Cervical Spine Dislocation & Whiplash Flashcards
What are the 2 types of cervical spine dislocation?
- unilateral facet dislocation
- bilateral facet dislocation
What is the mechanism of a unilateral facet dislocation?
flexion with rotation
(pulls facet forward on opposite side)
What is the mechanism of a bilateral facet dislocation?
hyperflexion
What is the stability of a unilateral facet dislocation?
stable until reduced
(therefore treat as unstable)
What is the stability of a bilateral facet dislocation?
unstable
What structures are damaged with a unilateral facet dislocation?
- ruptured interspinous ligaments
- ruptured facet capsular ligaments
- sprained PLL
- articular process Fx common
(requires fusion post-reduction)
What are the radiographic findings of a unilateral facet dislocation?
Lat:
- bowtie sign
- <25% anterolisthesis
AP: focal rotation
What sign of unilateral facet dislocation is seen only on an axial CT?
hamburger sign
What is the clinical significance of a unilateral facet dislocation?
neurologic deficit in 25% of pts
What 3 forms of facet dislocation can occur with a flexion and rotation mechanism?
Unilateral:
- partial dislocation
- perched facets
- complete dislocation
(lecture only)
What is a perched facet joint?
vertebral facet joint whose inf articular process appears to sit ‘perched’ on ipsi sup articular process of the vertebra below
What structures are damaged with a bilateral facet dislocation?
- interspinous lig
- lig flavum
- facet capsules
- PLL
- 50% have disc herniation
What are the radiographic findings of a bilateral facet dislocation?
- 50%+ anterolisthesis
- widened interspinous space
- NO bowtie sign
What is the clinical significance of a bilateral facet dislocation?
neurologic deficit in 75% of pts
(greater reduction in spinal canal space)
How would the spinal cord appear on a T2 MRI in the area of a bilateral facet dislocation?
cord = bright d/t hemorrhage
What is whiplash associated disorder?
cervical sprain-strain injury
What are the possible mechanisms for whiplash associated disorder?
- 20-60% of MVAs
- hyperextension-hyperflexion
- acceleration-deceleration
What is the name of the classification system for whiplash associated disorder (WAD)?
Quebec task force on WAD
What is a grade 0 WAD?
no complaints, no physical signs
What is a grade 1 WAD?
neck pain/stiffness/tenderness only, no physical signs
What is a grade 2 WAD?
neck complaint + MSK signs
What is a grade 3 WAD?
neck complaint + neurologic signs
What is a grade 4 WAD?
neck complaint + fracture or dislocation
What are the common presentations of Whiplash?
- often asymptomatic
- muscle inj
What are the less common presentations of whiplash?
- disc inj
- ligament inj
- neuro inj
- dislocation
- Fx
- brain inj
What are the radiographic findings of whiplash?
- prevertebral soft tissue abnormalities
- abnormal vertebral alignment
- abnormal discs
(CANNOT BE Dx ON ANY IMAGING)
When does maximum tenderness typically occur in patients with whiplash?
3 days post-inj, once cortisol and swelling go down
What abnormal soft tissue findings of whiplash can be seen radiographically?
- widened prevertebral soft tissues
- soft tissue emphysema (tracheal & laryngeal injury)
What abnormal soft tissue findings of whiplash are not visible radiographically?
- brain inj (contusion, hemorrhage, concussion)
- cord contusion & hemorrhage
- muscle inj
What signs of laryngeal injury may be seen in a patient with whiplash?
- dysphagia
- hoarseness
What pre-existing factor would make whiplash injuries heal slower?
pre-existing degenerative change leading to cord contusion and hemorrhage
What radiographic signs of abnormal vertebral alignment may be seen in a patient with whiplash?
- loss of lordosis
- acute kyphotic angulation
- widened interspinous space
- altered flexion patterns
What static imaging findings would suggest instability in a whiplash patient?
- localized acute kyphosis
- interspinous widening >2mm indicative; >1.5x definitive)
- facet gapping
What dynamic imaging findings would confirm instability in a whiplash patient?
- translational instability on flex/ext views (3.5mm translation)
- angular instability (11+ degrees angular motion compared to adjacent segments)
What are the minimal diagnostic series for cervical spine radiographs?
AP
lateral
APOM
What additional views may be obtained only after standard views have ruled out cervical spine fracture or dislocation?
bilateral obliques
flexion/extension laterals
What are 3 radiographic signs of abnormal discs in a patient with WAD?
- acute disc widening
- annular vacuum clefts (trauma/degenerative)
- vacuum phenomenon (degenerative only)
What is the clinical significance of acute disc widening?
- alarm finding
- significant disc inj
- severe ligament disruption
What are annular vacuum clefts?
traumatic avulsion of the annulus d/t hyperflexion or hyperextension inj, which may represent instability
What is vacuum phenomenon?
degenerative finding involving the nucleus, appears as dark line (gas formation) in middle of nucleus
What is the diagnosis and what are the radiographic findings?
Unilateral facet dislocation
- bow tie sign
- ~25% Anterolisthesis
What is the diagnosis and what are the radiographic findings?
- 50%+ anterolisthesis
- NO bow tie sign
- widened interspinous space
