March 9, 2010

Blunt Traumatic Vertebral Artery Dissection

Fig.1: Axial CT image of the cervical spine shows a fracture of the right facet (arrows) extending to the transverse foramen of C6 in a neurologically intact blunt trauma patient.
Fig.2: Subsequent CT angiography of the neck shows a long-segment occlusion (red arrows) of the right vertebral artery from C6 up to base of the skull.

Why Screening for Blunt Cerebrovascular Injury (BCVI) in Trauma Patients?
  • If left untreated, carotid and vertebral artery injury can have a stroke rate ranging from 3-100% and 6-100% respectively
  • Stroke rate by BCVI depends on grade of injury: the higher the grade, the higher stroke rate
  • Screening protocols based on patient injury patterns and mechanism of injury have been instituted prior to neurologic sequelae to identify these injuries in asymptomatic patients and to initiate stroke-preventive treatment.
  • Based on current studies, early anticoagulant therapy reduces stroke rates and prevents neurologic morbidity from BCVI
Facts: Denver Screening Criteria
  • General guidelines to determine which blunt cerebrovascular injury (BCVI) patients should be evaluated for arterial injury.
  • Signs/symptoms of BCVI: arterial hemorrhage, cervical bruit in patient less than 50 years of age, expanding cervical hematoma, focal neurologic deficit, neurologic exam incongruous with head CT scan findings, stroke on secondary CT scan
  • Risk factors for BCVI: high-energy transfer mechanism with LeFort II or III fracture, cervical spine fracture pattern (subluxation, fracture extending into the transverse foramen, fractures of C1-C3), basilar skull fracture with carotid canal involvement, diffuse axonal injury with a Glasgow Coma Scale score less than 6, near hanging with anoxic brain injury
Facts: Denver Grading Scale for BCVI
  • Grade I: irregularity of the vessel wall or a dissection/intramural hematoma with less than 25% luminal stenosis
  • Grade II: intraluminal thrombus or raised intimal flap is visualized, or dissection/intramural hematoma with 25% or more luminal narrowing
  • Grade III: pseudoaneurysm
  • Grade IV: vessel occlusion
  • Grade V: vessel transection
Injury Patterns on Imaging That Should Raise a Suspicion for BCVI
  • Interfacet subluxation/dislocation
  • Fracture lines reaching an arterial structure
  • C1-C3 fracture
  • Basilar skull fracture with carotid canal involvement
  • LeFort II or III fracture due to high-impact trauma
1. Cothren CC and Moore EE. Blunt cerebrovascular injuries. Clinics 2005;60:489-496.
2. Delgado Almandoz JE, Schaefer PW, Kelly HR, et al. Multidetector CT angiography in the evaluation of acute blunt head and neck trauma: a proposed acute craniocervical trauma scoring system. Radiology 2010 (published online before print December 17, 2009).

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