Whiplash and Cervical Spine Injury

See also separate article on Spinal Cord 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/hour.¹ Whiplash-associated disorders (WAD) can be classified by the severity of signs and symptoms:²

• 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.

• The Canadian cervical spine rule applies to trauma patients who are alert (Glasgow coma scale of 15) and stable.
• It has been shown to be safe and reliable, missing only one unstable injury in a series of over 16,000 cases.

High risk factors

• Age 65 years or over
• Dangerous mechanism of injury
• Paraesthesia in extremities
• A dangerous mechanism of injury is considered to be:
  • A fall from a height of at least a metre or five stairs
  • An axial load to the head, e.g during diving
  • A motor vehicle collision at high speed (>100 km/h) or with rollover or ejection
  • A collision involving a motorised recreational vehicle
  • A bicycle collision

Low risk factors

• Simple rear end motor vehicle collision (excludes being pushed into oncoming traffic, being hit by a bus or a large truck, a rollover, and being hit by a high speed vehicle)
• Able to sit rather than lie down in the emergency department
• Ambulatory at any time
• Delayed (not immediate) onset of neck pain
• Absence of midline cervical spine tenderness

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 population.⁶
• 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
  • Tumours: brain tumours, bone tumours

• Cervical spine X-rays:⁷
  • A standard series of x-rays of the cervical spine consists of three views: anteroposterior, lateral and anteroposterior odontoid peg views.
  • The lateral view must show the top of the T1 vertebral body, and the odontoid peg view should show the lateral masses of the atlanto-axial articulation.
  • NICE recommends using an adapted version of the Canadian cervical spine rules that incorporates some aspects of the NEXUS rule to identify patients who need imaging of the cervical spine.⁷
  • Patients with any one of the following risk factors should have plain radiography (three views) of the cervical spine:⁸
    • Presence of neck pain or midline tenderness with:
      • Age 65 years or older
      • Dangerous mechanism of injury (see above)
    • Not considered safe to assess movement in the neck for reasons other than those above.
    • Considered safe to assess movement in the neck, and on assessment the patient cannot actively rotate the neck 45° to the left and right. Safe assessment can be carried out if the patient:
      • Was involved in a simple rear end motor vehicle collision
      • Is comfortable in a sitting position in the emergency department
      • Has been ambulatory at any time since injury with no midline cervical spine tenderness
      • Has delayed onset of neck pain
    • A definitive diagnosis of cervical spine injury is needed urgently (e.g. before surgery)
• CT scanning of cervical spine:⁷
  • CT scan is indicated if plain films are deemed inadequate, suspicious, or definitely abnormal, or if clinical suspicion of injury continues despite a normal radiograph.
  • Computed tomography is superior to plain radiography, with a reported sensitivity of 100% and specificity of 99%.
• MRI scanning of cervical spine:
  • The technique depicts soft tissue structures well, with reported sensitivities for intervertebral disc injury of 93%, posterior longitudinal ligament injury of 93%, and interspinous ligament injury of 100%.⁷
  • MR is 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 if 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 months.²A recent Cochrane review by Peloso et al found:⁹

• 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.
• Provision of adequate 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 possible.¹⁰
• Patients should receive instruction about exercises.¹¹ 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 effectiveness.¹²
  • 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 disability.¹³
• There is also some evidence for the benefit of chiropractic treatment for chronic whiplash injury.¹⁴

• 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 that:¹⁵
  • 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 injuries:¹⁶
  • Female gender
  • Older age
  • Neck pain on palpation
  • Muscle pain
  • Pain or numbness radiating from the neck to arms, hands or shoulders
  • Headache

Some studies have shown that the strongest prognostic indicators are factors that are present before impact. Lankester et al. found that the factors that showed significant association with poor outcome on both physical and psychological outcome scales were pre-injury back pain, high frequency of General Practitioner attendance, evidence of pre-injury depression or anxiety symptoms, front position in the vehicle and pain radiating away from the neck after injury.¹⁷

• 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.