The rapid development of diffuse brain swelling when the head suffers a second impact before brain injury from the first impact has cleared. A seemingly minor second impact on an already damaged brain can lead to a massive swelling and rapid deterioration of the casualty. Usually within seconds to minutes of the second impact, the initially conscious athlete loses consciousness, collapses, and shows evidence of respiratory failure. This post-concussion condition is often fatal and emphasizes that conservative guidelines should be followed before athletes are allowed to return to participation in a contact or collision sport after a head injury. See alsoconcussion.
Subjects: Sports and Exercise Medicine.