Reduced Blood Flow in Brain After Clinical Recovery From Acute Concussion
Some athletes who experience sports-related concussions have reduced blood flow in parts of their brains even after clinical recovery, according to a study. The results suggest a role for MRI in determining when to allow athletes with concussion to return to competition.
Concussions affect millions of people each year and are especially prevalent in contact sports like football. Sports are second only to motor vehicle crashes as a leading cause of traumatic brain injury among people between ages 15 and 24, according to the National Institutes of Health.
Decisions to clear concussed athletes to return to action are typically based on symptoms and cognitive and neurologic test results. An increasing amount of evidence, however, indicates that brain abnormalities persist beyond the point of clinical recovery after injury.
To find out more about this topic, researchers from the Medical College of Wisconsin in Milwaukee studied football players with concussion with arterial spin labeling, an advanced MRI method that detects blood flow in the brain.
“This measurement of blood flow is fully noninvasive, without radiation exposure,” said Yang Wang, MD, PhD, Associate Professor of Radiology at the Medical College of Wisconsin. “We use arterial blood water as a contrast tracer to measure blood flow change, which is highly associated with brain function.”
Dr. Wang and colleagues studied 18 players with concussion and 19 players without concussion. They obtained MRI of the players with concussion within 24 hours of the injury and a follow-up MRI eight days after the injury. The researchers compared the results of players with concussions with those of the control players. Clinical assessments were obtained for both groups at each time point, as well as at the baseline before the football season.
The players with concussion demonstrated significant impairment on clinical assessment at 24 hours post injury, but returned to baseline levels at eight days. In contrast to clinical manifestation, the players with concussion demonstrated a significant blood flow decrease at eight days, relative to 24 hours post injury, while the players without concussion had no change in cerebral blood flow between the two time points.
“In eight days, the concussed athletes showed clinical recovery,” Dr. Wang said. “However, MRI showed that even those in clinical recovery still had neurophysiologic abnormalities. Neurons under such a state of physiologic stress function abnormally and may become more susceptible to second injury.”
Although the reasons for reduced cerebral blood flow in athletes with concussion are still under investigation, the findings may have important implications for decisions on when athletes are ready to return to play after head injuries, according to the study’s principal investigator, Michael McCrea, PhD, Professor of Neurosurgery and Neurology and Director of Brain Injury Research at the Medical College of Wisconsin.
“For years, we’ve relied on what athletes are telling us,” Dr. McCrea said. “We need something more objective, and this technology may provide a greater measurement of recovery.”
The Medical College of Wisconsin scientists are continuing their research as Phase II winners of the Head Health Challenge, an initiative from the National Football League and General Electric to develop ways to speed diagnosis and improve treatment for concussion. Dr. McCrea and his team are also cochairing the Concussion Assessment, Research, and Education Consortium (CARE) project, a national effort that will enroll more than 30,000 college athletes, thus potentially making it the largest study of concussions to date.
“The nature of this research allows us to study the mechanisms of injury and recovery directly in humans rather than in animal models,” Dr. McCrea said. “Our ultimate aim is to better understand the time course of neurobiological recovery after concussion.”
Other coauthors on the study are Lindsay D. Nelson, PhD; Ashley A. LaRoche; Adam Y. Pfaller; Andrew S. Nencka, PhD; and Kevin M. Koch, PhD.
Researchers Find Link Between Early-Stage Brain and Heart Diseases
Researchers in the Netherlands studying thousands of healthy adults have found a connection between very early stages of brain and heart diseases. “Heart and brain diseases are big problems in aging individuals and are expected to grow even more,” said Hazel Zonneveld, MD, of the Department of Epidemiology and Radiology at Erasmus University Medical Center in Rotterdam, Netherlands. “We know that myocardial infarction, heart failure, and atrial fibrillation are associated with an increased risk of stroke and dementia. Our study investigates whether the heart-brain link is present at an earlier stage of disease.”
Dr. Zonneveld and colleagues analyzed data from 2,432 participants in the Rotterdam Study (57.4% women, mean age 56.6), a prospective, population-based study designed to investigate chronic diseases in Rotterdam’s aging population. Participants with overt heart disease, dementia, and brain infarcts (ie, strokes) were excluded from the analysis.