Feb. 7, 2023 – Images of uncontrollable tremors, shaking, involuntary spasms. It's a visibly unnerving condition that's recently been going viral on social media.
Late last month, a video resurfaced from 2021 of Angelia Desselle, a then 45-year-old woman from Louisiana attempting to walk while supposedly experiencing these symptoms, which she claims were developed after receiving a COVID-19 vaccine. This is just one example of many.
Since Desselle's video was reposted on Twitter, it's been viewed more than 72 million times, helping to reignite controversy over the safety of COVID vaccinations. Her original video – first posted on Facebook -- was flagged by the site as part of an effort to combat misinformation, according to Politifact. One of the recent retweets had this context added: "the video … has been debunked by multiple news outlets and local and federal health officials, showing no association of Desselle's alleged 2 days of symptoms with the COVID vaccine."
Yet these types of videos linger. Vaccine skeptics see them as supporting their beliefs that the vaccines are dangerous, despite mountains of evidence to the contrary and international public safety pronouncements.
Aside from outright attempts to mislead, experts have an explanation for the shaking: In many cases, these atypical physical movements can be attributed to a common, disabling condition called functional neurological disorder or FND, according to neurologist Alfonso Fasano, MD, chair in Neuromodulation and Multi-Disciplinary Care at the University of Toronto and a clinician investigator at the Krembil Brain Institute, part of the University Health Network.
FNDs are believed to be related to altered brain network activity (that is, disruption in the brain's normal mechanisms for controlling the body), and possibly “triggered by a combination of abnormal physical and psychological experiences,” according to the Functional Neurological Disorder Society.
“This is as common as it is poorly understood,” says Fasano, who is co-author of a study looking at patients who visited a doctor with neurological symptoms following a COVID-19 infection or vaccination.
He says many of the patients that he's seen in the clinic (including 43% of study participants) have a functional disorder that sometimes lingers just below the surface and waits for something to trigger it.
“There is really something wrong with them and something wrong in the brain; their brain functions in a different way,” says Fasano.
Moreover, while factors like psychological stressors, underlying illness (or infections like COVID-19 and the flu), and past traumas appear to predispose some patients to FNDs, others develop the syndrome without any explicable cause.
A Perfect Storm
Functional nerve disorders are not a new phenomenon; they've been reported in one form or another since the Middle Ages. Today, an estimated 4% to 12% of the population have them, and it is a common diagnosis in neurology clinics.
What makes them different this time around is the “perfect storm” – ongoing pandemic stress and fatigue, the social media megaphone and its ability to reach millions of people in real time at the same time, and global vaccination campaigns – all of which make it more common to attribute the development of nerve disorder symptoms to the vaccines.
“Vaccines have been associated with neuromuscular issues after receipt, but this is a very rare side effect,” says Matthew Laurens, MD, MPH, pediatric infectious disease specialist and a professor of pediatrics at the University of Maryland School of Medicine in Baltimore.
“Guillain-Barré syndrome, a rare disorder where the body's immune system damages nerves, was reported in association with the 1976 swine flu vaccination campaign,” he says. But “sometimes events happen to individuals just after they receive a vaccine and they are not at all related to the vaccine.”
Neurological events like Guillain-Barré or involuntary muscle twitching (known as myoclonus) have been more frequently reported after infection itself. A study published in the Annals of Neurology last year showed that simply contracting COVID-19 significantly raised a person's risk for neurological events.
“The upshot was that the chances of having a neurological event after catching COVID were roughly 600-fold higher than after being vaccinated, which means for the general population, that it's unlikely that the COVID vaccines are related to a movement disorder,” says Jennifer Frontera, MD, study co-author and a neurologist with New York University's Langone Health.
Even becoming infected by the virus may just reveal what was already under the surface. “There really hasn't been a lot to suggest that COVID itself causes a movement disorder,” says Frontera. “I suspect that in some cases, it may unmask a movement disorder.”
Fasano agrees. "Like any medical act or minor trauma, anything can trigger functional disorders in people who are at risk for them.”