Reduced T-cell densities in cranial nerves of patients who died with SARS-CoV-2 infection

Excerpt

SARS-CoV-2 patients show a highly variable disease course, ranging from asymptomatic infections to critical illness and death. Most of the fatalities occur in the older patient population and are linked to SARS-CoV-2-induced acute respiratory distress syndrome/diffuse alveolar damage (ARDS/DAD) of the lung, followed by multi-organ failure [20]. In addition to causing ARDS/DAD, SARS-CoV-2 infection may also affect the central and peripheral nervous system. Associations with Guillain-Barré syndrome (GBS), isolated cranial neuropathy, Miller Fisher syndrome and polyneuritis cranialis or chronic inflammatory demyelinating polyneuropathy (CIDP) have been described [3, 4, 6, 18]. Subclinical electrophysiological signs of trigeminal nerve involvement have been demonstrated recently in the majority of SARS-CoV-2 infected patients [2]. In line with clinical findings, in COVID-19 patients with isolated anosmia, the olfactory nerves displayed histological signs of inflammation and damage at autopsy [9] and also the olfactory bulb and tract showed axonal damage in some cases [7]. Although controversial, the olfactory route has been suggested as an entry point for SARS-CoV-2 to invade the CNS [8, 12]. In a subset of patients, viral protein was also detected within other cranial nerves (IX and X) [11]. Based on this, we hypothesized that the cranial nerves of patients who died with SARS-CoV-2 infection might show neuropathological signs of involvement. …