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Researchers in the United Kingdom report two cases of functional neurological disorder (FND) that occurred in women in their 30s after they received a COVID-19 vaccine.
The report follows an article published earlier this year in JAMA Neurology about videos shared on social media that showed symptoms seemingly consistent with FND.
Symptoms of FND include muscle weakness, fatigue, cognitive impairment, dizziness, and impaired gait.
The current investigators, led by Matthew Butler, PhD, from the Neuropsychiatry Research Group, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, United Kingdom, conclude that case reports such as these will likely increase as more people get vaccinated against COVID-19.
They suggest that clinicians consider FND in the differential diagnosis when assessing post-vaccine neurologic symptoms.
The researchers stress that FND is treatable, that no brain damage is involved, and that it is not caused by some toxin in the vaccine.
"It is recognized that some acute responses to vaccinations mimic symptoms of allergic reaction or anaphylaxis, such as panic, collapse, and laryngeal dystonia, which do not have an immunological cause and are not directly related to the vaccine constituents," Butler told Medscape Medical News.
The case reports were published online July 15 in The Journal of Neuropsychiatry Clinical Neurosciences.
Case Report No. 1
The first case reported by Butler and his team involved a 38-year-old woman who had no significant past medical history and who had received the first dose of the Pfizer-BioNTech SARS-CoV-2 vaccine.
Twenty minutes after receiving the vaccine, she developed an odd sensation that she described as "weakness" around her left ear. During the rest of the day, this weakness spread to her mouth, left arm, and leg. When she woke the next morning, she had difficulty moving the left side of her face and experienced heaviness in her left leg.
The woman was taken to the emergency department. Her blood pressure, glucose level, and heart rate were found to be normal, as were electrocardiogram and brain CT data. She was then discharged with a diagnosis of either a transient ischemic attack or Bell's palsy and began a course of aspirin 75 mg once a day.
Two months after receiving her vaccination, she underwent an examination in a general neurology clinic. The patient had ongoing left-sided weakness, particularly involving grip strength, which had been gradually improving.
She also reported ongoing difficulties with short-term memory, such as losing track of conversations or forgetting why she came into a room.
The only abnormality on neurologic examination was mild weakness in the left lower limb with positive hip abductor and Hoover's sign.
FND was diagnosed on the basis of positive neurologic measures, including Hoover's sign, hip abduction test results, and symptom variability. The results were explained and demonstrated to the patient.
Case Report No. 2
The second case involved a 36-year-old woman who had no significant past medical history. She received the first dose of Moderna SARS-CoV-2 vaccine in her right arm and experienced no noticeable side effects except soreness.
Four weeks later, she received the second dose in her right arm. A few minutes afterward, she noted weakness in her right hand and new right-leg limping, which lasted about 2 hours.
Associated fatigue, myalgia, and self-reported low-grade fever subsided within a day. On the second day after vaccination, she experienced severe bilateral leg heaviness and difficulties in fine movements of the right hand. In addition, she had exertional fatigue after walking short distances. These symptoms persisted for several days, after which she sought medical attention.
On examination, the woman was noted to have right upper-extremity weakness. MRI of the brain and spine were normal, as were electromyography and nerve conduction velocity studies.
Physical therapy was initiated, and her right-sided weakness improved. A few weeks later, she awoke with new-onset left-sided upper- and lower-limb weakness.
The patient continued to report various difficulties, including tightness and heaviness in her neck muscles, difficulty performing routine activities of daily living, and difficulting tolerating any exertions beyond limited isometric exercises during physical therapy. Although she complained of rapid muscle fatigue, she was able to hold a 1-lb weight, and her reflexes were normal.
While walking, she dragged her right foot, and there was no arm swing on the right side. When asked to run, she moved both arms and legs symmetrically.
The woman was diagnosed with functional weakness, tremor likely due to anxiety, and fatigue symptoms similar to those associated with chronic fatigue syndrome.
Reports of neurologic impairment after being vaccinated for COVID-19 began surfacing on Facebook and other social media earlier this year, as vaccinations for COVID-19 became more widespread.
As reported at the time by Medscape Medical News, these cases garnered the attention of David Kim, MD, from the Division of Cognitive Behavioral Neurology at Massachusetts General Hospital, Boston, Massachusetts.
Kim and colleagues wrote a viewpoint article that was published in April in JAMA Neurology regarding the growing number of FND symptoms being reported on Facebook and YouTube.
"We thought it would be useful to explain more about what functional neurological disorder is, as many people are not familiar with it," Kim told Medscape Medical News at the time. "We wanted to provide some contextual information about the condition, as these reports may not necessarily mean the vaccine is unsafe."
Kim noted that in FND, physical symptoms can occur 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."
Million Dollar Question?
What causes FND is the million dollar question, Butler noted.
"FND is complex. It can mimic neurological disorders, like stroke or atherosclerosis or epilepsy, but it's not the same thing," he said.
"There is no structural damage to the brain, and there is absolutely no evidence from any literature that there is a toxic substance in the vaccine that could cause any damage," he added.
Butler noted that, "if you think of the brain as a computer," stroke represents damage to the physical hardware of the computer. By contrast, FND is more akin to software damage.
"So it's a glitch in the software that is preventing the signals getting through from the brain to the body," he said.
In a study published in 2019 in The Journal of Neuropsychiatry and Clinical Neurosciences titled "Hiding in Plain Sight," Stoyan Popkirov, MD, Ruhr University Bochum, Bochum, Germany, and colleagues write that FND is a common disorder that has been misrepresented in the media and has been associated with stigma and misinformation.
Unlike other historically misunderstood illnesses, such as epilepsy or AIDS, FND cannot be detected on electroencephalography or immunoassay. Results of routine laboratory and imaging tests are typically normal, they note.
So for large parts of the medical community and the public, FND is considered an elusive, "medically unexplained" disorder. The diagnosis is one of exclusion. It is almost indistinguishable from malingering, which it is not, the researchers write.
The diagnosis of FND can often be hard to accept by patients. Often, doctors will continue looking for a cause of the symptoms and will order myriad tests until something unrelated is discovered.
Lifting the stigma and mystery surrounding FND will require a shift in medical and societal attitudes, write the investigators.
"Psychiatrists, neurologists, psychologists, physiotherapists, occupational therapists, and everyone else who is involved in caring for patients with FND need to work together toward improving health care provision for this common and disabling disorder," they write.
Butler reports no relevant financial relationships.
J Neuropsychiatry Clin Neurosci. Published online July 15, 2021. Abstract
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Cite this: Two More Reports of Functional Neurological Disorder After COVID-19 Vaccine - Medscape - Aug 30, 2021.