Whiplash Injury
Introduction and prevalence
Whiplash injury is an acceleration-deceleration injury occurring to the cervical spine or neck region, usually in the context of a sporting injury, fall, or MVA. By definition, no visible structural pathologies in the bones, joints, and ligaments are identified following a comprehensive diagnostic workup, therefore, whiplash injuries remain a diagnosis of exclusion. In the US, whiplash injuries affect 0.3% of the people a year.
Etiology and Pathophysiology
The mechanism of injury to the neck stems from the difference in velocity of the head and upper torso when a sudden transitional injury occurs. The most common mechanism of a whiplash injury is a rear-end collision, responsible for half of the cases. With this type of collision, trunk is forced backwards and the neck hyperextends and then recoils forward. There are different theories regarding how this mechanism of injury causes such diverse symptoms, including CNS and PNS lesions, however the exact mechanisms are unclear.
Clinical presentation
Typically, the patient presents with neck pain and stiffness, interscapular pain, upper limb pain and paresthesia, temporomandibular dysfunction, occipital headache, visual disturbances, psychological distress, and concentration difficulties. A history of car accident or sport related injury is common.
Physical examination
A comprehensive examination of the cervical spine and trauma evaluation are necessary. Any midline tenderness or step deformity dictates a cervical collar, safe transfer to an emergency department, and further imaging. For otherwise well patients with a history of whiplash but no midline tenderness or step deformities, a neurological exam of the upper and lower extremities including strength and sensation is necessary to rule out any deficits.
Investigations
The Canadian cervical spine rules or NEXUS criteria are useful for the evaluation of cervical spine injuries in the emergency department. Based on these criteria, high risk injuries warrant a CT head and neck. MRI can be helpful in the evaluation of cord injury.
Management
First-line treatments include analgesics, NSAIDs, ice, and heat. Biofeedback, muscle relaxants, and injection of lidocaine intramuscularly have also been shown to be helpful in reducing pain symptoms of whiplash injury. For a late whiplash injury, the use of facet blocks, botulinum toxin injections, and radiofrequency neurotomy have limited benefits. Cervical fusion after a whiplash injury may be indicated for brachialgia.