"The study is the first to actually demonstrate what have been the commonly assumed cumulative effects of multiple concussions in high school athletes," according to lead author Michael W. (Micky) Collins, Ph.D., a neuropsychologist and assistant director of the University of Pittsburgh Center for Sports Medicine's Concussion Program. "The study indicates for the first time in the high school athlete population that prior concussions may indeed lower the threshold for subsequent concussion injury and increase symptom severity in even seemingly mild subsequent concussions," he said. "Our findings are significant because high school athletes in contact sports are at high risk for repeated concussions, yet it is a population that has been understudied regarding concussion management," Dr. Collins said. "Quite often the athlete's concussion history has weighed heavily in the return-to-play decision process, although this has been based on little scientific data. Our findings highlight the need for more long-term outcome studies in this population."
Concussion symptoms are not always reported by the athlete and the effects are difficult to objectively measure. Thus, the determination of when it is safe to return an athlete to play is not always straightforward, according to Dr. Collins. Previous research has shown that allowing enough time for the brain to heal and recover before return-to-play is crucial in preventing more severe damage from possible further brain trauma during contact play. Generally, he said, most athletes who sustain an initial concussion can recover completely as long as they are not returned to contact sports too soon.
More than 10 percent of high school athletes participating in contact sports in the United States sustain a concussion each season, according to previous studies. A concussion can occur when the brain is violently rocked back and forth inside the skull due to a blow to the head or upper body. A concussion is a trauma-induced alteration of mental status that may or may not result in loss of consciousness. Other symptoms may include disorientation, confusion, dizziness, amnesia and uncoordinated hand-eye movements.
Dr. Collins' team investigated 88 high school athletes who sustained concussions during the 2000-2001 school year and were evaluated as patients of the University of Pittsburgh Center for Sports Medicine's Concussion Program. Sixty athletes with no prior concussion history were compared to 28 athletes with a history of three or more concussions. The two groups were compared in terms of on-the-field presentation of four concussion severity markers following an in-study concussion. The symptom markers measured involved loss of consciousness, anterograde amnesia (loss of memory of events after injury), retrograde amnesia (loss of memory of events before injury), and confusion.
Compared to the group with no concussion history, the group of athletes with three or more concussions were nine times more likely to experience three out of the four on-the-field severity markers - loss of consciousness, anterograde amnesia, and confusion.
Addressing the severity markers specifically: The group with a history of three or more concussions were more than six times more likely to experience loss of consciousness; nearly four times more likely to have anterograde amnesia; and four times more likely to be confused. The odds ratio of retrograde amnesia between the two groups was not significant.
Athletes who participated in the study were from high schools in Pennsylvania, Michigan, Illinois, Oregon and Maine. Among the group with no prior concussion history, 92 percent were males and the average age was 15.8 years. Seventy-eight percent were football players, 8 percent were soccer players, and 5 percent were basketball players. A very small percentage of the group participated in baseball, ice hockey, lacrosse, cheerleading and wrestling, collectively. Among the group with concussion history, 82 percent were males and the average age was 16.1 years. Fifty-four percent played football, 18 percent played soccer, and a very small percentage of the group played basketball, ice hockey, lacrosse, wrestling and volleyball.
Other study authors are: Mark R. Lovell, Ph.D., director of the University of Pittsburgh Center for Sports Medicine's Concussion Program; Grant L. Iverson, Ph.D., University of British Columbia; Robert Cantu, M.D., Emerson Hospital, Concord, Mass.; Joseph Maroon, M.D., and Melvin Field, M.D., both of the department of neurological surgery, University of Pittsburgh School of Medicine.
The University of Pittsburgh Center for Sports Medicine's Concussion Program focuses on diagnosis and management of sports-related concussions in athletes of all levels. The program's internationally-known team of clinicians and researchers are leaders in studying the neurocognitive effects of sports-related concussions and developing better methods of post-concussion evaluation to determine when it is safe for an athlete to return to sports. One method the team has developed is ImPACT (Immediate Post-concussion Assessment and Cognitive Testing). Used worldwide, ImPACT is the first computerized testing system to evaluate the severity of concussions in athletes. For more information, please access http://www.
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