What are the treatment and management options for a patient with Moya Moya disease?

Treatment and Management of Moyamoya Disease

Surgical Revascularization: The Definitive Treatment

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

Surgical Approach Selection

Direct bypass (superficial temporal artery to middle cerebral artery anastomosis) is the preferred first-line surgical intervention, particularly for hemorrhagic moyamoya, as it reduces rebleeding from 7.6%/year to 2.7%/year (P=0.04). 3, 1, 2

• Direct bypass provides immediate revascularization and is technically superior when feasible 3
• The Japan Adult Moyamoya trial definitively demonstrated surgical benefit over medical therapy for hemorrhagic disease, with posterior hemorrhages (posterior cerebral or choroidal artery bleeding) obtaining the greatest benefit 3
• Combined direct and indirect approaches show 96% probability of remaining stroke-free over 5 years 3, 1

For pediatric patients, indirect revascularization (pial synangiosis, encephaloduroarteriosynangiosis) is preferred due to small vessel size making direct bypass technically difficult. 3, 1, 4

• Indirect procedures reduce stroke rates from 67% preoperatively to 4.3% at 5-year follow-up 3, 1
• These techniques rely on angiogenic proliferation over days to weeks rather than immediate revascularization 3, 1

Perioperative Management Protocol

Meticulous hemodynamic management is critical to minimize the 4%-16.5% risk of perioperative complications, particularly cerebral hyperperfusion syndrome (CHS). 3, 1

Pre-admission and Intraoperative Management:

• Admit for intravenous fluids overnight before surgery to maintain hydration while NPO 3
• Place arterial line before anesthesia induction 3
• Maintain systolic blood pressure at or above preoperative baseline; avoid SBP >180 mmHg 3, 1
• Maintain strict normocapnia with end-tidal CO₂ between 35-45 mmHg—hypocapnia causes vasoconstriction and ischemia in already compromised vessels 3, 1
• Keep patients euvolemic to mildly hypervolemic intraoperatively 3, 1
• Avoid mannitol as it can cause hypotension and decreased cerebral perfusion 3

Postoperative Management:

• Provide intravenous fluids at 1.5 times normal maintenance rate for 48-72 hours 3, 1
• Use perioperative sedation and painless wound techniques to prevent crying and hyperventilation in children, which lower PaCO₂ and induce ischemia 3, 1
• Monitor for CHS (16.5% overall incidence; 19.9% in adults, 3.8% in pediatrics), which presents as transient neurological deficits (70.2%), hemorrhage (15%), or seizures (5.3%) 3, 1
• Predictive factors for CHS include older age, severe preoperative hemodynamic impairment, dominant hemisphere surgery, and longer temporary occlusion time 3

Medical Management

Antiplatelet Therapy

Aspirin may be reasonable for prevention of ischemic events after revascularization surgery or in asymptomatic individuals for whom surgery is not anticipated (Class IIb recommendation). 1, 2

• Dosing: 81 mg daily in children with weight-based adjustments 1
• Evidence is mixed and practice varies globally, with antiplatelet use more common in Western countries than Asia where hemorrhagic presentation predominates 1
• Cilostazol (a vasodilator) may improve survival, cerebral blood flow, and cognition compared to other antiplatelet drugs, though requires further validation 1

Anticoagulation

Anticoagulants like warfarin are NOT recommended for most patients (Class III recommendation) due to hemorrhage risk and difficulty maintaining therapeutic levels, particularly in children. 1, 2

Adjunctive Medical Therapies

• Atorvastatin may improve collateral circulation post-revascularization and reduce migraine frequency 1, 5
• Aggressively manage diabetes—it is an independent predictor of recurrent ischemic stroke 1, 5
• Carefully manage hypertension and dyslipidemia without causing hypotension, as these are risk factors for cerebrovascular events 1, 5

Headache Management Considerations

Avoid medications that worsen cerebral perfusion in moyamoya patients with headaches: 5

• Do not use triptans (cause vasoconstriction in stenotic vessels) 5
• Avoid ergot derivatives (enhance vasoconstriction) 5
• Avoid CGRP antagonists (limit vasodilation needed for collateral flow) 5
• Avoid beta-blockers and calcium channel blockers (lower blood pressure and reduce cerebral perfusion) 5

Long-Term Surveillance

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

• Transcranial Doppler (TCD) may be useful in evaluation and follow-up (Class IIb recommendation) 1
• Techniques to measure cerebral perfusion and blood flow reserve (SPECT, PET, xenon-enhanced CT) assist in ongoing evaluation 3, 1, 2
• 27% of patients with unilateral disease eventually develop bilateral involvement, with younger patients at higher risk for progression 3
• Need for reoperation due to refractory disease ranges from 1.8% to 18% 3

Common Pitfalls to Avoid

• Never allow hyperventilation in moyamoya patients—this is a critical trigger for ischemic events due to hypocapnia-induced vasoconstriction 3, 1
• Do not delay surgical intervention in symptomatic patients—some patients stabilize without intervention but only after sustaining debilitating neurological disability 3
• Avoid hypotension, hypovolemia, and hyperthermia both intraoperatively and perioperatively 3, 1
• Do not assume asymptomatic patients are safe from events—they carry a 5% annual cerebrovascular event risk and should be evaluated for impaired cerebral perfusion 1, 2