What are the signs and symptoms of subarachnoid (below the arachnoid membrane) bleeding?

Signs and Symptoms of Subarachnoid Hemorrhage

The hallmark presentation of subarachnoid hemorrhage is a sudden onset of severe headache, described by approximately 80% of patients as "the worst headache of my life," often characterized as a thunderclap headache reaching maximal intensity immediately. 1

Primary Clinical Manifestations

Cardinal Symptoms

• Severe headache: Present in 74-80% of patients 2

  • Characterized as thunderclap (instantly peaking pain)
  • Often described as "the worst headache of my life"
  • Reaches maximal intensity immediately

• Nausea and vomiting: Present in 77% of patients 2

• Loss of consciousness: Occurs in 53% of patients 2

• Nuchal rigidity (stiff neck): Present in 35% of patients 2

Additional Signs and Symptoms

• Photophobia 2
• Brief loss of consciousness 2
• Focal neurological deficits, including cranial nerve palsies 2
• Seizures: Occur in up to 20% of patients, most commonly in first 24 hours 2, 1
  • More common with SAH associated with:
    • Intracerebral hemorrhage
    • Hypertension
    • Middle cerebral and anterior communicating artery aneurysms

Warning Signs: Sentinel Bleed

A critical aspect of SAH is the presence of warning signs before major rupture:

• Sentinel headache: Occurs in 10-43% of patients 2, 1
  • Usually occurs 2-8 weeks before major rupture 2
  • Typically milder than the headache associated with major rupture
  • May last for a few days
  • Often accompanied by nausea and vomiting
  • Meningismus (meningeal irritation) is uncommon after sentinel hemorrhage

Recognition of these warning signs is crucial as they increase the odds of early rebleeding 10-fold 2. Approximately 20% of patients (range 15-37%) report a sudden severe headache before the event leading to hospital admission 2.

Presentation by Severity Grade

Using the World Federation of Neurosurgical Societies (WFNS) scale 1:

Grade	Clinical Symptoms
I	Asymptomatic
II	Cranial nerve palsy
III	Mild hemiparesis
IV	Stupor, moderate to severe hemiparesis
V	Coma, decerebrate posturing

Diagnostic Considerations

The Ottawa SAH Rule can help identify patients requiring further investigation 2. Patients need additional investigation if they meet any of these criteria:

• Age ≥40 years
• Neck pain or stiffness
• Witnessed loss of consciousness
• Onset during exertion
• Thunderclap headache
• Limited neck flexion on examination

Common Pitfalls in Recognition

1. Misdiagnosis is common: Despite the classic presentation, misdiagnosis occurs in approximately 12% of cases 2

   • Misdiagnosis is associated with a nearly 4-fold higher likelihood of death or disability at 1 year 2
   • The most common diagnostic error is failure to obtain a noncontrast cranial CT 2

2. Variable presentation: Individual findings occur inconsistently, and the headache characteristics can vary 2

3. Failure to recognize sentinel bleeds: Recognizing warning leaks is critical as they precede catastrophic rupture 2

4. Death before medical attention: As many as 12% of patients die before receiving medical attention 2

For any patient presenting with sudden severe headache, maintaining a high index of suspicion for SAH is essential, as early diagnosis and treatment significantly impact morbidity and mortality outcomes.