The brain functional connectivity alterations in traumatic patients with olfactory disorder after low-level laser therapy demonstrated by fMRI.

BACKGROUND: Low-level laser therapy (LLLT) has been clinically accepted to accelerate the nerve regeneration process after a nerve injury or transection. We aimed to investigate the neuronal basis and the influence of LLLT on brain functional networks in traumatic patients with olfactory dysfunction. METHODS: Twenty-four Patients with traumatic anosmia/hyposmia were exposed to pleasant olfactory stimuli during a block-designed fMRI session. After a 10-week period, patients as control group and patients who had completed the sessions of LLLT were invited for follow-up testing using the same fMRI protocol. Two-sample t-tests were conducted to explore group differences in activation responding to odorants (p-FDR-corrected <0.05). Differences of functional connectivity were compared between the two groups and the topological features of the olfactory network were calculated. Correlation analysis was performed between graph parameters and TDI score. RESULTS: Compared to controls, laser-treated patients showed increased activation in the cingulate, rectus gyrus, and some parts of the frontal gyrus. Shorter pathlength (p = 0.047) and increased local efficiency (p = 0.043) within the olfactory network, as well as decreased inter-network connectivity within the whole brain were observed in patients after laser surgery. Moreover, higher clustering and local efficiency were related to higher TDI score, as manifested in increased sensitivity to identify odors. CONCLUSIONS: The results support that low-level laser induces neural reorganization process and make new connections in the olfactory structures. Furthermore, the connectivity parameters may serve as potential biomarkers for traumatic anosmia or hyposmia by revealing the underlying neural mechanisms of LLLT.

Assessment of factors influencing the olfactory bulb volume in patients with post-viral olfactory dysfunction.

PURPOSE: To investigate the factors influencing the volume of the olfactory bulb (OB) in patients with post-viral olfactory dysfunction (PVOD). METHODS: We collected 92 olfactory bulb volumes from patients with PVOD who underwent a sinus computed tomographic and magnetic resonance imaging (MRI) scan of the head and collected clinical information including gender, age, disease course, minimal cross-sectional area, nasal airway resistance, and olfactory function. OB volume was measured in MRI and the scans were evaluated according to the Lund-Mackay (LM) scoring system. RESULTS: Male patients with PVOD had a larger OB volume (ß = 0.284, P < 0.05). OB volume was smaller in patients with a longer course of olfactory dysfunction (ß = - 0.254, P < 0.05). According to the LM scoring system, patients with a higher anterior ethmoidal sinus score had smaller OB volume (ß = - 0.476, P < 0.05). CONCLUSIONS: The study revealed that gender, disease course, and the score of anterior ethmoidal sinusitis can affect the OB volume in patients with PVOD.

Deficits in peripheric and central olfactory measurements in smokers: evaluated by cranial MRI.

OBJECTIVES: Cigarette smoking remains a serious health problem all over the world. We investigated the peripheral and central olfactory pathways in young male smokers to determine whether there is a relationship between the amount of cigarettes smoked and duration of smoking and the dimensions of the olfactory areas. METHODS: In this retrospective study, cranial Magnetic Resonance Imaging (MRI) images of adult male smokers aged ≤ 40 years (n = 51) and 50 healthy male adults were analyzed. The olfactory bulbus (OB) volumes and olfactory sulcus (OS) depths, insular gyrus, and corpus amygdala areas were measured via cranial MRI. In the smoker group, the number of cigarettes smoked and duration of smoking were noted and the Brinkmann index was calculated. RESULTS: OB volume, OS depth, and the insular gyrus areas of the smokers were lower than in the control group (p < 0.05). There were no differences between the groups in terms of the corpus amygdala measurements (p > 0.05). No significant correlations were found between the number of cigarettes smoked daily, smoking duration, and the Brinkmann index and the peripheral and central olfactory measurements in our study (p > 0.05). CONCLUSIONS: In smokers, OB volumes, the OS, and the central areas decrease bilaterally, regardless of smoking duration and number of cigarettes smoked daily. This could be related to inflammatory mediators that may be harmful to the olfactory neuroepithelium, gray matter atrophy in the brain, or endothelial damage related to smoking and its effects on blood support to the brain and olfactory regions.

