What are the guidelines for assessing, diagnosing, and treating subarachnoid issues, including subarachnoid hemorrhage?

Subarachnoid Hemorrhage Assessment, Diagnosis, and Treatment Guidelines

Non-contrast head CT followed by CT angiography (CTA) or digital subtraction angiography (DSA) is the cornerstone of subarachnoid hemorrhage (SAH) diagnosis, with treatment focused on early aneurysm securing (within 24 hours) and nimodipine administration to improve neurological outcomes. 1

Diagnosis and Initial Assessment

Clinical Presentation

• Cardinal symptom: Sudden onset severe headache ("thunderclap headache")
• Associated symptoms: nausea, vomiting, neck pain/stiffness, photophobia, altered mental status
• Assess level of consciousness using Glasgow Coma Scale (GCS)

Diagnostic Algorithm

1. Non-contrast head CT scan:

   • First-line diagnostic test with sensitivity approaching 100% in first 12 hours
   • Repeat CT at 6 and 24 hours to evaluate for hematoma expansion 1

2. Lumbar puncture (LP):

   • Perform if CT is negative but clinical suspicion remains high
   • Especially important if presentation is >6 hours from symptom onset 1
   • Carefully planned LP needed to exclude SAH when CT is normal 2

3. Vascular imaging:

   • CTA or DSA with 3D rotational angiography to identify aneurysm location
   • For patients with aneurysmal pattern of SAH and no etiology identified, repeat DSA in 1-6 weeks (10% yield) 3
   • Consider MR angiography when CTA/DSA contraindicated (sensitivity 95%, specificity 89%) 3

Severity Assessment

• Hunt and Hess Grade:

  Grade	GCS	Focal Motor Deficit
  I	15	Absent
  II	13-14	Absent
  III	13-14	Present
  IV	7-12	Present or Absent
  V	3-6	Present or Absent

Initial Management

Airway and Breathing

• Secure airway if GCS ≤8 or deteriorating neurological status
• Maintain appropriate oxygenation without hyperventilation to prevent cerebral vasoconstriction 1

Blood Pressure Management

• Control blood pressure with titratable agents
• Target systolic BP <160 mmHg to reduce rebleeding risk
• Avoid excessive BP reduction which may compromise cerebral perfusion
• Use short-acting medications until aneurysm is secured 1

Aneurysm Treatment

• Secure aneurysm as early as possible (ideally within 24 hours) to reduce rebleeding risk
• Treatment options:
  • Endovascular coiling: Preferred for posterior circulation aneurysms
  • Surgical clipping: May be preferred for certain aneurysm morphologies
  • Decision between approaches should be multidisciplinary 1

Pharmacological Management

Nimodipine

• Only pharmacological treatment shown to improve neurological outcomes in clinical trials 3
• Dosage: 60 mg (two 30 mg capsules) orally every 4 hours for 21 consecutive days
• Start within 96 hours of SAH onset
• If patient cannot swallow: extract contents with syringe (labeled "Not for IV Use") and administer via nasogastric tube 4
• WARNING: Never administer intravenously - can cause significant hypotension 4

Management of Complications

Hydrocephalus

• Monitor for signs: declining consciousness, worsening headache
• Treatment: External ventricular drain (EVD) if symptomatic 1
• Can also be treated by lumbar puncture depending on site of obstruction 2

Delayed Cerebral Ischemia (DCI) and Vasospasm

• Highest risk between days 3-14 after SAH
• Monitor for new or worsening neurological deficits
• Prevention/Management:
  • Maintain euvolemia (avoid hypovolemia/hypervolemia)
  • Nimodipine administration
  • Induced hypertension for DCI treatment
  • Consider angioplasty and/or selective intra-arterial vasodilator therapy for symptomatic vasospasm 1

Electrolyte Disturbances

• Monitor serum sodium levels regularly (hyponatremia occurs in 10-30% of SAH patients)
• Consider fludrocortisone acetate or 3% hypertonic saline for correction 1
• Avoid hypotonic fluids which may worsen cerebral edema

Seizures

• Occurs in 5-15% of patients with SAH
• Prophylactic antiepileptic therapy with phenytoin sodium is generally accepted 5

Venous Thromboembolism

• Initiate prophylaxis once the aneurysm is secured 1

Monitoring

• Continuous neurological assessment to detect deterioration
• Transcranial Doppler to monitor for vasospasm
• Regular electrolyte monitoring, particularly sodium levels 1

Prognosis

• Case fatality after aneurysmal hemorrhage is approximately 50%
• One in eight patients with SAH dies outside hospital 2
• Outcome has improved over time with early intervention and aggressive management 3

Common Pitfalls to Avoid

• Delayed diagnosis: SAH can present with only headache; maintain high index of suspicion
• Missing the diagnosis with CT alone: LP needed if clinical suspicion high despite negative CT
• Inadequate blood pressure control: balance between preventing rebleeding and maintaining cerebral perfusion
• Delayed aneurysm treatment: secure aneurysm early to prevent rebleeding
• Failure to recognize and treat complications: monitor closely for hydrocephalus, vasospasm, and electrolyte disturbances
• Administering nimodipine intravenously: can cause significant hypotension 4