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Traumatic Middle Meningeal Artery Pseudoaneurysm

  • Background:
    • Intracranial pseudoaneurysms may arise from the distal MCA, ACA, (pericallosal artery - below the falx), or PCA (P2 segment adjacent to the tentorium).
    • Other less common locations include the petrous ICA or vertebral artery.
    • Pseudoaneurysms of the middle meningeal artery are rare, representing 27% of all intracranial traumatic aneurysms and less than 1% of all intracranial aneurysms.
 
  • Clinical Presentation:
    • 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. 
    • Although occurring much less frequently, they have also been reported to result in delayed intracranial hemorrhage as well.
 
  • 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.  
June 28, 2018

A 61-year-old woman with follow-up imaging 16 weeks after findings of multiple right-sided frontal, parietal, and temporal bone fractures as well as bilateral subdural, subarachnoid, and intraparenchymal hemorrhages, including bilateral anterior temporal lobe intraparenchymal hemorrhages. 

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