Magnetic resonance imaging findings in patients with idiopathic olfactory dysfunction and normal findings on nasoendoscopy.

OBJECTIVE: In presentations of anosmia or dysosmia, magnetic resonance imaging may be required to screen for intracranial pathology such as olfactory neuroblastomas and other intracranial masses impacting on the olfactory pathway. This study aimed to establish positive magnetic resonance imaging findings of anosmia or dysosmia for scans performed before the coronavirus disease 2019 pandemic. METHODS: The study examined the outcome of patients who presented with isolated olfactory dysfunction and who underwent magnetic resonance imaging between 2015 and 2019. RESULTS: Of the 131 patients, 41 (31.3 per cent) had normal scan findings, 50 (38.2 per cent) had insignificant paranasal mucosal disease and 6 (4.6 per cent) had mucosal thickening significant enough to require additional intervention. These interventions included repeat nasoendoscopy or commencement of intranasal or oral steroids. No patients had olfactory neuroblastoma. CONCLUSION: Only 4.6 per cent of the magnetic resonance imaging scans revealed abnormal findings related to anosmia or dysosmia, and none required ENT surgical intervention. None of the magnetic resonance imaging scans identified an olfactory neuroblastoma or intracranial masses impacting on the olfactory pathway.

The use of MRI in a tertiary smell and taste clinic: Lessons learned based on a retrospective analysis.

BACKGROUND: Olfactory dysfunction (OD) is a common but underreported problem that can significantly impact a patient's quality of life. OD is prevalent in over 5% of the adult population and can be broadly categorised into conductive and sensorineural causes. Magnetic Resonance Imaging (MRI) can form part of the diagnostic work up, although its exact role is often debated. OBJECTIVES: The aim of this study was to evaluate the value of MRI in managing patients with OD. DESIGN/METHOD: A retrospective analysis of the records of patients presenting to a national smell and taste clinic over a 5-year period was performed. Variables included demographics, endoscopic findings, final diagnosis, psychophysical smell test and imaging results. RESULTS: A total of 409 patients, with an age range of 10-93 years, underwent clinical assessment and smell testing, of which 172 patients (42%) had MRI scans. Imaging in younger age-groups was associated with a higher rate of positive findings, however identifiable causes for OD were recorded across the range. MRI provided both diagnostic and prognostic information in those with idiopathic, traumatic and congenital causes of OD. For example, MRI provided information on the extent or absence of gliosis in those with a head trauma history allowing further treatment and prognosis. CONCLUSION: We recommend the adjunct use of MRI in patients with a clear history and examination findings of head injury, congenital cases and in apparent idiopathic cases. MRI should be requested to compliment clinical findings with a view to aiding decision-making on treatment and prognosis independent of patient's age.

The Olfactory Nerve: Anatomy and Pathology.

The human sense of smell is the unique sense through which the olfactory system can identify aromatic molecules within the air and provide a taste sensation. Still, also it plays an essential role in several other functions, warning about environmental safety and even impacts our emotional lives. Recently, olfactory impairment has become an issue of interest due to the COVID-19 pandemic. The dysfunction may vary from only reduced smell detection (hyposmia) to complete loss of it (anosmia) but also includes changes in the normal perception of odors (parosmia). Computed tomography and magnetic imaging resonance are the modalities of choice to evaluate the olfactory pathways. Computed tomography is the initial imaging modality for olfactory disturbances, allowing recognition of sinonasal pathologies, inflammatory processes, or bone-related tumors. Magnetic imaging resonance with dedicated protocols for olfactory disorders enables a detailed assessment of the sinonasal compartment and the anterior cranial fossa. Provides a better depiction of olfactory bulb volume, morphology and signal intensity, as well the status of signal intensity of the central olfactory projection areas. Several diseases can affect the olfactory nerve, such as congenital disorders, trauma, inflammatory or infectious diseases, neoplasms, and even post-operative involvement. This article aims to review the normal anatomy of the olfactory nerve pathway and highlight the spectrum of conditions that most commonly affect it.

