A new article published in May at British Journal of Sports Medicine by experts from Spaulding Rehabilitation, Boston University, the Mayo Clinic and the Concussion Legacy Foundation, argues that the term “subconcussion” is a dangerous misnomer that should be retired. The authors call on the medical community and the media to replace the term with more specific terms so the public can better understand the risks of brain injuries and promote effective efforts to prevent chronic traumatic encephalopathy (CTE).
The public has been led to believe through media coverage and movies that concussions only cause CTE. But the research is clear: concussions don’t predict CTE status and concussive hits are often not the most difficult, making ‘sub-syntax’ misleading when describing effects’.
Dan Daneshvar, MD, PhD, senior author, chief of brain injury rehabilitation at Spaulding Rehabilitation, a member of Mass General Brigham Health Care System and assistant professor, Harvard Medical School
The authors believe that part of the confusion is a result of the fact that non-concussive head impacts are referred to as “subconcussions”, implying that they are less than concussion. Scientists often say that CTE is caused by “small, repeated impacts,” which leave out the effect of any “large, repeated impacts.”
Ross Zafonte, DO, president of Spaulding Rehabilitation and chair of the Department of Physical Medicine and Rehabilitation at Harvard Medical School, served as a co-author.
Previous studies report a high incidence of large repetitive impacts during soccer. Published studies of helmet sensors show that about 10 percent of head impacts experienced by football players are harder than the average concussion. That means if a football player suffers one concussion during a season of 1,000 hits to the head, about 100 hits were harder than that one concussion. One study showed that for every concussion a college football player experiences, they experience 340 higher-force blows to the head.
The authors of the article recommend replacing the term “subconcussion” with “nonconcussion” to better describe head impacts that do not result in concussion.
“We’ve always known that CTE is caused by head impacts, but until we did this analysis, I didn’t realize that I was absorbing hundreds of extreme impacts to the head for every concussion when I played football,” said Chris Nowinski, PhD, lead author. co-founder and CEO of the Concussion Legacy Foundation, and former Harvard football player. “Using the term subconcussion Of course it led me to imagine smaller successes, but now I suspect they are common larger hits play a bigger role in causing CTE than previously thought.”
The article also highlights how the term subconcussion has not only confused the debate about head impacts, but also about traumatic brain injuries. Studies consistently show that athletes exposed to hundreds of repeated impacts to the head in the absence of concussion still have changes in brain function, blood biomarkers of brain injury, and structural imaging changes that resemble changes in athletes with a diagnosed concussion. The concept of subconcussive injury has been incorporated into the debate to explain this ‘missing link’.
The authors suggest we stop using subconcussion, noting that the missing link is best described as subclinical traumatic brain injury (TBI). Subclinical TBI occurs when there are changes in brain function, biomarkers, or imaging without signs or symptoms of TBI.
“The human brain has more than 80 billion neurons, and we can be sure that an athlete can’t feel it when just one is injured,” said neurosurgeon Robert Cantu, MD, clinical professor of neurology, Boston University School of Medicine and Diagnostics and Therapeutic. head of Boston University’s ARDC-CTE Center. “Athletes, military veterans, and members of the community often suffer from subclinical traumatic brain injuries, and we recommend retiring subconcussion, an ill-defined term, when referring to brain injuries.”
By changing this nomenclature, the authors hope to clarify why concussions don’t predict who gets CTE, while the number and force of repeated blows to the head does. They implore the medical community and the media to properly name the effects and injuries that are not visible, which can advance the conversation to accelerate CTE prevention efforts, such as the CTE Prevention Protocol.
Source:
Journal Reference:
Nowinski, CJ, et al. (2024). The term “subconcussion” is a dangerous misnomer: impacts larger than concussion impacts may not cause symptoms. British Journal of Sports Medicine. doi.org/10.1136/bjsports-2023-107413.
