What is the treatment for a patient with suspected subarachnoid hemorrhage (SAH) due to a fall, with a negative repeat head computed tomography (CT) scan?

Management of Subarachnoid Hemorrhage with Negative Repeat Head CT

For patients with suspected subarachnoid hemorrhage (SAH) due to fall with a negative repeat head CT, further vascular imaging is essential to rule out underlying vascular abnormalities, particularly if the initial CT was positive for SAH.

Diagnostic Approach After Negative Repeat CT

When the repeat CT is negative but initial CT showed SAH:

1. Vascular imaging is mandatory 1

   • CTA (computed tomography angiography) should be performed first
   • If CTA is negative but clinical suspicion remains high, proceed to catheter angiography (DSA)
   • DSA remains the gold standard for detecting small aneurysms (<3mm)

2. Timing considerations

   • Catheter angiography has a yield of approximately 4.2% when performed 7 days after initial negative CTA 2
   • Consider repeat DSA if initial DSA is negative, as 3D rotational angiography can identify aneurysms in 25% of previously negative cases 1

Treatment Protocol

1. Transfer to appropriate facility

   • Patients with confirmed SAH should be managed at centers with neurosurgical expertise 1
   • Immediate neurosurgical consultation is required 1

2. Pharmacological management

   • Begin nimodipine 60mg orally every 4 hours for 21 days if presenting within 96 hours of SAH 1, 3
   • For patients with liver dysfunction, reduce dose to 30mg every 4 hours 3
   • If patient cannot swallow, extract capsule contents with syringe and administer via nasogastric tube 3

3. Supportive care

   • Liberal fluid administration to prevent delayed cerebral ischemia 4
   • Avoid antihypertensive medications unless severely elevated 4
   • Monitor for complications: rebleeding, hydrocephalus, vasospasm, seizures 5

Special Considerations

Perimesencephalic vs. Non-perimesencephalic SAH

• Perimesencephalic SAH (blood confined to cisterns around brainstem):

  • Better prognosis
  • Lower yield on repeat imaging (3.4%) 2
  • Some experts consider negative CTA sufficient 1

• Non-perimesencephalic SAH (diffuse pattern):

  • Higher risk of underlying aneurysm (5.1% yield on repeat imaging) 2
  • Requires more aggressive investigation with DSA 1

Common Pitfalls

1. Relying solely on negative repeat CT

   • CT sensitivity decreases over time (98-100% in first 12 hours, 57-85% by day 6) 6
   • Negative repeat CT does not exclude underlying vascular abnormality

2. Inadequate vascular imaging

   • Small aneurysms (<3mm) may be missed on CTA 1
   • Aneurysms near bony structures are particularly difficult to visualize 1

3. Premature discharge without adequate follow-up

   • Even with negative initial vascular studies, delayed repeat imaging may reveal abnormalities 2

Monitoring for Complications

1. Rebleeding risk

   • Highest in first 24-48 hours
   • Monitor neurological status closely
   • Avoid activities that increase intracranial pressure

2. Vasospasm

   • Peaks 7-10 days after hemorrhage
   • Nimodipine helps prevent this complication
   • Monitor for new neurological deficits

3. Hydrocephalus

   • May require surgical intervention (ventricular drain)
   • Monitor for declining mental status, headache, vomiting

By following this structured approach, you can optimize outcomes for patients with SAH even when repeat imaging is negative, reducing the risk of devastating complications.