Understanding Whiplash Injuries

Article written by Travis G Maak, BS & Jonathan N Grauer, MD

Background
Of the 13 million motor vehicle accidents that occur in the United States annually, approximately 8% of motor vehicle accident victims experience whiplash symptoms, which amount to approximately one million whiplash injuries in the United States annually. The estimated cost of managing these injuries is $29 billion dollars per year in the United States alone. Nevertheless, the specific anatomic injuries, mechanism of injury, diagnosis, and treatment options remain controversial.

What is whiplash?
Whiplash was first defined in 1928 as a hyperextension followed by hyperflexion injury of the neck. These injuries are most common after low-velocity, rear-end collisions. Classically, the injury is thought to occur when the head is thrown backwards, although hyperflexion of the neck may occur when the head rebounds in a forward direction. Soft tissue stretch injuries to the muscles, ligaments and other anatomic structures may lead to acute and chronic symptoms.

What are the symptoms?
Neck pain is the primary symptom associated with whiplash injury. Less commonly, pain can occur in the back of the head, jaw, shoulder, and upper and lower back. Whiplash victims may also experience dizziness, headache, neck stiffness, weakness and upper extremity numbness. These symptoms generally resolve over days or weeks, but may persist for years.

How is it diagnosed?
History alone is often enough to make the diagnosis of whiplash. Physical examination will often reveal decreased neck motion and possibly neck muscle spasm (tightness). If significant pain or neurologic deficit (weakness and/or numbness) is present, additional imaging may be needed to evaluate for fracture or other injury. X-rays provide assessment of bony anatomy and alignment. Magnetic resonance imaging (MRI) is occasionally considered if a neurologic deficit is noted.

How is it treated?
Whiplash injury is generally treated conservatively, and symptoms often resolve with time alone. Anti-inflammatory and analgesic medications, however, effectively reduce the pain in the short term. Muscle relaxants may also be considered to limit spasm. If acute pain is present, a rigid cervical collar is considered until pain improves. If symptoms persist, physical therapy may also be appropriate. The utility of this therapy, however, has been questioned by some. Local modalities (heat, ultrasound, massage, electrical stimulation) may benefit patients on a symptomatic basis. Chiropractic care has not been well substantiated in the literature, but may benefit some patients.

What is the treatment outcome?
Most whiplash symptoms are short-lived and disappear over the course of a few weeks with conservative therapy. Chronic symptoms, however, may require continued use of analgesic and anti-inflammatory medications. These chronic symptoms can have a profound effect on the life of whiplash victims. In fact, up to 26% of these patients are unable to return to full activity up to 6 months following the injury. Nevertheless, the majority of patients experience complete recovery.

Are there any complications?
The primary complication of whiplash injury is chronic whiplash syndrome – a group of disorders in which symptoms persist longer than 6 months. These symptoms exist despite a lack of radiographic or anatomic evidence of injury and often do not respond to standard treatments or reassurance. Although a soft tissue injury may be identified in some of these cases, the chronic symptoms are often disproportionate to what is expected for the specific injury. Litigation issues are also confounding variables and are difficult to resolve in this whiplash population.

Summary
Whiplash describes a hyperextension injury of the neck associated with pain symptoms not clearly localizable with imaging modalities. Patients are classically treated with rest and anti-inflammatory (possibly with analgesic and muscle relaxant medications). While the symptoms most often resolve within weeks to a few months with conservative therapy, some victims may continue to experience chronic symptoms.