COVID-19 is, for the most part, considered a respiratory disease; most people who contract it will experience "mild to moderate respiratory illness and recover without requiring special treatment"—that's according to the World Health Organization (WHO). But in the past seven months, as the coronavirus has ravaged the globe, experts have discovered that the disease can manifest in many different ways—not just the typical cough, fever, and fatigue.
The nervous system in general—comprised of the brain, spinal cord, and nerves—may be particularly susceptible to the disease. "COVID-19 has been associated with multiple neurologic symptoms such as headache, dizziness, myalgia, confusion, alteration of the sense of taste and smell, weakness, strokes, and seizures," William C. Davison MD, FAAN, neurologist at Northwestern Medicine Lake Forest Hospital, Illinois, tells Health. Now, more research has discovered that COVID-19 could cause further brain damage, through brain inflammation and nerve damage.
A recent study from researchers at University College London (UCL) in the UK, published in the journal Brain, analyzed data from 43 patients with either confirmed or suspected COVID-19. The patients varied in age from 16 to 85 years old, and were treated at the National Hospital for Neurology and Neurosurgery in London. Some of the patients had mild cases of the disease, while others had more severe symptoms, though neurological issues weren't dependent on the severity of symptoms—in some patients, neurological symptoms were the only indication of illness. Within the group of patients, five major categories of neurological and neuropsychiatric illnesses emerged: encephalopathies (damage or disease that affects the brain), inflammatory CNS syndromes like encephalitis or acute disseminated encephalomeyelitis (ADEM), ischemic strokes, peripheral neurological disorders like Guillain-Barré syndrome, and disorders that didn't fit a specific category.
Of all 43 patients, researchers wrote that those who suffered from a specific type of inflammatory syndrome, ADEM—which affected nine of the patients—warrants close surveillance. A rare, potentially fatal condition, ADEM is characterized by an attack on the body's myelin, the protective covering of nerve fibers in the central nervous system, by the body's immune system, per the National Institute of Neurological Disorders and Stroke. If this protective covering is absent or inadequate, nerves are unable to effectively transmit information. The symptoms that may result from ADEM range from headache and fatigue to visual loss and paralysis.
“ADEM is an inflammatory reaction to the central nervous system,” Dr. Davison says. “The coronavirus is the trigger, but we don’t currently know why it seems to cause a pathologic immune response.” The researchers reported that before the pandemic, they saw about one person with ADEM per month. During the study period, they saw at least one per week.
The UCL study shared the specifics of a few patients' diagnoses and symptoms. One patient, a 47-year-old woman later diagnosed with ADEM, presented with common COVID-19 symptoms, like fever and respiratory issues, for one week before experiencing a severe headache on the right side of her head, and numbness and weakness on her left side. Once diagnosed with ADEM, she was given high-dose intravenous methylprednisolone—but 48 hours after the start of her treatment, her condition worsened; her brain became so swollen that surgeons had no option but to perform a hemicraniectomy to remove part of her skull to relieve the pressure. The woman survived and reportedly continues to improve.
Also concerning to researchers were the incidences and severity of the strokes brought on by COVID-19. Eight patients out of all 43 suffered ischemic stroke, or a stroke caused by a blockage of an artery that supplies blood to the brain. The study detailed the case of a 58-year-old man, who presented with acute onset aphasia (loss of ability to understand or express speech) and right-sided weakness. He had a cough and felt tired for two days prior to seeking treatment. He eventually stabilized after treatment and was discharged to a rehabilitation unit. Rearchers noted, however, that more research needs to be done on the association between COVID-19 and stroke.
While these are only a few instances of severe cases of neurological complications due to COVID-19, it shows how challenging it can be for doctors treating COVID-19 patients. Patients who don’t display severe respiratory symptoms, such as breathing difficulties, may not be tested for neurological complications early enough to avoid damage. “Some patients go from no symptoms and a normal outcome to multiple organ failure and even death,” Dr. Davison says. “As far as I know, we cannot yet explain the large spectrum of symptoms and outcomes from COVID-19.”
The UCL study isn't the only research surrounding neurological issues that present with COVID-19; A slightly earlier study from the UK, published in The Lancet Neurology, found a range of neurological and psychiatric complications that may be linked to COVID-19. After analyzing findings from COVID-19 studies from around the world, including China, Italy and the US, the researchers identified almost 1,000 patients with COVID-19-associated brain, spinal cord and nerve disease. It's a small number, comparatively speaking when referencing all cases of COVID-19, but it signals the importance of remaining aware of these complications. "We should be vigilant and look out for these complications in people who have had COVID-19," said Dr. Michael Zandi, joint senior author of the UCL study, in a press release. Dr. Zandi added that only time will tell "whether we will see an epidemic on a large scale of brain damage linked to the pandemic."
While the neurological complications of COVID-19 are becoming more apparent, experts still aren't sure what's causing these presentations in coronavirus patients—but according to research, it may be a result of the systemic impact of the illness, as COVID-19 doesn't seem to directly attack the brain. The UCL study, for example, did not find SARS-CoV-2 in the brain fluid of any patients, suggesting that the virus doesn't impact the brain specifically. “Sometimes, these symptoms can be the result of systemic disease such as acute respiratory distress syndrome (ARDS), but other times may be related to either direct involvement of the virus to the nervous system or an abnormal immune response to the virus,” Dr. Davison says.
More research needs to be done on COVID-19's affect on the brain and nervous system, but authors of the UCL study believe they've offered the most recent, "detailed description of the neurological complications seen during and after COVID-19 infection," and can help provide opportunities for further research on the longterm consequences of the coronavirus pandemic.
The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.
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