Subarachnoid Hemorrhage (SAH)

1️⃣ Definition

Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space (between arachnoid and pia mater), where CSF circulates.

Two major types:

1. Aneurysmal SAH (aSAH) – (≈85%)
2. Non-aneurysmal SAH
• Perimesencephalic SAH
• Traumatic SAH
• AVM rupture
• Vasculitis
• Coagulopathy

2️⃣ Etiology

A. Ruptured Intracranial Aneurysm (Most Common)

Most aneurysms are saccular (berry) and occur at bifurcations in the Circle of Willis:

Risk Factors

• Hypertension
• Smoking (strongest modifiable risk)
• Polycystic kidney disease
• Ehlers-Danlos
• Family history
• Cocaine use

3️⃣ Pathophysiology

SAH is not just bleeding — it is a cascade of secondary brain injury.

Phase 1: Immediate Brain Injury (First 72 hours)

• Sudden ↑ ICP → ↓ CPP → global cerebral ischemia
• Sympathetic surge
• Myocardial stunning
• Pulmonary edema

Phase 2: Early Brain Injury (EBI)

• Blood breakdown products
• Inflammation
• BBB disruption
• Cerebral edema

Phase 3: Delayed Cerebral Ischemia (DCI)

Occurs day 3–14
Mechanisms:

• Vasospasm
• Microthrombosis
• Cortical spreading depolarization
• Inflammation

4️⃣ Clinical Features

Classic Presentation

“Worst headache of my life”
Thunderclap headache → peaks within seconds.

Other features:

• Vomiting
• Neck stiffness (meningeal irritation)
• Photophobia
• LOC
• Seizures (10–20%)
• Focal deficits (if large bleed)

Sentinel Headache-Minor leak days before rupture

5️⃣ Grading Systems 

A. Clinical Grading

Hunt & Hess

WFNS (Uses GCS)

Higher grade → worse prognosis.

B. Radiological Grading

Modified Fisher Scale (Predicts Vasospasm)

Grade 3–4 → high vasospasm risk.

6️⃣ Diagnosis

1️⃣ Non-Contrast CT Brain

• First-line
• Sensitivity:
• <6 hours: >95%
• After 24h: decreases

2️⃣ Lumbar Puncture

If CT negative but suspicion high:

Findings:

• Xanthochromia
• Persistent RBCs
• Elevated opening pressure

3️⃣ CT Angiography

• Detects aneurysm
• Rapid and widely available

4️⃣ Digital Subtraction Angiography (DSA)

Gold standard-Required if CTA negative but suspicion persists.

7️⃣ ICU Management 

Management goals:

1. Prevent rebleeding
2. Prevent vasospasm
3. Control ICP
4. Prevent systemic complications

8️⃣ Initial Resuscitation

ABC Approach

Airway

• Intubate if:
• GCS ≤8
• Airway compromise
• Severe agitation

Blood Pressure

Target SBP < 160 mmHg before securing aneurysm

Preferred agents:

• Nicardipine
• Labetalol

Avoid:

• Nitroprusside (↑ ICP)

9️⃣ Securing the Aneurysm

Must be done within 24 hours.

Options:

1️⃣ Endovascular Coiling

Preferred in most cases

2️⃣ Surgical Clipping

Landmark trial:
International Subarachnoid Aneurysm Trial (ISAT)
→ Coiling had better short-term outcomes.

🔟 Vasospasm & Delayed Cerebral Ischemia (DCI)

Occurs day 3–14
Peak: Day 7

Monitoring

• Clinical neuro exam
• Transcranial Doppler (TCD)
• CTA

Prevention-Nimodipine (ONLY proven therapy)

Reduces DCI and improves outcome
Does NOT reduce angiographic vasospasm.

Treatment of Vasospasm

1. Induced hypertension (after aneurysm secured)
2. Endovascular therapy:
• Balloon angioplasty
• Intra-arterial vasodilators

1️⃣1️⃣ ICP Management

• Head elevation
• Sedation
• EVD if hydrocephalus
• Hypertonic saline
• Avoid aggressive hyperventilation

1️⃣2️⃣ Hydrocephalus

Due to:

• Obstructed CSF flow
• Blood in ventricles

Management:

• External ventricular drain (EVD)

1️⃣3️⃣ Seizures

• Occur in 10–20%
• Prophylaxis not routine
• Levetiracetam preferred short-term

1️⃣4️⃣ Cardiac Complications

Neurogenic stunned myocardium

• Troponin elevation
• LV dysfunction
• Arrhythmias
• QT prolongation

Pathophysiology:-Massive catecholamine surge

1️⃣5️⃣ Pulmonary Complications

• Neurogenic pulmonary edema
• ARDS
• Aspiration

1️⃣6️⃣ Electrolyte Disturbances

Common:

Hyponatremia

Causes:

• SIADH
• Cerebral salt wasting (CSW)

Key differentiation:

Avoid hypovolemia → worsens vasospasm.

1️⃣7️⃣ Rebleeding

Highest risk in first 24h
Mortality 70%

Prevention:

• Early aneurysm securing
• BP control
• Avoid anticoagulation

1️⃣8️⃣ Prognosis

Mortality:

• Overall ≈30–40%
• Grade V >70%

Poor prognostic factors:

• High Hunt & Hess
• Thick SAH
• IVH
• Rebleed
• Delayed ischemia