The coronavirus disease 2019 (COVID-19) rapidly progressed to a global pandemic. Although patients totally recover from COVID-19 pneumonia, long-term effects on the brain still need to be explored. Here, two subtypes (mild type-MG and severe type-SG) with no specific neurological manifestations at the acute stage and no obvious lesions on the conventional MRI three months after discharge were recruited. Changes in gray matter morphometry, cerebral blood flow (CBF) and white matter (WM) microstructure were investigated using MRI. The relationship between brain imaging measurements and inflammation markers were further analyzed. Compared with healthy controls, the decrease in cortical thickness/CBF, and the changes in WM microstructure were observed to be more severe in the SG than MG, especially in the frontal and limbic systems. Furthermore, changes in brain microstructure, CBF and tracts parameters were significantly correlated with inflammatory markers. The indirect injury related to inflammatory storm may damage the brain, that led to these interesting observations. There are also other likely potential causes, such as hypoxemia and dysfunction of vascular endothelium, et al. The abnormalities in these brain areas need to be monitored in the process of complete recovery, which could help clinicians to understand the potential neurological sequelae of COVID-19.

BACKGROUND After the initial surge in COVID-19 cases, large numbers of patients were discharged from a hospital without assessment of recovery. Now, an increasing number of patients report postacute neurological sequelae, known as “long COVID” — even those without specific neurological manifestations in the acute phase. METHODS Dynamic brain changes are crucial for a better understanding and early prevention of “long COVID.” Here, we explored the cross-sectional and longitudinal consequences of COVID-19 on the brain in 34 discharged patients without neurological manifestations. Gray matter morphology, cerebral blood flow (CBF), and volumes of white matter tracts were investigated using advanced magnetic resonance imaging techniques to explore dynamic brain changes from 3 to 10 months after discharge. RESULTS Overall, the differences of cortical thickness were dynamic and finally returned to the baseline. For cortical CBF, hypoperfusion in severe cases observed at 3 months tended to recover at 10 months. Subcortical nuclei and white matter differences between groups and within subjects showed various trends, including recoverable and long-term unrecovered differences. After a 10-month recovery period, a reduced volume of nuclei in severe cases was still more extensive and profound than that in mild cases. CONCLUSION Our study provides objective neuroimaging evidence for the coexistence of recoverable and long-term unrecovered changes in 10-month effects of COVID-19 on the brain. The remaining potential abnormalities still deserve public attention, which is critically important for a better understanding of “long COVID” and early clinical guidance toward complete recovery. FUNDING National Natural Science Foundation of China.

The aim of this study was to evaluate the anatomical and clinical relationship between lacunar infarction and the corticospinal tract (CST) in patients with acute lacunar infarction and predict clinical outcome. We examined 28 pyramidal tract stroke patients in the acute phase or early subacute phase (<3 days) with a marked motor deficit. The anatomical location and the extent of CST involvement within the infarcts were visualized on three-dimensional colour-coded diffusion tensor tractography (DTT). With regard to the CST, all patients were divided into three clinical subgroups: Group 1 (intact type), Group 2 (partial involvement type) and Group 3 (whole involvement type). Subsequently, the severity of the motor deficit of each patient was determined according to the National Institutes of Health Stroke Scale (NIHSS) scores at the acute/early subacute phase (<3 days after onset of symptoms), early chronic phase (8-14 days) and outcome (30-60 days). NIHSS scores of Group 1 (12/28) were significantly lower than those of Group 2 (9/28) at the acute phase or early subacute phase (U = -2.816, p<0.01), and those of Group 2 were significantly lower than those of Group 3 (7/28) (U = -3.136, p<0.01). At outcome,NIHSS scores of Group 1 were significantly lower than those of Group 2 (U = -2.846, p<0.01), and scores of Group 2 were significantly lower than those of Group 3 (U = -3.130, p<0.01). At the same time, the NIHSS scores of each group gradually decreased from acute phase to outcome, Neurological improvement was statistically different among the three topographical types of infarction (H = 26.15, p<0.01; H = 11.03, p<0.01; H = 10.05, p<0.01). In conclusion, the three-dimensional colour-coded DTT allows in vivo differentiation of distinct CST stroke subtypes and may help in better establishing the prognosis for patients after CST stroke.

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