Whiplash Injury

Whiplash injury is a combined flexion/extension soft-tissue injury of the cervical spine, common in road traffic accidents. May also be caused by sports injuries, falls or assaults. There are two types of injury:

• Typical cervical hyperextension injuries occur in drivers/passengers of a stationary or slow-moving vehicle that is struck from behind. Body is thrown forward but the head lags, resulting in hyperextension of the neck. When the head and neck have reached maximum extension, the neck then snaps into flexion.
• A rapid deceleration injury throws the head forwards and flexes the cervical spine. The chin limits forward flexion but the forward movement may be sufficient to cause longitudinal distraction and neurological damage. Hyperextension may occur in the subsequent recoil.
  Whiplash injuries may occur at relatively low vehicle velocity impacts. One study showed the cervical muscle injury threshold to be about 8.0 km/hour¹.
  Whiplash-associated disorders (WAD) can be classified by the severity of signs and symptoms²:
  • Grade 0: no complaints or physical signs
  • Grade 1: indicates neck complaints but no physical signs
  • Grade 2: indicates neck complaints and musculoskeletal signs
  • Grade 3: neck complaints and neurological signs
  • Grade 4: neck complaints and fracture/dislocation

• Trauma and sports injuries are more common in young adults.
• Rates of whiplash are higher in persons using a seatbelt with shoulder restraint than with no restraint, but seatbelts often prevent more serious injuries
• Poor posture
• Poorly-fitted head restraints
• Women sustain higher rates of whiplash, probably because their neck muscles are less well developed than men's
• Narrowing of the cervical spinal canal due to acquired or congenital disorders predisposes to spinal cord damage with these types of injuries

The clinical symptoms of whiplash injury may not develop until 6-12 hours after the injury or even after a few days. These include:

• Typical clinical findings include neck pain, jaw pain, paraspinal muscle tightness and spasm. Neck pain usually develops shortly after the accident and may worsen and peak 1-2 days after the event.
• Interscapular and low back pain
• Reduced range of movements and neck tenderness
• Headache, dizziness, vertigo, blurring of vision
• Numbness in shoulders and arms. Paraesthesia and weakness in the arms and legs - depending on presence and site of any cord contusion
• There may be retropharyngeal swelling and dysphagia.
• Insomnia, anxiety (general anxiety and/or travel anxiety when in a car) or depression
• Leg weakness, hyperactive tendon reflexes in the legs, upgoing plantar response, and/or sphincter disturbance, suggests damage to the spinal cord
• Arm weakness or numbness suggests injury or entrapment to the nerve roots of the cervical spine
• Symptoms may be severe, but investigations often do not demonstrate any abnormality.

It is essential to consider serious injury in the immediate period following injury. Other possible causes of acute neck pain and stiffness include:
• Spinal fracture
• Cervical disc herniation
• Subarachnoid haemorrhage (may precede or occur at time of a road traffic accident)
• Meningitis or meningism due to systemic infection
• It is also essential to consider other causes of symptoms, e.g. person in a road traffic accident may have severe chest pain due to restraint from seatbelt but must consider possibility of acute myocardial infarction, especially in the elderly.
• If the neck symptoms persist then it is also very important to consider other causes of chronic neck pain, even though soft tissue 'whiplash' injuries may cause long-term symptoms. One study found the prevalence of persisting pain after whiplash injuries to be very similar to the prevalence of chronic neck pain in the general population³. Other possible causes of persistent neck pain and stiffness include:
  • Cervical spondylosis: results from narrowing of the canal around the spinal cord, with or without the formation of bony osteophytes
  • Cervical disc herniation
  • Tumours: brain tumours, bone tumours

• Cervical spine X-rays:
  • All seven cervical vertebrae must be clearly shown, as well as the superior part of T1
  • Patients with no midline cervical tenderness, no focal neurological deficit, normal alertness, and no painful distracting concurrent injury have a low probability of having suffered a cervical spine injuries, and therefore may not require cervical X-rays. Otherwise cervical spine X-rays should be considered
• CT scanning of cervical spine:
  • Is indicated if there is suspicion on the plain films that a fracture or displacement has occurred
• MRI scanning of cervical spine:
  • Indicated for patients with neurological signs, even if plain films are negative.
  • MRI can distinguish haematoma from oedema, which can have prognostic importance.
• CT myelography:
  • Indicated if MRI is not available, the patient cannot tolerate MRI, or MRI is contraindicated.

For patients with acute whiplash, there has been a trend towards active treatments to reduce pain and stiffness but the evidence remains conflicting. There is insufficient evidence to indicate the most effective treatments for patients with whiplash-related problems that has lasted for longer than six months².
A recent Cochrane review by Peloso et al found⁴:

• Intramuscular injection of lidocaine for chronic MND (mechanical neck disorders) and intravenous injection of methylprednisolone for acute whiplash are effective treatments.
• There is limited evidence of effectiveness of epidural injection of methylprednisolone and lidocaine for chronic MND with radicular findings.
• Other medications, including NSAIDs and muscle relaxants have contradictory or limited evidence of effectiveness.
• There is moderate evidence that Botox-A intramuscular injections for chronic MND are not better than saline.

However the following are considered to be appropriate management:

• Recovery and return to full function is best aided by sympathy and encouraging the patient to take an active role in dealing with the symptoms.
• Analgesia
• There is now good evidence that the use of collars in whiplash injury prolongs the recovery of the patient. Patients should be advised about neck mobilisation and encouraged to remain as active as possible⁵.
• Patients should receive instruction about exercises⁶. A recent study comparing education by GPs compared to physiotherapists found no significant differences in overall outcome and treatments by GPs and physiotherapists were of similar effectiveness⁷.
  • The long-term effects of GP care seemed to be better compared to physiotherapy for functional recovery, coping, and physical functioning.
  • Physiotherapy was found to be more effective than GP care on cervical range of motion at short-term follow-up.
• Patients with particularly severe symptoms or symptoms that are not resolving may benefit from referral to physiotherapy but physiotherapy treatment is most effective if started soon after the injury occurs.
• There is some evidence that acupuncture treatment in patients with chronic neck pain is associated with improvements in neck pain and disability⁸.
• There is also some evidence for the benefit of chiropractic treatment for chronic whiplash injury⁹.

• May cause variable difficulties and restrictions with employment, leisure activities, domestic and personal care.
• This may lead to financial as well as psychological difficulties

The prognosis of whiplash injury is variable and obviously depends on the severity and grade of the whiplash injury. There is great debate as to the expected prognosis which is only further confused by possible influence of compensation seeking behaviour. Many studies have only included small numbers of affected people and have had basic flaws with study design and have only served to increase debate.

• In 1995 the Quebec Task Force found that¹⁰:
  • 50% return to usual activity by 31 days
  • 26% are off work between 2 and 6 months
  • 12% remain off work 6 months after injury
  • 2% remain off work over 1 year
  • 15% with multiple injuries are off work after 6 months
• Suissa et al found the following to be independently associated with a slower recovery from whiplash injuries¹¹:
  • Female gender
  • Older age
  • Neck pain on palpation
  • Muscle pain
  • Pain or numbness radiating from the neck to arms, hands or shoulders
  • Headache

• Prevention of accidents: personal responsibility when driving, safe roads, avoiding alcohol before driving
• Prevention of sports injuries, particularly contact sports
• Properly fitted headrests play a major role in preventing or reducing the severity of whiplash injuries.