The fact that Covid-19 also affects organs other than the lungs is not new: the infection with the coronavirus is proving more and more to be a disease of the whole body, which does not spare nerves and the brain either. Several research teams have now compiled the neurological consequences and side effects that Covid-19 can cause. Accordingly, brain inflammation, damage to the myelin sheaths of the nerve tracts and also stroke occur not only in patients with severe courses, but also in mild cases. The percentage of such complications is low, but due to the high number of infections, this could affect thousands.
The coronavirus Sars-CoV-2 affects a whole range of tissues and organs of the body. In addition to the nose, airways and lungs, the virus-sensitive cells are also located in the intestine, in the blood vessels or in the kidney. The fact that up to two thirds of all infected develop olfactory disorders also demonstrates that the coronavirus also attacks the nerves. The virus can also reach the brain relatively unhindered via the olfactory nerve. In fact, Chinese doctors reported a conspicuous cluster of neurological symptoms in Covid 19 patients in Wuhan as early as April 2020.
More than a third of the 214 patients examined by them showed neurological symptoms of various types, from headaches to dizziness and delirium to convulsions and brain infections. Because Sars-CoV-2 also changes blood clotting, strokes occur more frequently than normal.
Brain infections, nerve damage and paralysis
So far, however, it has been unclear how often such neurological side effects of coronavirus infection occur. To provide more clarity here, Mark Ellul from the University of Liverpool and his colleagues evaluated case reports and studies published around the world by mid-May 2020. In total, they came across 901 cases of Covid 19 patients with neurological complications.
93 of these patients suffered from encephalopathy and thus extensive changes in the brain, eight cases of cerebral inflammation (encephalitis) occurred and 19 patients developed Guillain-Barré syndrome – a temporary paralysis caused by inflammatory nerve changes.
In addition, there were cases of inflammation and signs of failure of peripheral nerves or the spinal cord, as well as seizures and other symptoms of disturbed nerve function. So far, however, it remains to be seen whether the coronavirus causes these neurological diseases themselves or indirectly through the attacked immune system, as the researchers explain.
As the case analyzes showed, such neurological abnormalities occur not only in patients with severe courses, but also in mild cases. Ellul and his team describe the case of a 24-year-old man in Japan who initially only suffered from a sore throat, fever and exhaustion. After nine days, however, states of confusion and impaired consciousness developed, and there were also increasingly frequent seizures.
Research has shown severe inflammation of the brain caused by Covid-19. The condition of the man deteriorated so much that he had to be intubated and ventilated – not because of shortness of breath or lung damage, but because of the seizures.
“It is important that medical professionals worldwide are aware that Covid-19 can also cause encephalitis and other brain changes because they can have serious, sometimes life-changing consequences, ” emphasizes Ellul’s colleague Ava Easton. Similar to meningitis, encephalitis can lead to permanent failures and long-term consequences.
Even in mild cases without airway symptoms
Also very common among the neurological manifestations of Covid-19 seems to be a complication that otherwise occurs almost exclusively in children. In this acute disseminated encephalomyelitis (ADEM), the immune system attacks the myelin sheaths of the nerve pathways and thus disrupts nerve conduction. Typically, this autoimmune reaction occurs a few weeks after infection, but is well treatable with cortisone drugs and then subsides.
Typical symptoms are headache, visual disturbances, gait disorders and paralysis, but also seizures. As Ellul and his team now found, Covid-19 can also cause this encephalomyelitis in adults – even if there are almost no other typical infection symptoms. They describe the case of a middle-aged American who complained of headaches and muscle aches, then developed increasing speech disorders and paralysis of the left side of her face. Only a PCR test revealed her Sars-CoV-2 infection.
Michael Zandi from University College London and his colleagues also report such an accumulation of brain inflammation and encephalomyelitis. They had examined 43 Covid-19 patients who had been treated for neurological complications at their university hospital. Among the patients were twelve cases of encephalitis, ten with acute disseminated encephalomyelitis, eight with strokes and eight with Guillain-Barré syndrome and similar symptoms.
“Overall, we identified more of these neurological cases than we expected – and these patients did not always have pronounced airway symptoms,” says Zandi. Given the high number of cases in the corona pandemic, he also believes it very likely that there could be many such neurological complications overall – even if their proportion is not high compared to other symptoms and complications.
In his view, it is also important to keep a close eye on patients after an apparently survived infection, because some of these complications can only manifest themselves a few weeks later. “We should be vigilant and be prepared for such complications among those who have recovered,” said Zandi.