COVID can make the body attack itself. Medical imaging shows the results.

Posted at 4:36 PM, Feb 26, 2021
and last updated 2021-03-01 11:06:22-05

SAN DIEGO (KGTV) -- With the help of medical imaging, a new study is illustrating for the first time some of the rare consequences of COVID-19: how the disease can trick the body into attacking its own muscles, joints and nerves.

The study, published in the journal Skeletal Radiology, offers new insight into some of the mysterious symptoms of the disease, like “COVID toes.”

The authors include a series of C-T scans and MRIs that can help radiologists decipher which lingering aches, pains and swelling may be linked to the disease.

The imaging confirms what doctors have long suspected: that COVID-19 can trigger friendly fire from the immune system.

“It's an autoimmune reaction where the virus is triggering the body to attack itself, and that can be long lasting. That can even be permanent,” said Dr. Swati Deshmukh, a Northwestern University assistant professor of radiology and co-author of the study.

While the virus typically causes respiratory issues, the study notes COVID-19 can sometimes trigger complications like rheumatoid arthritis flares, psoriatic arthritis and autoimmune myositis.

“Certainly other viruses can cause muscle aches. Some other viruses can even cause joint problems. But the range of symptoms that we're seeing and the number of people who are experiencing these symptoms with COVID-19 -- it's nothing like we've seen before,” she said.

Experts still haven’t nailed down exactly why the virus can sometimes cause these overactive immune responses but there are several theories.

When antibodies stick to a virus, they can disable it, but it’s up to other immune cells to come in and destroy it. One theory is that some patients have trouble destroying these antibody-coated viruses (“immune complexes” in medical lingo), leading to a build-up of junk that can set off a chain reaction.

The end result is that confused immune cells attack friendly troops. “The virus is tricking the body into thinking that some of its own cells, some of its own muscles or joints, are alien and need to be removed,” Dr. Deshmukh explained.

The study lays out clues that radiologists should look for. It takes an expert’s eye but they look for inflammation or fluid buildup to reveal signs that joint or muscle symptoms are actually caused by a COVID-related immune response.

These lingering effects can occur either in patients with severe COVID or just a mild case, said Dr. Deshmukh. In some cases, imaging revealed clues that a patient had complications from COVID-19 before the patient was even aware they were infected, she said.

“COVID-19 is full of surprises and the numbers of people that have been infected are so astronomical that the number of what we would think are rare complications is actually not so rare at all,” she said.

She’s hopeful the study will lead to better diagnoses so patients can get targeted treatments.