely with the decreased I subscore (p=0.001). There was also a strong correlation between the TDI score and the Expanded Disability Status Scale (EDSS) (p=0.001). CONCLUSION: A strong inverse relationship between decreased odour identification ability of MS patients and FA values in the olfactory brain indicates that the reduction in I is more strongly affected by lesions in areas with high FA values, i.e., with an increased amount of affected white matter tracts.

Psychophysiological and electrophysiological testing of olfactory and gustatory function in patients with multiple sclerosis.

The olfactory (OF) and gustatory function in multiple sclerosis (MS) patients and possible influencing variables of the disease, such as depression or fatigue, were determined. In an open prospective controlled clinical study 30 patients with MS and 30 healthy controls matched for age, sex and smoking-habits were investigated. With Mini Mental State Examination cognitive dysfunction was excluded, with Expanded Disability Status Scale the patient's ability to accomplish the tests was ensured. The severity of depression was measured with the self-reported Beck Depression Inventory. The orthonasal olfactory function was derived with olfactory event related potentials (OERP) and TDI-score (Threshold, Discrimination and Identification, Sniffin' Sticks). Retronasal olfactory function was tested with Taste-Powder-score, gustatory function with Taste-strip-score. There was a significant loss of olfactory function measured with TDI-score [12/30 (40%), p = 0.002] and gustatory function [5/23 (21.7%), p < 0.001] in MS-patients, 23.8% (5/21) of MS-patients showed hyposmia with OERPs, significantly correlating with the TDI-score (p = 0.03). The Expanded Disability Status scale score inversely correlated with the TDI-score (p = 0.002). This study confirms the incidence of olfactory disorder in MS-patients and reveals a frequent gustatory deficit. The Identification subtest can be proposed as a marker of the OF in MS-patients: it includes complex cognitive tasks and may be influenced by depression and fatigue, which are common symptoms of MS. It inversely correlates with the disability status.

Olfactory and gustatory function in patients with multiple sclerosis.

BACKGROUND: The olfactory function (OF) and gustatory function in patients with multiple sclerosis (MS) can be limited. METHODS: We performed the testing of orthonasal (Threshold Discrimination Identification [TDI] score with Sniffin' Sticks) and retronasal (Taste Powder) OF and gustatory function (Taste Strips; Burghart, Wedel, Germany) in patients diagnosed with MS and healthy controls matching in age, sex, and smoking habits. RESULTS: Eight of 16 MS patients (50%) displayed hyposmia (TDI score, 28.75 ± 1.28; p = 0.06); the identification subtest significantly was restricted (12.63 ± 1.67; p = 0.001). Four of 16 MS patients (25%) had limited retronasal OF with a Taste Powder score of 4.5 ± 1.29. The gustatory function in 19% of MS patients was significantly limited (Taste Strip score, 5.33 ± 2.52; p = 0.02). Patients who estimated their ability to smell as diminished performed more poorly on retronasal OF testing (r =0.657; p = 0.046). CONCLUSION: This study confirms the incidence of olfactory disorder in MS patients that has been reported in the literature. Interestingly, a significant correlation between orthonasal and retronasal OF testing was not shown. A higher incidence of gustatory dysfunction was shown and might serve as another potential marker for this disease.

Correlation of olfactory dysfunction of different etiologies in MRI and comparison with subjective and objective olfactometry.

BACKGROUND: The clinical diagnosis of olfactory dysfunction of different etiologies has been standardized by the German Working Group of Olfactology and Gustology, but there is no agreement about the most suitable imaging modality for diagnosing this disorder. MATERIAL AND METHODS: A total of 24 patients (13 women, 11 men; mean age 52 years) with different types of olfactory dysfunction (anosmia, hyposmia) were examined by objective and subjective olfactometry and magnetic resonance imaging (MRI) of the olfactory bulb. RESULTS: There was a positive correlation between objective olfactometry and volumetry of the olfactory bulb but no correlation between subjective olfactometry and MRI. CONCLUSION: MRI allows an evaluation of the olfactory bulb and appears to be superior to other modalities such as computed tomography (CT). Objective olfactometry remains the gold standard for reliable diagnosis of olfactory dysfunction.

The scent-diffusing ventilator for rehabilitation of olfactory function after laryngectomy.

BACKGROUND: The larynx bypass (LB) is the only device capable of providing laryngectomy patients with the ability to smell. Our findings regarding one-time and long-term use did reveal an improved olfactory function in these patients. Because the LB is difficult to use, however, it is not appropriate for everyday use. Therefore, we devised a new instrument: the scent-diffusing ventilator (SV). METHODS: Between January 2006 and February 2007, we researched the olfactory function of 16 patients who had undergone a laryngectomy (13 men/3 women; median age, 63 years) by using the LB and the SV. Their olfactory function was measured with the Sniffin' Sticks test battery. Further practicability of both methods was determined through a visual analog scale (1-10). RESULTS: The patients' olfactory function significantly improved (SV median 8 versus LB median 7; p < 0.002). In addition, the SV was much easier to use than the LB (median, 6 versus 5; p < 0.001). CONCLUSION: Further technical improvements are necessary to make the SV an established part of the rehabilitation of the olfactory function after laryngectomy.