What if the etiology of the subarachnoid hemorrhage is MoyaMoya disease?

Management of Subarachnoid Hemorrhage in Moyamoya Disease

For subarachnoid hemorrhage (SAH) caused by Moyamoya disease, surgical revascularization is the recommended treatment to reduce the risk of rebleeding and improve outcomes. 1

Pathophysiology and Presentation

Moyamoya disease (MMD) can present with hemorrhagic events, including subarachnoid hemorrhage, which typically occurs due to:

• Rupture of deep neovascularization collaterals and pseudoaneurysms 1
• Disruption of fragile transdural anastomotic vessels 2
• Occasional associated aneurysms 1

Unlike typical aneurysmal SAH, Moyamoya-related SAH may occur from these fragile collateral vessels that develop as a compensatory mechanism for the progressive stenosis of the internal carotid artery and its branches.

Diagnostic Approach

1. Digital subtraction angiography (DSA): Gold standard for diagnosis of Moyamoya vasculopathy 1

   • Evaluate for Suzuki classification stage (I-VI)
   • Identify potential source of bleeding
   • Assess collateral circulation

2. MRI/MRA of the brain:

   • Evaluate for ischemic changes and parenchymal damage
   • Assess vascular stenosis and collateral formation
   • Look for "ivy sign" on T2-weighted FLAIR imaging (slow flow in affected territories) 1

3. CT/CTA:

   • Useful for evaluating acute hemorrhage
   • Less sensitive than MRI for demonstrating associated ischemic changes 1

Acute Management

1. Blood pressure management:

   • Maintain systolic blood pressure at or slightly above the patient's asymptomatic baseline
   • Avoid systolic blood pressure >180 mmHg 1, 3
   • Strict adherence to eucapnia is essential - hypocapnia can cause vasoconstriction and worsen cerebral blood flow 4

2. Seizure prophylaxis:

   • Levetiracetam (>1000 mg total daily dose) may be preferred over phenytoin due to:
     • Fewer drug interactions
     • Possible neuroprotective effects in SAH 5
     • Better tolerability profile 6

3. Hydration management:

   • Maintain euvolemic to mildly hypervolemic state 1, 3
   • Avoid mannitol as it may decrease cerebral perfusion pressure 1, 3
   • Intravenous fluids at 1.5 times normal maintenance rate for 48-72 hours 3

Definitive Treatment

Direct surgical revascularization is strongly recommended for hemorrhagic presentation of Moyamoya disease 1, 3:

• Direct bypass (STA-MCA) reduces rebleeding rates from 7.6%/year to 2.7%/year 3
• Surgical revascularization promotes thrombosis/regression of fragile collaterals by reducing hemodynamic stress 1
• Success rates of approximately 80% for preventing rebleeding 1

Perioperative Considerations

1. Pre-surgical preparation:

   • Preadmission for intravenous fluid administration overnight to maintain hydration 1
   • Arterial line placement before anesthesia induction 1

2. Intraoperative management:

   • Maintain normocapnia with end-tidal CO₂ between 35-45 mmHg 1
   • Keep euvolemic to mildly hypervolemic 1
   • Avoid mannitol 1

3. Post-operative monitoring:

   • Monitor for cerebral hyperperfusion syndrome (CHS), which occurs in approximately 16.5% of cases 1, 3
   • Maintain strict blood pressure control (systolic <130 mmHg) to mitigate CHS 1, 3
   • Watch for transient neurological deficits (70.2%), hemorrhage (15.0%), and seizures (5.3%) 1

Long-term Management

1. Antiplatelet therapy:

   • Consider aspirin (75-100mg daily) following direct revascularization surgery 3
   • Antiplatelet use may be reasonable for prevention of ischemic events 1

2. Follow-up imaging:

   • Regular clinical and radiographic follow-up is recommended 3
   • Monitor for disease progression and development of bilateral involvement 3

3. Avoid medications that cause vasoconstriction:

   • Triptans, ergots, and certain migraine therapies should be avoided 3

Pitfalls to Avoid

1. Aggressive blood pressure lowering: May compromise cerebral perfusion in patients with already compromised vasculature 4

2. Hyperventilation: Can cause hypocapnia leading to vasoconstriction and worsened cerebral blood flow 4

3. Endovascular treatment with stents or angioplasty: Shows low success rates (25%) and high complication rates (including devastating hemorrhage in 7%) 1, 3

4. Dehydration: Can trigger ischemic events due to hemodynamic compromise 1

5. Anticoagulation: Generally not recommended due to increased hemorrhage risk 3