Magnetic Resonance Imaging as a Diagnostic and Research Tool in Patients with Olfactory Dysfunction: A Systematic Review.

BACKGROUND: Patients with acquired, idiopathic olfactory dysfunction (OD) commonly undergo magnetic resonance imaging (MRI) evaluation to rule out intracranial pathologies. This practice is highly debated given the expense of MRI relative to the probability of detecting a treatable lesion. This, combined with the increasing use of MRI in research to investigate the mechanisms underlying OD, provided the impetus for this comprehensive review. OBJECTIVE: The purpose of this systematic review was to both assess the utility of MRI in diagnosis of idiopathic OD and to describe MRI findings among mixed OD etiologies to better understand its role as a research tool in this patient population. METHODS: A literature search of PubMed, Embase, Cochrane, Web of Science, and Scopus for studies with original MRI data for patients with OD was completed. Studies exclusively investigating patients with neurocognitive deficits or those studying traumatic or congenital etiologies of OD were excluded. RESULTS: From 1758 candidate articles, 33 studies were included. Four studies reviewed patients with idiopathic OD for structural pathologies on MRI, of which 17 of 372 (4.6%) patients had a potential central cause identified, and 3 (0.8%) had an olfactory meningioma or olfactory neuroblastoma. Fourteen studies (42.4%) reported significant correlation between olfactory bulb volume and olfactory outcomes, and 6 studies (18.8%) reported gray matter volume reduction, specifically in the orbitofrontal cortex, anterior cingulate cortex, insular cortex, parahippocampal, and piriform cortex areas, in patients with mixed OD etiologies. Functional MRI studies reported reduced brain activation and functional connectivity in olfactory network areas. CONCLUSION: MRI uncommonly detects intracranial pathology in patients with idiopathic OD. Among patients with mixed OD etiologies, reduced olfactory bulb and gray matter volume are the most common abnormal findings on MRI. Further research is required to better understand the role of MRI and its cost-effectiveness in patients with acquired, idiopathic OD.

Analysis of conductive olfactory dysfunction using computational fluid dynamics.

Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal-nasopharynx pressure at maximum flow, we established a cut-off value at which nasal breathing can be differentiated from combined mouth breathing in COD patients. We found that increased nasal resistance led to mouth breathing and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects. In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa. Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.

Cortical Atrophy, White Matter Lesions, and Bulb Configuration in Patients with Idiopathic Olfactory Loss and Other Causes of Olfactory Loss.

INTRODUCTION: While magnetic resonance imaging (MRI) is not included in the current guidelines for diagnosing olfactory disorders in the most recent position paper on olfactory dysfunction, both 1.5T and 3T MRI are commonly used in the diagnostic workup of many patients with olfactory loss. Often, MRI is used to rule out intracranial tumours, but other useful information may be obtained from MRI scans in these patients. The potential of MRI in olfactory loss depends on sufficient knowledge of structural changes in different aetiologies of olfactory loss. We present common clinical MRI findings in olfactory loss and evaluate the usefulness of structural integrity scores in differentiating between aetiologies. METHODS: In this study, we investigated if white matter hyperintensities (WMHs, measured by Fazekas score), global cortical atrophy (GCA), and medial temporal lobe atrophy (MTA) are more common in patients with idiopathic olfactory loss than in patients with acquired olfactory loss due to other aetiologies. Furthermore, we compared olfactory bulb (OB) configurations in different olfactory loss aetiologies. RESULTS: In 88 patients with olfactory loss, WMHs, GCA, and MTA were not more significant findings on MRI in idiopathic olfactory loss (n = 51) compared with other causes of acquired olfactory loss (Fazekas score p = 0.2977; GCA score p = 0.6748; MTA score p = 0.7851). Bulb configurations differed in patients suffering from post-traumatic olfactory loss and may aid in identifying the underlying aetiology in patients where trauma is among the suspected causes of olfactory loss. CONCLUSION: We recommend that structural MRI with an OB sequence is included in the diagnostic evaluation of olfactory loss with suspected congenital and post-traumatic aetiology and should be considered in idiopathic olfactory loss with suspected central aetiology (e.g., tumour).

