Moyamoya Disease¶

VERSION: 1.0 CREATED: January 31, 2026 STATUS: Initial build

DIAGNOSIS: Moyamoya Disease

ICD-10: I67.5 (Moyamoya disease), I63.9 (Cerebral infarction, unspecified), I61.9 (Nontraumatic intracerebral hemorrhage, unspecified), I67.1 (Cerebral aneurysm, nonruptured), I63.50 (Cerebral infarction due to unspecified occlusion or stenosis of unspecified cerebral artery)

CPT CODES: 70553 (MRI brain with/without contrast), 70544-70549 (MRA head/neck), 36224 (cerebral angiography), 70496 (CTA head), 78607 (brain SPECT), 78816 (brain PET), 61711 (STA-MCA bypass), 61624 (EDAS/EMS), 95816 (EEG)

SYNONYMS: Moyamoya disease, moyamoya syndrome, moyamoya vasculopathy, spontaneous occlusion of the circle of Willis, progressive intracranial steno-occlusive disease, MMD, quasi-moyamoya, moyamoya angiopathy, puff of smoke disease

SCOPE: Diagnosis and management of moyamoya disease and moyamoya syndrome in adults. Covers acute stroke management in moyamoya, diagnostic workup, medical management, surgical revascularization evaluation and options, and long-term monitoring. Distinguishes moyamoya disease (idiopathic, bilateral) from moyamoya syndrome (secondary to other conditions). Excludes pediatric moyamoya (different surgical considerations and natural history) and other causes of ischemic stroke covered in separate templates.

PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

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1. LABORATORY WORKUP¶

1A. Essential/Core Labs¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
CBC with differential (CPT 85025)	STAT	STAT	ROUTINE	STAT	Polycythemia (compensatory in chronic ischemia); anemia (worsens ischemia); thrombocytosis (risk factor); baseline for surgery	Normal; polycythemia → chronic cerebral ischemia; anemia → optimize Hgb
CMP (BMP + LFTs) (CPT 80053)	STAT	STAT	ROUTINE	STAT	Electrolytes; glucose (hypo/hyperglycemia worsen ischemic injury); renal function (contrast planning); hepatic function	Normal; glucose 80-180 (avoid hypoglycemia); optimize metabolic parameters
Coagulation studies (PT/INR, PTT) (CPT 85610, 85730)	STAT	STAT	ROUTINE	STAT	Baseline coagulation; pre-surgical evaluation; hemorrhagic presentation; anticoagulation status	Normal; prolonged → evaluate cause before antiplatelet/surgical therapy
Lipid panel (CPT 80061)	-	ROUTINE	ROUTINE	-	Cardiovascular risk factor assessment; moyamoya syndrome workup (atherosclerotic component)	LDL <70 (high vascular risk); optimize lipids
HbA1c (CPT 83036)	-	ROUTINE	ROUTINE	-	Diabetes assessment; glycemic control affects stroke risk and outcomes	<7%; elevated → optimize diabetes management
ESR (CPT 85651) / CRP (CPT 86140)	STAT	STAT	ROUTINE	STAT	Inflammatory markers; exclude vasculitis as cause of moyamoya syndrome; autoimmune conditions	Normal; elevated → consider vasculitis, autoimmune, or infectious etiology
TSH (CPT 84443)	-	ROUTINE	ROUTINE	-	Thyroid disease associated with moyamoya syndrome (especially Graves disease); autoimmune thyroiditis	Normal; hyperthyroidism → Graves/moyamoya association
Blood glucose (CPT 82947)	STAT	STAT	ROUTINE	STAT	CRITICAL: Hypoglycemia worsens ischemic injury in moyamoya; hyperglycemia increases infarct volume	80-180 mg/dL; AVOID hypoglycemia (<70); treat hyperglycemia >180
Type and screen (CPT 86900/86901)	-	STAT	-	STAT	Preparation for potential surgical intervention; hemorrhagic presentation	Available for cross-match
Pregnancy test (β-hCG) (CPT 84703)	STAT	STAT	ROUTINE	STAT	Pregnancy increases stroke risk in moyamoya; alters surgical and medical management	Document; positive → high-risk OB involvement

