Identifying the culprit behind enduring COVID-19 symptoms
Ultra-high-resolution MRI scans have revealed that brainstem inflammation could be a causal factor of long-term COVID-19 symptoms in severe cases.
Utilizing ultra-high-resolution MRI scans, researchers from the University of Cambridge and the University of Oxford (both UK) have imaged a previously inaccessible part of the brain to reveal inflammation in the brainstems of patients who had severe cases of COVID-19. The team suggests that these changes underlie the long-term consequences of the disease and that this area of the brain could be a therapeutic target for addressing the root cause of long-term COVID-19 symptoms.
The brainstem, which connects the brain to the spinal cord, controls a range of basic bodily functions and reflexes such as breathing, heart rate, pain and blood pressure. Patients with severe COVID-19 have often displayed symptoms several weeks after hospital admission that indicate brainstem damage, including breathlessness, fatigue and anxiety. It is impossible to harness conventional MRI to image inflammatory changes in the brainstem due to its small size and inaccessible position. As a result, researchers have only been able to visualize these changes in COVID-19 patients’ brains post-mortem.
To address this gap in our understanding of the disease in living patients, the team leveraged 7-Tesla ultra-high-resolution MRI scanners to detect inflammatory changes in living patients. The ultra-high magnetic field produced by these scanners interacts with active immune cells, enabling them to detect inflammation in the brain.
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The team scanned 30 individuals who had been hospitalized with severe COVID-19 early in the pandemic. The control group consisted of 51 age-matched individuals with no prior history of COVID-19 infection.
They correlated the MRI signals with disease severity (measured by hospital admission and COVID-19 severity scale), inflammatory response during acute illness, functional recovery, depression and anxiety.
The ultra-high-resolution MRI scans uncovered damage, including inflammation, to the area of the brainstem linked with breathlessness, fatigue and anxiety, namely the medulla, pons and midbrain. These effects were greater than changes due to age and gender, and were more noticeable in those with severe COVID-19.
The brainstem changes also indicate the root of psychiatric effects of the disease such as fatigue and anxiety, as patients with a greater immune response also had higher levels of depression and anxiety.
Co-leader of the study James Rowe (University of Cambridge) concluded, “The brainstem is the critical junction box between our conscious selves and what is happening in our bodies. The ability to see and understand how the brainstem changes in response to COVID-19 will help explain and treat the long-term effects more effectively.”
The finding that inflammation in the brainstem could be the cause of long-term COVID-19 symptoms helps create an understanding of the impact of COVID-19 on the brain and body, which might lead to more effective treatments. Monitoring changes in the brainstem during treatment could also allow clinicians to track treatment progress.
In the future, ultra-high-resolution MRI scanners could also elucidate the mechanisms behind other conditions associated with brainstem inflammation such as multiple sclerosis and dementia.
