What is whiplash, its presentation, evaluation, and treatment?

Whiplash Injury: Presentation, Evaluation, and Treatment

Whiplash is a neck injury resulting from rapid acceleration-deceleration mechanism that causes soft tissue damage in the cervical spine, commonly occurring in motor vehicle accidents, particularly rear-end collisions. 1, 2

Definition and Mechanism

• Whiplash describes a sudden biphasic movement of the head and cervical spine (reclination followed by inclination) that typically occurs during motor vehicle accidents, especially rear-end collisions 2
• The injury affects multiple soft tissue structures in the neck including muscles, ligaments, facet joints, and discs 1, 3
• The term "whiplash-associated disorders" (WAD) refers to the collection of symptoms that develop following this mechanism of injury 4

Clinical Presentation

• Symptoms typically develop with a latency of several hours after the injury 2

• Common symptoms include:

  • Neck pain and stiffness (present in virtually all cases) 1, 4
  • Reduced range of cervical motion 4
  • Occipital headaches (in over 50% of cases) 4
  • Point tenderness in the cervical spine 1
  • Upper extremity pain or paresthesia 1
  • Muscle spasm in paraspinal and suboccipital regions 1

• The Quebec Classification of Whiplash-Associated Disorders (WAD) categorizes severity:

  • Grade I: Neck pain, stiffness without physical signs
  • Grade II: Neck pain with musculoskeletal signs (decreased range of motion)
  • Grade III: Neck pain with neurological signs
  • Grade IV: Neck pain with fracture or dislocation 2, 4

Evaluation

Clinical Assessment

• Detailed history focusing on mechanism of injury and symptom progression 1
• Physical examination to assess:
  • Cervical range of motion 4
  • Tenderness on palpation of cervical spine, paraspinal and suboccipital muscles 1
  • Neurological examination for radicular symptoms 1
  • Assessment for signs of cervical instability 1

Imaging

• Initial imaging should be guided by clinical suspicion for fracture or instability 1

• Plain radiographs:

  • Low sensitivity (36%) for identifying cervical injuries 1
  • Minimum of 3 views (anteroposterior, lateral, and open-mouth odontoid) when performed 1
  • Flexion-extension views are often inadequate in the acute setting due to muscle spasm 1

• CT scan:

  • Significantly more sensitive than radiographs (98% sensitivity) 1
  • Recommended when fracture is suspected based on clinical criteria (NEXUS or Canadian C-Spine Rules) 1
  • Sufficient to rule out clinically significant cervical spine injuries 1

• MRI:

  • Most sensitive for detecting soft tissue injuries but has limited value in WAD diagnosis 1
  • Tends to overestimate severity of ligament injuries (specificity 64-77%) 1
  • May show signal changes in craniocervical ligaments, paraspinal muscle atrophy, and muscle fat infiltration 1
  • Generally no correlation between MRI findings and WAD symptoms or progression 1

Treatment

Acute Phase

• Early mobilization and return to normal activities are recommended over immobilization with cervical collars 1

• Prolonged immobilization with rigid collars can lead to complications:

  • Pressure sores (especially after 48-72 hours) 1
  • Increased intracranial pressure in patients with co-existing head injury 1
  • Potential airway problems 1
  • May not effectively restrict displacement of unstable injuries 1

• Pharmacological management:

  • Non-steroidal anti-inflammatory drugs for pain and inflammation 3
  • Short-term muscle relaxants for significant muscle spasm 3
  • Limited use of opioids if necessary for severe pain 3

Chronic Phase

• For persistent neck pain:

  • Physical therapy focusing on range of motion exercises and strengthening 3, 5
  • Medial branch blocks of the dorsal rami may be considered to determine if facet joints are the source of pain 3
  • Radiofrequency neurotomy can provide substantial relief (8-12 months) when facet joints are confirmed as pain generators 3

• Psychological support:

  • Assessment for psychological factors that may contribute to chronicity 5
  • Cognitive behavioral therapy for patients with significant psychological distress 5

Prognosis

• 15-40% of patients with acute whiplash pain develop chronic neck pain 3
• The cervical facet joint is the most common source of chronic neck pain after whiplash injury 3
• Poor prognostic factors include:
  • High initial pain intensity 5
  • Psychological distress 5
  • Pre-existing neck pain 4
  • Limited cervical range of motion 4

Common Pitfalls and Caveats

• Overreliance on imaging findings: Diagnosis of WAD is primarily clinical, as imaging often shows no specific findings 1
• Excessive immobilization: Prolonged use of cervical collars may delay recovery 1
• Failure to address psychological factors: Stress responses and psychological factors play important roles in chronicity 5
• Overlooking facet joint pain: This is the most common source of chronic pain after whiplash 3
• Unnecessary surgical intervention: Surgery is rarely indicated for WAD in the absence of specific structural pathology 3