What are the signs, symptoms, diagnosis, evaluation, treatments, and complications of Subarachnoid Hemorrhage (SAH)?

Subarachnoid Hemorrhage: Signs, Symptoms, Diagnosis, Evaluation, Treatment, and Complications

Signs and Symptoms

The hallmark presentation of subarachnoid hemorrhage (SAH) is a sudden-onset, severe headache described as "the worst headache of my life" by approximately 80% of patients who can provide a history. 1, 2

• Thunderclap headache (instantly peaking pain) is the classic presentation, with headache reaching maximal intensity immediately 1
• A warning or sentinel headache may precede the major SAH in 10-43% of patients, often occurring 2-8 weeks before overt rupture 1
• Nausea and/or vomiting occurs in approximately 77% of patients 1
• Loss of consciousness is reported in about 53% of patients 1
• Nuchal rigidity (stiff neck) is present in approximately 35% of patients 1
• Photophobia is a common associated symptom 1
• Focal neurological deficits, including cranial nerve palsies, may be present 1
• Seizures occur in up to 20% of patients, most commonly in the first 24 hours 1, 3

Diagnosis and Evaluation

Initial Assessment

• The Ottawa SAH Rule should be applied to identify patients at high risk for SAH 1
  • Age ≥40 years
  • Neck pain or stiffness
  • Witnessed loss of consciousness
  • Onset during exertion
  • Thunderclap headache
  • Limited neck flexion on examination

Diagnostic Algorithm

1. Non-contrast head CT is the cornerstone of SAH diagnosis 1, 3

   • Sensitivity approaches 100% within first 3 days, decreasing to 93% at 24 hours and 57-85% by day 6 3
   • Should be performed on a high-quality scanner and interpreted by a board-certified neuroradiologist 1

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

   • For patients presenting >6 hours from symptom onset: lumbar puncture (LP) for xanthochromia evaluation is necessary 1, 3
   • Spectrophotometric analysis of CSF for xanthochromia has a sensitivity of 100% and specificity of 95.2% 1

3. For confirmed SAH:

   • Digital subtraction angiography (DSA) is indicated to diagnose/exclude cerebral aneurysm(s) 1
   • DSA helps determine the optimal strategy for aneurysm intervention 1

Treatment

Initial Management

• Immediate transfer to a high-volume center (>35 SAH cases/year) with multidisciplinary neurointensive care services 3
• Blood pressure control is essential to reduce rebleeding risk while maintaining cerebral perfusion 2, 3
  • Systolic blood pressure should be maintained below 160 mmHg using titratable agents like nicardipine, labetalol, or clevidipine 2

Medical Management

• Nimodipine 60 mg every 4 hours for 21 consecutive days is recommended for all SAH patients to improve neurological outcomes by reducing the incidence and severity of delayed cerebral ischemia 3, 4
• Acetaminophen should be administered to all patients with SAH-associated headache as the foundation of pain management 2
• Maintenance of euvolemia rather than hypervolemia is recommended to prevent delayed cerebral ischemia (DCI) 3, 5
• Seizure prophylaxis should be considered, especially in the first 24 hours 3, 5
• Acute symptomatic hydrocephalus should be managed by cerebrospinal fluid diversion via external ventricular drainage or lumbar drainage 3

Definitive Treatment

• Early securing of the ruptured aneurysm (within 24-72 hours) is recommended to prevent rebleeding 3, 5
• For aneurysms amenable to both techniques, endovascular coiling is generally preferred over surgical clipping, especially for posterior circulation aneurysms 3
• Complete obliteration of the aneurysm should be the goal whenever possible 3

Complications and Their Management

Rebleeding

• Risk is highest within the first 24-72 hours 5
• Prevention through early aneurysm securing and blood pressure control 3, 5

Delayed Cerebral Ischemia (DCI)

• Occurs in up to 30% of SAH patients who survive the initial hemorrhage 6
• Prevention with nimodipine administration is the cornerstone of management 3, 6
• For symptomatic DCI, induced hypertension is recommended unless contraindicated 3, 6

Hydrocephalus

• Can occur acutely or develop over days to months following SAH 5
• Treated with external ventricular drainage (acute) or permanent CSF diversion (chronic) 3, 5

Seizures

• Occur in up to 20% of patients, most commonly in first 24 hours 1, 3
• More common in SAH associated with intracerebral hemorrhage, hypertension, and middle cerebral and anterior communicating artery aneurysms 1

Medical Complications

• Cardiac dysfunction, neurogenic pulmonary edema, electrolyte abnormalities, and infections are common 7
• Require vigilant monitoring and prompt treatment to prevent secondary brain injury 7

Common Pitfalls and Caveats

• Misdiagnosis occurs in up to 12% of cases, with the most common error being failure to obtain a non-contrast head CT 1, 3
• Sentinel headaches are frequently missed, but recognizing them can be lifesaving 1
• CT sensitivity decreases significantly after 5-7 days, requiring lumbar puncture for diagnosis 1
• CTA alone is insufficient to rule out SAH as it only evaluates for vascular pathology, not hemorrhage 1
• Nimodipine can cause hypotension; if administered intravenously by mistake, significant hypotension may require cardiovascular support with pressor agents 4