"There have been several studies suggesting there are differences between boys and girls as far as [concussion] symptom reporting and the duration of symptoms," said Dr. Shayne Fehr, a pediatric sports medicine specialist at Children's Hospital of Wisconsin.
In his new study, Fehr also found those differences. He tracked 549 patients, including 235 girls, who sought treatment at a pediatric concussion clinic.
Compared to the boys, the girls reported more severe symptoms and took nearly 22 more days to recover, said Fehr, also an assistant professor of pediatric orthopedics at the Medical College of Wisconsin.
He was due to present the findings this week at the annual meeting of the American Medical Society for Sports Medicine, held in New Orleans. Studies presented at medical meetings are typically viewed as preliminary until published in a peer-reviewed journal.
A concussion is any brain injury that disturbs normal functioning. Concussions are typically caused by a jolt or blow to the head, often in collision sports such as hockey or football, according to the American Academy of Pediatrics (AAP).
In the new study, Fehr tracked patients aged 10 to 18, all treated between early 2010 and mid-2012. Each patient reported on their symptoms, how severe they were and how long it took from the time of the injury until they were symptom-free.
In addition to reporting more severe symptoms, girls took an average of 56 days to be symptom-free. In comparison, the boys took 34 days. Overall, the time to recovery was 44 days when boys and girls were pooled.
That duration of symptoms, Fehr said, is much longer than what people commonly think. "Commonly you hear that seven to 10 days [for recovery] is average," he said.
Fehr did not find age to be linked with severity of symptoms. Most of the injuries -- 76 percent -- were sports-related, with football accounting for 22 percent of the concussions.
The top five reported symptoms were headache, trouble concentrating, sensitivity to light, sensitivity to sound and dizziness. Boys and girls, in general, reported the same types of symptoms, Fehr said, but the girls reported more severity and for a longer time period.
"This confirms what has been reported before," said Dr. John Kuluz, director of traumatic brain injury and neurorehabilitation at Miami Children's Hospital, who reviewed the findings.
While he said the 44-day recovery seems lengthy, he added that it probably reflects the boys and girls studied. They all went to a concussion clinic, so their injuries may have been more severe.
What's not known, Fehr said, is why the differences exist and whether they are related to more reporting of symptoms right after the injury by girls or if girls are truly more significantly affected.
"I wouldn't treat girls any differently than boys,'' he said.
For both genders, it's important to be seen by a doctor and not return to play prematurely, which can be dangerous or even fatal, according to the AAP. Anyone with a history of concussion is at higher risk for another injury.