What are the classic presentation and initial management of a subarachnoid hemorrhage?

Subarachnoid Hemorrhage: Classic Presentation and Initial Management

Classic Presentation

The hallmark presentation of subarachnoid hemorrhage (SAH) is the sudden onset of "the worst headache of my life," described by approximately 80% of patients who can give a history. 1 This headache is characterized by extremely sudden onset and immediately reaching maximal intensity (thunderclap headache).

Additional classic presenting features include:

• Nausea and vomiting (77% of patients)
• Loss of consciousness (53% of patients)
• Nuchal rigidity/stiff neck (35% of patients)
• Photophobia
• Focal neurological deficits including cranial nerve palsies
• Seizures in up to 20% of patients, most commonly in the first 24 hours 1

Warning Signs and Sentinel Bleeds

A warning or sentinel headache that precedes the major SAH is reported by 10-43% of patients 1. These sentinel bleeds:

• Typically occur 2-8 weeks before overt SAH
• Present with milder headache than major rupture but may last several days
• May include nausea/vomiting, but meningismus is uncommon
• Increase the odds of early rebleeding 10-fold 1
• Recognition of these warning leaks is critical as they may be lifesaving

Diagnostic Approach

1. Noncontrast cranial CT scan is the cornerstone of SAH diagnosis:

   • Sensitivity in first 12 hours: 98-100%
   • Sensitivity at 24 hours: 93%
   • Sensitivity at 6 days: 57-85% 1

2. Lumbar puncture should be performed if CT is negative but clinical suspicion remains high:

   • Key factors: timing of LP in relation to SAH, red/white blood cell counts, presence of xanthochromia, detection of bilirubin 1

3. MRI may be useful in select cases:

   • Fluid-attenuated inversion recovery, proton density, diffusion-weighted imaging, and gradient echo sequences can detect SAH when CT is negative
   • Limited by availability, logistics, motion artifact, and cost in emergency settings 1

Initial Management

1. Urgent evaluation and treatment are essential due to high risk of rebleeding:

   • 3-4% risk in first 24 hours (possibly higher)
   • Highest risk within 2-12 hours after initial bleed
   • 1-2% daily risk in first month 1

2. Determine severity using validated scales (Hunt and Hess, World Federation of Neurological Surgeons) as this is the most useful indicator of outcome 1

3. Aneurysm management:

   • Early surgical clipping or endovascular coiling to prevent rebleeding 2
   • Factors affecting triage for aneurysm repair: severity of initial bleed, interval to admission, blood pressure, gender, aneurysm characteristics, hydrocephalus, early angiography, and presence of ventricular drain 1

4. Nimodipine administration:

   • Standard dose: 60 mg orally every 4 hours for 21 consecutive days
   • Start as soon as possible within 96 hours of SAH onset
   • Reduces the severity of neurological deficits resulting from vasospasm 3
   • If patient cannot swallow, capsule contents can be extracted and administered via nasogastric tube 3

5. Management of complications:

   • Hydrocephalus: May require ventricular drainage 4
   • Vasospasm: Volume expansion and induced hypertension (after aneurysm is secured) 5
   • Seizures: Prophylactic antiepileptic therapy may be considered 5

Common Pitfalls and Caveats

1. Misdiagnosis is common (12% rate in recent data) and associated with nearly 4-fold higher likelihood of death or disability at 1 year 1

2. Most common diagnostic error is failure to obtain a noncontrast cranial CT 1

3. SAH accounts for only 1% of all headaches evaluated in the emergency department, requiring high index of suspicion 1

4. Up to 12% of patients die before receiving medical attention 1

5. Nimodipine administration: Never administer intravenously as it can cause significant hypotension requiring cardiovascular support 3

6. Delayed cerebral ischemia from vasospasm is a major cause of morbidity and mortality, typically developing within the first 2 weeks after hemorrhage 6