Recurrent Concussion in Sports
Rate of Recovery Increases after Successive Concussions
The recognition and management of concussions have received a great deal of attention in the last five to ten years from researchers involved in the field of sports medicine. This research is changing the way that concussions are diagnosed, treated, and managed.
Along with a better understanding of the impaired neurological functioning of a concussed brain, recent research has focused on the neurological impairment of the brain after multiple concussions. The research is sobering and needs to be brought to the attention of all athletes, parents, coaches, and medical professionals working directly with athletes.
New Research on Recurrent Concussions
A recent study (August, 2007) published in the Journal of Neurosurgery studied the difference in the rate of restoring visual-kinesthetic integration (balance) in collegiate athletes who had experienced a single concussion versus recurrent concussion episodes.
One hundred sixty collegiate athletes underwent preseason testing using a variety of concussion measurement tools including a post-concussion symptoms checklist, neuropsychological evaluations, and postural responses to visual field motion. These tests established a baseline performance for each athlete.
Thirty-eight athletes sustained mild traumatic brain injuries (MTBI) during the season with nine of these athletes sustaining a second MTBI within one year of the initial injury. All athletes were asymptomatic (complained of no signs or symptoms of injury) by day 10 of testing. However, balance deficits were evident at least 30 days post-injury.
Elongated Balance Impairment Associated with Recurrent Concussion
These results alone are significant. It means that although athletes did not feel any symptoms (headache, nausea, dizziness, confusion) from the initial injury, they still had deficits in their kinesthetic awareness (ability to balance). The athletes’ brains were still not completely healed from the initial injuries even though the athletes did not feel any symptoms of the MTBI.
This is significant because most athletes are currently released to return to play after their symptoms have dissipated. This data suggests that a resolution of symptoms is not a good indicator of a healed brain.
The study then compared the recovery rate of balance symptoms between the athletes who had sustained one MTBI and those who had sustained a second MTBI. The results showed that athletes with a previous MTBI demonstrated significantly slower rates of recovery in neurological function after the second MTBI episode.
Increase in Severity of On-Field Symptoms with Recurrent Concussions
In addition to a slower rate of recovery, athletes with recurrent concussions also experience more severe on field signs and symptoms at the time of subsequent injuries. This conclusion was documented in a study of 173 high school athletes published in the Journal of Neurosurgery (November 2002).
The results of this study revealed that athletes with three or more concussions were more likely to experience on field loss of consciousness, anterograde amnesia (loss of memory for events immediately following injury), retrograde amnesia (loss of memory for events immediately preceding the injury), and confusion after a subsequent concussion. This study was the first to document a cumulative effect of multiple concussions.
Athletes with recurrent concussions take longer to recover and are at risk for more severe on-field presentation of symptoms with subsequent concussions. Recent research has also revealed that returning athletes to play based on athletes being “asymptomatic” may not be good practice. Objective measurement tools may be a better indicator of healing than subjective reporting of symptoms.
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