Can an 11 mm unruptured cerebral aneurysm be definitively treated during the same session as a diagnostic cerebral angiogram if it is suitable for endovascular coiling, stent‑assisted coiling, or flow‑diverter placement?

Same-Session Treatment of 11mm Unruptured Aneurysm During Diagnostic Angiogram

Yes, an 11mm unruptured cerebral aneurysm can be treated during the same session as a diagnostic cerebral angiogram if it is suitable for endovascular intervention, though this requires careful pre-procedural planning and patient preparation, particularly regarding antiplatelet therapy for stent-assisted techniques.

Treatment Decision Framework

Size-Based Treatment Indication

• An 11mm aneurysm clearly meets treatment criteria across all major guidelines, as this size falls well above the threshold where rupture risk exceeds treatment risk 1.
• Large unruptured aneurysms greater than 10mm should be treated in all healthy patients younger than 70 years of age 1.
• The 2015 AHA/ASA guidelines emphasize that aneurysm size is a strong predictor of both rupture risk and should be carefully considered when planning repair 1.

Same-Session Treatment Feasibility

The key limitation is not technical capability but rather pre-procedural preparation:

• If the patient is already on dual antiplatelet therapy (aspirin and clopidogrel/ticagrelor), same-session treatment with stent-assisted coiling or flow diversion is feasible 1.

• If the patient is NOT on antiplatelet therapy, same-session treatment is limited to:

  • Simple coiling (if the aneurysm has favorable neck-to-dome ratio)
  • Balloon-assisted coiling techniques 1

• Stent-assisted coiling and flow-diverter placement require periprocedural dual-antiplatelet therapy to prevent arterial thromboembolism, which creates a significant barrier to same-session treatment in unprepared patients 1.

Endovascular Technique Selection

For an 11mm aneurysm, multiple endovascular options exist:

• Simple coiling can be performed if the aneurysm has a narrow neck and favorable geometry 1.
• Stent-assisted coiling is indicated for wide-necked aneurysms and has been FDA-approved since 2002, with newer generation devices offering improved deliverability 1.
• Flow-diverting stents (such as Pipeline) represent an emerging option for large aneurysms, though they require strict adherence to FDA indications and dual antiplatelet therapy 1, 2.
• The double or triple microcatheter technique can be employed for complex morphology 3.

Critical Pre-Procedural Requirements

Before proceeding with same-session treatment, verify:

• Patient is on appropriate antiplatelet regimen if stent-assisted techniques are anticipated (typically aspirin 325mg and clopidogrel 75mg daily for 3-7 days pre-procedure) 1.
• Multidisciplinary agreement between experienced cerebrovascular surgeons and endovascular specialists regarding treatment approach 1.
• High-quality 3D rotational angiography is available to fully characterize aneurysm morphology and determine optimal treatment strategy 1, 4.
• Treatment is performed at a high-volume center (>20 cases annually), as low-volume centers have inferior outcomes 1.

Practical Clinical Approach

If Diagnostic Angiogram is Scheduled

Most commonly, same-session treatment is NOT performed because:

1. Antiplatelet therapy cannot be initiated if the aneurysm characteristics are unknown before the diagnostic study 1.
2. Multidisciplinary discussion should occur after full aneurysm characterization to determine optimal approach (endovascular vs. surgical clipping) 1.
3. Patient counseling about risks and benefits of both endovascular and microsurgical options should occur before definitive treatment 1.

Staged Approach is Standard

The typical workflow involves:

1. Diagnostic cerebral angiography with 3D rotational imaging to fully characterize the aneurysm 1, 4.
2. Multidisciplinary conference with neurosurgery and neurointerventional teams to determine optimal treatment 1.
3. Patient counseling regarding treatment options 1.
4. Initiation of dual antiplatelet therapy if endovascular treatment with stent assistance is planned 1.
5. Definitive treatment session 3-7 days later once antiplatelet therapy is therapeutic 1.

Treatment Modality Selection for 11mm Aneurysm

Endovascular vs. Surgical Considerations

• Endovascular coiling should be considered first for aneurysms amenable to both techniques, based on ISAT trial data showing better outcomes 1.
• Microsurgical clipping provides more durable protection with significantly lower recurrence rates (0.10-0.26% annually) compared to coiling (23-33.6% recanalization) 1.
• In older patients (>60 years), endovascular approaches are favored because long-term durability is less critical and perioperative risks are lower 1.
• Location matters: Basilar apex and vertebrobasilar aneurysms favor endovascular treatment, while middle cerebral artery aneurysms may favor surgical clipping 1.

Aneurysm-Specific Factors

• Wide-neck aneurysms (neck-to-dome ratio >0.5) require adjunctive techniques such as balloon remodeling or stent assistance 1.
• Very large aneurysms and those with high neck-to-dome ratios generally benefit more from surgical approaches 1.
• Complete obliteration should be the goal whenever technically feasible, as incomplete treatment carries higher rebleeding risk 1.

Common Pitfalls to Avoid

• Do not proceed with stent-assisted coiling or flow diversion without adequate antiplatelet therapy, as this dramatically increases thromboembolic complications 1.
• Do not rely solely on CTA for treatment planning of complex aneurysms; DSA with 3D rotational imaging provides superior morphological detail 1, 5, 4.
• Do not treat at low-volume centers (<20 cases annually); transfer to high-volume centers with experienced teams 1.
• Do not assume all 11mm aneurysms require the same approach; location, morphology, patient age, and medical comorbidities all influence optimal treatment selection 1.

Post-Treatment Surveillance

• Delayed follow-up vascular imaging is mandatory to detect aneurysm remnants, recurrence, or de novo aneurysm formation 1.
• Endovascular-treated aneurysms require more frequent surveillance due to higher recanalization rates (17.4% retreatment rate vs. 3.8% for surgical clipping) 1.
• MRA at 3T is the preferred surveillance modality for coiled aneurysms, offering 95% sensitivity 6.