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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June 28, 2018
Traumatic Middle Meningeal Artery Pseudoaneurysm
- Background:
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Intracranial pseudoaneurysms may arise from the distal MCA, ACA, (pericallosal artery - below the falx), or PCA (P2 segment adjacent to the tentorium).
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Other less common locations include the petrous ICA or vertebral artery.
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Pseudoaneurysms of the middle meningeal artery are rare, representing 27% of all intracranial traumatic aneurysms and less than 1% of all intracranial aneurysms.
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- Clinical Presentation:
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Cases usually present as epidural hematomas as these lesions have a high risk of rupture, leading to rapid neurologic deterioration usually 3-30 days after the initial trauma.
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Although occurring much less frequently, they have also been reported to result in delayed intracranial hemorrhage as well.
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- Key Diagnostic Features:
- On a noncontrast CT, they may be spontaneously hyperdense due to partial thrombosis. Also, a hyperdense hematoma may be seen adjacent to the lesion.
- On a contrast enhanced CT an enhancing area within a hematoma may be seen, without pooling of contrast on delayed imaging.
- CTA shows enhancement following the vascular contrast pool, usually with incomplete filling of the ”sac” due to partial thrombosis.
- Catheter angiography gives the definitive diagnosis and allows for endovascular management. A lobulated arterial outpouching is seen with delayed washout. Also the post-aneurysmal segment may show slow flow.
- Differential Diagnoses:
- True aneurysm – location and history of recent trauma help differentiate in this case. The location would be atypical for a “true” saccular aneurysm, which usually arises centrally in the region of the Circle of Willis, and often at branching points.
- Treatment:
- Endovascular management is performed more commonly than surgical clipping or excision.
- Occlusion of the proximal vessel utilizing endovascular liquid embolics is preferred to coiling. This is because these lesions are pseudoaneurysms, with no real wall, so the ”endosaccular” treatment approach has a high risk of intraprocedural rupture.
- If parent vessel occlusion is not possible, the pseudoaneurysm can be managed with a covered stent.
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