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Skull and Spine Disorders

Clearing of the cervical spine on clinical grounds has become the standard of care in alert adult patients.

Factors associated with higher risk of fracture:

  1. Glasgow Coma Score <14
  2. Neck tenderness
  3. Loss of consciousness
  4. Neurologic deficit
  5. Drug ingestion
  6. Specific mechanism of injury: motor vehicle accident, fall from a height >3 m

Indications for screening CT of cervical spine:

Frequency: 1–3% of all trauma cases;

C2, C6 >C5, C7 >C3, C4 >C1

Cervical spine trauma accounts for of all spinal cord injuries!

Location:

  1. upper cervical spine = C1/2 (19–25%): atlas (4%), odontoid (6%)
  2. lower cervical spine = C3–7 (75–81%)
  3. cervicothoracic junction (9–18%)
  4. multiple noncontiguous spine fractures (15–20%)

Site: vertebral arch (50%), vertebral body (30%), intervertebral disk (25%), posterior ligaments (16%), dens (14%), locked facets (12%), anterior ligament (2%)

Associated with injury to:

N.B.: 5–8% of patients with fractures may have normal radiographs!

Normal range of motion: 10–20° during flexion and extension; 4–12° of lateral tilting

Cx: neurologic deterioration with delay in diagnosis

  1. HYPERFLEXION INJURY (46–79%)
    1. Odontoid fracture
    2. Simple wedge fracture (stable)
    3. Flexion teardrop fracture = avulsion of anteroinferior corner by anterior ligament (unstable)
      • Most severe + unstable injury of C-spine

      Location: C5, C6, C7
      • triangular fragment in soft tissues anterior to vertebral body
      • retrolisthesis
      • widening of facets
      • narrowing of spinal canal
      • mild kyphosis

      Associated with: ligamentous tears, spinal cord compression

      Subaxial Injury Classification and Scoring (CT Severity Score for Entire Spine, 2007)*

      Injury CategoryPoint Value
      Injury Morphology
      Compression1
      Burst2
      Distraction3
      Translation / rotation4
      Discoligamentous complex
      Intact0
      Indeterminate2
      Disrupted3
      Neurologic status
      Intact0
      Root injury1
      Spinal cord injury
      incomplete2
      complete3
      Cord injury + ongoing compression4
      Total Score:3 manageable without surgery
      4 indeterminate;
      5 need for surgical intervention

      * a separate score is given to each injured level


      Triangular teardrop fracture without posterior element distraction / vertebral body translation should be characterized as (1) compression or (2) burst injury.
    4. Anterior subluxation
    5. Bilateral facet lock = interlocking of articular surfaces (unstable)
      • anterolisthesis of affected vertebra by ½ vertebral body width
      • mild focal kyphosis
      • soft-tissue swelling
      • no rotation
    6. Anterior disk space narrowing
    7. Spinous process fracture = clay shoveler's fracture
      = sudden load on flexed spine with avulsion fracture of C6 / C7 / T1 (stable)
    8. Flexion instability = isolated rupture of posterior ligaments
      • Dx may be missed without delayed flexion views
      • no fracture
      • interspinous widening
      • loss of facet parallelism
      • widening of posterior portion of disk
      • anterolisthesis >3 mm
      • focal kyphosis
  2. HYPEREXTENSION INJURY (20–38%)
    Mechanism: impact on forehead / face, whiplash
    • High risk for neurologic deficit!
    • Radiographs may be completely normal!
    1. Hyperextension dislocation
      followed by immediate realignment
      • upper extremity paresthesia to complete quadriplegia
      • disruption of anterior longitudinal ligament, annulus, intervertebral disk, lig. flavum
      • prevertebral swelling hemorrhage + edema
      • stripping of posterior longitudinal ligament
      • tears of paraspinal muscles
      • widening of disk space anteriorly
      • avulsion of anteroinferior endplate
      • transverse dimension of anteroinferior avulsion fragment greater than vertical dimension
    2. Extension teardrop fracture
      = avulsion of intact fibers of anterior longitudinal ligament off anteroinferior endplate
      Location: C2, C3
      • acute central cord syndrome (in up to 80%)
      • vertical dimension of triangular fragment greater than transverse dimension
    3. Neural arch fracture of C1 (stable fracture = anterior ring + transverse ligament intact)
      • vertically oriented fracture of posterior arch (stable if isolated / part of Jefferson burst fracture)
    4. Anterior arch fracture of C1
      • biomechanically stable
      • transverse fracture through inferior pole / midportion at attachment of atlantodental lig. / longus colli m.
    5. Uni- / bilateral laminar fracture commonly part of a burst fracture / pedicolaminar fracture-separation / flexion teardrop fracture
      • extension into adjacent spinous process (frequent)
    6. Subluxation (anterior / posterior)
    7. Hangman's fracture
  3. FLEXION-ROTATION INJURY (12%)
    1. Unilateral facet lock (oblique views!, stable fracture)
      • anterolisthesis <¼ vertebral body width
      • “bow-tie” sign = the 4 rotated facets on LAT view
      • decrease in spinolaminar space
      • rotation of spinous process (on AP view)
      • “naked facet” (on CT)
  4. VERTICAL COMPRESSION (4%)
    = axial loading
    1. Jefferson fracture
    2. Burst fracture = intervertebral disk driven into vertebral body below (fracture may be stable / unstable)
      • loss of posterior vertebral body height with several fragments:
        • sagittal fracture component extending to inferior endplate
        • retropulsed fragment from posterior superior margin in spinal canal
        • interpedicular widening
        • posterior element fracture

      Associated with: widening of apophyseal joints, fracture of posterior vertebral arches
  5. LATERAL FLEXION / SHEARING (4–6%)
    1. Uncinate fracture
    2. Isolated pillar fracture
    3. Transverse process fracture
    4. Lateral vertebral compression

Normal Variants as Pitfalls in Cervical Trauma!!navigator!!

