Concussions can cause longer-than-expected brain blood flow impairment in children, according to researchers at Cincinnati Children’s and the University of Cincinnati.

The study, led by Todd Maugans, MD, a pediatric neurosurgeon at Cincinnati Children’s, was published online Nov. 30 in the journal Pediatrics. Kim Cecil, PhD, a researcher in the Division of Pediatric Radiology, was chief co-investigator in the study.

The study assessed symptoms, memory and reaction time and well as MRI findings of brain injury, metabolic disruptions and brain blood flow in 12 children aged 11 to 15 who suffered sports-related concussions. The results were compared to 12 non-injured children of similar ages.

Results revealed that concussions led to reduced cerebral blood flow in most kids, who also showed slower reaction time.  These effects lasted as long as 14 days for 73 percent of the children studied and longer than 30 days for 36 percent of the athletes.

On the positive side: MRI scans revealed no chemical changes, bleeding, torn nerves or other signs of longer-lasting brain damage.

Avoiding second impact is crucial

The study findings raise questions about how soon injured students should return to school, and to their sports. The findings also reinforce medical concerns about the risks of second impact syndrome.

“In the recovery phase, rest and avoidance of a second head injury is imperative. A graduated return-to-play strategy is essential,” Maugans says.

By itself, this study is not enough to change current recommendations that young athletes should stay out one to two weeks and then gradually return to full play. However, to be safe, the longer a child rests after a first concussion, the better.

“When blood flow is low, another injury could be catastrophic,” Maugans says. “Second impact syndrome is rare, but in some children and young adults two seemingly minor concussions within a few weeks can lead to serious brain damage or death."

More research is needed to fully explore the links between concussion and reduced blood flow. In a future study, Maugans says he plans to include testing with a rapid form of ultrasound that can detect reduced blood flow even while an injured child is on the sidelines.

‘Brain rest’ debate continues

More research also is needed to determine how long a child should stay out of school following a concussion. Some experts say a child with concussion symptoms should avoid anything requiring intense concentration, including homework, video games and text messaging.

“The concept of cognitive rest, or ‘brain rest,’ is not based on an strong evidence,” Maugans says. “However, our data suggests that the brain may not be operating at 100 percent for a protracted period of time, so brain rest makes common sense. Kids may not feel well nor perform well in school if the cerebral blood flow is low.”