1B. Extended Workup (Second-line)¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Sickle cell screen (hemoglobin electrophoresis) (CPT 83020)	-	ROUTINE	ROUTINE	-	Sickle cell disease is most common cause of moyamoya syndrome in African Americans; may present as stroke	Normal hemoglobin pattern; HbSS or HbSC → sickle cell-related moyamoya syndrome
ANA (CPT 86235)	-	ROUTINE	ROUTINE	-	SLE-associated moyamoya syndrome; autoimmune vasculopathy screening	Negative; positive → further autoimmune workup
Anti-dsDNA (CPT 86225)	-	ROUTINE	EXT	-	SLE confirmation if ANA positive	Negative; positive → lupus workup
Thyroid antibodies (anti-TPO, anti-thyroglobulin) (CPT 86376, 86800)	-	ROUTINE	ROUTINE	-	Autoimmune thyroid disease (Graves, Hashimoto) associated with moyamoya	Negative; positive → autoimmune thyroid-associated moyamoya syndrome
Homocysteine (CPT 83090)	-	ROUTINE	ROUTINE	-	Hyperhomocysteinemia as vascular risk factor; associated with moyamoya in some studies	<15 μmol/L; elevated → folate/B12/B6 supplementation
Antiphospholipid antibody panel (CPT 86235, 86147)	-	ROUTINE	ROUTINE	-	Antiphospholipid syndrome can cause progressive intracranial stenosis mimicking moyamoya	Negative; positive → anticoagulation consideration
Complement levels (C3, C4) (CPT 86160, 86161)	-	ROUTINE	EXT	-	Low complement in active SLE or other complement-mediated vasculopathy	Normal; low → active autoimmune process
Protein C, Protein S, Antithrombin III (CPT 85303, 85306, 85300)	-	-	EXT	-	Thrombophilia workup in young patient with moyamoya and stroke	Normal; deficiency → additional stroke risk factor
Ferritin / Iron studies (CPT 82728, 83540)	-	ROUTINE	ROUTINE	-	Iron deficiency anemia can trigger TIA/stroke in moyamoya; maintain adequate iron stores	Ferritin >50; iron deficiency → supplement before surgery

1C. Rare/Specialized (Refractory or Atypical)¶

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
RNF213 gene testing (CPT 81479)	-	-	EXT	-	Founder mutation for moyamoya in East Asian populations; p.R4810K variant; confirmed susceptibility gene; may guide family screening	Wild-type; p.R4810K variant → confirmed genetic susceptibility; family screening indicated
ACTA2 gene testing	-	-	EXT	-	Smooth muscle actin mutations cause moyamoya syndrome with systemic vascular disease (aortic aneurysm, coronary disease)	Normal; mutation → screen for systemic vascular involvement
BRCC3/MTCP1 gene testing	-	-	EXT	-	X-linked moyamoya with short stature	Normal; mutation → specific syndrome
Neurofibromatosis type 1 screening (clinical + genetic)	-	-	EXT	-	NF1 is associated with moyamoya syndrome; café-au-lait spots, neurofibromas, optic glioma	No features; features present → NF1-associated moyamoya syndrome
Down syndrome assessment (karyotype if not known)	-	-	EXT	-	Trisomy 21 associated with moyamoya syndrome; higher prevalence than general population	Normal karyotype; trisomy 21 → known association
CSF analysis	-	EXT	-	EXT	If CNS vasculitis or infection in differential; atypical presentation	Normal; abnormal → alternate diagnosis

2. DIAGNOSTIC IMAGING & STUDIES¶

2A. Essential/First-line¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
CT head without contrast (CPT 70450)	STAT	STAT	-	STAT	Acute presentation: ischemic stroke vs hemorrhage; SAH screening; baseline	Ischemic infarct (hypodensity); hemorrhage (hyperdensity); SAH	None
CTA head and neck (CPT 70496/70498)	STAT	STAT	-	STAT	Rapid vascular assessment; bilateral ICA terminal/proximal MCA/ACA stenosis or occlusion; collateral network	Classic: Bilateral terminal ICA stenosis/occlusion with "puff of smoke" basal collaterals; evaluate Circle of Willis; external carotid collaterals	Contrast allergy; renal insufficiency (hydrate)
MRI brain with and without contrast (CPT 70553)	-	URGENT	ROUTINE	-	Infarct characterization; ivy sign (leptomeningeal enhancement from slow flow); chronic changes; hemorrhage (GRE/SWI)	Infarcts (often watershed distribution); "ivy sign" on post-contrast FLAIR (leptomeningeal collateral enhancement); SWI: microbleeds (hemorrhagic risk); flow voids in basal ganglia (moyamoya vessels)	MRI-incompatible implants
MRA head (time-of-flight) (CPT 70544)	-	URGENT	ROUTINE	-	Non-invasive vascular assessment; bilateral ICA stenosis; MCA/ACA flow reduction; collateral visualization	Bilateral terminal ICA stenosis/occlusion; diminished MCA/ACA flow; prominent moyamoya collaterals	Same as MRI
MRA neck (CPT 70547)	-	URGENT	ROUTINE	-	Cervical ICA assessment; extracranial disease; distinguish from atherosclerotic stenosis	Normal cervical ICAs (disease starts intracranially in true moyamoya); extracranial stenosis → atherosclerotic etiology	Same as MRI

