Case of the Week

Background:

• Blunt cerebrovascular injury (BCVI) is detected in 1.2–3% of trauma admissions.
  • Highly associated with spinal fractures: up to 8% of C1–C3 fractures; up to 2% of C4–C7 fractures
  • Multiple types of injury: minimal intimal injury, dissection with raised flap or intimal thrombus, intramural hematoma, pseudoaneurysm, occlusion, transection, and AVF formation
  • Can occur in the setting of seemingly mild trauma (as in this case, intense coughing and skiing)
• Pseudoaneurysm can be contained by adventitia or perivascular tissues.

Clinical Presentation:

• Highly variable clinical findings:
  • Focal neurologic deficit, Horner syndrome, hematoma or hemorrhage, cervical bruit
  • Neurologic symptoms incongruous with initial nonangiographic cross-sectional imaging findings
  • Latent period (average 72 hours)
• The Expanded Denver Criteria are used to determine patients who need CTA screening for BCVI after trauma.
• Infarct is primary driver of morbidity and mortality. Carotid dissections have worse prognosis than vertebral dissections. Grades III–V have worse outcomes.

Key Diagnostic Features:

• CTA of the neck is the standard of care screening modality. Sensitivity with modern 16+ slice scanners is nearly 100%.
  • MRA is an adjunct exam, but sensitivity can be as low as 50%.
  • MRI finding of crescentic hyperintensity on fat-suppressed T1 surrounding the vessel lumen indicates intramural hematoma.
  • Digital subtraction angiography does not provide information about the vessel wall and is only indicated when an endovascular intervention is planned.
• Denver Criteria are more widely used. Grading is based around incidence of stroke. Higher grades indicate a greater risk of stroke.
  •   Grade I: dissection or intramural hematoma with <25% luminal narrowing; includes nonstenotic vessel wall irregularity
  •   Grade II: dissection or intramural hematoma with >25% luminal narrowing; visible intimal flap or intraluminal thrombus
  •   Grade III: pseudoaneurysm
  •   Grade IV: complete occlusion
  •   Grade V: arterial transection or AVF formation
• Pseudoaneurysm represents contained rupture and demonstrates ballooning of the free wall and often some compression of the vessel lumen. Look for a narrow neck/opening.

Differential Diagnoses:

• Atherosclerosis: calcification versus intramural hematoma—hematoma should be bright on the T1 fat-saturated images
• Carotid fibromuscular dysplasia: has a string of beads appearance, also seen in renal arteries
• Vasospasm (posttraumatic spasm): repeat imaging; spasm resolves after several hours
• Vasculitis, hypoplastic ICA: Rare. Look for asymmetrically small carotid canal or hypoplastic vertebral arteries (uniform narrowing along length of vessel)
• Pitfalls: suboptimal contrast timing, carotid canal BCVI easy to overlook, tortuous V3 segment may mask BCVI. 
  • Use 3D postprocessing software to optimally assess the vessels off the standard axes (MPR).
  • T1 black-blood flow suppression can help mitigate a poorly timed contrast exam.

Treatment:

• Generally, all Grade I–IV BCVIs are treated with antithrombotic therapy (aspirin, etc) for stroke prevention
• Surgical/endovascular (especially for Grade V or worsening imaging/clinical presentation)
• Direct pressure for expanding hematoma (until surgical intervention)
• Stents only for aneurysms refractory to other treatments
• Follow-up imaging should be obtained 7–10 days after initial detection to evaluate for progression that may necessitate an intervention