A middle-aged American woman is believed to be the first person to suffer from a rare type of brain swelling following a diagnosis of COVID-19, the respiratory illness caused by the SARS-CoV-2.

The 58-year-old airline worker developed a case of acute necrotizing encephalitis, or ANE, a rare complication of influenza and other viral infections typically seen in children, according to the US National Library of Medicine.

“This is significant for all providers to be aware of and looking out for in patients who present with an altered level of consciousness. We need to be thinking of how we’re going to incorporate patients with severe neurological disease into our treatment paradigm,” said Elissa Fory, M.D., a Henry Ford neurologist who was part of the team of medical experts involved in making the diagnosis, in a statement. “This complication is as devastating as severe lung disease.”

After three days of coughing, fever, and an “altered mental state,” the woman's nasopharyngeal swab tested positive for the novel coronavirus responsible for the global pandemic. On March 19, the Henry Ford Health System says the woman was transported by ambulance to the emergency department and showed signs of confusion and disorientation. Doctors ordered CT and MRI scans, which revealed abnormal damage in the thalami and temporal lobes, areas of the brain associated with cognitive and memory function. People with some types of ANE will go on to develop damage, or lesions, in certain parts of the brain that can eventually lead to swelling, bleeding, and tissue death.

MRI image (left) and CT scan (right) show abnormalities in the temporal lobes and thalami brain regions, as well as evidence of hemorrhage. Radiology

“Approximately one-third of individuals with acute necrotizing encephalopathy type 1 do not survive their illness and subsequent neurological decline. Of those who do survive, about half have permanent brain damage due to tissue necrosis, resulting in impairments in walking, speech, and other basic functions,” writes the National Institutes of Health.

“Over time, many of these skills may be regained, but the loss of brain tissue is permanent. Other individuals who survive their illness appear to recover completely.”

Accumulating evidence suggests that some individuals diagnosed with COVID-19 may develop cytokine storm syndrome, an overreaction of the immune system that can result in a breakdown of the blood-brain barrier, according to a March 16 study published in The Lancet. Though neurological complications associated with COVID-19 are unclear, doctors have reported that a rare subset of those diagnosed with COVID-19 also develop complications in the brain.

“This is the first reported case of COVID-19-associated acute necrotizing hemorrhagic encephalopathy. As the number of patients with COVID-19 increases worldwide, clinicians and radiologists should be watching for this presentation among patients presenting with COVID-19 and altered mental status,” write the study authors in the journal Radiology.

Influenza A has similarly been linked to ANE in both children and adults. In 2018, two siblings who had not received the flu shot were diagnosed with the condition following an Influenza A (H1N1) virus infection. Neuroimaging revealed damage in the brain consistent with ANE. The older child recovered fully and was discharged two weeks after being sick, but the younger sibling developed severe brain swelling and died after 11 days. A 2017 case report describes a 55-year-old man who was diagnosed with ANE after also being diagnosed with Influenza A. In this case, it is hypothesized that the cytokine storm may have played a role in the swelling of his brain.

The woman was given intravenous immunoglobin rather than steroids as these may exacerbate COVID-19 lung injury. As of April 1, she was reportedly hospitalized in serious condition.