The coronavirus may invade the brain, according to doctors who performed brain scans on a COVID–19 patient who lost her ability to taste and smell.
The unnamed 25-year-old radiographer was working on a COVID-19 ward when she developed a mild dry cough that lasted for a day, according to a case study published in the journal JAMA Neurology. She then developed a severe loss of smell and taste. Doctors looked inside the woman’s nose but found no problems, and her chest scans were clear.
But an MRI brain scan revealed changes in adjacent areas to the nose and olfactory nerves, wrote Dr. Letterio S. Politi, of the Istituto Clinico Humanitas and Humanitas University in Milan, Italy, and colleagues. As a disruption of these senses is a symptom of COVID-19, the woman was tested for the coronavirus. Her results can back positive.
After 28 days, doctors performed a follow-up MRI scan and the signs of problems had eased. She later recovered from anosmia.
The team also performed brain scans on two other COVID-19 patients with anosmia 12 and 25 days after their symptoms started, but found no issues.
Given the fact the woman had COVID-19, it is unlikely the findings were be the result of another condition, the team wrote. As such, the case is thought to be the first report of a COVID-19 patient showing a change in signalling “compatible with viral brain invasion” of the outer layer of the cerebrum linked to olfaction, they said.
Judging by the scans, the team “speculate that SARS-CoV-2 might invade the brain” through the olfactory system and result in problems with smell and taste. But the doctors said further research is needed to confirm the hypothesis.
The study was published the same day as a review of research related to neurological problems in patients with coronaviruses, the family of pathogens which the bug which causes COVID-19 is a member of. The team at the Yale School of Medicine found the most common neurological problems in COVID-19 patients are the loss of smell and taste, as well as headaches. However, others have been reported to experience stroke, issues with consciousness, seizures, and brain damage, known as encephalopathy. The findings were also published in JAMA Neurology.
Dr Tim Nicholson, clinical senior lecturer and honorary consultant neuropsychiatrist at King’s College London, U.K. who was not involved in the study, said in a statement that by showing changes in the structure of brain regions involved with detecting smells and taste that improved over time, the paper provides evidence that losing these faculties “might be due to direct brain invasion by the virus” rather than changes to the lining of the nose.
But Nicholson said: “As it is only a single case caution is needed in extrapolating this to other cases but it adds interesting supportive data and indicates a method of investigating the cause of this interesting and common symptom of COVID-19.”
Dr. Michael Zandi, consultant neurologist at the National Hospital for Neurology and Neurosurgery, U.K. who also wasn’t involved in the paper, said in a statement “the temporary nature of the changes is reassuring.”
Zandi said: “Detailed clinical studies of the brain in individuals who have had SARS-CoV-2 infection, including brain imaging, spinal fluid and blood analysis, and study of pathological specimens including post-mortem where available will help us understand what exactly is going on and help us treat those with serious brain and nerve involvement.”
As the graph by Statista below shows, the U.S. is the country with the most known COVID-19 cases.