The new study identified 43 suspected or confirmed coronavirus sufferers, aged between 16 and 85, who were treated at the specialist unit at University College Hospital in London.
Researchers identified 10 cases of transient encephalopathies – a temporary brain dysfunction – with delirium, which corresponds with other studies finding evidence of delirium with agitation. There were also 12 cases of brain inflammation, eight cases of strokes and eight others with nerve damage, mainly Guillain-Barré syndrome.
Nine out of 12 cases of those with brain inflammation conditions were diagnosed with ADEM, known to be triggered by viral infections.
The team in London normally sees around one adult patient with ADEM per month, but that increased to at least one per week.
Dr Ross Paterson, the joint first author of the paper, said: “Given that the disease has only been around for a matter of months, we might not yet know what long-term damage Covid-19 can cause.
“Doctors need to be aware of possible neurological effects, as early diagnosis can improve patient outcomes. People recovering from the virus should seek professional health advice if they experience neurological symptoms.”
SARS-CoV-2, the virus causing Covid-19, was not detected in the cerebrospinal brain fluid of any of the patients tested, suggesting the virus did not directly attack the brain to cause the neurological illness.
In some patients, researchers found evidence that the brain inflammation was likely to have been caused by an immune response to the disease, suggesting that some neurological complications of Covid-19 might come from the immune response rather than the virus itself.
Dr Michael Zandi, the study co-author, said: “We identified a higher than expected number of people with neurological conditions such as brain inflammation, which did not always correlate with the severity of respiratory symptoms. We should be vigilant and look out for these complications in people who have had Covid-19.
“Whether we will see an epidemic, on a large scale, of brain damage linked to the pandemic – perhaps similar to the encephalitis lethargica outbreak in the 1920s and 1930s after the 1918 influenza pandemic – remains to be seen.”
The NHS last week promised to launch a bespoke rehabilitation scheme for Covid-19 patients in recognition of growing evidence that the infection can have long-term effects on some patients.
The package will include access to physiotherapists and mental health support and will also offer an online peer-support “community for survivors”, aimed particularly at those who may be recovering at home alone.
The new findings add clinical descriptions and detail to another recent study, which also involved Dr Zandi and co-author Dr Hadi Manji, identifying 153 people with neurological complications from Covid-19.
This paper also confirmed the previously reported findings of a higher than expected number of patients with stroke, which results from the excessive stickiness of the blood in Covid-19 patients.