What is the management approach for Moyamoya disease?

Management of Moyamoya Disease

Surgical revascularization is the definitive treatment for all patients with symptomatic moyamoya disease or those with evidence of compromised cerebral perfusion, as this markedly reduces stroke risk from 67% preoperatively to 4.3% at 5-year follow-up. 1, 2

Surgical Management: The Primary Treatment

All patients with ongoing ischemic symptoms and/or evidence of compromised cerebral perfusion should undergo revascularization surgery (Class I, Level B recommendation). 1, 2, 3 Even clinically asymptomatic patients demonstrating radiographic or functional evidence of impaired cerebral perfusion should be considered surgical candidates. 2, 3

Surgical Technique Selection

• Direct bypass (superficial temporal artery to middle cerebral artery) is the most appropriate intervention for adults, particularly for hemorrhagic moyamoya, reducing rebleeding from 7.6%/year to 2.7%/year (P=0.04). 2, 3

• Indirect revascularization techniques (pial synangiosis, encephaloduroarteriosynangiosis) are preferred in children due to small vessel size making direct bypass technically difficult. 2

• Combined direct and indirect approaches have shown improved results, with 96% probability of remaining stroke-free over 5 years. 4

• The key factor in successful outcome is surgeon and institutional experience with moyamoya care. 1

Perioperative Management: Critical for Preventing Complications

Perioperative stroke occurs in 4%-18% of surgical cases, making meticulous management essential. 1, 5

Hemodynamic optimization: 1, 3

• Maintain systolic blood pressure at or above preoperative baseline; slight elevation may be beneficial
• Provide intravenous fluids at 1.5 times normal maintenance rate for 48-72 hours postoperatively 4
• Avoid hypotension, hypovolemia, hyperthermia 4, 3

Respiratory management: 1, 2

• Maintain strict normocapnia with end-tidal CO₂ 35-45 mmHg
• Avoid hypocarbia as it causes vasoconstriction and ischemia in already compromised vessels

Minimize triggers of hyperventilation: 4, 3

• Use perioperative sedation, painless wound dressing techniques, and absorbable sutures
• Crying and hyperventilation in children can lower PaCO₂ and induce ischemia (Class IIb recommendation)

Medical Management: Adjunctive Therapy

Antiplatelet Therapy

Aspirin may be considered in individuals with moyamoya after revascularization surgery or in asymptomatic individuals for whom surgery is not anticipated (Class IIb recommendation). 4, 1, 3 However, evidence for efficacy is mixed and practice varies globally, with more common use in Western countries than Asia where hemorrhagic presentation is more prevalent. 4, 2, 5

• Typical dosing: 81 mg daily in children, weight-based dosing in adults 2
• Used to prevent microthrombi at stenosis sites 2

Anticoagulants like warfarin are NOT recommended for most patients (Class III recommendation) due to hemorrhage risk and difficulty maintaining therapeutic levels in children. 4, 2, 3

Hemodynamic and Metabolic Optimization

Maintain optimal cerebral perfusion through: 2, 3

• Euvolemia to mild hypervolemia
• Normocapnia and normothermia
• Adequate blood pressure
• Avoiding anemia and hypoglycemia 5

Management of Comorbidities

Diabetes is an independent predictor of recurrent ischemic stroke and requires aggressive management. 1, 2 Hypertension and dyslipidemia are also risk factors for cerebrovascular events in asymptomatic moyamoya. 2

Diagnostic Evaluation

Cerebral digital subtraction angiography (DSA) remains the gold standard for diagnosis, particularly for unilateral lesions or cases complicated by atherosclerosis. 1, 3

Three angiographic findings are required: 1, 3

1. Stenosis of the distal ICA bifurcation and proximal ACA/MCA
2. Dilated basal collateral arteries ("puff of smoke" appearance)
3. Bilateral abnormalities

Perfusion imaging (SPECT, PET, xenon-enhanced CT) and cerebrovascular reactivity assessment are critical for treatment planning and identifying patients with compromised cerebral blood flow reserve (Class IIb recommendation). 1, 3

Long-Term Surveillance

Serial follow-up is necessary given 5% annual risk of cerebrovascular events in asymptomatic patients and 20% disease progression rate over mean 6-year follow-up. 1, 2, 3

• Patients with unilateral moyamoya should obtain annual imaging with MRA or CTA to assess for disease progression for at least 3-5 years (Class IIb recommendation). 1
• TCD may be useful in evaluation and follow-up (Class IIb recommendation). 4
• Techniques to measure cerebral perfusion and blood flow reserve may assist in ongoing evaluation (Class IIb recommendation). 4, 3

Common Pitfalls to Avoid

Do not screen asymptomatic relatives or individuals without strong family history - there is insufficient evidence to justify screening studies in the absence of a strong family history or predisposing medical conditions (Class III recommendation). 4

Avoid triggers of cerebral vasoconstriction: 2, 3

• Hyperventilation, crying, coughing, straining, or fever can precipitate ischemic events in children
• These activities lower PaCO₂ and induce vasoconstriction in already compromised vessels

Recognize that cerebral hyperperfusion syndrome occurs in 16.5% overall (3.8% in pediatric patients, 19.9% in adults) and requires vigilant postoperative monitoring. 2