Sports-associated Recurrent Brain Injuries -- United States

There are an estimated 300,000 sports-related brain concussions in the United States each year. The "second impact syndrome" (SIS) has been reported when a second concussion occurs within hours, days, or weeks following a prior concussion. SIS causes rapid brain swelling resulting in coma or death. SIS can be prevented using American Academy of Neurology recommendations to protect athletes from returning to sports too soon after a concussion. CDC is working to determine the incidence of SIS and promote the use of prevention guidelines.

The popularity of contact sports in the United States exposes a large number of people to the risk of brain injury. Repeated brain injuries, including repeated mild concussions, can have severe or fatal outcomes, especially when the second injury occurs too soon, before recovery from the first has taken place.

Following a head impact, athletes with any symptoms of concussion should not return to activity until examined by a physician familiar with guidelines for the prevention of recurrent brain injuries. Symptoms warning of concussion include brief confusion or unsteadiness, with or without loss of consciousness. Even mild brain concussions can be dangerous if these guidelines are ignored.

One of the primary functions of CDC is to characterize a public health problem through surveillance and identify what puts people at risk. Data are needed to identify populations at highest risk for SIS. CDC is developing a multistate system for traumatic brain injury surveillance. Based on this surveillance system, CDC in collaboration with participating states, is developing methods to conduct surveillance for sports-related second impact syndrome.

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES