Since the COVID-19 pandemic began, there has been a concern that survivors might be at an increased risk of neurological disorders. This concern, initially based on findings from infections with other coronaviruses, was rapidly followed by case series studies of the current pandemic. Multiple studies reported on the long-term outcomes of SARS survivors in Toronto in 2003. Most patients had persistent functional disabilities and were unable to return to their work. Their persisting debilitating physical symptoms included musculoskeletal pains, profound fatigability, shortness of breath, psychological distress, and major sleep problems [53,54]. These neurological long-term sequelae strongly suggest that they had been caused by an infection or inflammation in the CNS as a causative factor.
Following the initial surge of infections by SARS-CoV-2, focus has shifted to managing the longer-term sequelae of illness survivors. Post-acute COVID-19 syndrome (known colloquially as long COVID-19) is emerging as a prevalent syndrome. It encompasses a plethora of debilitating symptoms (including fatigue, breathlessness, pain, palpitations, sleep disturbance, and cognitive impairment (“brain fog”), which can last for weeks or months following the acute stage, even after a mild illness [55,56]. These symptoms thus greatly resemble those seen in follow-up studies of SARS2002/3 survivors [53,54]. As in the case of SARS-CoV, these neurological long-term sequelae of SARS-CoV-2 strongly suggest that their cause is an infection or inflammation in the CNS, not only in the lungs. Most patients recover from COVID-19 within a few weeks, but in surprisingly many, the (neurological) symptoms can continue for a long time [55,56]. These symptoms refer to imbalance in the central autonomous network (CAN) with sympathetic dominance, “dysautonomia.” This dysautonomia is supposed to be caused by cerebral hypoperfusion that leads to an overactive sympathetic system (fight or flight) with correspondingly reduced parasympathetic (relax) activity [57].
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