gms | German Medical Science

Objective: SARS-CoV-2 was first reported in Wuhan, China, at the beginning of 2020 leading to a global pandemic in the following. Though COVID-19 is mainly discussed in the context of respiratory symptoms, neurological symptoms are present in many patients. The aim of our study was to investigate subcortical white matter changes in acute and recovered COVID-19 patients compared to healthy controls and to correlate these structural changes to neuropsychological and neurocognitive testings.

Methods: 50 patients were prospectively included in this study. The cohort consisted of 16 patients with acute SARS-CoV-2 infection, 21 recovered patients and 13 healthy controls. DTI imaging was performed at a 3T or 1.5T MRI scanner with 31 gradient directions. A workflow for probabilistic tractography built upon FSL 6.0.3 (fsl.fmrib.ox.ac.uk) was used for analysis of 42 subcortical fibre tracts including protocols for correction of susceptibility- and eddy current-induced errors. Fractional anisotropy (FA) and mean diffusity (MD) were analysed as well as tract lengths and -volumes normalized to the specific whole-brain-volume. Comprehensive neuropsychological verbal and non-verbal testing was performed.

Results: In acute cases, significant differences were found regarding normalized volumes of the Inferior and Middle Longitudinal Fasciculus, Superior Thalamic Radiation (STR) and Acoustic Radiation as well as the Anterior Thalamic Radiation and Forceps Minor regarding normalized tract lengths (p<0.05). Comparing recovered cases with controls, apart from right STR, no significant differences could be found. Regarding mean FA and mean MD, we found significant differences for a majority of tracts in acute cases. Neuropsychology showed lower scores for acute and recovered patients in executive functioning and attention.

Conclusion: Specific patterns of structural white matter changes and neuropsychological findings in acutely infected and recovered COVID-19 patients were identified. Nevertheless, functional implications of the observed white matter changes have to be discussed in context with corresponding grey matter alterations, also with respect to possible residua in recovered patients.