If not recognized and repaired, such complications may result in permanent brain injury or death. A loss of consciousness of 24 or more hours is a severe head injury that usually results in permanent damage. Most fighters with such injuries are admitted to the hospital. In severe head injuries, the pressure wave recedes but, in addition to any epidural, subdural, or intra-cerebral hematomas, there may be brain lacerations from skull fragments, strokes from occlusions of blood vessels, and tears in fiber tracts. Fighters who recover from severe head injuries may have paralysis of one or both sides of the body, and difficulty in thinking, speaking, and seeing.
A knockout, or loss of consciousness, occurs for one of three reasons:
- The brain is injured as it bangs against the opposite side of the skull
- There is a disruption in the nerve message systems of the brain. At the base of the brain is a small part of the brainstem called the Reticular Activating System or RAS. A disruption of the RAS may cause a person to pass out.
- There is a disruption in blood flow to the brain. During a stroke, a loss of circulation to a part of the brain to a blood vessel blockage results in permanent loss of function. A knockout may also result in a loss of blood flow to the brain but the result is temporary. If a fighter is hit “on the button,” or square on the jaw, the force of the blow is transmitted directly to the Temporomandibular joint (TMJ) where it temporarily disrupts cerebral circulation.
A knockdown is different from a knockout. In a knockdown, the pressure wave from the blow temporarily shuts down the inner ear, the balance control center, and stun the fighter but it does not injure the brain.
A knockout from a blow occurs because of the force of the blow, the duration of the blow (force over time), and where the blow lands. A knockout may be the result of an acceleration or deceleration blow to the brain.