Altered glucose metabolism of the olfactory-related cortices in anosmia patients with traumatic brain injury.

PURPOSE: Impaired brain cortices contribute significantly to the pathophysiological mechanisms of post-traumatic olfactory dysfunction (PTOD). This study aimed to use 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to measure cerebral cortices' metabolism activity and then to explore their associations with olfaction in patients with PTOD. METHODS: Ethics committee-approved prospective studies included 15 patients with post-traumatic anosmia and 11 healthy volunteers. Olfactory function was assessed using the Sniffin' Sticks. Participants underwent 18F-FDG PET/CT scan and the image data were collected for the voxel-based whole brain analysis. Furthermore, the standardized uptake value ratio (SUVR) of the whole brain regions was measured and correlated with olfactory function. RESULTS: Patients with post-traumatic anosmia showed significantly reduced glucose metabolism in bilateral rectus, bilateral superior and medial orbitofrontal cortex (OFC), bilateral thalamus, left hippocampus and parahippocampus and left superior temporal pole (all p < 0.001). In contrast, patients with post-traumatic anosmia had significantly increased glucose metabolism in the bilateral insula (all p < 0.001). SUVR values among a total of 17 cerebral cortices including frontal, limbic, and temporal regions were significantly and positively correlated with olfactory function. The cerebral cortices with the top three correlations were the right middle frontal OFC (r = 0.765, p = 0.001), right caudate (r = 0.652, p = 0.010) and right putamen (r = 0.623, p = 0.002). CONCLUSION: Patients with post-traumatic anosmia presented with distinct patterns of brain metabolism and key cortices that highly associated with the retained olfactory function were identified. The preliminary results further support the potential use of PET imaging for precisely assessing brain metabolism in patients with PTOD.

A tool developed for Chinese olfactory screening: culturally adapted version of "Quick olfactory Sniffin' Sticks Test (Q-Sticks)".

BACKGROUND: The odor identification test is culture-dependent. OBJECTIVES: This study aimed to develop a culturally adapted version of the 5-item Quick olfactory Sniffin' Sticks Test (Q-Stick) to adapt to the clinical environment in China. METHODS: The study included 3 phases: (1) develop a culturally adapted version of Q-Stick by replacing unfamiliar odors in the original Q-Stick test (N = 344); (2) validate the culturally adapted version of Q-Stick against two widely used olfactory tests: the Sniffin' Sticks olfactory test and the 12-item Cross-Cultural Smell Identification Test (CC-SIT) (N = 286); 3) evaluate the test-retest reliability of the culturally adapted version of Q-Stick (N = 60). RESULTS: After modification of the interference items, the correct recognition rate of leather was changed from 54.65% to 90.00%. The adapted version of the Q-Stick score significantly correlated with both the Sniffin' Sticks score (r = 0.7642, p < .0001) and CC-SIT score (r = 0.7403, p < .0001). Normal olfaction is indicated if the culturally adapted version of the Q-Stick score > 4 (specificity 70.00%, sensitivity 83.33%, Youden index 0.533) and Q-Stick score ≤ 4 indicates olfactory dysfunction. The 3-month test-retest reliability coefficient was as high as 0.96. CONCLUSIONS AND SIGNIFICANCE: The culturally adapted version of Q-Stick is an effective and stable screening tool to identify patients with olfactory dysfunction in China.

A novel irrigation device with superior nasal irrigation efficiency to the classic rinse bottle.

BACKGROUND: The ability of saline irrigation to detach the mucous and the flow-limiting effect of the nasal valve has not been well explored. The objective of this study was to compare the removal efficiency of a novel irrigation device with an extended nozzle versus a classic rinse bottle. METHODS: Transparent casts of the unoperated sinonasal cavity were made by 3D printing. Yogurt was used to simulate mucous. The cast filled with 5 ml yogurt was fixed in six head positions and irrigated with 120 ml, 175 ml, and 240 ml dyed water through the novel device and the rinse bottle. The irrigation efficiency was the ratio of the weight of yogurt washed away divided by the total weight of yogurt. RESULTS: The irrigation stream of a long nozzle with a side opening was different from the irrigation stream of the outlet within the nasal vestibule. The novel devices presented with continuous water stream directly upwards to the anterior part of the olfactory cleft. Depending on different head positions, it was easy for the novel devices to achieve an irrigation efficiency of 100% when the cast was irrigated with 120 ml or 175 ml water. There was still a tiny amount of yogurt left in the olfactory cleft when the cast was irrigated with 240 ml water under each head position for the rinse bottle. The irrigation efficiency was volume-dependent, and the average irrigation efficiency of the rinse bottle at 240 ml only reached 69.1%. CONCLUSIONS: The novel irrigation device presented with superior nasal irrigation efficiency to the classic rinse bottle. A continuous water stream directly upwards to the anterior part of the olfactory cleft combined with an extended nozzle overcoming the flow-limiting effect of the nasal valve promotes nasal irrigation efficiency.

