Diagnostic Approach and Management of Subarachnoid Hemorrhage

Initial Diagnostic Approach

Non-contrast CT scan is the first-line diagnostic test for suspected Subarachnoid Hemorrhage (SAH), with sensitivity approaching 100% within the first 3 days after onset, as recommended by the American Heart Association 1, 2
If SAH is confirmed, vascular imaging should be performed to identify the cause of hemorrhage, according to the International Stroke Society 3, 4
High-quality CTA is initially preferable to catheter angiography for detecting aneurysms with sensitivity >90% for most aneurysms, as stated by the American College of Radiology 3, 5
However, CTA has limitations in detecting aneurysms <3mm in size, those adjacent to bone structures, and in providing complete characterization of aneurysm neck and relationship to parent vessels, as noted by the American Heart Association 1, 5

Negative CTA findings in patients with confirmed SAH, as recommended by the International Stroke Society 3, 6, 4
Diffuse aneurysmal pattern of SAH on initial CT, according to the American Heart Association 6, 5
When detailed aneurysm characterization is needed for treatment planning, as stated by the American Heart Association 6, 7
When determining if an aneurysm is amenable to endovascular therapy, as recommended by the American Heart Association 6, 8

DSA with 3-dimensional rotational angiography is considered the gold standard for aneurysm detection and characterization, as stated by the American College of Radiology 7, 5
3D rotational angiography has been shown to identify aneurysms in 25% of patients with previously negative 2D angiograms, according to the American College of Radiology 5

After aneurysm identification, patients should be transferred to a tertiary center with neurosurgical expertise, as recommended by the International Stroke Society 3, 4
The aneurysm should be secured urgently (ideally within 24-48 hours) by endovascular coiling or microsurgical clipping, according to the International Stroke Society 3, 4, 9
For most patients eligible for both treatment approaches, endovascular coiling is preferred based on better long-term outcomes, as stated by the International Stroke Society 3, 4
DSA provides the most detailed information for determining the optimal treatment approach, as recommended by the American Heart Association 6, 7

DSA is both the gold‑standard imaging modality for diagnosing and characterizing intracranial aneurysms and the platform through which endovascular therapy (e.g., coiling) can be delivered in the same procedure. [10][11]
3‑D rotational angiography performed during DSA supplies detailed information on aneurysm size, neck configuration, and relationship to parent and branch vessels, which is essential for deciding whether immediate endovascular treatment is feasible. 10

In patients presenting with acute subarachnoid hemorrhage, 61 % were referred to endovascular treatment based on pre‑procedure imaging, and 93 % of those underwent successful coiling during the same session. [10][11]

Aneurysms that are giant (> 25 mm), have daughter sacs, display fusiform or dissecting morphology, or involve arteries supplying normal brain tissue are often not suitable for same‑session endovascular therapy and require more extensive pre‑treatment planning. [12][13]

Aneurysms with wide necks, branch vessels arising from the aneurysm dome, or other unfavorable anatomic configurations are generally better managed with microsurgical clipping rather than immediate endovascular coiling; the diagnostic angiogram serves as a roadmap for subsequent surgical intervention. [10][11]