Olfactory Cleft Opacification in COVID-19 Related Smell Loss: CT Findings and Correlation With Objective Testing

Abstract

Objectives: Besides the common symptoms of the coronavirus disease 2019 (COVID-19) including fever, shortness of breath, and cough, a “sudden loss of smell” has recently been added as a diagnostic symptom. The relationship between paranasal sinus computed tomography (PNS CT) and sudden loss of smell in COVID-19 was examined. Materials and Methods: Two groups were selected for the study, the COVID-19 and the control groups. The control group consisted of 40 patients who applied to our clinic with headache and therefore underwent PNS CT. The other group consisted of 40 patients with COVID-19 who were diagnosed with sudden loss of smell with the Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test. Clinical and demographic characteristics, tomography results, and olfactory test scores of patients with COVID-19 loss of smell and control group patients were recorded. The relationship between CT changes in the olfactory cleft and the degree of loss of smell was evaluated. The “Opacification in the olfactory cleft” was accepted as a positive CT finding. Results: Comparison of patients with COVID-19 who had a loss of smell and the control group indicated that a significant difference was observed in terms of CT findings ( P = .022). When we evaluated the paranasal CTs obtained from our patients with loss of smell, the CT of 13 patients showed pathological findings ( P < .05). As the COVID-19 progressed (pneumonia and respiratory failure), the degree of loss of smell increased ( P < .05). A statistically significant relationship was found between the CCCRC score and the presence of PNS CT findings ( P = .0012). Conclusion: The PNS CT findings are significant in patients with COVID-19 with a loss of smell and were significantly associated with the degree of loss of smell. In patients with olfactory loss due to COVID-19, PNS CT can help in diagnosis. However, for this imaging to be diagnostic, a larger patient series is needed.

Comparison of Brain Activation Patterns during Olfactory Stimuli between Recovered COVID-19 Patients and Healthy Controls: A Functional Near-Infrared Spectroscopy (fNIRS) Study

“…Olfactory dysfunction may be due to olfactory cleft opacification and olfactory bulb degeneration, detected by magnetic resonance imaging (MRI) of the olfactory bulb and computer tomography of the paranasal sinus [9]. Furthermore, there has been a report on the association between opacification in the olfactory cleft and the degree of loss of smell [10]. Olfactory dysfunction is thought to manifest when viral replication in the non-neural olfactory cells indirectly cause damage to the olfactory receptor nerves [11].…”

Neuroradiological Basis of COVID‐19 Olfactory Dysfunction: A Systematic Review and Meta‐Analysis

“…Study characteristics for aggregate studies and individual case reports are summarized in Tables I-III, and S3-S6. Briefly, there were 7 case-control studies (N = 353), [25][26][27][28][29][30][31] 11 case series (N = 154), 16,[32][33][34][35][36][37][38][39][40][41] and 12 case reports (N = 12), 17,18,[42][43][44][45][46][47][48][49][50][51] Mild irregularity with preserved J-shape (n = 2) 13 Contour lobulations (n = 5) 13 Rectangular shape (n Diffusely increased signal (n = 9) 13 Hyperintense foci without halo (n = 11) 13 Hyperintense foci with halo (n = 5) 13 Microhemorrhages (n = 4) 13 8/50 (16%) opacification noted on CT and/or MRI (57.4%). MRI demonstrated bilateral and unilateral olfactory cleft opacification in 49 patients 16,26,27,40 and 4 patients, respectively.…”

“…16,40 In 13 patients imaged using CT, it was not reported if opacification was found in only one or both olfactory clefts. 31 Figure 3 shows T2-weighted coronal MR image demonstrating complete opacification of bilateral olfactory clefts in a patient with COVID-19 and OD. 40 In the control group, 3 out of 67 patients had olfactory cleft opacification (4.5%).…”

“…One patient with COVID-19 infection without OD had bilateral olfactory cleft opacification seen on MRI. 27 In the two patients without COVID-19 infection and OD, it was not stated if opacification affected one or both clefts on CT. 31 Data on olfactory cleft opacification in patients with COVID-19 infection and OD, and control subjects, was reported in five aggregate studies. 16,26,27,31,40 Data from these aggregate studies was pooled in a meta-analysis, along with individual patient data compiled from case reports and small case series, as demonstrated in Figure 4.…”

“…27 In the two patients without COVID-19 infection and OD, it was not stated if opacification affected one or both clefts on CT. 31 Data on olfactory cleft opacification in patients with COVID-19 infection and OD, and control subjects, was reported in five aggregate studies. 16,26,27,31,40 Data from these aggregate studies was pooled in a meta-analysis, along with individual patient data compiled from case reports and small case series, as demonstrated in Figure 4. The pooled prevalence of olfactory cleft opacification in patients with COVID-19 infection and OD was 63% (95% CI = 0.38-0.82, I 2 = 73%, N = 115), which was significantly higher than the pooled prevalence of 4% (95% CI = 0.01-0.13, I 2 = 0%, N = 67) in control subjects, which consisted of 7 normosmic COVID-19 patients, and 60 normosmic non-COVID-19 individuals.…”