What is the best course of treatment for a patient with an 8x8 mm saccular aneurysm on the right vertebral artery?

Treatment of 8x8mm Saccular Aneurysm on Right Vertebral Artery

Endovascular coiling is the preferred treatment for this posterior circulation saccular aneurysm, with the procedure ideally performed within 24-48 hours if ruptured, or electively after careful risk assessment if unruptured. 1

Immediate Clinical Assessment

Determine rupture status immediately, as this fundamentally changes management urgency and mortality risk:

• If ruptured (subarachnoid hemorrhage present): This is a medical emergency requiring treatment within 24-48 hours to prevent catastrophic rebleeding, which carries 50-80% mortality 1
• If unruptured: Proceed with elective evaluation balancing rupture risk against treatment complications 2

Transfer the patient immediately to a high-volume tertiary center (>35 aSAH cases/year) with both neuroendovascular and cerebrovascular surgery capabilities, as this improves outcomes 1

Treatment Selection

Endovascular coiling is strongly preferred over surgical clipping for posterior circulation aneurysms when technically feasible 1. The 2023 AHA/ASA guidelines specifically state that coiling is preferred over clipping for posterior circulation aneurysms if amenable 1.

Treatment Algorithm:

1. Primary endovascular coiling should be the first-line approach 1, 2

   • Complete obliteration is the goal, as incomplete treatment significantly increases rebleeding risk 1, 2
   • At 8mm diameter, this aneurysm is amenable to standard coiling techniques 1

2. Avoid stents or flow diverters if the aneurysm is amenable to primary coiling or clipping, as these are associated with increased morbidity and mortality in ruptured aneurysms due to required dual antiplatelet therapy 1

3. Surgical clipping via lateral suboccipital approach is reserved for cases where:

   • Endovascular access is not feasible 3, 4
   • Large intraparenchymal hematoma requires evacuation 1
   • The aneurysm has unfavorable morphology for coiling 1

Pre-Treatment Medical Management

If the aneurysm is unsecured (not yet treated):

• Control blood pressure with titratable agents to avoid severe hypertension (target systolic BP <160 mmHg is reasonable) while maintaining cerebral perfusion pressure 1
• Avoid severe hypotension and blood pressure variability, as both increase risk 1

If ruptured, start nimodipine immediately (60mg orally every 4 hours for 21 days) to reduce delayed cerebral ischemia 1, 2

Post-Treatment Surveillance

Immediate post-procedure imaging is mandatory to confirm complete aneurysm obliteration and identify any remnants requiring retreatment 1, 2

Delayed follow-up vascular imaging (timing individualized, typically 6-12 months) is required because:

• Posterior circulation aneurysms treated with coiling have higher recurrence rates than clipped aneurysms 1
• Incomplete obliteration or recurrence requires retreatment with repeat coiling or surgical clipping 1, 2

Critical Pitfalls to Avoid

Do not use routine antifibrinolytic therapy beyond 72 hours, as it does not improve outcomes 1

Do not perform proximal vertebral artery occlusion alone for saccular aneurysms, as this can lead to delayed aneurysm rupture through collateral flow, particularly with large aneurysms 5

Ensure both endovascular and neurosurgical specialists evaluate the aneurysm before treatment decisions are finalized 1