SC Connecticut News

Long COVID has a range of symptoms, including the lesser-known sensation of internal tremors, often without any visible evidence. A new Yale-based study reveals that over one-third of participants report experiencing this symptom, which feels like internal vibrations.

Harlan Krumholz, MD, SM, highlights the severity: “These are people who are suffering substantially, and a part of what contributes to their suffering is this symptom.”

Since the pandemic began in 2020, Long COVID has emerged as a poorly understood aspect of SARS-CoV-2. Some patients never fully recover from their initial infection and develop various symptoms ranging from gastrointestinal issues to chronic fatigue. Researchers at Yale School of Medicine have now added internal tremors to this list. According to their study published on July 26 in the American Journal of Medicine, some Long COVID patients experience an invisible twitching or vibrating sensation.

“Many patients [who had this symptom] were being dismissed because doctors hadn’t heard of this before – and many patients wondered if anyone else had experienced it,” says Krumholz. He hopes the study will help people feel less isolated.

Krumholz's team initially focused on cardiovascular disease but pivoted during the pandemic to address SARS-CoV-2. Working with immunologist Akiko Iwasaki, PhD, they turned their attention to Long COVID. They noticed some patients describing a “very unusual syndrome” involving sensations akin to muscle tremors or vibrating nerves under the skin.

Unlike neurological conditions such as Parkinson’s that cause visible tremors, these Long COVID symptoms lacked discernible shaking or detectable spasms. The team found fewer than ten scientific studies describing similar phenomena, according to Tianna Zhou, MD.

To understand how widespread internal tremors are, Krumholz and Iwasaki surveyed 423 members of a Long COVID research group at Yale. All participants had contracted COVID-19 between May 2022 and June 2023. Of these respondents, 37% reported experiencing internal tremors.

Zhou notes that “it’s not a symptom that seems to be commonly reported.” The sensations ranged from bothersome to intolerable for most respondents. Those with internal tremors also reported worse overall health and greater financial strain compared to other Long COVID patients.

Despite its invisibility, Krumholz emphasizes that “it’s not trivial.” The survey found those with internal tremors were more likely to report nervous system conditions and symptoms like dizziness and heart rate issues.

Krumholz underscores that Long COVID is “not really one disease.” Internal tremors may indicate a subtype with specific treatment implications. He hopes identifying various symptoms will aid researchers in pinpointing causes and developing therapies for affected individuals whose lives remain disrupted by lingering effects of the virus.

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