Clinical Scorecard: Mirror Intracranial Aneurysms (MIAs): Assessing Patient Risk Related to Symmetry or the Impact of Multiple Aneurysms?

At a Glance

Key Highlights

• MIAs are bilateral aneurysms on corresponding arteries, often located at high turbulent flow sites like MCA and ICA terminus.
• Aneurysm multiplicity, including MIAs, is associated with increased rupture risk compared to singular aneurysms.
• Risk stratification models incorporate aneurysm morphology (size, aspect ratio, size ratio) and patient factors to guide elective treatment decisions.

Guideline-Based Recommendations

Diagnosis

• Confirm unruptured intracranial aneurysms via angiographic imaging (CTA, MRA, or DSA).
• Classify aneurysms into singular, asymmetrical multiple, or mirror intracranial aneurysms based on anatomical criteria.
• Exclude mycotic, vasculitic, AVM-associated, extradural, previously treated aneurysms, and lesions too small to confirm as aneurysms.

Management

• Individualize treatment decisions by weighing rupture risk against procedural risks.
• Consider elective intervention for high-risk aneurysms identified by morphology and multiplicity.
• Monitor MIAs closely due to their anatomical clustering at high-stress bifurcations and potential increased rupture hazard.

Monitoring & Follow-up

• Perform longitudinal follow-up with repeat angiographic imaging to assess aneurysm growth and morphological changes.
• Document symptoms at diagnosis and during follow-up to detect clinical changes.
• Use multidisciplinary team review to integrate imaging and clinical data for ongoing risk assessment.

Risks

• Aneurysmal subarachnoid hemorrhage carries approximately 50% mortality at 1 month.
• Multiplicity of aneurysms, including MIAs, increases rupture risk compared to singular aneurysms.
• Treatment risks must be balanced against rupture risk in an individualized manner.

Patient & Prescribing Data

Adults with unruptured intracranial aneurysms identified and followed at neurosurgical centers

Risk stratification using morphological and patient factors guides elective treatment; MIAs may require heightened surveillance due to anatomical and hemodynamic considerations.

Clinical Best Practices

• Use standardized imaging protocols (MRA, CTA, DSA) for accurate aneurysm detection and classification.
• Apply consensus adjudication by experienced neurosurgeons and neuroradiologists to reduce classification bias.
• Incorporate validated rupture risk models (e.g., PHASES Score, ISUIA data) alongside morphological parameters for clinical decision-making.
• Exclude confounding aneurysm types and prior treatments to maintain cohort homogeneity in risk assessment.
• Maintain secure, anonymized data collection with multidisciplinary input for comprehensive patient management.

References

• PHASES Score and ISUIA Data
• Risk of Aneurysm Rupture (ROAR) Study
• Hemodynamic Factors in Aneurysm Formation