Whiplash is a relatively common injury that occurs to a person's neck following a sudden acceleration-deceleration force, most commonly from motor vehicle accidents. The term "whiplash injury" describes damage to both the bone structures and soft tissues, while "whiplash associated disorders" describes a more severe and chronic condition.
Whiplash is most commonly caused by a motor vehicle accident in which the car the person is riding in is not moving, and is struck from a vehicle from behind without notice. It is commonly thought the rear impact causes the head and neck to be forced into hyperextension as the seat pushes the person's torso forward - and the unrestrained head and neck fall backwards. After a short delay the head and neck then recover and are thrown into a hyperflexed position.
More recent studies investigating high-speed cameras and sophisticated crash dummies have determined that after the rear impact the lower cervical vertebrae (lower bones in the neck) are forced into a position of hyperextension while the upper cervical vertebrae (upper bones in the neck) are in a hyperflexed position. This leads to an abnormal S-shape in the cervical spine after the rear impact that is different from the normal motion. It is thought that this abnormal motion causes damage to the soft tissues that hold the cervical vertebrae together (ligaments, facet capsules, muscles).
The most common symptoms related to whiplash include:
- Neck pain and stiffness.
- Shoulder pain and stiffness.
- Jaw pain (temporomandibular joint symptoms).
- Arm pain.
- Arm weakness.
- Visual disturbances.
- Ringing in the ears (tinnitus).
- Back pain.
In the more severe and chronic case of "whiplash associated disorder" symptoms can include:
- Drug dependency.
- Post-traumatic stress syndrome.
- Sleep disturbance (insomnia).
It seems that excessive rest and immobilization have been shown to have greater chances of chronic symptoms. This is explained by loss of range of motion leading to increased pain and stiffness. Immobilization also causes muscle atrophy (muscle wasting) and decreased blood flow and healing of damaged muscles.
Physical therapy can be useful in helping to wean a patient from a cervical collar as well as to help strengthen muscles and reduce painful motions. Occupational therapy can be used to help return the patient to the work environment.