Aneurysmal Subarachnoid Hemorrhage (aSAH) – Anesthetic Considerations

🔹 Introduction

Aneurysmal subarachnoid hemorrhage (aSAH) is a catastrophic neurological event caused by rupture of an intracranial aneurysm, leading to arterial bleeding into the subarachnoid space. It accounts for 5–10% of all strokes and carries high morbidity and mortality.

Anesthetic management requires an understanding of the pathophysiology, hemodynamic goals, and surgical/endovascular options.

🔹 Etiology and Pathophysiology

✅ Causes:

• Rupture of saccular (berry) aneurysm (85%)
• Other causes: Trauma, AVMs, mycotic aneurysms

✅ Pathophysiological effects:

• ↑ Intracranial Pressure (ICP) → ↓ Cerebral Perfusion Pressure (CPP)
• Cerebral ischemia
• Risk of rebleed
• Cerebral vasospasm
• Hydrocephalus
• Electrolyte disturbances (SIADH, cerebral salt wasting)

🔹 Clinical Presentation

• Sudden severe “thunderclap” headache
• Neck stiffness, photophobia
• Vomiting, loss of consciousness, seizures
• Meningeal signs
• Focal neurological deficits
• Cranial nerve palsies (e.g., CN III in posterior communicating aneurysm)

🔹 Diagnosis

• Non-contrast CT brain: First-line
• CT angiography (CTA) or Digital Subtraction Angiography (DSA): To identify aneurysm
• Lumbar puncture: If CT negative but suspicion high → xanthochromia

🔹 Grading Systems

1. Hunt and Hess Grade

2. WFNS Grading (based on GCS and focal deficit)

🔹 Complications of aSAH

🔹 Goals of Anesthetic Management

🔹 Definitive Treatment Options

1. Surgical Clipping

• Craniotomy to place clip at aneurysm neck
• Preferred for middle cerebral artery aneurysms

2. Endovascular Coiling

• Intravascular platinum coils occlude aneurysm
• Preferred in poor grade patients, posterior circulation aneurysms

🔹 Anesthetic Management for Clipping

🔸 Preoperative

• Stabilize vitals, control BP (MAP < 110 mmHg)
• Nimodipine (60 mg PO/NG every 4 h)
• Correct hyponatremia, hypokalemia
• EVD if hydrocephalus present

🔸 Induction

• Avoid hypertensive surges → risk of rebleed
• Use propofol, short-acting opioids (remifentanil/fentanyl)
• Lidocaine and β-blockers (esmolol) to blunt laryngoscopy
• RSI if ↓ GCS or risk of aspiration

🔸 Maintenance

• TIVA or balanced technique
• Keep ICP low, MAP to maintain CPP (~60–70 mmHg)
• Mild hypocapnia (PaCO₂ ~ 32–35 mmHg)
• Osmotic therapy (mannitol, hypertonic saline) as needed
• Normothermia, avoid hyperglycemia

🔸 Monitoring

🔸 Temporary Arterial Occlusion

• May be needed to clip the aneurysm
• Use barbiturate/propofol bolus to reduce CMRO₂
• Controlled hypotension in select cases (not routine)

🔹 Anesthetic Management for Coiling

• Procedure under general anesthesia (GA) or conscious sedation
• GA preferred in:
• High-grade SAH
• Posterior circulation aneurysms
• Anticipated long procedure
• Heparinization during procedure
• Maintain normocapnia, normotension
• Sudden bradycardia → may indicate aneurysm rupture

🔹 Postoperative Care

🔹 Triple H Therapy (for Vasospasm)

• Hypertension
• Hypervolemia
• Hemodilution

Previously standard, now controversial. Current practice = goal-directed euvolemia and BP augmentation.

🔍 Viva / Exam Highlights

Q: What drug improves outcomes in aSAH?
A: Nimodipine (prevents vasospasm and DCI)

Q: What’s the most dangerous time for rebleeding?
A: First 24 hours

Q: What is the gold standard for aneurysm detection?
A: Digital Subtraction Angiography (DSA)

Q: How is CSW differentiated from SIADH?
A: CSW = Hypovolemia + hyponatremia (↑ urine Na); SIADH = Euvolemia/hypervolemia + hyponatremia

🧠 Summary Table

📚 References

• Miller’s Anesthesia, 9th Edition – Chapter on Cerebrovascular Disease
• Cottrell and Young’s Neuroanesthesia
• BJA Education: Management of aSAH
• StatPearls: Subarachnoid Hemorrhage
• WFSA: Subarachnoid Hemorrhage Tutorial