Spinal Trauma Imaging Approach to Diagnosis Part I

Imaging Diagnosis Management:

• Cervical spinal trauma & radiographic variants simulating disease
• Cervical spine
• Arthritis
• Neoplasms
• Infection
• Post-Surgical cervical spine

• Cranio-cervical and upper cervical stability is dependent on transverse, superior and inferior bands of the C1-C2 ligament, alar ligaments, along with a few other ligaments

Cervical Trauma

• The C/S is vulnerable to injury. Why?
• Stability has been sacrificed for greater mobility
• Cervical vertebrae are small and interrupted by multiple foraminae
• The head is disproportionately heavy and acts as an abnormal lever especially when forces act against a rigid torso
• Additionally, C/S is prone to degeneration which makes it more vulnerable to trauma
• In young children, ligaments are more luxed vs. disproportionately large head size
• In children, the fulcrum of movement is at C2/3 thus making injuries more common in the upper C/S and craniocervical junction. In children, S.C.I.W.O.R.A. may occur when no evidence of fracture present
• In adults, the fulcrum of movement is at C5/6 thus making lower C/S more vulnerable to trauma especially during extremes of flexion
  
• Cervical Trauma categorized according to mechanisms of injury (Harris & Mirvis classification)

Hyperflexion Injury: Stable vs. Unstable

• Flexion teardrop Fx (most severe fracture, unstable)
• Bilateral facet dislocation (severe injury w/o fracture, unstable)
• Anterior subluxation (potentially unstable) can be very subtle injury
• Clay Shoveller Fx (lower C/S SP avulsion, stable)
• Simple wedge compression (most benign Fx, stable)
• Hyperflexion-rotation with unilateral facet dislocation
• Obtain a thorough history
• Perform physical exam including a neurological exam
• Consider NEXUS criteria (National Emergency X-radiography Utilization Study)
  

Imaging Techniques:

• Begins with x-radiography especially in cases with no significant neurological compromise
• Clear neutral lateral view first
• If x-radiography is unrewarding but high probability of severe trauma and neurological deficit present, CT scanning w/o contrast is required
• Consider CT scanning in patients with pre-existing changes: advance spondylosis, DISH, AS, RA, post-surgical spine, congenital abnormalities (Klippel-Feil syndrome, etc.)

Vertical compression:

• Jefferson aka burst Atlas Fx (unstable especially if the Transverse ligament is torn, cord paralysis in 20-30% only)
• Why? Due to fragments dissociation and canal widening
• Burst Fx of the Thoracic or Lumbar spine (unstable, cord paralysis may occur)

How to Assess Spinal Radiographs in Trauma Cases:

• Construct 5-lines on the lateral view
• Note if facets are well-aligned and symmetrical
• Ensure symmetry of the disc height
• Note any widening or fanning of the inter-spinous distance
• Carefully examine prevertebral soft tissues
• Evaluate atlanto-dental interval (ADI)

• In cases of trauma, evaluate and clear neutral lateral first
• Do not perform flexed and extended views in acute cases before x-rays or CT scanning exclude significant instability
• Pay extra attention to prevertebral soft tissues
• If thicker than normal limits, consider severe post-traumatic bleed
• Subtle asymmetry and widening of posterior disc height and facets with inter-spinous fanning may be a key feature of significant tearing of posterior ligaments

Hyperflexion Injuries (M/C Mechanism)

• More frequent in sub-axial C/S C-3-C7)
• Unstable injuries:
• Flexion teardrop fracture (M/C C5 & C6) v. unstable
  
• Key rad features:
  

• Large “teardrop” triangular anterior body fragment
• Fanning of the SPs, posterior disc and facet widening indicating tearing of major spinal ligaments and instability
• A posterior shift of the vertebral body fracture suggests direct anterior cord/vessels compression
• Bulging prevertebral soft tissue >20-mm at C6-7
• 80% of cases may be paralyzed on the spot or develop significant paralysis soon after

Acute Neck Trauma. What are the vital radiographic features? What is the diagnosis?

• CT scanning w/o contrasts with sagittal reconstruction. Note C7 Flexion teardrop Fx.
• CT may help with further delineation and preoperative planning
• May follow with MR imaging and evaluation of the neurological injury

• Fluid sensitive (T2) sagittal MRI slice of Flexion teardrop fracture at C4 and possibly C5
• Note high signal intensity lesion in the cord and surrounding ligaments indicating cord edema and ischemia
• Management: neurosurgical with spinal fusion
• Complications:
• Quadriplegia/paraplegia
• Respiratory complications
• Disability, changes in the quality of life
• Decreased life expectancy

• Bilateral facet dislocation (unstable)
• Mechanism: Flexion-distraction injury
• Key radiography: anteriorly displaced body 50% or more
• Facets override and locked (can be perched left image)
• Major tearing of ligaments
• Chances of severe cord compression and paralysis
• Patients with ligaments laxity and degenerative changes are at higher risk
• Initial x-radiography is the first step

CT scanning w/o Contrast is Crucial:

• Further delineation of this injury
• Facet fractures, pedicle fracture
• Management planning

Sagittal fluid sensitive MRI of bilateral C5 facet dislocation, large ischemic cord injury and posterior soft tissue injuries

• Management:
• X-radiography, then CT scanning then immediate closed reduction (esp. if the patient is conscious)
• Followed in some more complicated cases by MRI and then surgical care
• If the patient is awake and neurologically stable, CT and closed reduction are adequate
• Complicated cases and failed closed reduction may require surgical stabilization
• Complications: spinal cord injury and paralysis
• Delayed ligamentous laxity and instability

• Unilateral facet dislocation (flexion-rotation injury) less severe than bilateral dislocation
• Most commonly missed unstable cervical injury on x-radiography
• Key rad features: body anteriorly translated 25% facets appear misaligned and blurred, SPs rotated on frontal views
• Clinically may be presented as one-sided radiculopathy esp. C6 or C7
• CT scanning is required to evaluate further facet/pedicle fractures
• Pre-reduction evaluation and care planning
• Management: closed reduction esp. in a conscious patient
• Complications: acute disc herniation/retropulsion, ligamentous laxity, neurological injury

Spinal Trauma Imaging Approach

Resources:

• emedicine.medscape.com/article/824380-overview
• emedicine.medscape.com/article/248236-overview#a9
• emedicine.medscape.com/article/397896-overview#a3
• www.aafp.org/afp/1999/p331.html