What is the recommended examination and treatment plan for a patient suspected of having a subarachnoid hemorrhage (SAH)?

Examination and Management of Suspected Subarachnoid Hemorrhage

For patients suspected of having SAH, immediately obtain a noncontrast head CT scan, and if negative but clinical suspicion remains high, proceed with lumbar puncture for xanthochromia analysis—this two-step approach remains the diagnostic cornerstone despite advances in imaging technology. 1

Initial Clinical Assessment

Maintain a high index of suspicion for SAH in patients presenting with:

• Sudden severe headache reaching maximum intensity within 1 hour (thunderclap headache) 1
• Neck pain or stiffness 1
• Witnessed loss of consciousness 1
• Onset during exertion 1
• Limited neck flexion on examination 1

Critical pitfall: 15-37% of patients with confirmed SAH had a warning leak (sentinel hemorrhage) with sudden severe headache before the catastrophic event—missing this warning bleed can be fatal. 1

Grade severity immediately using validated scales (Hunt and Hess or World Federation of Neurological Surgeons), as initial clinical grade is the most useful predictor of outcome. 1, 2

Diagnostic Algorithm

Step 1: Noncontrast Head CT (First-Line Test)

Perform noncontrast head CT immediately as the cornerstone diagnostic test. 1

Timing-dependent sensitivity:

• Within 6 hours of symptom onset: 98.7-100% sensitivity 1, 3
• At 12 hours: 98-100% sensitivity 1
• At 24 hours: 93% sensitivity 1
• At 6 days: 57-85% sensitivity 1

For patients presenting within 6 hours with negative high-quality CT (interpreted by fellowship-trained neuroradiologists), the risk of missed SAH is <1.5 per 1000 cases, potentially sufficient to exclude SAH without lumbar puncture. 1 However, this applies only to patients with classic presentations—not those with atypical presentations such as primary neck pain, syncope, seizure, or new focal neurological deficits. 1

Step 2: Lumbar Puncture (If CT Negative or Nondiagnostic)

Perform LP if:

• CT is negative but clinical suspicion remains high 1
• Patient presents >6 hours from symptom onset 1
• Patient has atypical presentation 1

LP timing and interpretation:

• Perform LP >6-12 hours after symptom onset to allow xanthochromia development 1
• Analyze CSF by spectrophotometric analysis for xanthochromia (sensitivity 100%, specificity 95.2%) 1
• Document red blood cell counts, white blood cell counts, and bilirubin detection 1

Critical pitfall: Proper specimen handling and correct CSF interpretation are essential—improper technique leads to false results. 1

Step 3: Vascular Imaging to Identify Aneurysm Source

Once SAH is confirmed, immediately proceed with CT angiography (CTA) to identify the bleeding source. 4, 2

CTA characteristics:

• Overall sensitivity: 96.5% for all aneurysms 1, 4
• Sensitivity for aneurysms >3 mm: 98.4% 1
• Sensitivity for aneurysms <3 mm: only 61% 1
• Specificity: 88-100% depending on aneurysm size 1

When to proceed to catheter angiography (DSA):

• CTA is negative or inconclusive but diffuse SAH pattern suggests aneurysmal source 1
• Aneurysm <3 mm suspected 1
• Pretreatment planning for endovascular therapy 1
• DSA with 3D rotational angiography remains the gold standard (>98% sensitivity and specificity) 2

Alternative imaging considerations:

• MRI/MRA: Not recommended for acute diagnosis due to limited availability, longer study time, motion artifact sensitivity, and practical limitations in acutely ill patients 1
• MRA sensitivity: 85-100% for aneurysms ≥5 mm, but only 56% for aneurysms <5 mm 1

Immediate Management Priorities

Blood Pressure Control

Control hypertension using titratable agents to balance rebleeding risk versus maintaining cerebral perfusion pressure. 1, 2

• Target systolic BP <160 mmHg (values above increase rebleeding risk) 2
• Avoid aggressive reduction that compromises cerebral perfusion 2

Pharmacological Neuroprotection

Administer oral nimodipine 60 mg every 4 hours immediately and continue for 21 consecutive days. 1, 2, 5

• This is the only medication proven to improve neurological outcomes in SAH 1, 5
• Critical administration warning: Never administer nimodipine intravenously—this can cause fatal hypotension 5
• If patient cannot swallow, extract capsule contents with 18-gauge needle and administer via nasogastric tube with 30 mL normal saline flush 5

Transfer and Definitive Treatment

Transfer immediately to high-volume center (>35 SAH cases/year) with neurosurgical and endovascular capabilities. 1, 2

Secure the aneurysm within 24 hours to reduce rebleeding risk (which carries 70-90% mortality). 4, 2

• Early rebleeding occurs in 4-13.6% within first 24 hours 1
• More than one-third of rebleeds occur within 3 hours 1

Treatment modality selection:

• For aneurysms amenable to both clipping and coiling, endovascular coiling should be considered first based on superior outcomes in randomized trials 1, 4
• Posterior circulation aneurysms particularly benefit from coiling (relative risk 0.41 for death or dependency) 2
• Complete aneurysm obliteration is the goal whenever technically feasible 1, 2

Monitoring for Complications

• Acute hydrocephalus: Manage with CSF drainage (external ventricular drain or lumbar drain) 1, 2
• Maintain euvolemia to prevent delayed cerebral ischemia—do not use prophylactic hypervolemia 1, 2
• Monitor for seizures: Occur in up to 20% of patients, most commonly in first 24 hours 1

Common Pitfalls to Avoid

• Do not skip LP after negative CT >6 hours from onset—CT sensitivity declines significantly after 6 hours 1
• Do not rely on CTA alone if diffuse SAH pattern present but CTA negative—proceed to DSA due to limited sensitivity for small aneurysms 1
• Do not delay aneurysm treatment beyond 24-48 hours unless compelling contraindications exist 4, 2
• Do not administer nimodipine intravenously—this is a fatal error 5
• Do not use triple-H therapy (hypervolemia, hypertension, hemodilution)—maintain euvolemia instead 2
• Do not miss atypical presentations (neck pain alone, syncope, seizure, focal deficits)—these still require full workup 1