MRI Assessment of Cerebral Blood Flow in Nonhospitalized Adults Who Self-Isolated Due to COVID-19 (2022) Kim et al

[Milo]

Abstract
Background
Neurological symptoms associated with coronavirus disease 2019 (COVID-19), such as fatigue and smell/taste changes, persist beyond infection. However, little is known of brain physiology in the post-COVID-19 timeframe.

Purpose
To determine whether adults who experienced flu-like symptoms due to COVID-19 would exhibit cerebral blood flow (CBF) alterations in the weeks/months beyond infection, relative to controls who experienced flu-like symptoms but tested negative for COVID-19.

Study Type
Prospective observational.

Population
A total of 39 adults who previously self-isolated at home due to COVID-19 (41.9 ± 12.6 years of age, 59% female, 116.5 ± 62.2 days since positive diagnosis) and 11 controls who experienced flu-like symptoms but had a negative COVID-19 diagnosis (41.5 ± 13.4 years of age, 55% female, 112.1 ± 59.5 since negative diagnosis).

Field Strength and Sequences
A 3.0 T; T1-weighted magnetization-prepared rapid gradient and echo-planar turbo gradient-spin echo arterial spin labeling sequences.

Assessment
Arterial spin labeling was used to estimate CBF. A self-reported questionnaire assessed symptoms, including ongoing fatigue. CBF was compared between COVID-19 and control groups and between those with (n = 11) and without self-reported ongoing fatigue (n = 28) within the COVID-19 group.

Statistical Tests
Between-group and within-group comparisons of CBF were performed in a voxel-wise manner, controlling for age and sex, at a family-wise error rate of 0.05.

Results
Relative to controls, the COVID-19 group exhibited significantly decreased CBF in subcortical regions including the thalamus, orbitofrontal cortex, and basal ganglia (maximum cluster size = 6012 voxels and maximum t-statistic = 5.21). Within the COVID-19 group, significant CBF differences in occipital and parietal regions were observed between those with and without self-reported on-going fatigue.

Data Conclusion
These cross-sectional data revealed regional CBF decreases in the COVID-19 group, suggesting the relevance of brain physiology in the post-COVID-19 timeframe. This research may help elucidate the heterogeneous symptoms of the post-COVID-19 condition.

Evidence Level
2.

Technical Efficacy
Stage 3.


My comments: This is a Toronto Canada team that refers to ME in the article as it relates to fatigue. I have never heard from these authors before. They are planning a longitudinal follow-up of these patients.

Link to paper: https://onlinelibrary.wiley.com/doi/10.1002/jmri.28555

 

[RedFox]

Using control with a less harmful virus is a good design.

 

[Trish]

I'd prefer a design with a no recent virus healthy comparitor group too. I think there are 2 problems with the control group here. One, they may have had covid but a faulty test. Two, other viruses can also lead to post viral syndromes too, so it's not clear what is being compared.

 

[rvallee]

Using control with a less harmful virus is a good design.

The control here seems to be any pathogen other than COVID, with maybe COVID as well anyway, given mass reinfections and the unreliability of the tests. Could be a much milder one. Could be worse. Could be a different one for every single "control", even COVID.

I don't think this is a good way of studying this. Other pathogens cause the same problems and the issues aren't evenly distributed, some have none while a few will be severely disabled with no way to tell them apart. It doesn't tell us much. The way medical research works, they are looking for outcomes that are near universal, the difference-maker. It doesn't work for this type of problem since the outcome has little relation to its cause and we don't know what factors are important.

Medicine's definition of disease is teleological, whatever happens between cause and outcome, it always leads to that outcome. It could be longer and vary a bit in severity, but the outcome is the same and is unique to this disease. This is a completely different category of problem and they keep trying to cram it in the old boxes. Doesn't work. Won't work.