  1. Congenital absence of posterior arch(es)
  2. Congenital cleft (smooth well-corticated)
  3. Os odontoideum
  4. Os terminale
  5. Partial ossification of atlanto-occipital membrane
  6. Ponticulus posticus = bone excrescence partially covering horizontally oriented vertebral artery
  7. Arcuate foramen = bone excrescence completely surrounding vertebral artery

Signs of Significant Cervical Vertebral Trauma!!navigator!!

  1. most reliable + specific:
    • widening of interspinous space (43%)
    • widening of facet joint (39%)
    • displacement of prevertebral fat stripe (18%)
  2. reliable but nonspecific:
    • wide retropharyngeal space >7 mm (31%)

    DDx: mediastinal hemorrhage of other cause, crying in children, S/P difficult intubation)
  3. nonspecific:
    • loss of lordosis (63%)
    • anterolisthesis / retrolisthesis (36%)
    • kyphotic angulation (21%)
    • tracheal deviation (13%)
    • disk space: narrow (24%), wide (8%)

Atlas Fracture!!navigator!!

Prevalence: 4% of cervical spine injuries, 25% of craniocervical injuries

Associated with: axis fracture (44%), fractures of C7 (25%), C2 pedicle (15%), extraspinal fractures (58%)

N.B.: A ring tends to fracture in more than one place!

Types:

  • I Isolated fracture of posterior arch hyperextension
  • II Isolated fracture of anterior arch (rare)
  • III Bilateral posterior arch fractures + uni- / bilateral anterior arch fracture axial loading
    1. Jefferson fracture
      [Sir Geoffrey Jefferson (1886–1961), neurosurgeon in Manchester, England]
      • comminuted burst fracture of ring of C1 (unstable) with 4 uni- / bilateral ipsilateral anterior + posterior fractures
      • lateral displacement of lateral masses (self-decompressing) on AP view

      DDx:Pseudo-Jefferson fracture = lateral offset of lateral masses of atlas without fracture = fusion anomaly of anterior / posterior arches of C1 (in children as lateral masses of atlas ossify earlier than C2)
  • IV fracture of lateral mass excessive lateral flexion
  • V Transversely oriented anterior arch fracture avulsion of longus colli / atlantoaxial ligament

Burst and lateral mass fractures are unstable and can be associated with tears of the transverse ligament, which may compromise the atlantodental relationship dorsal displace-ment of dens compression of thecal sac and its contents.

Axis Fracture!!navigator!!

Prevalence: 17–20% of cervical spine fractures

Associated with: fractures of C1 in 8%

Odontoid / Dens Fracture (59%)

Prevalence: 59% of C2 fractures

  • Type I avulsion fracture through odontoid tip (1–8%) at attachment of alar ligaments
    • obliquely oriented fracture through tip of odontoid that is difficult to detect
      Prognosis: bone fusion in almost 100% with collar / halo immobilization
  • Type II fracture through base of dens (54–60%)
    Cx: nonunion (in 26% of nonsurgical treatment, with fracture gap 6-mm increased to 67%)

    Axial CT alone misses >50%!
  • Type III horizontal subdental fracture (39–42%) through cancellous portion of body
    Prognosis: heals in 88% with immobilization

DDx: os odontoideum, ossiculum terminale, hypoplasia of dens, aplasia of dens

Hangman's Fracture (23%)

= TRAUMATIC SPONDYLOLISTHESIS

Prevalence: 23% of C2 fractures, 4% of cervical fractures

  • 2nd most common C2 fracture; unstable

Mechanism: direct impact to face compressive hyperextension / distractive hyperflexion

Associated with: neurologic sequelae in only 26%, atlas fracture in 6–26%, other cervical fractures in 8–32%

Types:

  • I minimally displaced with <2-mm translation, NO angulation / posterior intervertebral disk space widening (stable)
  • II anterior angulation >11° + anterior translation distractive flexion / compressive hyperextension
  • III (7–10% of hangman fractures) severe distractive flexion + bilateral facet dislocation / fracture-dislocation
  • bilateral vertical pars interarticularis fracture of C2 separation of body from posterior arch decompression of spinal canal
  • fracture through posterior body of C2
  • prevertebral soft-tissue swelling >5 mm at anterior-inferior margin of C2
  • ± widening of C2-C3 disk space
  • ± bilateral interfacetal dislocation
  • anterior subluxation of C2 on C3:
  • disruption of C1–C2 spinolaminar line
  • disruption of C2–C3 posterior vertebral body line
  • avulsion of anteroinferior corner of C2 (= rupture of anterior longitudinal ligament) = teardrop fracture

Outline