Patterns of Gray and White Matter Volume Alterations in Patients With Post-Traumatic Anosmia: A Voxel-Based Morphometry Study.

Objective: Traumatic brain injury is one of the major causes of human olfactory dysfunction and leads to brain structure alterations, mainly in the cortical olfactory regions. Our study aimed to investigate volume changes in the gray matter (GM) and white matter (WM) in patients with post-traumatic anosmia and then to explore the relationship between GM volume and olfactory function. Methods: Ethics committee approved prospective studies which included 22 patients with post-traumatic anosmia and 18 age- and gender-matched healthy volunteers. Olfactory function was assessed using the Sniffin' Sticks. High-resolution 3-dimensional T1 MRIs of the participants were acquired on a 3T scanner and the data were collected for voxel-based morphometry (VBM) analysis. Furthermore, the GM and WM volumes of the whole brain regions were compared and correlated with olfactory function. Results: The analysis revealed significant GM volume reduction in the orbitofrontal cortex (OFC), gyrus rectus (GR), olfactory cortex, insula, parahippocampal, temporal pole, and cerebellum (all P < 0.001) in patients. Besides, WM volume loss was also found in the OFC, GR, and insula (all P < 0.001) in patients. All WM atrophy areas were connected to areas of GM volume loss spatially. Correlation analysis showed the olfactory scores were significantly positively correlated with the GM volume of the occipital cortex (P < 0.001, and P FWE < 0.05), while no significant correlation was found between the Sniffin' Sticks test scores and the WM volume in patients. Conclusion: The reduction of GM and WM volume in olfactory-related regions was responsible for olfactory dysfunction in post-traumatic patients. The occipital cortex may play a compensation mechanism to maintain the residual olfactory function. To our knowledge, we report here for the first time on white matter volume alterations specifically in post-traumatic patients with anosmia.

Clinical Implications of Psychophysical Olfactory Testing: Assessment, Diagnosis, and Treatment Outcome.

PURPOSE OF REVIEW: Olfactory dysfunction dramatically impairs quality of life with a prevalence of 20% in the general adult population. Psychophysical olfactory testing has been widely used to evaluate the ability to smell due to its validated utility and feasibility in clinic. This review summarizes the current literature regarding psychophysical olfactory testing and the clinical relevance of the olfactory testing with different components. Furthermore, the review highlights the diagnosis and treatment value of olfactory subtests in patients with olfactory dysfunction. RECENT FINDINGS: With the accumulation of studies of psychophysical olfactory testing in olfactory disorders, the clinical relevance of olfactory testing with different components is expanding. Different olfactory domains present with distinct olfactory processing and cortical activity. Psychophysical assessment of olfaction with three domains reveals different levels of olfactory processing and might assist with analyzing the pathophysiologic mechanism of the various olfactory disorders. Furthermore, olfactory thresholds provided the largest amount of non-redundant information to the olfactory diagnosis. Sinonasal olfactory dysfunction and non-sinonasal-related olfactory dysfunction are emerging classifications of smell disorders with certain characteristics of olfactory impairment and different responses to the therapy including steroids, sinus surgery, and olfactory training. SUMMARY: These recent advancements should promote the understanding of psychophysical olfactory testing, the association between individual subcomponents and neurophysiological processes, and pave the way for precision assessment and treatment of the olfactory dysfunction.

Development of Chinese odor identification test.

BACKGROUND: Olfactory dysfunction significantly reduces quality of life, with a prevalence as high as 20% in the general adult population. Odor identification (OI) tests are culturally dependent and widely used in clinical and epidemiological evaluations of olfaction. We aimed to develop a Chinese odor identification test (COIT) based on the Sniffin' Sticks identification test. METHODS: Patients (n=60) with olfactory disorders and healthy controls (n=404) were recruited in the Smell and Taste Center of a tertiary-care university hospital. Unfamiliar odors in the Sniffin' Sticks identification test were replaced to create a 16-item COIT, which was validated with a simplified Chinese version of the Cross-culture Smell Identification Test (CC-SIT) and Sniffin' Sticks. A test-retest reliability of COIT was also conducted. RESULTS: Six odors with a correct recognition rate <75% were replaced with familiar odors for Chinese. The COIT score significantly correlated with both Sniffin' Sticks (r=0.755 P<0.0001) and CC-SIT score (r=0.7462 P<0.0001). Based on the testing results of an additional 120 subjects, we concluded that scores of 12-16, 7-11, and 0-6 corresponded to normosmia, hyposmia, and anosmia, respectively. The 3-month test-retest-reliability coefficient was as high as 0.83. CONCLUSIONS: The COIT is an effective tool for assessing olfactory function in the Chinese population.