What is a catastrophic Subarachnoid Hemorrhage (SAH)?

Definition of Catastrophic Subarachnoid Hemorrhage (SAH)

A catastrophic subarachnoid hemorrhage refers to a severe, life-threatening bleeding into the subarachnoid space that results in rapid clinical deterioration, often leading to death or severe disability, typically occurring after the rupture of a cerebral aneurysm. 1

Key Characteristics of Catastrophic SAH

Clinical Presentation

• Sudden onset of the "worst headache of life" (thunderclap headache)
• Rapid neurological deterioration
• May present with:
  • Loss of consciousness (occurs in up to 53% of cases) 1
  • Nausea/vomiting (77% of cases) 1
  • Nuchal rigidity (35% of cases) 1
  • Focal neurological deficits
  • Seizures (up to 20% of patients, most commonly in first 24 hours) 1

Mortality and Morbidity

• Approximately 12% of patients die before receiving medical attention 1
• Overall 30-day mortality rate is approximately 45% 2
• Rebleeding carries an extremely high mortality rate of 70% 2
• One-third of survivors remain dependent 3

Pathophysiology and Risk Factors

Causes

• 85% of cases result from ruptured cerebral aneurysms 3
• 10% from non-aneurysmal perimesencephalic hemorrhage 3
• 5% from various rare conditions 3

Warning Signs

• Sentinel bleeds or warning leaks occur in 15-37% of cases 1
• These minor hemorrhages typically occur 2-8 weeks before catastrophic rupture 1
• Recognizing these warning signs is critical as diagnosis of a sentinel bleed before catastrophic rupture can be lifesaving 1

Diagnosis

Diagnostic Algorithm

1. Immediate non-contrast head CT is the cornerstone of diagnosis 1

   • Sensitivity approaches 100% in first 3 days after SAH 1
   • Sensitivity decreases after 5-7 days 1

2. If CT is negative but clinical suspicion remains high:

   • Perform lumbar puncture to evaluate for xanthochromia 1
   • MRI with fluid-attenuated inversion recovery, proton density, diffusion-weighted imaging, and gradient echo sequences may help diagnose SAH when CT is negative 1

3. Vascular imaging:

   • Digital subtraction angiography (DSA) is indicated to diagnose/exclude cerebral aneurysms 1
   • CT angiography may be used but has limitations for aneurysms <3mm 1

Grading Systems

SAH severity is commonly assessed using standardized scales:

• Hunt and Hess Scale:

  • Grade I: Asymptomatic or minimal headache
  • Grade II: Moderate to severe headache, nuchal rigidity, no neurologic deficit other than cranial nerve palsy
  • Grade III: Drowsiness, confusion, mild focal deficit
  • Grade IV: Stupor, moderate to severe hemiparesis
  • Grade V: Coma, decerebrate posturing

• World Federation of Neurological Surgeons Scale:

  • Based on Glasgow Coma Scale and presence of focal motor deficits 2

Management Considerations

Immediate Management

• Treat as a medical emergency requiring immediate evaluation by physicians with stroke management expertise 1
• Urgent neurosurgical consultation 1
• Blood pressure control (target SBP <160 mmHg) to reduce rebleeding risk 2
• If on anticoagulants, urgent reversal of anticoagulation 2

Definitive Treatment

• Patients should be managed in centers with neurosurgical expertise 1
• Treatment options include surgical clipping and endovascular coiling 2
• Nimodipine administration to all patients to reduce risk of delayed cerebral ischemia 2

Complications

Early Complications

• Rebleeding risk is highest in first 24 hours (15% "ultraearly rebleeding") 2
• Acute hydrocephalus requiring CSF diversion 2
• Global brain ischemia 1

Delayed Complications

• Vasospasm occurs in 30-70% of patients 2
• Delayed cerebral ischemia 2
• Approximately 15-20% of patients suffer stroke or die from vasospasm despite maximal therapy 2

Pitfalls in Diagnosis and Management

• Misdiagnosis or delayed diagnosis is common (12% of cases in recent data) 1
• Most common diagnostic error is failure to obtain a non-contrast head CT scan 1
• Patients with warning leaks may present with milder headaches that can be misdiagnosed 1
• SAH accounts for only 1% of all headaches evaluated in emergency departments, requiring high index of suspicion 1

Understanding catastrophic SAH and its warning signs is critical for early intervention, as prompt diagnosis and treatment significantly impact patient outcomes and survival.