New research confirms that relying on emergency room data to estimate the prevalence of childhood concussions doesn't deliver a complete picture because many seek treatment in primary care.

The study, from the Children's Hospital of Philadelphia health network, included about 8,000 kids who sought concussion treatment there over four years.

About 80 percent were treated in primary care offices, which researchers say is appropriate unless there are severe symptoms, including seizures or blurred vision.

The researchers say their findings show that kids' doctors need to be up to speed on concussion symptoms and treatment.

Symptoms may include headaches, dizziness or confusion after a blow to the head.

The study was published Tuesday in the journal JAMA Pediatrics.