Quantitative Analysis of the Olfactory System in COVID-19: An MR Imaging Study

Altunışık, Erman; Baykan, Ali Haydar; Şahin, Şükrü; Aydın, Elçin; Ertürk, Şükrü Mehmet

doi:10.3174/ajnr.a7278

Cited by 26 publications

(23 citation statements)

References 35 publications

(29 reference statements)

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“…The summary of demographic and methodologic characteristics for each included study can be found in Table 1 . The most frequently reported structural measurements were right OB volume and left OB volume with six studies [ 4 , 33 – 35 , 37 , 39 ], right OS depth and left OS depth with five studies [ 4 , 33 , 34 , 37 , 39 ], and signal intensity of OB with three studies [ 31 , 38 , 39 ]. Quality assessment of the included studies by the NOS scale indicated a fair status for most of the articles, with the total score ranging from two to seven (Table 2 ).…”

Section: Resultsmentioning

confidence: 99%

“…Mean right and mean left OS depths have been evaluated in five studies with pooled population of 436 individuals (155 COVID-19 cases and 281 non-COVID-19 controls) [ 4 , 33 , 34 , 37 , 39 ]. There was no statistically significant difference in right OS depth (SMD, − 0.237; 95% CI, − 0.697 to 0.223; P = 0.3122; I 2 = 80.12%; P Q = 0.005; Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Altunisik et al demonstrated that both mean right and mean left OT lengths were significantly lower in patients diagnosed with COVID-19 and persistent OD than in normosmic healthy controls ( P < 0.001 and P = 0.003, respectively) [ 34 ].…”

Section: Resultsmentioning

confidence: 99%

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Olfactory system measurements in COVID-19: a systematic review and meta-analysis

et al. 2022

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Purpose The neurotropism of SARS-CoV-2 and the consequential damage to the olfactory system have been proposed as one of the possible underlying causes of olfactory dysfunction in COVID-19. We aimed to aggregate the results of the studies which reported imaging of the olfactory system of patients with COVID-19 versus controls. Methods PubMed and EMBASE were searched to identify relevant literature reporting the structural imaging characteristics of the olfactory bulb (OB), olfactory cleft, olfactory sulcus (OS), or olfactory tract in COVID-19 patients. Hedge’s g and weighted mean difference were used as a measure of effect size. Quality assessment, subgroup analyses, meta-regression, and sensitivity analysis were also conducted. Results Ten studies were included in the qualitative synthesis, out of which seven studies with 183 cases with COVID-19 and 308 controls without COVID-19 were enrolled in the quantitative synthesis. No significant differences were detected in analyses of right OB volume and left OB volume. Likewise, right OS depth and left OS depth were also not significantly different in COVID-19 cases compared to non-COVID-19 controls. Also, we performed subgroup analysis, meta-regression, and sensitivity analysis to investigate the potential effect of confounding moderators. Conclusion The findings of this review did not confirm alterations in structural imaging of the olfactory system, including OB volume and OS depth by Covid-19 which is consistent with the results of recent histopathological evaluations. Supplementary Information The online version contains supplementary material available at 10.1007/s00234-022-03014-8.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Olfactory system measurements in COVID-19: a systematic review and meta-analysis

et al. 2022

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“…In current practice, olfactory imaging is not routinely performed for COVID‐19 patients with OD. However, neuroimaging abnormalities related to COVID‐19‐associated OD have been gaining attention, including abnormalities of the olfactory bulb, olfactory sulcus, olfactory cleft, and olfactory tract on imaging 14,15 . These imaging findings may shed light on the mechanisms underlying COVID‐19‐associated OD, 16 offering insight into the route of entry of the SARS‐CoV‐2 virus, and involvement of anatomical structures in the brain and olfactory pathways 17 .…”

Section: Introductionmentioning

confidence: 99%

“…However, neuroimaging abnormalities related to COVID‐19‐associated OD have been gaining attention, including abnormalities of the olfactory bulb, olfactory sulcus, olfactory cleft, and olfactory tract on imaging. 14 , 15 These imaging findings may shed light on the mechanisms underlying COVID‐19‐associated OD, 16 offering insight into the route of entry of the SARS‐CoV‐2 virus, and involvement of anatomical structures in the brain and olfactory pathways. 17 Moreover, knowledge gained from such data may enable clinicians to more accurately predict the clinical course, and develop targeted interventions to treat COVID‐19‐associated OD.…”

