First evidence of brainstem involvement in COVID-19

Respiratory failure in COVID-19 patients is likely to have a neurogenic component. An Italian study provided the first combined neuropathological, neurophysiological, and clinical evidence of brainstem involvement, suggesting viral trafficking via the vagus nerve between lung and brainstem.

Dr Tommaso Bocci (University of Milan, Italy) and colleagues acquired neuropathological data from people who died of COVID-19 and healthy controls to assess brainstem involvement in COVID-19 [1]. Histopathological analysis was performed in 2 patients who died of respiratory failure due to COVID-19-related pneumonia. The results were compared with 2 COVID-19-negative patients who died of non-neurological conditions. To clarify whether neuropathological findings had a functional correlate, the blink reflex was assessed in 11 patients with severe COVID-19, healthy subjects, and non-COVID-19 ICU patients. The glabellar and corneal reflexes were also evaluated.

Autopsies showed extensive neuronal damage and a higher number of corpora amylacea in the medulla oblongata of COVID-19 patients. Immunohistochemistry revealed the presence of SARS-CoV-2 virus in the brainstem. Latencies of the first response (RI) did not differ. However, the medullary second response (RII) of the supraorbital blink reflex was impaired in COVID-19 patients compared with controls and non-COVID-19 ICU patients. Clinically, the glabellar reflex was reduced or absent.

The results suggest that brainstem involvement likely contributes to respiratory failure in COVID-19 patients, as was postulated by Manganelli et al. [2] and Baig et al. [3], Dr Bocci concluded. “Most importantly, SARS-CoV-2 immunohistochemically detected in the vagus nerve fibres is an original and previously unreported finding, which suggests viral trafficking between brainstem and lung.”

1. Bulfamante G, et al. Brainstem damage in COVID-19. OPR-054, EAN 2021 Virtual Congress, 19–22 June.
2. Manganelli F, et al. Neurol Sci. 2020;41:1663–5.
3. Baig AM, et al. ACS Chem. Neurosci. 2020;11(7):995–8.

 

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Posted on 18 August 202118 August 2021