June 2, 2020 - Brain scans show that the SARS-CoV-2 virus, which causes COVID-19, may alter parts of the brain and cause a loss of smell, doctors from the U.S. and Italy say in a new JAMA Neurology paper.
The authors describe the scans of a 25-year-old Italian radiographer who began experiencing symptoms after working in a COVID-19 ward. The woman had a mild dry cough for a day and then lost her sense of smell and taste.
Evaluations of her nose and scans of her chest showed no signs of abnormalities, they wrote, and she didn’t have a fever.
However, a brain scan showed inflammation in her olfactory bulb, which involves the sense of smell. Then they gave her a COVID-19 test, and she was positive. They ruled out other causes for the loss of smell, such as other viral infections.
“We can speculate that SARS-CoV-2 might invade the brain through the olfactory pathway and cause an olfactory dysfunction,” they wrote.
In follow-up brain scans 28 days later, the abnormalities had disappeared. The woman recovered her sense of smell.
At the same time, the doctors didn’t find brain abnormalities in two other patients with COVID-19 who also lost their sense of smell, they wrote. The patients had brain scans 12 days and 25 days after symptoms started.
The normal brain imaging in other COVID-19 patients and the recovery in the 25-year-old patient’s follow-up scans “suggest that imaging changes are not always present in COVID-19 or might be limited to the very early phase of infection,” they wrote.
The temporary changes are “reassuring,” Michael Zandi, a consultant neurologist at the National Hospital for Neurology and Neurosurgery in London, told Science Media Centre, a UK-based group that communicates science to the public. The center gathered reactions from four neuroscience experts who weren’t involved with the study.
“We know from previous research that some individuals who have had SARS-CoV-2 infection may develop neurological and psychiatric symptoms,” Zandi said. “What remains to be seen is to what extent symptoms are due to viral infection of the brain itself or secondary effects including inflammation in the brain triggered by the immune system’s response to the virus.”