Concussions are never the result of a penetrating injury to the brain. They are always the result of a “whiplash of the brain” where the brain is subjected to a linear or rotational acceleration. The brain damage is caused by the shear forces of the “whiplash” and the impact of the brain against the hard inner surfaces of the skull.
The majority of concussion injuries are not caused by a direct blow to the head. Any force directed to the body that causes the head to “whiplash” is sufficient to cause a concussion. Mayo Clinic states that the majority of sports-related concussions are the result of forces to the body and not directly to the head.
Biomechanical studies have proven that rotational forces are a major cause of concussions. Rotational forces are predominant in car accidents and motor vehicle collisions. The “three-point” safety belt system may save lives, but it is a major cause of concussion injuries. Instead of restraining both shoulders, it restrains only one. The result is a severe rotational force as the upper body is twisted by the restraint of the left shoulder of driver and the right shoulder of the passenger.
Any alteration of mental state caused by a whiplash of the brain qualifies as a concussion according to the most commonly recognized medical definition of concussion.
The large majority of concussions are “whiplash” injuries of the brain, where the brain is “whipped” back and forth in what is medically termed a “coup-contra coup” injury in which the brain is violently slammed back and forth against the hard inner surfaces of the skull. Remember: 90% of brain injuries are concussions and nearly 90% occur without a loss of consciousness.
Whiplash of the cervical spine (neck) is easy to understand-and well accepted in the medical literature. Remember: The “head-bone is connected to the neck bone”. The same forces that cause a whiplash of the neck cause even greater forces to the brain. It is a matter of simple physics that the forces are greater the farther out on the whip (the farther away from the fulcrum).
The most common type of motor vehicle collision is the “rear-ender” where the victim’s vehicle is struck from behind. This causes an “acceleration/deceleration” biomechanical model which biomechanical experts recognize as “biphasic”. In the acceleration phase, the vehicle is violently pushed forward with the seat pushing the trunk forward while restrained by the shoulder and lap belt. The neck and head is not so restrained except by the head rest which is often improperly adjusted and the head actually goes backward above the head rest.
Then comes the second phase where the body rebounds forward. As it does so, the “three point” restraint system in most automobiles restrains only one of the twohyuman shoulders, either the left shoulder of the driver or the right shoulder of the passenger. This causing a dramatic “rotation” of the upper torso. It is well known that the brain is more susceptible to rotational forces which cause greater injury. It is quite common for the driver to have more damage to the left side of the neck and the passenger to the right side of the neck. In many cases, the driver’s head and neck is turned, looking at the rear view mirror or watching for traffic, causing additional rotation force. Experts have called this phenomenon the “complex interplay of seat design, occupant mass, occupation position, and vehicle dynamics” which produces whiplash injuries to both the neck and the brain. Centeno, Minor Impact Soft Tissue Injury, Pain Res Manage, Vol 10(2), pp. 71-4 (2005) See Panjabi, Biomechanics of Whiplash Injury, Orthopade, 1996 27(12):81-9; Foreman, Whiplash Injuries: The Cervical Acceleration/Deceleration Syndrome, ?????
Another expert contends that airbags, which are made to prevent fatal injury (death), are actually contributing to cause concussions.