Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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May 25, 2023
Blunt Cerebrovascular Injury – Denver Grade III (Pseudoaneurysm)
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