Olfactory Cleft Length: A Possible Risk Factor for Persistent Post-COVID-19 Olfactory Dysfunction.

INTRODUCTION: To date, little is known about predisposing factors for persistent COVID-19-induced olfactory dysfunction (pCIOD). The objective was to determine whether olfactory cleft (OC) measurements associate with pCIOD risk. MATERIAL AND METHODS: Three subgroups were recruited: group A included patients with pCIOD, group B included patients without olfactory dysfunction following SARS-CoV-2 infection (ntCIOD), and group C consisted in controls without past history of SARS-CoV-2 infection (noCOVID-19). Olfactory perception threshold (OPT) and visual analog scale for olfactory impairment (VAS-olf) were obtained. OC measurements were obtained through computed tomography scans. Results were subsequently compared. RESULTS: A total of 55 patients with a mean age of 39 ± 10 years were included. OPT was significantly lower in pCIOD patients (group A: 4.2 ± 2.1 vs. group B: 12.3 ± 1.8 and group C: 12.2 ± 1.5, p < 0.001). VAS-olf was significantly higher in pCIOD (group A: 6 ± 2.6 vs. group B: 1.7 ± 1.6 and group C: 1.6 ± 1.5, p < 0.001). OC length was significantly higher in group A (42.8 ± 4.6) compared to group B (39.7 ± 3.4, p = 0.047) and C (39.8 ± 4, p = 0.037). The odd of pCIOD occurring after COVID-19 infection increased by 21% (95% CI [0.981, 1.495]) for a one unit (mm) increase in OC length. The odd of pCIOD occurring was 6.9 times higher when OC length >40 mm. CONCLUSION: Longer OC may be a predisposing factor for pCIOD. This study is expected to encourage further research on OC morphology and its impact on olfactory disorders.

Comparison of Olfactory Cleft Width and Volumes in Patients with COVID-19 Anosmia and COVID-19 Cases Without Anosmia.

INTRODUCTION: The aim of this study was to assess the relationship between olfactory cleft width/volume and COVID-19-related anosmia. METHODS: This study consisted of PCR-proven COVID-19 patients. Cases with COVID-19-related anosmia constituted Group 1 and cases without any olfactory dysfunction (OD) throughout COVID-19 infection or after recovery constituted Group 2. A total of 50 patients were included in the study, comprising 24 cases in Group 1 and 26 cases in Group 2. Group 1 patients underwent a 4-item-odor identification test during active symptoms and a Sniffin' Sticks test after reconversion of PCR results to negative. All patients in Group 2 also underwent the Sniffin' Stick test to document normosmia. All cases had paranasal sinus CT performed. Olfactory cleft widths and olfactory volumes were measured. The differences in width and volume between groups and the correlation with odor test scores (threshold-discrimination-identification [TDI]) were calculated. In addition, regression analyzes analysis was performed for cleft widths, volumes, and TDI scores according to age. RESULTS: Olfactory cleft widths and olfactory volumes were significantly higher in Group 1 than those in Group 2 (p = 0.001; p < 0.01). There was a significant negative correlation between total TDI scores and olfactory cleft widths and total olfactory volumes (r = -0.665; r = -0.731, respectively). Patients younger than 40 years of age had significantly higher right olfactory cleft width, left olfactory cleft width, and olfactory cleft volume than those in patients older than 40 years of age (p = 0.004, p = 0.005, p = 0.003; p < 0,01, respectively). However, patients younger than 40 years of age had a significantly lower total TDI score and in all other values individually (t-d-i) than those in patients older than 40 years of age (p = 0.004; p < 0.01). CONCLUSION: Patients with COVID-19-related OD had larger olfactory cleft width and volumes than those without OD in this study. Total TDI score was found to be inversely correlated with cleft width and volume.

Radiologic Assessment of the Sinonasal Tract, Nasopharynx and Mastoid Cavity in Patients with SARS-Cov-2 Infection Presenting with Acute Neurological Symptoms.

BACKGROUND: Acute neurological sequela in patients with COVID-19 infection include acute thromboembolic infarcts related to cytokine storm and post infectious immune activation resulting in a prothrombotic state. Radiologic imaging studies of the sinonasal tract and mastoid cavity in patients with COVID-19 infection are sparse and limited to case series. In this report, we investigate the radiologic involvement of nasal cavity, nasopharynx, paranasal sinuses, and mastoid cavity in patients with SARS-CoV-2 infection who presented with acute neurological symptoms. METHODS: Retrospective review of medical records and neuroradiologic imaging in patients diagnosed with acute COVID-19 infection who presented with acute neurological symptoms to assess radiologic prevalence of sinus and mastoid disease and its correlation to upper respiratory tract symptoms. RESULTS: Of the 55 patients, 23 (42%) had partial sinus opacification, with no evidence for complete sinus opacification. The ethmoid sinus was the most commonly affected (16/55 or 29%). An air fluid level was noted in 6/55 (11%) patients, most commonly in the maxillary sinus. Olfactory recess and mastoid opacification were uncommon. There was no evidence of bony destruction in any of the studies, Cough, nasal congestion, rhinorrhea, and sore throat were not significantly associated with any radiological findings. CONCLUSION: In patients who present with acute neurological symptoms, COVID-19 infection is characterized by limited and mild mucosal disease within the sinuses, nasopharynx and mastoid cavity. LEVEL OF EVIDENCE: 4.

