The corona virus apparently not only attacks the airways and lungs, but also the nervous system. In Wuhan, a good 36 percent of Covid-19 patients showed neurological symptoms – from sensory failures to headaches and dizziness to strokes and cramps, as a study reveals. The researchers conclude that SARS-CoV-2, like the closely related coronaviruses SARS and MERS, can affect the central nervous system.
So far, fever, dry cough and general weakness have been the main symptoms of infection with SARS-CoV-2. They arise because the coronavirus primarily affects cells in the airways and lungs that carry the so-called ACE2 receptor on their surface. However, there are other cell types with this docking point in the body, among others in the kidney, the digestive tract, the heart and also the nervous system.
Not just the lungs affected
Could the coronavirus attack other organs beyond the lungs? In fact, there is already evidence that SARS-CoV-2 can affect the heart muscle and cause acute myocarditis. Studies have shown that a biomarker in the blood, which is released by destroyed and dying heart muscle cells, was often elevated in patients with severe courses of the coronavirus infection.
But the nervous system can also be attacked by the corona virus, as Ling Mao from the Union Clinic in Wuhan and his colleagues report. For their study, they evaluated the medical records of 214 patients with Covid-19 from three clinics in Wuhan to determine whether they showed neurological abnormalities and symptoms and what they were. “As far as we know, this is the first detailed report on neurological manifestations of hospitalized patients with Covid-19,” the researchers say.
Neurological symptoms in a good third of patients
The result: “36.4 percent of the patients had different types of neurological symptoms, which included the central nervous system, the peripheral nervous system and the skeletal muscles,” the researchers report. The typical central nervous symptoms most often included headache and dizziness, but also clouded consciousness, movement disorders, strokes and convulsions occurred in some patients.
Typical signs of peripheral nerve involvement included loss of smell and taste – a symptom that is reported to occur in up to two out of three cases in Covid patients in Europe. But visual impairments and nerve pain also occurred in some Covid patients in Wuhan, as Mao and his colleagues report. There were also indications that muscle cells had also been attacked and damaged by the virus.
The nerves and brain often react before the lungs
The neurological disorders appear to appear relatively early in the course of the disease – in some cases even before the typical Covid symptoms. “Some patients with fever and headache were initially sent to the neurology ward because blood tests and lung CTs on Covid-19 remained negative,” said Mao and his team. “But a few days later, these patients also had the typical Covid 19 symptoms.”
The researchers also observed that patients with more severe courses of Covid-19 were more likely to show neurological symptoms – 45 percent compared to around 30 percent in milder cases. “Autopsies of some of the patients who died from Covid-19 showed that their brain tissue had increased blood flow, fluid accumulation and some neurons were degenerate,” report Mao and his colleagues. It is not yet possible to determine whether these are general signs of inflammation or the concrete consequences of the virus attack.
“Nevertheless, we should closely monitor such neurological manifestations in patients with Covid-19, because especially in cases with severe courses they could have contributed to the death of the patients,” say the scientists.
Not an isolated case among corona viruses
If these neurological effects of a SARS-CoV-2 infection were confirmed, this would not be an isolated case among coronaviruses: “Neurological damage has also been demonstrated in infections with other coronaviruses such as SARS and MERS-CoV,” the researchers explain. “This is how SARS nucleic acids were detected in the brain fluid and also in the brain tissue of patients.”
It is still unclear in which way SARS-CoV-2 triggers the neurological symptoms – whether directly through nerve cells or indirectly through inflammatory reactions or other body-specific reactions to the infection. However, it is known that cells of the nervous system and muscles also carry ACE2 receptors, according to the researchers. And SARS and MERS coronaviruses are known to directly affect the central nervous system – the pathological mechanism could be the same in SARS-CoV-2.
“Not yet the entire spectrum of neurological consequences”
“When doctors see patients with neurological symptoms during the pandemic, they should always be suspected of having a SARS-CoV-2 infection as a differential diagnosis,” stated Mao and his colleagues. “Otherwise, this can lead to misdiagnosis and prevent the chance of treating a coronavirus infection in good time and preventing further transmission.”
Andrew Josephson of the University of California in San Francisco comments in an accompanying editorial that the acquisition and research of the neurological effects of Covid-19 are still at the beginning. “It is clear that this small study does not reflect the full spectrum of the neurological consequences of Covid-19 – we still have a lot to learn by performing neurological tests on larger patient groups,” said the neurologist. “But even this first look at the neurological manifestations places neurologists on the front line of the pandemic.” (JAMA Neurology, 2020; doi: 10.1001 / jamaneurol.2020.1127)
Source: JAMA Neurology
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