Evaluation of the olfactory bulb volume and morphology in patients with coronavirus disease 2019: can differences create predisposition to anosmia?

SUMMARY OBJECTIVE: This study aimed to investigate whether the volume and morphology of the olfactory bulb are effective in the occurrence of anosmia in patients after COVID-19 infection. METHODS: The olfactory bulbus volume was calculated by examining the brain magnetic resonance imaging of cases with positive (+) COVID-19 polymerase chain reaction test with and without anosmia. Evaluated magnetic resonance imaging images were the scans of patients before they were infected with COVID-19. The olfactory bulbus and olfactory nerve morphology of these patients were examined. The brain magnetic resonance imaging of 59 patients with anosmia and 64 controls without anosmia was evaluated. The olfactory bulb volumes of both groups were calculated. The olfactory bulb morphology and olfactory nerve types were examined and compared between the two groups. RESULTS: The left and right olfactory bulb volumes were calculated for the anosmia group and control group as 47.8±15/49.3±14.3 and 50.5±9.9/50.9±9.6, respectively. There was no statistically significant difference between the two groups. When the olfactory bulb morphology was compared between the two groups, it was observed that types D and R were dominant in the anosmia group (p<0.05). Concerning olfactory nerve morphology, type N was significantly more common in the control group (p<0.05). CONCLUSIONS: According to our results, the olfactory bulb volume does not affect the development of anosmia after COVID-19. However, it is striking that the bulb morphology significantly differs between the patients with and without anosmia. It is clear that the evaluation of COVID-19-associated smell disorders requires studies with a larger number of patients and a clinicoradiological approach.

Evaluation of the Neuroanatomical Basis of Olfactory Dysfunction in the General Population.

Importance: Olfactory dysfunction is a prodromal manifestation of many neurodegenerative disorders, including Alzheimer and Parkinson disease. However, its neuroanatomical basis is largely unknown. Objective: To assess the association between olfactory brain structures and olfactory function in adults 30 years or older and to examine the extent to which olfactory bulb volume (OBV) mediates the association between central olfactory structures and olfactory function. Design, Setting, and Participants: This cross-sectional study analyzed baseline data from the first 639 participants with brain magnetic resonance imaging (MRI) in the Rhineland Study, an ongoing population-based cohort study in Bonn, Germany. Participants were enrolled between March 7, 2016, and October 31, 2017, and underwent brain MRI and olfactory assessment. Data were analyzed from March 1, 2018, to June 30, 2021. Exposure: Volumetric measures were derived from 3-T MRI T1-weighted brain scans, and OBV was manually segmented on T2-weighted images. The mean volumetric brain measures from the right and left sides were calculated, adjusted by head size, and normalized to all participants. Main Outcomes and Measures: Performance on the 12-item smell identification test (SIT-12) was used as a proxy for olfactory function. Results: A total of 541 participants with complete data on MRI-derived measures and SIT-12 scores were included. This population had a mean (SD) age of 53.6 (13.1) years and comprised 306 women (56.6%). Increasing age (difference in SIT-12 score, -0.04; 95% CI, -0.05 to -0.03), male sex (-0.26; 95% CI, -0.54 to 0.02), and nasal congestion (-0.28; 95% CI, -0.66 to 0.09) were associated with worse olfactory function (SIT-12 scores). Conversely, larger OBV was associated with better olfactory function (difference in SIT-12 score, 0.46; 95% CI, 0.29-0.64). Larger volumes of amygdala (difference in OBV, 0.12; 95% CI, 0.01-0.24), hippocampus (0.16; 95% CI, 0.04-0.28), insular cortex (0.12; 95% CI, 0.01-0.24), and medial orbitofrontal cortex (0.10; 95% CI, 0.00-0.20) were associated with larger OBV. Larger volumes of amygdala (volume × age interaction effect, 0.17; 95% CI, 0.03-0.30), parahippocampal cortex (0.17; 95% CI, 0.03-0.31), and hippocampus (0.21; 95% CI, 0.08-0.35) were associated with better olfactory function only in older age groups. The age-modified association between volumes of central olfactory structures and olfactory function was largely mediated through OBV. Conclusions and Relevance: This cross-sectional study found that olfactory bulb volume was independently associated with odor identification function and was a robust mediator of the age-dependent association between volumes of central olfactory structures and olfactory function. Thus, neurodegeneration-associated olfactory dysfunction may primarily originate from the pathology of peripheral olfactory structures, suggesting that OBV may serve as a preclinical marker for the identification of individuals who are at an increased risk of neurodegenerative diseases.

