This article includes discussion of whiplash injuries, acceleration-deceleration injury, cervical myofascial pain syndrome, cervical sprain, chronic whiplash syndrome, hyperextension injury, late whiplash syndrome, and whiplash. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
This article reviews whiplash injuries, one of the most controversial topics in neurology. Some may agree with the study that whiplash injuries do not exist in Lithuania, where compensation is not an issue, and may believe that chronic whiplash complaints have psychosocial rather than neurologic origins. Others may find the Lithuania study terribly flawed and may believe that the etiology of the chronic pain arises from facet joints or perhaps central sensitization. And yet others may wish to never see another patient with whiplash again. Reading this review will be sure to stimulate a vigorous forum discussion.
• Whiplash-associated disorders are commonly seen by neurologists, with neck pain and headache persisting in about 20% of patients at 1 year.
• Rear-end collisions can cause a hyperextension-flexion neck injury.
• Neck pain is usually due to myofascial or facet injury.
Historical note and terminology
Whiplash is an acceleration-deceleration mechanism of energy transfer to the neck that may result from rear-end or side-impact motor vehicle collisions. Common whiplash is a trauma causing cervical musculoligamental sprain or strain due to hyperextension-flexion and excludes fractures or dislocations of the cervical spine, head injury, or alteration of consciousness.
Chronic or late whiplash syndrome refers to persistent symptoms present more than 6 months after the accident. Other terms that some clinicians prefer include "cervical sprain," "cervical myofascial pain syndrome," "acceleration-deceleration injury," and "hyperextension injury." Terms for this type of injury in other languages include le coup du lapin in French and schleudertrauma in German (Evans 1995).
In 1995, the Quebec Task Force proposed a classification system for whiplash injuries (Spitzer et al 1995). Grade 1 signifies neck complaints of pain, stiffness, or tenderness without physical signs. Grade 2 represents neck complaints and musculoskeletal signs including decreased range of motion and point tenderness. Grade 3 indicates neck complaints and neurologic signs including decreased or absent deep tendon reflexes, muscle weakness, and sensory deficits. Grade 4 includes neck complaints and fracture or dislocation.
Controversy about late whiplash syndrome is paralleled by similar controversy about the sequelae of usually mild head and neck injuries that often occurred in railway accidents in the second half of the 19th century: "railway spine" (Evans 1994; Evans 2010). In publications from 1866 to 1882, Erichsen proposed that these injuries were due to "molecular disarrangement" or anemia of the spinal cord. In 1879, Rigler proposed compensation neurosis as the cause of an epidemic of compensation claims for railway accidents in Prussia. In 1888, Oppenheim disagreed with this explanation and popularized the term "traumatic neurosis." Charcot felt that posttraumatic symptoms were actually due to hysteria and neurasthenia. Throughout the 19th century in the United States, as today, there were misgivings about physicians becoming involved in medico-legal cases. A common concern was that physicians were available as hired guns with any opinion for a price.
The whiplash mechanism of injury may have first been recognized in United States Navy pilots who developed neck injuries from acceleration-deceleration forces when their planes were launched by catapults following World War I. Although the pilots were shortly thereafter provided with headrests and shoulder harnesses, automakers in the civilian sector took some 50 years to provide the same safety equipment. Crowe, an orthopedist, is often cited as coining the term "whiplash" during a lecture in 1928 (Crowe 1964); however, the first use I have found in the medical literature appeared in an article by another orthopedist, Davis, in 1945 (Davis 1945).
The term "whiplash" became widely used in the 1950s. In an influential paper in 1953, Gay and Abbott provided a good clinical review, but incorrectly attributed the injury to flexion followed by hyperextension of the neck in rear-end collisions (Gay and Abbott 1953). In 1955, Severy and colleagues reported a pioneering series of staged rear-end collisions using humans and anthropomorphic dummies and correctly identified the sequence of hyperextension followed by flexion of the neck (Severy et al 1955). Human volunteers were used in the front car at collision speeds up to 10 mph; dummies were used for higher-velocity collisions. However, volunteers were used in the rear car even in 20-mph collisions without injury, as the flexion-extension injury is not nearly as harmful. This observation should be remembered when critics of whiplash injuries wonder why they rarely, if ever, see the drivers of the rear car as patients.
Many clinicians believe that whiplash primarily results in myofascial injuries. In 1938, Kellgren described distinctive patterns of referred pain from injection of different muscles with a 6% solution of sodium chloride (Kellgren 1938). An American orthopedist, Steindler, used the terms "trigger point" and "myofascial pain" for the first time in 1939 (Steindler 1939).
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