In a small prospective study, participants who previously had COVID-19, even those with mild illness, had significantly decreased CVR, compared with never-infected individuals.
Results also showed cerebral blood flow (CBF) was greater in never-infected versus previously infected participants, and whole-brain CVR was lower in previously infected versus never-infected participants. Although CVR was also smaller in those with versus those without post-COVID neurologic conditions, the difference was not considered significant.
“It is important to remember that while our findings were statistically significant, we had a relatively small sample size – 25 total participants – and so we encourage future larger studies in this domain to see if these results are reproducible at a larger scale,” lead author Andrew Callen, MD, assistant professor of radiology, Neuroradiology Section, University of Colorado at Denver, Aurora, said in an interview.
“In a practical sense, it may encourage treating clinicians to be more aggressive with preventative neurovascular and cardiovascular health measures and/or screening in this patient population,” Dr. Callen said.
The findings were published online in the American Journal of Roentgenology.
The acute phase SARS-CoV-2 infection “is associated with strokes that have features of both vascular inflammation and thromboembolism,” the investigators note.
Moreover, following the acute phase of infection, up to three-quarters of patients “experience persistent neurologic symptoms not attributable to another diagnosis, including headache, difficulty concentrating, vision changes, disequilibrium, and fatigue,” they write.
Preliminary studies “suggest a potential role for endothelial and circulatory dysfunction” in these symptoms, they add.
The researchers note that vessel wall imaging is an MRI technique that can detect and characterize arterial vascular inflammation and may differentiate vasculitic arterial pathology from atherosclerotic pathology.
Dr. Callen conducted previous research assessing cerebral vasoreactivity in women living with HIV. He noted that this is a population at a much higher risk of stroke, compared with uninfected individuals with otherwise similar cardiovascular risk factors, even when their viral load is controlled with antiretroviral therapies.
Evidence has pointed to chronic endothelial dysfunction in these individuals, and endothelial function and dysfunction can be measured through vasoreactivity testing, Dr. Callen said.
“As the COVID pandemic progressed, not only did we observe an increased rate of stroke in individuals acutely infected with COVID, but histopathological evidence began to emerge which suggested that the COVID-19 virus had tropism to and often damaged the vascular endothelium,” he noted.
This emerging evidence prompted Dr. Callen to wonder whether “individuals previously infected with COVID might also demonstrate long-term impairment in cerebral vasoreactivity or if we might see abnormalities using high resolution vessel wall imaging.”
In the current study, 15 individuals with prior SARS-CoV-2 infection (11 women, 4 men; mean age, 43 years) were compared with 10 never-infected individuals (8 women, 2 men; mean age, 43 years) who functioned as the control group.
The previously infected individuals, of whom three had prior critical infection and 12 had prior mild infection, were assessed, on average, about 8 months after infection. Of this group, seven had various post-COVID neurologic conditions, including headache, memory impairment, insomnia, depression, disequilibrium, fatigue, personality change, phantosmias (detecting smells that aren’t present), dysgeusia (taste disorder), and tinnitus.
All participants underwent MRI and vessel wall imaging. The MRI included arterial spin labeling perfusion imaging with acetazolamide stimulus to measure CBF and calculate CVR. The vessel wall imaging examinations used a contrast-enhanced black-blood 3D T1-weighted sequence.