Whiplash is a slang term for a condition called cervical acceleration, deceleration syndrome (CAD). There are facts and myths surrounding the subject of whiplash. Let’s look at some of the facts...
1. The origin of CAD. The history of CAD dates back before automobiles were commonplace. The first case of severe neck pain arose from a train collision around the time of 1919 and was originally called “railroad spine.” The number of whiplash injuries sharply rose after the mass adoption of cars due to rear-end crashes.
2. Whiplash synonyms. As stated previously, the term "cervical acceleration-deceleration disorder" is a popular title as it explains the mechanism of injury, where in the classic rear-end collision, the neck is initially extended back as the car is propelled forward, leaving the head hanging in space. Once the tissues stretch enough in the front of the neck, the head and neck flex forward very rapidly, forcing the chin towards the chest. This over-stretches the soft tissues in the back of the neck. Another term for whiplash is WAD or Whiplash Associated Disorders. In 1995, the Quebec Task Force categorized injuries associated with whiplash by the type of tissues that were found to be injured. Here, WAD Type I represents patients with symptoms/pain but normal range of motion and no real objective findings like muscle spasm. Type II includes injuries to the soft tissues that limit neck motion with muscle spasm but no neurological loss (sensation or muscle strength). WAD Type III includes the Type II findings plus neurological loss. Finally, type IV involves fractures of the cervical spine.
3. Head rest facts: Prior to the invention of head rests, whiplash injuries were much more common and more serious because the head was propelled in a “crack-the-whip” like fashion. However, headrests are frequently not adjusted correctly as they are either too low and/or too far away from the head. If the seat back is reclined, this further separates the head from the headrest. The proper position of the head rest should be near the center of gravity of the head, or about 9 cm (~3.5 inches) below the top of the head, or at minimum, at the top of the ears. Equally important is that it should be as close as possible to the back of the head. When the distance reaches 4 inches away from the head, there is an increased risk of injury, especially if it’s also set too low. When the headrest is properly positioned, the chances of head injury are decreased by up to 35% during a rear-end collision.
4. Seat back angle. The degree of incline of the seat back can also contribute to injury of the cervical spine. As stated above, as the seat is reclined, the head to headrest distance increases, furthering the chance for injury. A second negative effect is called “ramping.” Here, the body slides up the seat back resulting in the head being positioned over the top of the head rest. Also, the degree of “spring” of the seat back contributes to the rebound of the torso during the CAD process.
5. Concussion: The notion that the head has to hit something to develop a concussion is not true. Also, the idea that a loss of consciousness is needed to develop a concussion is also false. Simply, the rapid forward/backward movement of the head is enough force for the brain (which is suspended by ligaments) to literally slam into the inner walls of the skull and can result in concussion. The symptoms associated with concussion are referred to as post-concussive syndrome or mild-traumatic brain injury.
