COVID Vaccine 'Side Effect' or Functional Neurological Disorder?

April 14, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

The development of unusual movements after COVID-19 vaccination may be a result of functional neurological disorder rather than being a direct adverse effect of the vaccine, it has been suggested.

Writing in a "Viewpoint" published online in JAMA Neurology April 9, two neurologists and a psychiatrist report the recent circulation of videos on social media about major neurologic adverse events, including continuous movements of the trunk and limbs or walking difficulties after administration of the COVID-19 vaccine. Some of these videos have been viewed millions of times by the public, they note.

While these videos may be unsubstantiated, and it is not definitively known if the COVID-19 vaccine was administered in these cases, it was reported in the news that at least one patient was told by their physician that the diagnosis was conversion disorder, also known as functional neurological disorder (FND), the authors note.

In addition, the Functional Neurological Disorder Society released a statement in January pointing out that the conditions described in these videos are seemingly consistent with FND, they add.

"We thought it would be useful to explain more about what functional neurological disorder is, as many people are not familiar with it," lead author David Kim, MD, told Medscape Medical News. "We wanted to provide some contextual information about the condition, as these reports may not necessarily mean the vaccine is unsafe."

Kim, who is part of the division of cognitive behavioral neurology at Massachusetts General Hospital, Boston, explained that in FND, physical symptoms can be brought about after events such as head injury, surgery, vaccination, other medical procedures, or life events such as loss of employment.

"Many different factors can bring these symptoms on and while there are definitely cases associated with stressful events, it is not necessarily stress-induced," he said. "However, the event itself does not cause the condition, rather it is the reaction of the patient to the event."

FND is now viewed as a true brain-based disorder, Kim noted. "While in the past it has been described as psychosomatic, we are now moving away from that terminology, towards the idea of a neurological disorder that affects function. It is a neuro-psychiatric disorder on the borderline between neurology and psychiatry."

The authors believe that some of these cases of unusual movements reported after COVID vaccination are likely to be FND.

"In these cases, it is not the substance in the vaccine that is causing the condition, but the common side effects that can occur after vaccination such as aches and chills bring the attention of the patient to their bodily functions and this reaction can become maladaptive, triggering FND," Kim said.

"We believe that healthcare professionals should be more aware of FND at the current time. They need to know that the general public are aware that some people are experiencing movement disorders after COVID vaccination, and that this conversation is happening on social media," he commented. "If they see patients with these symptoms, they could consider FND to be one possibility."

The authors emphasize that because they have not seen the individual patients, they cannot comment on any specific cases. 

"But as some of these videos circulating can be consistent with the condition being FND, and especially with news reports indicating that at least one patient was given that diagnosis, we wanted to raise awareness of this condition among health professionals," Kim added.  

He explained that, in the past, FND has been a diagnosis of exclusion but now it is diagnosed with a clinical history and physical examination, looking for appropriate rule-in signs. Ancillary testing such as neuroimaging, electrophysiological studies, and blood tests are often used to rule out other conditions.

"Neurologists have a lot of training in this condition as it is the second-most common reason for a patient to visit a neurologist after headache," Kim noted.

It is managed with education, counseling, physical rehabilitation and cognitive behavioral therapy. "A key part of the therapeutic process is working with the patient to explain the diagnosis. If they understand the condition, they do better. Patients can learn distraction techniques to allow more fluid movements," he reported.

"As neurologists, and healthcare professionals more broadly, we must explain transparently and nonjudgmentally the nature of FND, including that these symptoms are real but not the direct result of toxic vaccine effects," the authors write.

"Transparency and effective communication are needed in our society more than ever, and a condition as prevalent and potentially debilitating as FND can no longer remain marginalized and in the shadows. Effective communication will help educate the public and reduce fears so that patients can make informed decisions for themselves on receiving the vaccine to reduce the risk of COVID-19," they conclude.

JAMA Neurol. Published online April 9, 2021. Full text  

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