What is the appropriate management for a suspected subarachnoid hemorrhage?

Management of Suspected Subarachnoid Hemorrhage

The appropriate management for suspected subarachnoid hemorrhage (SAH) requires urgent evaluation with noncontrast head CT followed by lumbar puncture if CT is negative, as this is a medical emergency with high risk of early rebleeding and poor outcomes. 1

Diagnosis

Initial Evaluation

• Maintain a high index of suspicion for SAH in patients with acute onset of severe headache, as SAH accounts for only 1% of all headaches evaluated in emergency departments but is frequently misdiagnosed 1
• Recognize warning signs such as sentinel headache (which may occur in up to 20% of patients within 2-8 weeks before major rupture), nausea, vomiting, loss of consciousness, or focal neurological deficits 1
• Rapidly determine clinical severity using validated scales (e.g., Hunt and Hess, World Federation of Neurological Surgeons) as this is the most useful indicator of outcome 1

Diagnostic Algorithm

1. Noncontrast head CT scan - cornerstone of SAH diagnosis 1

   • Sensitivity in first 3 days is very high (close to 100%) 1
   • Sensitivity declines to 93% at 24 hours and 57-85% by day 6 1
   • CT should be performed as soon as possible after symptom onset 1

2. Lumbar puncture if CT is negative 1

   • Key factors for CSF examination: timing in relation to SAH, red and white blood cell counts, presence of xanthochromia, detection of bilirubin 1
   • Proper technique, specimen handling, and interpretation are critical 1

3. Advanced imaging when indicated:

   • MRI with fluid-attenuated inversion recovery, proton density, diffusion-weighted imaging, and gradient echo sequences can diagnose SAH when CT is negative 1
   • Digital subtraction angiography (DSA) with 3D rotational angiography is indicated for detection of aneurysms 1
   • CT angiography (CTA) may be used initially, but has limitations for aneurysms <3mm 1
   • If CTA is negative with diffuse SAH pattern, follow with DSA 1

Acute Management

Immediate Interventions

• Transfer patients to high-volume centers (>35 SAH cases per year) with experienced cerebrovascular surgeons, endovascular specialists, and multidisciplinary neuro-intensive care services 1
• Control blood pressure with titratable agents to balance risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure 1
• Administer oral nimodipine to all patients (60 mg every 4 hours for 21 consecutive days) to improve neurological outcomes 1, 2

Aneurysm Management

• Perform surgical clipping or endovascular coiling of ruptured aneurysm as early as feasible to reduce rebleeding risk 1
• For aneurysms amenable to both techniques, endovascular coiling should be considered 1
• Complete obliteration of the aneurysm is recommended whenever possible 1
• Perform immediate cerebrovascular imaging after aneurysm repair to identify remnants requiring treatment 1

Management of Complications

• Treat acute symptomatic hydrocephalus with cerebrospinal fluid diversion (external ventricular drainage or lumbar drainage) 1
• Maintain euvolemia and normal circulating blood volume to prevent delayed cerebral ischemia (DCI) 1
• Induce hypertension for patients with DCI unless blood pressure is elevated at baseline or cardiac status precludes it 1
• Monitor for vasospasm with transcranial Doppler (TCD) technology, with Lindegaard ratios of 5-6 indicating severe spasm requiring treatment 1
• Screen for and treat heparin-induced thrombocytopenia and deep venous thrombosis 1

Special Considerations

Perimesencephalic SAH

• Patients with blood confined to cisterns around midbrain generally have good prognosis 3
• Some authors suggest negative CTA may be sufficient in classic perimesencephalic SAH pattern, but this remains controversial 1

Non-aneurysmal Causes

• Consider other etiologies when angiography is negative, including:
  • Intracranial artery dissections
  • Dural arteriovenous malformations
  • Mycotic aneurysms (especially with history of systemic infection or endocarditis) 3, 4
  • Trauma
  • Bleeding disorders
  • Substance abuse 3

Follow-up

• Patients who undergo coiling or clipping should have delayed follow-up vascular imaging 1
• Consider retreatment (repeat coiling or microsurgical clipping) if there is a clinically significant remnant 1
• Treat chronic symptomatic hydrocephalus with permanent CSF diversion 1

Common Pitfalls

• Failure to obtain noncontrast cranial CT is the most common diagnostic error 1
• Misdiagnosis is associated with nearly 4-fold higher likelihood of death or disability at 1 year 1
• Relying solely on CTA without DSA in cases of diffuse SAH pattern may miss small aneurysms 1
• Overlooking the possibility of a sentinel bleed, which may present with milder symptoms but precedes catastrophic rupture 1
• Inadequate blood pressure control between symptom onset and aneurysm obliteration 1