Whiplash, whose formal term is whiplash associated disorders (WAD), is a range of injuries to the neck caused by or related to a sudden distortion of the neck associated with extension, although the exact injury mechanisms remain unknown. The term "whiplash" is a colloquialism. "Cervical acceleration–deceleration" (CAD) describes the mechanism of the injury, while WAD describes the subsequent injuries and symptoms. Whiplash is commonly associated with motor vehicle crashes, usually when the vehicle has been hit in the rear; however, the injury can be sustained in many other ways, including headbanging, bungee jumping and falls. It is one of the most frequently claimed injuries on vehicle insurance policies in certain countries; for example, in the United Kingdom, 430,000 people made an insurance claim for whiplash in 2007, accounting for 14% of every driver's premium. In the United States, it is estimated that more than 65% of all bodily injury claims are whiplash related, translating to around $8 billion in economic costs per year. Before the invention of the car, whiplash injuries were called "railway spine" as they were noted mostly in connection with train collisions. The first case of severe neck pain arising from a train collision was documented around 1919. The number of whiplash injuries has since risen sharply due to rear-end motor vehicle collisions. Given the wide variety of symptoms associated with whiplash injuries, the Quebec Task Force on Whiplash-Associated Disorders coined the phrase 'Whiplash-Associated Disorders'. While there is broad consensus that acute whiplash is not uncommon, the topic of chronic whiplash is controversial, with studies in at least three countries showing zero to low prevalence, and some academics positing a linkage to financial issues.
Signs and symptoms
Symptoms reported by affected people include: pain and aching to the neck and back, referred pain to the shoulders, sensory disturbance (such as pins and needles) to the arms and legs, and headaches. Symptoms can appear directly after the injury, but often are not felt until days afterwards. Whiplash is usually confined to the spine. The most common areas of the spine affected by whiplash are the neck and middle of the spine. "Neck" pain is very common between the shoulder and the neck. The "missing link" of whiplash may be towards or inside the shoulder and this would explain why neck therapy alone frequently does not give lasting relief. Cognitive symptoms following whiplash trauma, such as being easily distracted or irritated, seems to be common and possibly linked to a poorer prognosis.
Cause The exact injury mechanism that causes whiplash injuries is forceful sudden hyperextension followed by hyperflexion of the cervical vertebrae, mainly spraining the nuchal ligament and the Anterior Longitudinal Ligament respectively. A whiplash injury may be the result of impulsive retracting of the spine, mainly the ligament: anterior longitudinal ligament which is stretched or tears, as the head snaps forward and then back again causing a whiplash injury. A whiplash injury from an automobile accident is called a cervical acceleration–deceleration injury. Cadaver studies have shown that as an automobile occupant is hit from behind, the forces from the seat back compress the kyphosis of the thoracic spine, which provides an axial load on the lumbar spine and cervical spine. This forces the cervical spine to deform into an S-shape where the lower cervical spine is forced into a kyphosis while the upper cervical spine maintains its lordosis. As the injury progresses, the whole cervical spine is finally hyper-extended. Whiplash may be caused by any motion similar to a rear-end collision in a motor vehicle, such as may take place on a roller coaster or other rides at an amusement park, sports injuries such as skiing accidents, other modes of transportation such as airplane travel, or from being hit, kicked or shaken.. Whiplash associated disorders sometimes include injury to the cerebrum. In a severe cervical acceleration–deceleration syndrome, a brain injury known as a coup contrecoup injury occurs. A coup contrecoup injury occurs as the brain is accelerated into the cranium as the head and neck hyperextend, and is then accelerated into the other side as the head and neck rebound to hyper-flexion or neutral position. "Volunteer studies of experimental, low-velocity rear-end collisions have shown a percentage of subjects to report short-lived symptoms", From this type of research, it has been inferred that whiplash symptoms might not always have any pathological (injury) explanation. However, over the last decade, academic surgeons in the UK and US have sought to unravel the whiplash enigma. A 1000-case, four-year observational study published in 2012 said that the "missing link" in whiplash injuries is the trapezius muscle which may be damaged through eccentric muscle contraction during the whiplash mechanism described above and below. Another study suggested that "shneck pain" was in the nearby supraspinatus muscle and this resulted from a seemingly asymptomatic form of shoulder impingement. Shoulder impingement is commonly asymptomatic and the shoulder may be injured along with the neck in a motor vehicle accident. Whiplash due to The Referred Shoulder Impingement Syndrome was successfully treated using conventional treatments for shoulder impingement including anti-inflammatory steroids and non steroids, and by avoiding the overhead position of shoulder impingement during the day and night time. All of this work demonstrates that historically and indeed presently whiplash patients' pain sources may be missed if it is outside of the neck. Hence the pathology in whiplash may have been missed and the treatment ineffective.
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