“There are an estimated 1.7 to 3.8 million traumatic brain injuries each year in the United States, according to the CDC, of which 10 percent arise due to sports and recreational activities.  Sustaining an injury while playing sports can range from a mild physical trauma such as a scalp contusion or laceration to severe a traumatic brain injury (TBI) with concurrent bleeding in the brain or coma. It is important to recognize when a head trauma is severe or has resulted in a TBI because it is crucial to seek immediate medical attention.  A traumatic brain injury (TBI) is defined as a form of acquired brain injury from a blow or jolt to the head or a penetrating head injury that disrupts the normal function of the brain. A TBI can result when the head suddenly and violently hits an object, or when an object pierces the skull and enters brain tissue.”

American Association of Neurologiva Surgeons (https://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Sports-related-Head-Injury)