What is the recommended diagnostic and management approach for patients with aneurysmal subarachnoid hemorrhage (aSAH) using Digital Subtraction Angiography (DSA)?

Digital Subtraction Angiography in Aneurysmal Subarachnoid Hemorrhage

DSA with 3-dimensional rotational angiography is the gold standard for detection of aneurysms in patients with aSAH and should be performed for definitive diagnosis and treatment planning, except when the aneurysm was previously diagnosed by a noninvasive angiogram. 1

Diagnostic Algorithm for aSAH

1. Initial Diagnostic Workup:

   • Non-contrast head CT as first-line test 1
   • If CT is negative but clinical suspicion remains high, proceed to lumbar puncture 1
   • MRI (fluid-attenuated inversion recovery, proton density, diffusion-weighted imaging, and gradient echo sequences) may be considered when CT is negative 1

2. Angiographic Evaluation:

   • CTA may be performed initially in the workup of aSAH 1
   • If an aneurysm is detected on CTA, this may help guide treatment decisions 1
   • However, if CTA is inconclusive, DSA is mandatory (except possibly in classic perimesencephalic SAH) 1

3. Role of DSA:

   • DSA with 3D rotational angiography provides the best morphological depiction of aneurysm anatomy with high spatial resolution 1
   • Essential for determining whether an aneurysm is amenable to coiling or to expedite microsurgical clipping 1
   • Superior to 2D angiography for detecting aneurysms 1

Advantages of DSA over Other Imaging Modalities

• Superior Detection: DSA is more sensitive than CTA for detecting aneurysms <3mm in size 1
• Complete Evaluation: Allows assessment of collateral circulation and hemodynamics
• Treatment Planning: Provides critical information for deciding between endovascular coiling and surgical clipping 1
• Interventional Capability: Enables immediate transition to therapeutic intervention

Limitations and Considerations

• Radiation Exposure: Multiple radiological examinations (CT, CTA, DSA) can result in substantial radiation doses 1
• Invasiveness: DSA is an invasive procedure with associated risks
• Resource Utilization: Requires specialized equipment and expertise

Special Clinical Scenarios

Negative Initial CTA

• When CTA is negative but diffuse aSAH pattern is present, 2D and 3D cerebral angiography should be performed 1
• In one study, delayed repeat DSA detected small aneurysms in 14% of cases with initially negative findings 1

Perimesencephalic SAH

• In classic perimesencephalic hemorrhage, a negative CTA may be sufficient to rule out aneurysmal hemorrhage 1
• However, this remains controversial and many experts still recommend DSA for confirmation 1

Post-Treatment Follow-up

• After aneurysm repair, immediate cerebrovascular imaging is recommended to identify remnants or recurrence 1
• For patients who undergo coiling or clipping, delayed follow-up vascular imaging should be performed 1
• Strong consideration should be given to retreatment if there is a clinically significant (growing) remnant 1

Clinical Severity Assessment

• The initial clinical severity of aSAH should be determined using validated scales (Hunt and Hess, World Federation of Neurological Surgeons) 1
• These scales are the most useful indicators of outcome after aSAH 1

Treatment Considerations

• Urgent evaluation and treatment is critical due to high risk of early rebleeding 1
• For patients with ruptured aneurysms amenable to both endovascular coiling and neurosurgical clipping, endovascular coiling should be considered 1
• Low-volume hospitals (<10 aSAH cases per year) should consider early transfer to high-volume centers (>35 aSAH cases per year) 1

Pitfalls to Avoid

• Relying solely on CTA: While CTA technology has improved, it still has limitations in detecting small aneurysms (<3mm) 1, 2
• Overlooking secondary vascular lesions: Some cases may have additional vascular abnormalities that might be missed without DSA 3
• Misinterpreting vasospasm: DSA remains superior for evaluating vasospasm, which can be difficult to assess accurately on CTA 4
• Delayed diagnosis: aSAH is frequently misdiagnosed; maintain high suspicion in patients with acute onset of severe headache 1

By following this evidence-based approach to DSA in aSAH, clinicians can optimize diagnosis, treatment planning, and ultimately patient outcomes.