Brain MRI Findings in Patients with Post COVID-19 Condition: Frequency and Longitudinal Changes in a Nationwide Cohort Study

Liv Lygre Furevik^1,2*Oksana Lapina¹Elisabeth Stokke Lindland^2,3Einar August Høgestøl^2,4Oliver Marcel Geier^1,5Kristina Devik⁶Anette Huuse Farmen⁷Heidi Øyen Flemmen⁸Hanne Flinstad Harbo^2,4Åse Hagen Morsund⁹Vojtech Novotny⁴Hilde Karen Ofte¹⁰Kenneth Ottesen Pedersen¹¹Trine Haug Popperud⁴Barbara Ratajczak-Tretel¹²Christian Samsonsen^13,14Per Selnes¹⁵Oivind Torkildsen^16,17Ragnhild Marie Undseth¹¹Anne Hege Aamodt^14,18,4Mona Kristiansen Beyer^1,2Marion Ingeborg Boldingh^2,4

• ¹Division of Radiology and Nuclear Medicine, Oslo universitetssykehus, Oslo, Norway
• ²Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
• ³Department of Radiology, Sorlandet sykehus HF Arendal, Arendal, Norway
• ⁴Department of Neurology, Oslo universitetssykehus, Oslo, Norway
• ⁵Center for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway
• ⁶Department of Neurology, Sykehuset Namsos, Namsos, Norway
• ⁷Department of Neurology, Sykehuset Innlandet Lillehammer, Lillehammer, Norway
• ⁸Department of Neurology, Sykehuset Telemark HF, Skien, Norway
• ⁹Department of Neurology, Molde sjukehus, Molde, Norway
• ¹⁰Department of Neurology, Nordlandssykehuset HF, Bodø, Norway
• ¹¹The Intervention Centre, Oslo universitetssykehus, Oslo, Norway
• ¹²Department of Neurology, Sykehuset Ostfold HF, Grålum, Norway
• ¹³Department of Neurology and Clinical Neurophysiology, St Olav's Hospital HF, Trondheim, Norway
• ¹⁴Department of Neuromedicine and Movement Science, Faculty of Medicine and Health Sciences, Norges teknisk-naturvitenskapelige universitet, Trondheim, Norway
• ¹⁵Department of Neurology, Akershus Universitetssykehus HF, Lørenskog, Norway
• ¹⁶Department of Neurology, Haukeland Universitetssjukehus, Bergen, Norway
• ¹⁷Department of Clinical Medicine, Universitetet i Bergen, Bergen, Norway
• ¹⁸Institute of Population Health, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom

Background: Prolonged neurological symptoms following COVID-19 are common, yet few longitudinal studies describe brain MRI findings in this patient group. The use of contrast enhanced sequences is particularly lacking. We address this knowledge gap by reporting the frequency and longitudinal changes in brain MRI findings among patients with post COVID-19 condition exhibiting neurological symptoms. Methods: This prospective multicenter study included 140 adult patients referred for persistent neurological symptoms following COVID-19. Brain MRI was performed at both six and 12 months after infection onset, reporting white matter hyperintensities, cerebral microbleeds, and additional pathological findings including contrast enhancement. White matter hyperintensities were compared with a healthy control group. Results: The prevalence of white matter hyperintensities was comparable to healthy controls, and microbleeds were found at rates comparable to population studies, with longitudinal changes being infrequent. Lesions consistent with inflammation or demyelination were present in 4% (5/120) of patients at six months. Cranial nerve enhancement was found in 7% (7/94) of patients, persisting up to 12 months, predominantly affecting the oculomotor nerve. However, enhancement occurred without clinically detected ocular muscle paresis. Conclusion: Our findings indicate that brain MRI primarily serves to exclude differential diagnoses in post COVID-19 condition, with limited clinical benefit of repeated imaging in the absence of new symptoms. However, signs of long-term inflammatory processes can be observed, and detection is improved by contrast enhanced sequences.