How to manage a 48-year-old male with a traumatic subarachnoid hemorrhage (SAH) and a confirmed short segment dissection with possible pseudoaneurysm formation in the right proximal A2 (Anterior Cerebral Artery) segment after a skull base fracture?

Management of Traumatic A2 Dissection with Possible Pseudoaneurysm Formation

For a 48-year-old male with traumatic subarachnoid hemorrhage and confirmed A2 segment dissection with possible pseudoaneurysm formation after skull base fracture, close monitoring with follow-up CTA in the next few days is appropriate, with pipeline stenting indicated if the pseudoaneurysm enlarges.

Initial Assessment and Risk Stratification

• This case represents a traumatic dissection of the right proximal A2 segment of the anterior cerebral artery with possible pseudoaneurysm formation
• Critical features:
  • Location: Right proximal A2 immediately after AComm takeoff
  • Vessel caliber: Narrowed to 0.5mm at stricture (normal A1/A2 diameter ~1.5mm)
  • Anatomical complication: Herniation into sphenoid sinus due to skull base fracture
  • Length of dissection: 13mm segment

Management Approach

Immediate Management

• Maintain systolic blood pressure <160 mmHg to reduce risk of rebleeding while ensuring adequate cerebral perfusion 1
• Avoid profound hypotension (mean arterial pressure <65 mmHg) 1
• Proceed with planned follow-up CTA in the next few days to assess for pseudoaneurysm enlargement

Treatment Decision Algorithm

1. If follow-up imaging shows pseudoaneurysm enlargement:

   • Pipeline stenting is appropriate for this dissection with pseudoaneurysm formation
   • Flow diverters are reasonable for ruptured fusiform/blister aneurysms to reduce mortality (Class 2a, Level C-LD) 1

2. If pseudoaneurysm remains stable:

   • Continue close monitoring with serial imaging
   • Consider delayed intervention if patient stabilizes and pseudoaneurysm persists

Evidence-Based Rationale

• For traumatic dissections with pseudoaneurysm formation in the anterior circulation, endovascular treatment with flow diverters is reasonable to reduce mortality 1
• The 2023 AHA/ASA guidelines specifically state: "For patients with aSAH from ruptured fusiform/blister aneurysms, the use of flow diverters is reasonable to reduce mortality" (Class 2a, Level C-LD) 1
• In cases where complete obliteration is not feasible in the acute phase, partial obliteration to secure the rupture site with delayed definitive treatment is reasonable 1

Special Considerations for This Case

• The herniation of the vessel into the sphenoid sinus due to skull base fracture creates a complex anatomical situation
• The narrow caliber at the stricture point (0.5mm) may complicate endovascular navigation
• The risk of rebleeding must be balanced against the risks of intervention in this traumatic setting

Monitoring and Follow-up

• Continuous neurological assessment to detect deterioration 2
• Regular monitoring of serum sodium levels to avoid fluctuations that can worsen neurological outcomes 2
• Maintain euvolemia and avoid hypovolemia/hypervolemia 2
• Initiate venous thromboembolism prophylaxis once aneurysm is secured 2

Potential Pitfalls and Caveats

• Dual antiplatelet therapy required for pipeline stenting may increase hemorrhagic risk in a patient with recent traumatic SAH
• The narrow vessel caliber (0.5mm at stricture) may limit endovascular options or increase procedural risk
• The skull base fracture and herniation into the sphenoid sinus creates a complex anatomical situation that may complicate both endovascular and surgical approaches

This case represents a rare and complex presentation requiring careful consideration of the risks and benefits of intervention versus observation. The decision to proceed with pipeline stenting if the pseudoaneurysm enlarges is supported by current guidelines for management of fusiform/blister aneurysms.