Sinonasal surgery alters brain structure and function: Neuroanatomical correlates of olfactory dysfunction.

Olfactory dysfunction (OD) is more common than hearing loss, partial blindness, or blindness and can have a significant impact on the quality of life. Moreover, unexplained OD is an early biomarker in neurodegenerative diseases and increases 5-year mortality risk. Structural alterations in olfactory eloquent brain regions may represent the neuroanatomical correlates of OD. Previous studies have demonstrated reduced gray matter (GM) volume in areas of presumed olfactory relevance in patients with OD. However, being cross-sectional in nature, these studies do not provide evidence of causality, for which longitudinal work is required. At present, however, longitudinal studies addressing olfactory structural plasticity are limited, both in number and methodological approach: to our knowledge, such work has not included parallel functional imaging to confirm the relevance of structural change. We therefore performed a longitudinal multimodal neuroimaging study investigating structural and functional plasticity in 24 patients undergoing surgical treatment for chronic rhinosinusitis, compared with 17 healthy controls. We demonstrated functionally significant structural plasticity within the orbitofrontal, anterior cingulate and insular cortices, and temporal poles in patients 3 months after surgery. Of interest, GM volume decreased in these regions, in association with increased psychophysical scores and BOLD signal. To our knowledge, this is the first study to demonstrate both structural and functional plasticity of the central olfactory networks, thereby confirming these areas as neuroanatomical correlates of olfactory function/dysfunction.

Evaluation of taste and smell disorders in pediatric COVID-19 Cases

SUMMARY OBJECTIVE: Pediatric coronavirus disease 2019 (COVID-19) cases have a high risk of contagiousness, as they usually progress with asymptomatic or mild respiratory symptoms. Disorder in taste and/or smell has rarely been reported in pediatric cases. In our study, early diagnosis and isolation measures were emphasized by evaluating the clinical, laboratory, and radiological imaging findings of pediatric COVID-19 cases presenting with symptoms of taste and/or smell disorder. METHODS: Seven cases aged 0-18 years were included in the study. The severe acute respiratory syndrome coronavirus-2 polymerase chain reaction test was performed for the seven cases presented with taste and/or smell disorders. Clinical findings, laboratory tests, and radiological imaging of all the cases were evaluated on the day of admission and on the fifth day. RESULTS: Seven (5.7%) of 122 pediatric COVID-19 cases had disorder in taste and/or smell. In two cases, pneumonia findings were detected in thorax computed tomography imaging. It was observed that all the patients fully recovered at the latest on the 21st day. In the cranial diffusion magnetic resonance imaging of a case, diffusion restriction was detected in the corpus callosum splenium. CONCLUSION: Although less common than adults, children with COVID-19 may also have taste and smell disorders, and this may be accompanied by central nervous system imaging findings.