Section: Introductionmentioning

confidence: 99%

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

Tan

et al. 2022

The Laryngoscope

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Objective Olfactory dysfunction (OD) is a common presenting symptom of COVID‐19 infection. Radiological imaging of the olfactory structures in patients with COVID‐19 and OD can potentially shed light on its pathogenesis, and guide clinicians in prognostication and intervention. Methods PubMed, Embase, Cochrane, SCOPUS were searched from inception to August 1, 2021. Three reviewers selected observational studies, case series, and case reports reporting radiological changes in the olfactory structures, detected on magnetic resonance imaging, computed tomography, or other imaging modalities, in patients aged ≥18 years with COVID‐19 infection and OD, following preferred reporting items for systematic reviews and meta‐analyses guidelines and a PROSPERO‐registered protocol (CRD42021275211). We described the proportion of radiological outcomes, and used random‐effects meta‐analyses to pool the prevalence of olfactory cleft opacification, olfactory bulb signal abnormalities, and olfactory mucosa abnormalities in patients with and without COVID‐19‐associated OD. Results We included 7 case–control studies (N = 353), 11 case series (N = 154), and 12 case reports (N = 12). The pooled prevalence of olfactory cleft opacification in patients with COVID‐19 infection and OD (63%, 95% CI = 0.38–0.82) was significantly higher than that in controls (4%, 95% CI = 0.01–0.13). Conversely, similar proportions of cases and controls demonstrated olfactory bulb signal abnormalities (88% and 94%) and olfactory mucosa abnormalities (2% and 0%). Descriptive analysis found that 55.6% and 43.5% of patients with COVID‐19 infection and OD had morphological abnormalities of the olfactory bulb and olfactory nerve, respectively, while 60.0% had abnormal olfactory bulb volumes. Conclusion Our findings implicate a conductive mechanism of OD, localized to the olfactory cleft, in approximately half of the affected COVID‐19 patients. Laryngoscope, 132:1260–1274, 2022

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Topographical Distribution of Neuroanatomical Abnormalities Following COVID-19 Invasion

Kiyak,

Ijezie,

Ackah

et al. 2023

Clin Neuroradiol

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Purpose This systematic review is aimed at synthesising the literature base to date on the frequency and topographical distribution of neuroanatomical changes seen on imaging following COVID-19 invasion with a focus on both the acute and chronic phases of the disease. Methods In this study, 8 databases were systematically searched to identify relevant articles published from December 2019 to March 2022 and supplemented with a manual reference search. Data were extracted from the included studies and narrative synthesis was employed to integrate the findings. Results A total of 110 studies met the inclusion criteria and comprised 119,307 participants (including 31,073 acute and 143 long COVID-19 patients manifesting neurological alterations) and controls. Considerable variability in both the localisation and nature of neuroanatomical abnormalities are noted along the continuum with a wide range of neuropathologies relating to the cerebrovascular/neurovascular system, (sub)cortical structures (including deep grey and white matter structures), brainstem, and predominant regional and/or global alterations in the cerebellum with varying degrees of spinal involvement. Conclusion Structural regional alterations on neuroimaging are frequently demonstrated in both the acute and chronic phases of SARS-CoV‑2 infection, particularly prevalent across subcortical, prefrontal/frontal and cortico-limbic brain areas as well as the cerebrovascular/neurovascular system. These findings contribute to our understanding of the acute and chronic effects of the virus on the nervous system and has the potential to provide information on acute and long-term treatment and neurorehabilitation decisions.

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Quantitative Analysis of the Olfactory System in COVID-19: An MR Imaging Study

Cited by 26 publications

References 35 publications

Olfactory system measurements in COVID-19: a systematic review and meta-analysis

Olfactory system measurements in COVID-19: a systematic review and meta-analysis

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

Topographical Distribution of Neuroanatomical Abnormalities Following COVID-19 Invasion

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