NEW research using advanced high-resolution Tesla (7T) magnetic resonance imaging (MRI) has demonstrated that long COVID is associated with microscopic abnormalities in the brainstem, with inflammation present up to 18 months after infection. Whilst previous conventional MRI studies have shown no structural abnormalities in the brainstem of patients with long COVID, 7T scanners have enabled researchers to analyse the nervous systems of patients in greater detail.
The study involved 31 patients who were hospitalised during the peak of the pandemic, before vaccinations were available, and 51 healthy individuals of similar age. Researchers conducted ultra-high field 7T MRI scans of their brains at least three months after discharge.
The results showed significant structural changes, identified as increases in MR susceptibility (χ), in the COVID group (P(FDR) < 0.0001; d = 4.96), particularly in the pons (P(FDR) = 0.00042, d = 4.01) and medulla (P(FDR) = 0.0035; d = 3.37). Two significant clusters of increased χ were identified in the medulla, in regions associated with respiratory function and body homeostasis (Cluster 1: P(FDR) < 0.0001; d = 4.56; Cluster 2: P(FDR) < 0.0001; d = 4.86).
Additionally, statistical analysis revealed a significant correlation between the severity of initial disease, inflammation markers, and the extent of brainstem damage. In particular, mean χ values in the medulla clusters were positively correlated with the highest C-reactive protein (R = 0.36; p = 0.041) and worse functional outcomes (R = 0.60; p = 0.0046). It was also weakly associated with the WHO severity index [R = 0.40; p = 0.046; Pr(post.) = 0.70; BF:2.3] and length of hospital admission [R = 0.37; p = 0.054; Pr(post.) = 0.7; BF = 3.1]. It was also found that signs of brain inflammation were present up to 18 months after contracting the virus.
The results suggest that symptoms of long COVID such as fatigue, breathlessness, and elevated heart rates are linked to damage in the brainstem regions that regulate these functions. These abnormalities are more pronounced in patients who experienced more severe COVID-19 infections, longer hospital stays, and higher inflammatory responses during acute infection. These findings have important implications for clinical practice, as recognising long COVID as a brainstem injury offers a new direction for targeted therapies to reduce inflammation and improve patient outcomes.
Katrina Thornber, EMJ
Reference
Rua C et al. Quantitative susceptibility mapping at 7 T in COVID-19: brainstem effects and outcome associations. Brain. 2024;DOI:10.1093/brain/awae215.
