Aneurysmal Subarachnoid Hemorrhage (SAH): Diagnosis, Grading, Management and Recent Advances

1. Clinical diagnosis

• Sudden-onset, severe thunderclap headache, often described as “worst headache of life”
• Vomiting, photophobia, neck stiffness
• Transient loss of consciousness, seizure
• Altered sensorium or focal neurological deficits
• Fundus may show subhyaloid hemorrhage (Terson syndrome)

2. Investigations

1. Non-contrast CT brain: first investigation
   • Demonstrates hyperdense blood in basal cisterns, Sylvian fissures, interhemispheric fissure or ventricles.
   • Sensitivity is greatest early after onset, approximately 98% within 6-12 hours, and declines with time.
2. Lumbar puncture (LP)
   • If CT is negative but clinical suspicion remains high, particularly after >6 hours.
   • CSF: persistent RBCs in successive tubes and xanthochromia support SAH.
3. CT angiography (CTA)
   • Detects aneurysm and guides definitive treatment.
   • Can be used after CT, but may identify incidental unruptured aneurysms.
4. Digital subtraction angiography (DSA)
   • Gold standard for aneurysm characterization, especially where CTA is inconclusive or SAH is confirmed with no aneurysm seen on CTA.
5. MRI/MRA
   • Helpful in selected delayed presentations or when CT/CTA is nondiagnostic, but it does not replace LP when suspicion remains high.

3. Grading of SAH

A. Hunt and Hess clinical grading

B. WFNS grading

C. CT grading: Modified Fisher scale

4. Management

A. Initial stabilization

• Admit to neuro-ICU/neurosurgical center.
• ABC, oxygenation, IV access, cardiac monitoring.
• Assess GCS, pupils and focal deficits repeatedly.
• Treat fever, hypoxia, hypotension, hyperglycemia and seizures.
• Analgesia, antiemetics, stool softener and bed rest until aneurysm is secured.
• Maintain euvolemia using isotonic fluids.

B. Prevent rebleeding

• Control severe hypertension with titratable IV drugs while avoiding hypotension and reduced cerebral perfusion.
• Short-course tranexamic acid may be considered only when early aneurysm occlusion is unavoidably delayed. It is not routine therapy.
• Avoid antiplatelets and anticoagulants where possible; reverse anticoagulation when indicated.
• Definitive aneurysm occlusion early, preferably within 24 hours:
  • Endovascular coiling: preferred for many posterior circulation aneurysms and anatomically suitable aneurysms.
  • Microsurgical clipping: useful for accessible MCA aneurysms, aneurysms with large hematoma requiring evacuation, or unfavorable anatomy for coiling.

C. Prevent delayed cerebral ischemia and vasospasm

• Oral nimodipine 60 mg every 4 hours for 21 days is standard, unless hypotension prevents it.
• Monitor clinically for DCI, especially days 4-14.
• Surveillance: serial neurological examinations, transcranial Doppler, CTA/CT perfusion where needed.
• If symptomatic DCI occurs:
  • Ensure euvolemia.
  • Raise blood pressure carefully after aneurysm is secured, provided there is no cardiac contraindication.
  • Consider endovascular rescue therapy: balloon angioplasty for proximal vasospasm and/or intra-arterial vasodilators in selected cases.
• Routine “triple-H therapy” is obsolete. Hypervolemia and prophylactic hypertension are avoided.

D. Treat complications

• Acute hydrocephalus / raised ICP: external ventricular drain (EVD).
• Seizures: treat clinical or electrographic seizures. Routine prolonged anticonvulsant prophylaxis is not advised for all patients.
• Hyponatremia: distinguish SIADH from cerebral salt wasting; maintain volume and correct sodium cautiously.
• DVT prevention: intermittent pneumatic compression initially, followed by pharmacological prophylaxis after aneurysm is secured when safe.
• Screen and manage cardiac dysfunction, pulmonary edema, infection and anemia.

5. Recent advances

1. Early aneurysm treatment in high-volume centers
   Current guidance emphasizes prompt transfer to centers offering both clipping and endovascular procedures, with repair preferably within 24 hours.
2. Improved DCI detection
   Multimodal monitoring using transcranial Doppler, CTA, CT perfusion, continuous EEG and invasive brain-tissue monitoring in selected poor-grade patients helps detect DCI before established infarction.
3. Endovascular developments
   Coiling remains common, while adjuncts such as balloon-assisted coiling, stent-assisted coiling and, in carefully selected cases, flow-diverting devices expand options for difficult aneurysms.
4. Targeted rather than routine vasospasm therapies
   Nimodipine remains the only routine pharmacological therapy with established outcome benefit. Routine statins, intravenous magnesium, endothelin-receptor antagonists and prophylactic hypervolemia have not demonstrated sufficient benefit for standard use.
5. Data-driven risk prediction
   Machine-learning DCI prediction models are being studied, but remain investigational and should not replace clinical assessment. A 2024 systematic review found substantial heterogeneity and the need for external validation (PubMed PMID 37667079).
6. CSF drainage research
   EVD or lumbar drainage strategies are actively studied for blood clearance, hydrocephalus and DCI reduction. Evidence is evolving, so use remains individualized rather than universal. A 2025 meta-analysis addressed this question (PubMed PMID 41432805).

Conclusion