Evaluation of odor recognition threshold measurement methods in T&T olfactometry: A survey study

OBJECTIVE

The odor recognition thresholds in T&T olfactometry are measured by either the examiner's judgment of the patients' odor expression for each standard odor or by the patient's choice of the correct response from an olfactory term table. This study aimed to clarify the correct odor expressions and use of the olfactory term table.

METHODS

A questionnaire was administered to otolaryngologists or medical staff in charge of testing at facilities where T&T olfactometry is performed. The questionnaire consisted of the facility's background, environment and procedures of T&T olfactometry, choice of the correct answer with five different standard odors, and use of the olfactory term table. For the choices, the expressions used were those considered correct at Nippon Medical School Tama Nagayama Hospital and the Kyoto Nose and Allergy Clinic.

RESULTS

A total of 81 valid responses were obtained. Most respondents belonged to medical and educational institutions (59.3%, 48/81). The laboratories in the respondents' institutions were completely ventilated using various methods. Clinical laboratory technicians inspected 51.7% (45/81) of the facilities. The order of standard odors in the odor recognition threshold test differs depending on the facility. When the examiner was unsure about the answer given by the patient in the odor recognition threshold test, 16.1% (9/56) of the respondents chose "present the olfactory term table," 33.9% (19/56) chose "increase the concentration," and 37.5% (21/56) chose "present the olfactory term table" or "increase the concentration," depending on the situation. A total of 96.4% (54/56) of the facilities treated odor expressions other than those in the olfactory term table as correct, and the odor expressions that were considered correct differed from facility to facility. Of the respondents, 80.2% (65/81) answered "I know the olfactory term table," and the mean value of satisfaction with the current olfactory term table was 4.4 ± 3.0. Of the respondents, 81.5% (53/65) answered that "the timing of presenting the olfactory term table should be standardized in all facilities."

CONCLUSION

In the odor recognition threshold test by T&T olfactometry, this study revealed that the odor expressions considered as correct answers for the standard odors and the use of the olfactory term table differed among facilities.

Efficacy of tokishakuyakusan and mecobalamin on post-infectious olfactory dysfunction: A prospective multicenter study

OBJECTIVE

To determine if tokishakuyakusan (TSS) is effective for treating post-infectious olfactory dysfunction (PIOD) compared with vitamin B12 (mecobalamin).

METHODS

We conducted a randomized, nonblinded clinical trial. Patients with PIOD enrolled in 17 hospitals and clinics from 2016 to 2020 were randomly divided into two groups, and we administered TSS or mecobalamin for 24 weeks. Their olfactory function was examined using interviews and T&T olfactometry. The improvement of olfactory dysfunction was assessed following the criteria of the Japanese Rhinologic Society.

RESULTS

Overall, 82 patients with PIOD were enrolled in this study. In the TSS and mecobalamin groups, 39 patients completed the medication regimen. In the TSS and mecobalamin groups, olfactory dysfunction was significantly improved based on self-reports and olfactory test results. The improvement rate of olfactory dysfunction was 56% in the TSS group and 59% in the mecobalamin group. Early intervention within 3 months produced a better prognosis than the treatment initiated after 4 months. Furthermore, age and sex differences were not observed. Both medications produced no severe adverse events.

CONCLUSION

The present study showed that TSS and mecobalamin might be useful for treating PIOD.

Relationship between cognitive impairment and olfactory function among older adults with olfactory impairment

OBJECTIVE

Understanding the relationships among aging, cognitive function, and olfaction may be useful for diagnosing olfactory decline in older adults. Olfactory function declines in the early stage of neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. Aging and cognitive impairment are associated with olfactory decline. Moreover, the assessment of hyposmia and anosmia is paramount to the diagnosis of neurodegenerative diseases. We aimed to assess the relationships among aging, cognitive function, and olfaction in patients with olfactory impairment.

METHODS

This observational study included 141 patients with olfactory deterioration who presented with dementia, mild cognitive impairment (MCI), age-related hyposmia, or postviral olfactory dysfunction (PVOD). The patients underwent T&T olfactometry, a self-administered odor questionnaire (SAOQ), a visual analog scale (VAS), and a Mini-Mental State Examination.

RESULTS

T&T odor recognition thresholds decreased with aging (p < 0.01) and cognitive impairment (p < 0.08). The average T&T recognition thresholds were 5.1,4.6,4.2, and 3.7 in dementia, MCI, age-related hyposmia, and PVOD, respectively. Moreover, the average differences between the detection and recognition thresholds were 3.7, 2.8, 2.3, and 2.0 in dementia, MCI, age-related hyposmia, and PVOD, respectively. Hyposmia with dementia presented the highest recognition thresholds (p < 0.05) and the largest differences between the T&T detection and recognition thresholds, compared with age-related hyposmia and PVOD (p < 0.05). Hyposmia with dementia had the highest SAOQ and VAS scores compared with the other groups (p < 0.05).

CONCLUSION

The possibility of dementia should be investigated in patients with hyposmia, including those with high T&T recognition thresholds, a large difference between the T&T detection and recognition thresholds, and high SAOQ and VAS scores.

Self-reported course of olfactory impairment determines outcome for successful surgical intervention in nasal polyps with anosmia

BACKGROUND

Olfactory impairment is one of important symptoms of Chronic rhinosinusitis with nasal polyps (CRSwNP). However, the relationship between course of olfactory impairment and postoperative symptom improvement was still unclear.

OBJECTIVE

The aim of this study was to assess the relationship between the self-reported course of olfactory loss and the degree of improvement in olfaction to determine the timing for successful surgical intervention in improving olfaction in patients with CRSwNP.

MATERIALS AND METHODS

A total of 86 CRSwNP patients with loss of smell and undergoing functional endoscopic sinus surgery (FESS) were recruited consecutively. The self-reported course of smell lose before treatment was recorded. Olfactory function was recorded before and after FESS using T&T Olfactometry.

RESULTS

Fifty-seven patients demonstrated recovery of olfaction and 29 patients no-recovery. The average recovery time of smell loss in the study was 2.6 weeks. The course of smell loss showed moderate accuracy as a marker for determining the timing for successful FESS; with up to 4.5 years of self-reported smell loss being the cut-off point for recovery of smell following FESS.

CONCLUSION

This study suggests that FESS in CRSwNP patients with self-reported significant olfactory impairment for less than 4.5 years may lead to improvement in olfaction.

SIGNIFICANCE

FESS in CRSwNP patients with self-reported significant olfactory impairment persisting for less than 4.5 years may lead to considerable improvement in olfaction in these patients.