It’s possible that more than half of American kids with sports-related concussions are not being treated for their injuries, according to a new study in the journal Pediatrics. That means that between 500,000 and 1.2 million kids 18 or younger received no medical evaluation, treatment or advice after sustaining a potentially dangerous traumatic brain injury.

The study points out that sports- and recreation-related concussions (SRRCs) are the biggest source of concussions for kids—about 44 million children participate in recreational sports every year, and about between 1 and 2 million of them end up with an SRRC.

That number is more precise than previously known, the study says. Previous looks at sports concussions in kids focused on college or high school student athletes to the exclusion of younger kids and recreational players. Previous estimates often cited data from a 1991 survey. This study looked at concussion data from 2013 gathered from the National Electronic Injury Surveillance System and other databases to count child athletes seen by physicians in office settings, emergency rooms and athletic training facilities as well as those not seen by any health professionals.

The study calculated that between four and six for every 100,000 kids are hospitalized every year for SRRCs, while another 148 to 214 kids per every 100,000 end up in the emergency room. They found that of kids who had head injuries in high school sports settings, about 22 percent were seen by athletic trainers.

“We estimated between 582,228 and 635,728 SRRCs are treated annually by healthcare providers in the U.S. for an incidence between 748 and 816 SRRCs per 100,000 children per year,” the study authors wrote.

The study authors say the findings indicate a need for better recording of these sports-related traumatic brain injuries in kids and a need for physicians and athletic trainers to be well-versed in concussion treatment in minors.

Still, up to 53 percent of all high school sports-caused brain injuries and up to 56 percent of sports concussions in kids younger than 14 are never reported to any healthcare provider at all, the study found.

With those numbers in mind, the study also calls for a "cultural shift” to help parents, coaches and kids be more aware of how to prevent and recognize concussions.