Concussions can reduce blood flow to young athletes' brains for a month or more, although their brains also appear more resilient in many ways than those of similarly injured adults, researchers report.
A single sports-related concussion in a young person generally produces minor trauma, which the researchers described as more of a disruption to brain function than the structural and metabolic damage similar concussions inflict on adult brains.
The findings come from a study assessing the effects of concussions on nine boys and three girls, ages 11 to 15, who'd been injured during football, soccer or wrestling. The study group comprised three girls injured while playing soccer, one boy injured while wrestling and seven boys injured on the football field. Two football players were knocked unconscious during the incidents; three of the football players had suffered previous concussions more than a year earlier.
When the researchers, led by Dr. Todd Maugans, a pediatric neurosurgeon at Cincinnati Children's Hospital Medical Center, compared injured athletes' brains to brains of healthy youngsters of the same age and sex, MRIs found less blood flowing through the injured athletes' brains in the immediate aftermath of their head injuries. The brain-injured athletes also had slower reaction times.
However, by the two-week mark, blood flow for 27 percent of the injured athletes returned nearly to the levels of healthy subjects and most of their symptoms had resolved. Follow-up at a month or more found 64 percent of the injured athletes had normal blood flow again, and everyone's reaction times were normal, according to results published online today in the journal Pediatrics.
With 36 percent of the group experiencing persistent blood flow reductions a month or more after their injuries, the findings "suggest that the brain may not be fully recovered from a physiological injury for more than a month," Maugans told ABCNews.com "Ours is the first study to suggest that, by examining the pathophysiology (biological nature of the injury) rather than just the clinical manifestations such as symptoms and neuropsychological alterations."
The authors theorized that diminished blood flow produces some of the symptoms associated with concussions, most of which resolve with time. They were unable to say what long-term effects might result from lessened blood flow. Maugans said that in addition to further studying altered blood flow in the brains of kids who have suffered concussions in organized sports, "it needs to be studied in adults (college and pro athletes) who have not been studied at all."
The 13-year-old wrestler suffered a severe concussion, which left him with a few minutes of weakness in his arms and legs, followed by confusion, severe headache and vomiting. Emergency MRI studies of his brain, spinal cord and blood vessels in his neck were normal, but two weeks after his injury, blood flow remained about 35 percent of normal, and he left the study for medical treatment, the authors wrote.
Attention has increased in recent years to the long-term cognitive effects of brain injuries, particularly blows to the head during sports. With that has come increased use of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), which was among the tools used by Maugans and his fellow researchers to assess the effects of concussions on young athletes. A computerized, 20-minute quiz, ImPACT evaluates health history, symptoms, sleep and medications, along with word recall and reaction time. An athlete takes the test to establish a baseline level of brain function and can repeat it after a concussion to detect impairments in cognition and other brain functions.