Olfactory Cleft Width and Volume: Possible Risk Factors for Postinfectious Olfactory Dysfunction.

OBJECTIVES/HYPOTHESIS: Upper respiratory tract infections are a common cause of temporary and permanent olfactory dysfunction in the general population. Postviral or postinfectious olfactory loss (PIOL) develops only in rare cases. The aim of this study was to investigate the anatomical features of olfactory cleft (OC) in patients with PIOL to shed light on possible predisposing factors for PIOL. STUDY DESIGN: Retrospective study. METHODS: We retrospectively evaluated paranasal sinus computed tomography (CT) scan results of patients diagnosed with PIOL. A control group consisted of normosmic individuals who underwent paranasal sinus CT scans before septoplasty surgery. We compared the olfactory fossa depth, OC width, and volume on the CT scans of the PIOL and control groups. RESULTS: In total, 71 individuals fulfilled the study criteria (PIOL group, n = 32; control group, n = 39). There was no statistically significant difference in the olfactory fossa depth in the two groups. The OC width and volume in the PIOL group was found to be significantly increased than that in the control group (P < .001 for both). CONCLUSIONS: Patients with PIOL had increased OC width and volume than the healthy controls. An extra-wide olfactory cleft may be a predisposing factor in the pathogenesis of PIOL. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:5-9, 2021.

Individual variability of olfactory fMRI in normosmia and olfactory dysfunction.

PURPOSE: The diagnosis of olfactory dysfunction is mainly based on psychophysical measurements. The aim of the current study was to investigate how well the olfactory functional magnetic resonance imaging (fMRI) can effectively distinguish between normosmic people and subjects with olfactory dysfunction. METHODS: Thirty-eight participants were recruited for the study. Group 1 consisted of 22 subjects with olfactory dysfunction (mean age = 44.3 years, SD = 18.6), and Group two consisted of 16 participants with normal olfactory function (mean age = 49.6 years, SD = 11.6). Olfactory functions were assessed in great detail for all participants, and brain activation in response to odorous stimulation was assessed using fMRI. RESULTS: The between-group comparison showed stronger odor induced brain activation of the primary olfactory area and the insular cortex among the normosmic group as compared to the dysosmic group. As indicated by the individual analysis, positive responses in the primary olfactory cortex were significantly higher in normosmic people (94%) than in subjects with olfactory dysfunction (41%). However, there was no association between individual fMRI parameters (including the percentage of BOLD signal change, activated cluster size and peak z value), and psychophysical olfactory test scores. Receiver operating characteristic analysis suggested the subjects could not be differentiated from normosmics based on their BOLD signal from the primary olfactory area, orbitofrontal cortex, or the insular cortex. CONCLUSION: There are large inter-individual variabilities for odor-induced brain activation among normosmic subjects and subjects with olfactory dysfunction, due to this variation, at present it appears problematic to diagnose olfactory dysfunction on an individual level using fMRI.

Diagnostic Accuracy of MRI-Based Morphometric Parameters for Detecting Olfactory Nerve Dysfunction.

