MRI Confirms Persistent Concussion Effects in Athletes 1 Year After Resuming Play
-Brain recovery lagged behind clinical recovery, increasing risk for long-term consequences
by Zeena Nackerdien PhD, CME Writer, MedPage Today October 23, 2019
Study Authors: Nathan W. Churchill, Michael G. Hutchison, et al.
Target Audience and Goal Statement: Neurologists, sports medicine doctors, psychologists, radiologists, emergency department physicians, family physicians
The goal of this observational study was to test the hypothesis that concussion-related brain alterations seen at symptomatic injury and medical clearance to return to play in college athletes will have dissipated by 1 year after return to play.
Question Addressed: Would effects from concussion persist at 1 year after a college athlete was medically cleared to return to play?
Study Synopsis and Perspective:
Acute trauma to the brain, such as the impact of a sports injury, a car accident, or a fall, could result in a concussion. Brain injuries may occur in a coup-countercoup fashion, in which the brain bumps into the interior of the skull, where it is hit, as well as on the opposite side, resulting in damaging bruises at two sites in the brain. Biomechanical injury to neurons in the brain are thought to contribute to post-concussive vulnerability.
- Imaging markers of brain injury were still seen on MRI when concussed athletes were cleared to return to play, and evidence of brain injury persisted for 12 months after return to play, in this observational study of college athletes.
- Realize that the diagnosis of concussion and determination of return to play are currently based on symptom status and brief evaluations of cognition and balance, but these assessments only indirectly reflect the underlying brain injury.
Competitive sports and recreational activities account for as many as 3.8 million concussions in the U.S. each year, with half of these transient brain injuries going unreported. About 1 million athletes have reported having two or more concussions. Recurrent concussion is associated with a higher risk of post-concussion syndrome -- a complex disorder in which various symptoms (such as headaches and dizziness) last for weeks and sometimes months after the injury.
However, the diagnosis of a concussion is currently based on symptom status and brief evaluations of cognition and balance. Similarly, a return to play is determined mainly by symptom resolution of a graded exercise protocol.
In a new study published in Neurology, Tom Schweizer, PhD, of St. Michael's Hospital in Toronto, Canada, and colleagues used longitudinal MRI to investigate brain recovery after a concussion. They reported that different aspects of brain physiology showed different patterns of recovery over time, with only a subset of MRI parameters showing non-significant concussion effects at 1 year after return to play. Moreover, the effects of concussion on the brain also vary as a function of clinical measures, including acute symptom severity and time to return to play, for all examined MRI parameters, they noted.
A total of 24 college athletes with concussion (mean age 20, 54% women) and 122 without concussion (mean age 20.3, 49% women) were enrolled in this observational study. Athletes were recruited via a sports medicine clinic at a single institution. The included athletes who played volleyball, hockey, soccer, football, rugby, basketball, lacrosse, and water polo.
All athletes completed baseline assessments with the Sport Concussion Assessment Tool 3 (SCAT3). Three MRI scans were performed: the first scan was performed about 4 days, on average, after the injury; the second one was performed when the athlete received clearance to return to play; and the final scan was performed 1 year after the return to play. Athletes who did not have concussions also underwent MRIs at the start of their respective seasons. Key effects of concussion on MRI parameters were evaluated at post-injury time points.
Imaging markers of brain injury were still seen when concussed athletes were cleared to return to play, and evidence of brain injury persisted for 12 months after return to play. Significant reductions in cerebral blood flow of 10 mL/100g/m were observed in concussed versus healthy athletes. Using an imaging approach that maps how water molecules move in the white matter of the brain, the researchers showed that the brains of concussed athletes exhibited possible evidence of tissue swelling 1 year after return to play.
Prior sports concussions studies have identified both focal increases and decreases in brain connectivity. But in the current study, measurements of the patterns of resting brain activity in the organ's gray matter and measurements of the lines of communication in the brain's white matter showed a return to normal 1 year after a return to play.
"Brain recovery after concussion may be a more complex and longer-lasting process than we originally thought," said co-author Nathan Churchill, PhD, also of St. Michael's Hospital.
"There is growing concern for the long-term health risks associated with concussion. However, we still know relatively little about how the brain recovers from concussion over the long-term, which is needed to understand the potential cause of these health concerns," he told MedPage Today.
This study had several limitations, the authors noted. Exertion and subconcussive impacts after return to play may have influenced results. In addition, athletes with concussion had MRIs only after injury, and not at baseline.
Source Reference: Neurology 2019; DOI: 10.1212/WNL.0000000000008523
Study Highlights and Explanation of Findings:
Based on one of the longest follow-up studies of brain recovery in university-level athletes to date, researchers found that the brains of concussed athletes still continued to show signs of injury 1 year after receiving full medical clearance.
"This research is striking because the length of time of the follow-up is unprecedented," said Churchill in a press release.
"At the moment, safe return-to-play is largely based on the resolution of symptoms, but this is an indirect measure of brain recovery," Churchill told MedPage Today. At medical clearance, "concussed athletes showed differences in brain structure and function compared to uninjured athletes, suggesting incomplete recovery. More importantly, 1 year later, some aspects of the brain looked normal, but others still showed signs of ongoing recovery."
"At return to play, face-value indications of the injury -- such as cognitive impairment and symptoms -- appear to have cleared," said Schweizer in the press release. "However, our findings show early and long-term brain changes in response to the concussion. This suggests a potential risk for long-term consequences, given the evidence of worse outcomes if a second concussion occurs before recovery is complete."
These findings are consistent with smaller studies that have used various imaging and electrical measurement tools to assess post-concussion effects, said Robert Cantu, MD, of the Boston University Chronic Traumatic Encephalopathy (CTE) Center, who was not involved in the study.
"When someone is symptomatically completely cleared of all post-concussion symptoms and is neurologically normal on examination -- when I, as a clinician in my office, determine the eye-tracking is normal, the cognition is normal, the balance is normal, the symptom checklist is back to baseline -- I'm going to send that individual through a return-to-play protocol and allow them to return to play," Cantu said in an interview with MedPage Today.
"At that point, there are still a wide number of studies that are not yet back to normal," he continued. "It's unnerving because we worry that we're possibly not being conservative enough in terms of when we send people back based just on the neurologic exam and the symptom checklist."
But many of these measurement tools -- such as evoked potentials, diffusion tensor MRI, and functional MRI -- are not recognized by the American Board of Radiology, Cantu added. "They are not clinical tools that a doctor in his office will order up and use as stop-go criteria."
"By the end of the study, the concussed athletes were determined to be fully recovered based on clinical assessment, and had otherwise fully returned to normal work and school activities," Churchill said. "This is important, as it suggests that there are long-lasting brain changes even with full clinical recovery. It also raises new questions about when -- if ever -- the brain returns to 'normal,' and whether the long-lasting brain changes we see are related to worse outcomes if the athletes sustain another concussion before recovery is completed."
Reviewed by Henry A. Solomon, MD, FACP, FACC Clinical Associate Professor, Weill Cornell Medical College