Olfactory Bulb MRI and Paranasal Sinus CT Findings in Persistent COVID-19 Anosmia.

BACKGROUND AND PURPOSE: There is limited literature consisting of case reports or series on olfactory bulb imaging in COVID-19 olfactory dysfunction. An imaging study with objective clinical correlation is needed in COVID-19 anosmia in order to better understand underlying pathogenesis. MATERIAL AND METHODS: We evaluated 23 patients with persistent COVID-19 olfactory dysfunction. Patients included in this study had a minimum 1-month duration between onset of olfactory dysfunction and evaluation. Olfactory functions were evaluated with Sniffin' Sticks Test. Paranasal sinus CTs and MRI dedicated to olfactory nerves were acquired. On MRI, quantitative measurements of olfactory bulb volumes and olfactory sulcus depth and qualitative assessment of olfactory bulb morphology, signal intensity, and olfactory nerve filia architecture were performed. RESULTS: All patients were anosmic at the time of imaging based on olfactory test results. On CT, Olfactory cleft opacification was seen in 73.9% of cases with a mid and posterior segment dominance. 43.5% of cases had below normal olfactory bulb volumes and 60.9% of cases had shallow olfactory sulci. Of all, 54.2% of cases had changes in normal inverted J shape of the bulb. 91.3% of cases had abnormality in olfactory bulb signal intensity in the forms of diffusely increased signal intensity, scattered hyperintense foci or microhemorrhages. Evident clumping of olfactory filia was seen in 34.8% of cases and thinning with scarcity of filia in 17.4%. Primary olfactory cortical signal abnormality was seen in 21.7% of cases. CONCLUSION: Our findings indicate olfactory cleft and olfactory bulb abnormalities are seen in COVID-19 anosmia. There was a relatively high percentage of olfactory bulb degeneration. Further longitudinal imaging studies could shed light on the mechanism of olfactory neuronal pathway injury in COVID-19 anosmia.

Olfactory Cleft Measurements and COVID-19-Related Anosmia.

OBJECTIVE: This study aimed to investigate the differences in olfactory cleft (OC) morphology in coronavirus disease 2019 (COVID-19) anosmia compared to control subjects and postviral anosmia related to infection other than severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). STUDY DESIGN: Prospective. SETTING: This study comprises 91 cases, including 24 cases with anosmia due to SARS-CoV-2, 38 patients with olfactory dysfunction (OD) due to viral infection other than SARS-CoV-2, and a control group of 29 normosmic cases. METHODS: All cases had paranasal sinus computed tomography (CT), and cases with OD had magnetic resonance imaging (MRI) dedicated to the olfactory nerve. The OC width and volumes were measured on CT, and T2-weighted signal intensity (SI), olfactory bulb volumes, and olfactory sulcus depths were assessed on MRI. RESULTS: This study showed 3 major findings: the right and left OC widths were significantly wider in anosmic patients due to SARS-CoV-2 (group 1) or OD due to non-SARS-CoV-2 viral infection (group 2) when compared to healthy controls. OC volumes were significantly higher in group 1 or 2 than in healthy controls, and T2 SI of OC area was higher in groups 1 and 2 than in healthy controls. There was no significant difference in olfactory bulb volumes and olfactory sulcus depths on MRI among groups 1 and 2. CONCLUSION: In this study, patients with COVID-19 anosmia had higher OC widths and volumes compared to control subjects. In addition, there was higher T2 SI of the olfactory bulb in COVID-19 anosmia compared to control subjects, suggesting underlying inflammatory changes. There was a significant negative correlation between these morphological findings and threshold discrimination identification scores. LEVEL OF EVIDENCE: Level 4.

Paranasal sinuses computed tomography findings in anosmia of COVID-19.

OBJECTIVE: Olfactory dysfunction in coronavirus disease-2019 (COVID-19) is poorly understood. Thus, mechanistic data are needed to elucidate the pathophysiological drivers of anosmia of COVID-19. METHODS: We performed the current study in patients who presented with anosmia and COVID-19 as documented by the polymerase chain reaction (PCR) assay between April 1st and May 15st, 2020. We assessed for the conductive causes of anosmia with computed tomography (CT) of paranasal sinuses. RESULTS: 49 patients who presented with anosmia and positive PCR assay for COVID-19 were included. The average age was 45 ± 12.2 years. Complete anosmia was present in 85.7% of patients and 91.8% of patients reported sudden onset of olfactory dysfunction. Taste disturbance was common (75.5%). There were no significant pathological changes in the paranasal sinuses on CT scans. Olfactory cleft and ethmoid sinuses appeared normal while in other sinuses, partial opacification was detected only in some cases. CONCLUSION: We did not find significant mucosal changes or olfactory cleft abnormality on CT imaging in patients with anosmia of COVID-19. Conductive causes of anosmia (i.e., mucosal disease) do not seem play a significant role in anosmia of COVID-19.