Specialized scanning helps to understand the potential effects of the virus on the brain.
One of the first spectroscopic imaging studies of neurological damage in COVID-19 patients have been reported by researchers at Massachusetts General Hospital (MGH) in American Journal of Neuroradiology. Examining six patients using specialized magnetic resonance imaging (MR) techniques, they found that patients with COVID-19 with neurological symptoms showed some of the same metabolic disorders in the brain as other patients who suffered from oxygen deprivation (hypoxia) for other reasons. , but there are also noticeable differences.
Although it is primarily a respiratory disease, COVID-19 infection affects other organs, including the brain. The main effect of the disease on the brain is thought to be through hypoxia, but few studies have documented the specific types of damage that distinguish COVID-19-related brain damage. Several thousand patients with COVID-19 have been observed in MGH since the onset of the outbreak earlier this year, and this study includes findings from three of these patients.
The severity of neurological symptoms varies, ranging from one of the most well-known – temporary loss of sense of smell – to more severe symptoms such as dizziness, confusion, seizures and stroke. “We were interested in characterizing the biological basis of some of these symptoms,” said Dr. Eva-Maria Ratay, a researcher in the Department of Radiology and senior author of the study. “Moving forward, we are also interested in understanding the long-term effects of COVID-19, including headaches, fatigue and cognitive impairment. The so-called “brain fog” and other injuries that have been found to persist long after the acute phase, “added Ratay, also an associate professor of radiology at Harvard Medical School.
The researchers used 3 Tesla magnetic resonance spectroscopy (MRS), a specialized type of scan that is sometimes called a virtual biopsy. MRS can identify neurochemical abnormalities even when structural imaging findings are normal. The brains of patients with COVID-19 showed a decrease in N-acetyl-aspartate (NAA), an increase in choline and an increase in myo-inositol, similar to those seen with these metabolites in other patients with white matter abnormalities (leukoencephalopathy). after hypoxia without COVID. One of the patients with COVID-19, who showed the most severe damage to the white matter (necrosis and cavitation), had a particularly pronounced increase in lactate MRS, which is another sign of brain damage from lack of oxygen.
Two of the three patients with COVID-19 were intubated in the intensive care unit during imaging, which was performed as part of their care. One had COVID-19-related necrotizing leukoencephalopathy. Another has experienced a recent cardiac arrest and has shown subtle changes in white matter in structural MR. The third has no clear encephalopathy or recent cardiac arrest. Control cases that did not include COVID included one patient with white matter impairment due to hypoxia from other causes (post-hypoxic leukoencephalopathy), one with white matter impairment associated with sepsis, and a normal healthy age-appropriate volunteer.
“The key question is whether only a decrease in oxygen to the brain causes these changes in white matter, or whether the virus itself attacks white matter,” said MGH neuroradiologist Otto Rapalino, PhD, who shared his first authorship with Harvard-MGH postdoctoral fellow Dr. Aquila. Fan ax.
Compared to conventional structural MR imaging, “MRS can better characterize pathological processes such as neuronal damage, inflammation, demyelination and hypoxia,” adds Weerasekera. “Based on these findings, we believe it can be used as a tool for disease surveillance and therapy.”
Reference: “Spectroscopic findings of cerebral MR in 3 consecutive patients with COVID-19: preliminary observations” by O. Rapalino, A. Veerasekera, SJ Moum, K. Aikerman-Haerter, BL Edlow, D. Fischer, A. Torado-Carvajal , ML Loggia, SS Mukerji, PW Schaefer, RG Gonzalez, MH Lev and E.-M. Ratay, October 29, 2020, American Journal of Neuroradiology.
DOI: 10.3174 / ajnr.A6877
The study was supported by the James C. McDonnell Foundation, National Institutes of Health and National Institute of Neurological Disorders and Stroke.