, according to a study presented at the 2020 CNS-ICNA Conjoint Meeting, held virtually this year. Furthermore, cerebral blood flow at 4-6 weeks predicts recovery during the next 4 weeks in 77% of children.
“This is the first study to examine cerebral blood flow changes in children with persistent postconcussion symptoms,” said Karen Barlow, MBChB, associate professor of biomedical sciences at the University of Queensland in St. Lucia, Australia. “Our findings support the link between neurovascular unit dysfunction and persistent postconcussion symptoms in children, potentially because of injury or dysfunction in the GABAergic interneurons.”
Quantifying cerebral tissue perfusion
At least 25% of children with concussion have persistent postconcussion symptoms at 1 month post injury. Understanding the factors that influence the speed of recovery may help clarify the biology of postconcussion symptoms and suggest new treatments. In previous research, Dr. Barlow and colleagues found that children with early recovery (i.e., recovery by 4 weeks post injury) have decreases in cerebral blood flow, when compared with normal children. Children with persistent symptoms, however, have increases in cerebral blood flow. Dr. Barlow and colleagues conducted a new study to examine how cerebral blood flow changes in children with persistent postconcussion symptoms.
The investigators recruited participants through the randomized controlled Play Game trial, which examined melatonin as a treatment for persistent postconcussion symptoms. Among the exclusion criteria were history of assault, drug or alcohol use, significant past medical or psychiatric history, concussion within the previous 3 months, and use of psychoactive medications.
Children entered the study at 4-8 weeks after injury and received treatment for 4 weeks. Participants underwent 3-D pseudo-continuous arterial spin–labeled MRI before and after the treatment period (i.e., at 5 and 10 weeks post injury). This imaging technique provides a quantitative assessment of cerebral tissue perfusion. “You can do it without manipulating the cerebral circulation, making it particularly useful for research and in children,” said Dr. Barlow.
She and her colleagues evaluated recovery using the Post-Concussion Symptom Inventory. They defined good recovery as a total score at or below baseline at 10 weeks post injury. They considered any children who did not meet this criterion to have poor recovery.
Speed of blood-flow change varied
In all, 124 children were eligible for the study, and 76 had MRIs at both time points. Fourteen participants were excluded because of motion artifacts, slice truncation, and normalization failure. The population’s average age was approximately 14 years. About half of participants were males. The first MRI was performed at 37 days post injury, and the second MRI at around 70 days post injury. Twenty-three children had good recovery.
Children with poor recovery at 10 weeks had higher relative cerebral blood flow, compared with children with good recovery. Treatment group, age, and sex did not affect the changes in relative cerebral blood flow over time. Dr. Barlow and colleagues also measured mean total gray matter cerebral blood flow. Children with poor recovery had higher cerebral blood flow at 5 and 10 weeks post injury, compared with children with good recovery. In addition, cerebral blood flow changed more slowly in participants with poor recovery, compared with those with good recovery. Logistic regression analysis indicated that the mean absolute gray matter cerebral blood flow at 4-6 weeks post injury significantly predicted which children would recover by 10 weeks post injury, with an area under the receiver operating characteristic curve of 77%.
Funders for the study included Alberta Children’s Hospital, the Canadian Institutes of Health Research, and the University of Calgary. Dr. Barlow had no disclosures or conflicts of interest.
SOURCE: Barlow K et al. CNS-ICNA 2020. Abstract PL100.