What is the recommended treatment for a dissecting pseudoaneurysm (false aneurysm) following transsphenoidal surgery, specifically regarding endovascular treatment?

Endovascular Treatment of Transsphenoidal Surgery Dissecting Pseudoaneurysm

Endovascular treatment with stent-assisted coil embolization or flow-diverting stents is the preferred first-line approach for iatrogenic internal carotid artery pseudoaneurysms following transsphenoidal surgery, provided intraoperative hemostasis was achieved and the patient is hemodynamically stable. 1, 2

Treatment Algorithm

Immediate Management (If Active Bleeding)

• Achieve hemostasis first through immediate packing of the surgical field 2
• Stabilize the patient hemodynamically before considering definitive treatment 2
• If hemostasis cannot be achieved endoscopically, emergent parent vessel occlusion may be necessary 3

Diagnostic Workup

• Obtain digital subtraction angiography (DSA) within 3-9 days of the vascular injury to define pseudoaneurysm anatomy 1, 2
• DSA is superior to MRA or CTA for precise anatomic definition of these lesions 3
• Assess for enlargement on serial imaging if treatment is delayed 2

Definitive Endovascular Treatment Options

Option 1: Flow-Diverting Stents (Pipeline Embolization Device)

• Preferred for cavernous ICA pseudoaneurysms where parent vessel preservation is critical 2
• Requires dual antiplatelet therapy (aspirin 325 mg daily + clopidogrel 75 mg daily or ticlopidine 250 mg twice daily) for at least 4 weeks, then transition to single antiplatelet therapy 3, 2
• Complete obliteration typically achieved by 3 months post-procedure 2
• Critical caveat: Risk of short-term bleeding exists during the period before complete pseudoaneurysm thrombosis, so only use if hemostasis is secure 2

Option 2: Stent-Assisted Coil Embolization

• Effective for achieving complete angiographic occlusion with parent vessel preservation 1
• Requires antiplatelet therapy similar to flow-diverting stents 3
• Maintain ACT between 300-350 seconds during the procedure 3
• Continue heparin for 24 hours postoperatively (APTT 1.5-2.3 times control) if arterial dissection is present 3

Option 3: Parent Vessel Occlusion with Coiling

• Reserved for cases where vessel preservation is not feasible or patient cannot tolerate antiplatelet therapy 4
• Must assess collateral circulation via balloon test occlusion before permanent occlusion 3
• Higher risk of ischemic complications, particularly for posterior circulation pseudoaneurysms 5, 6

Special Considerations for Posterior Circulation

For posterior cerebral artery (PCA) pseudoaneurysms:

• Surgical bypass (SCA-PCA) should be strongly considered over endovascular occlusion 5
• Endovascular P1 sacrifice risks thalamoperforator and circumflex perforator infarction 5
• Only 2 prior cases reported; one treated surgically with good outcome, one treated endovascularly with fatal outcome 6
• Conservative management with observation is an option if the pseudoaneurysm is small and patient is stable, as spontaneous healing can occur 6

Anticoagulation Management

During Procedure

• Administer heparin bolus (70 units/kg) to maintain ACT 300-350 seconds for stent procedures 3
• For high-risk cases with visible dissection, consider abciximab (0.25 mg/kg loading dose, then 10 µg/min infusion for 12-24 hours) 3

Post-Procedure

• Continue aspirin (325 mg daily) and clopidogrel (75 mg daily) for minimum 4 weeks until stent endothelialization is complete 3
• For patients with persistent dissection or mural thrombosis, maintain heparin infusion for 24 hours (APTT 1.5-2.3 times control) 3
• Enoxaparin 1 mg/kg twice daily subcutaneously is an alternative to IV heparin 3

Follow-Up Imaging Protocol

• First angiogram at 1 month post-treatment to assess initial response 2
• Second angiogram at 3 months to confirm complete obliteration 2
• If incomplete occlusion persists, additional coiling or continued observation may be needed 3
• Long-term follow-up at 6 months and 1 year with DSA or high-quality MRA 3
• Annual imaging thereafter for life, as late rupture can occur over a decade after initial injury 4

Critical Pitfalls to Avoid

• Do not attempt endovascular treatment during active hemorrhage without first achieving hemostasis 2
• Do not use flow-diverting stents if dual antiplatelet therapy is contraindicated (e.g., recent hemorrhage, planned surgery) 2
• Do not sacrifice parent vessels without assessing collateral circulation, especially in posterior circulation 5
• Do not assume the pseudoaneurysm is stable even years after transsphenoidal surgery; rupture can occur more than 10 years later 4
• Avoid endovascular P1 occlusion due to perforator stroke risk; consider surgical bypass instead 5

When Endovascular Treatment Fails or Is Not Feasible

• Surgical options include direct clipping, bypass with trapping, or parent vessel ligation 5, 6
• Combined endovascular and endonasal surgical approaches can be used for complex cases with rupture 4
• Conservative management with close observation is acceptable for small, stable pseudoaneurysms in neurologically intact patients 6