BACKGROUND AND PURPOSE: Although olfactory dysfunction is a common cranial nerve disorder, there are no simple objective morphometric criteria to assess olfactory dysfunction. The aim of this study was to evaluate the diagnostic performance of MR imaging morphometric parameters for detecting olfactory dysfunction. MATERIALS AND METHODS: This prospective study enrolled patients from those presenting with olfactory symptoms who underwent both an olfactory function test and MR imaging. Controls without olfactory dysfunction were recruited during the preoperative work-up for pituitary adenoma. Two independent neuroradiologists measured the olfactory bulb in 3D and assessed olfactory bulb concavity on MR imaging while blinded to the clinical data. Diagnostic performance was assessed using receiver operating characteristic curve analysis. RESULTS: Sixty-four patients and 34 controls were enrolled. The patients were significantly older than the controls (mean age, 57.8 ± 11.9 years versus 47.1 ± 12.1 years; P < .001). Before age adjustment, the olfactory bulb height was the only olfactory bulb parameter showing a significant difference between patients and controls (1.6 ± 0.3 mm versus 2.0 ± 0.3 mm, P < .001). After age adjustment, all parameters and olfactory bulb concavity showed significant intergroup differences, with the olfactory bulb height having the highest area under the curve (0.85). Olfactory bulb height was confirmed to be the only significant parameter showing a difference in the detection of olfactory dysfunction in 22 pairs after matching for age and sex (area under the curve = 0.87, P < .001). Intraclass correlation coefficients revealed moderate-to-excellent degrees of inter- and intrareader agreement. CONCLUSIONS: MR imaging morphometric analysis can differentiate patients with olfactory dysfunction, with the olfactory bulb height having the highest diagnostic performance for detecting olfactory dysfunction irrespective of age.

Relationship Between Olfactory Disturbance After Acute Ischemic Stroke and Latent Thalamic Hypoperfusion.

Odor detection, recognition, and identification were assessed in 19 acute ischemic stroke patients who had no magnetic resonance imaging-detectable thalamic lesions but in whom technetium-99m ethyl cysteinate dimer single photon emission tomography revealed thalamic hypoperfusion. Although these patients were unaware of reduced olfactory function, they exhibited significantly lower scores in tests for odor identification and recognition threshold as compared with 9 ischemic stroke controls that had normal thalamic hypoperfusion. However, absolute odor detection thresholds were similar in the 2 groups. These results demonstrate the usefulness of cerebral perfusion scintigraphy in assessing sensory loss after ischemic stroke and provide further evidence for the role of the thalamus in olfaction.

Olfactory cleft and sinus opacification differentially impact olfaction in chronic rhinosinusitis.

OBJECTIVES: Prior studies have indicated that olfactory cleft (OC) opacification correlates with olfaction in patients with chronic rhinosinusitis (CRS). However, the results have been unclear in patients without polyps. The purpose of this study was to further explore the relationship between OC opacification, sinus opacification, and olfactory function in patients with CRS. METHODS: One hundred and forty-eight patients with CRS were prospectively enrolled across five institutions. Olfactory function was evaluated using the Sniffin' Sticks tests (Burghardt, Wedel, Germany) and the 17-item Questionnaire of Olfactory Disorders (QOD-NS). Computed tomography (CT) scans for each patient were acquired and Lund-Mackay scores recorded. Opacification of the OC was determined using OsiriX MD (Pixmeo, Bernex, Switzerland) and correlated with olfaction scores. RESULTS: A total of 148 CRS patients, 73 CRS without nasal polyps (CRSsNP) and 75 CRS with nasal polyps (CRSwNP), as well as 30 control subjects were enrolled. Overall OC opacification averaged 63.7% in CRS patients and 47.1% in control subjects (P < 0.001). In the overall cohort, OC opacification significantly correlated with threshold, discrimination, and identification (TDI) (r = -0.520; P < 0.001) and QOD-NS scores (r = 0.374; P < 0.001). CRSwNP patients demonstrated a significant correlation between OC opacification and TDI scores (r = -0.464; P < 0.001) but not the CRSsNP group (r = -0.143; P = 0.229). Lund-Mackay score correlated with TDI in both the CRSsNP (r = -0.300; P = 0.010) and CRSwNP (r = -0.271; P = 0.019) groups. CONCLUSION: CT opacification is associated with olfactory dysfunction differentially based on nasal polyp status. Smell loss in CRSwNP correlated with both OC opacification and Lund-Mackay score, whereas CRSsNP correlated only with Lund-Mackay score, indicating different relationships between olfactory function and local inflammatory processes in these disorders. LEVEL OF EVIDENCE: 2 Laryngoscope, 130:2311-2318, 2020.