Updated: 9/16/2019

Vertebral Artery Injury

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Introduction
  • Incidence of vertebral artery injury (VAI) 
    •  0.5% of all trauma patients 
      • 70% of VAI in blunt trauma has associated cervical fracture
      • 33%-39% of all cervical spine fractures 
    • 0.3% anterior cervical spine surgery
    • 4.1-8.2% posterior cervical spine surgery (C1-2 transarticular screws)
  • Pathophysiology
    • blunt traumatic injury
      • pathoanatomy
        • highest injury risk at point of entry into C6 transverse foramen
        • second highest risk at C1-2 articulation
    • iatrogenic injury during elective surgery 
      • safe zone
        • C1: avoid dissection cephalad to the C1 posterior arch > 1.5 cm lateral to midline 
  • Prognosis
    • impact of VAI difficult to predict
    • many patients initially asymptomatic
      • some progress to cerebral ischemia or stroke with permanent neurologic deficit 
    • variable symptomatology
Anatomy
  • 4 arterial segments
    • V1
      • extraosseous
      • origin at subclavian artery, anterior to C7 transverse process, to the entry point of C6 transverse foramen
    • V2
      • within the transverse foramina of C6-C1
      • most traumatic injuries occur here
      • high risk during drilling, tapping, insertion of lateral mass or pedicle screws
    • V3
      • superior aspect of the arch of atlas to foramen magnum
      • VA is vulnerable during lateral exposure and laminectomy of C1
      • high risk of C1-2 transarticular screws are directed caudally and laterally
    • V4
      • intradural extension from foramen magnum to unite with contralateral vertebral artery
      • forms the basilar artery
    • most injuries from cervical trauma in V2 (foraminal segment) 
  • Anomalous anatomy
    • reported prevalence of 2.7% in anterior cervical surgery
      • transverse foramen may be medial to or within 1.5mm of the uncovertebral joint
    • reported prevalence of 2.3-20% in the atlantoaxial region
      • high-riding C2 foramen
      • C2 pedicle erosion
      • C2 lateral mass thinning
Classification
 
 Biffl VAI Injury Grading
Grade I  • arteriographic appearance of vessel dissection/intraumural hematoma; <25% luminal stenosis
 
Grade II  • intraluminal thrombosis or raised intimal flap; dissection/intramural hematoma with >25% luminal stenosis

Grade III  • pseudoaneurysm
Grade IV  • vessel occlusion
Grade V
 • vessel transections
 
 
 
Presentation
  • History 
    • consists of recent:
      • cervical spine trauma
        • C1 or C2 fractures
        • subaxial facet fractures and dislocations
      • elective surgery of the cervical spine or craniocervical junction
  • Symptoms
    • variable in presentation and time of onset
    • vertebrobasilar insufficiency manifests with
      • dizziness
      • vertigo
      • nausea
      • diplopia
      • blindness
      • ataxia
      • bilateral weakness
      • oropharyngeal dysfunction
Imaging
  • Radiographs
    • xrays of certain fracture patterns raise suspicion for VAI
  • CT angiography (CTA) 
    • identification of local occlusion or extravasation
    • sensitivity reported at 100%
    • indications for the trauma patient (any single criteria is an indication)
      • unexplained central or lateralizing neurologic deficit
      • evidence of acute cerebral infarct on CT scan of head
      • GCS <9
      • evidence of diffuse axonal injury
      • facial fracture or Le Fort type-II or III fracture
      • cervical spine fracture or subluxation
        • C1, 2, 3 fracture
        • Fracture extension into the transverse foramen
        • VAI demonstrated in 20%
      • cervical spinal cord injury
      • hanging injuries
      • major thoracic injury or first-rib fracture
  • Magnetic resonance angiography (MRA)
    • identification of local occlusions/stenosis
    • sensitivity 93.9%
    • indications
      • cervical spine fractures with neurologic deficits attributable to damaged vertebral or basilar artery perfusion
    • sensitivity and specificity
Treatment
  • Post-operative anticoagulation
    • goal is to prevent thromboembolic sequelae of injury
      • intravenous heparin
      • acetylsalicylic acid (aspirin)
        • indications
          • first line of treatment
        • modalities
          • heparin, aspirin, clopidogrel, IV thrombolysis, glycoprotein IIb/IIIa antagonists (abciximab, eptifibatide, tirofiban)
    • contraindications:
      • major intracranial infarction
      • intraspinal hematoma/arteriovenous fistula
  • Operative reduction and stabilization as neccessitated by fracture pattern
  • Surgical techniques to control hemorrhage (see Techniques)
  • Immediate intra-operative angiography
    • can assist intra-operative decision making
  • Post-operative management following iatrogenic injury
    • observation
      • further intervention dictated by clinical course
    • immediate post-operative angiography
      • detects vascular complications
      • confirms adequate collateral cerebral circulation
      • allows embolization of fistulae or pseudoaneurysm
Techniques
  • Hemostatic tamponade
    • utilization of topical hemostatic agents, bone wax
    • if injured during C1-2 transarticular screw placement, can tamponade by screw insertion
    • risks include:
      • delayed hemorrhage
      • fistula formation
  • Microvascular repair
    • allows restoration of normal blood flow
    • minimizes risk of ischemic complications
    • technically demanding
  • Direction ligation
    • consider intraoperative angiography first to evaluate collateral circulation
    • risks certain morbities
      • cerebellar infarction
        • loss of flow via the posterior inferior cerebellar atery (PICA)
      • isolated cranial nerve paresis
      • hemiplegia
  • IR-guided embolization 
Complications
  • Complications may occur days to years following injury
    • arteriovenous fistula
    • late-onset hemorrhage
    • pseudoaneurysm
      • may be delayed presentation
    • thrombosis with embolic incidents
    • cerebral ischemia/Stroke
      • persistent vertigo
    • death
 

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