2B. Extended¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
Conventional cerebral angiography (DSA) (CPT 36224)	-	ROUTINE	ROUTINE	-	GOLD STANDARD for diagnosis and Suzuki staging; defines vascular anatomy for surgical planning; evaluates collateral pathways; may reveal aneurysms on collaterals	Suzuki staging (I-VI); bilateral ICA terminal stenosis/occlusion; moyamoya collateral network; aneurysms on collaterals or posterior circulation; EC-IC collateral assessment	Invasive (stroke risk 0.5-1% in moyamoya — INCREASED risk due to fragile collaterals); contrast allergy; renal insufficiency
CT perfusion (CPT 70496)	STAT	STAT	-	STAT	Acute hemodynamic assessment; identify penumbra; assess cerebrovascular reserve; helpful for surgical planning	Prolonged MTT/TTP; decreased CBF with maintained CBV (misery perfusion); stage I-II hemodynamic failure	Contrast; radiation
MR perfusion (ASL or DSC) (CPT 70553)	-	URGENT	ROUTINE	-	Non-invasive perfusion assessment; cerebrovascular reserve; serial monitoring without contrast (ASL); pre/post-surgical comparison	Decreased perfusion in ICA territory; asymmetric CBF; improved perfusion post-surgery	Same as MRI
Acetazolamide SPECT challenge (CPT 78607)	-	-	ROUTINE	-	Cerebrovascular reserve testing; assesses autoregulatory capacity; identifies "steal" phenomenon; helps determine surgical candidacy	Normal: >10% increase in CBF with acetazolamide; abnormal: failed augmentation or paradoxical decrease (steal) → surgery indicated	Sulfonamide allergy; severe hepatic disease; prior acetazolamide reaction
Transcranial Doppler (TCD) (CPT 93886)	-	URGENT	ROUTINE	-	Non-invasive monitoring of MCA velocities; detect vasospasm; serial follow-up; screen for moyamoya in sickle cell	Elevated MCA velocities (stenosis); absent flow (occlusion); postoperative bypass patency monitoring	Inadequate temporal windows
EEG (routine) (CPT 95816)	-	URGENT	ROUTINE	-	"Re-buildup" phenomenon (slow recovery of background activity after hyperventilation is pathognomonic); seizure evaluation; baseline for surgery	"Re-buildup" pattern: slow waves persist >5 min after hyperventilation stops (reflects impaired cerebrovascular reserve); epileptiform activity if seizures	None; avoid prolonged hyperventilation during EEG in moyamoya (can trigger ischemia)

2C. Rare/Advanced¶

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
Xenon CT (CPT 70450)	-	-	EXT	-	Quantitative CBF measurement with acetazolamide challenge; research and specialized centers	Quantitative CBF maps; reserve assessment	Limited availability; xenon inhalation
15O-PET (oxygen extraction fraction) (CPT 78816)	-	-	EXT	-	Gold standard for cerebral hemodynamic assessment; OEF elevation indicates misery perfusion (stage II failure); strongest predictor of stroke risk	Elevated OEF → stage II hemodynamic failure → surgical revascularization most beneficial	Limited availability; cyclotron required
BOLD-fMRI with CO2 challenge	-	-	EXT	-	Non-invasive cerebrovascular reactivity mapping; emerging technique; CO2-BOLD CVR correlates with stroke risk	Impaired CVR in ICA territories; asymmetry; guides surgical planning	Same as MRI; patient cooperation

3. TREATMENT¶

3A. Acute/Emergent¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Normal saline (0.9% NaCl)	IV	CRITICAL: Maintain euvolemia; dehydration is major trigger for ischemic events in moyamoya; aggressive hydration during acute presentation	125-250 mL/h :: IV :: :: 125-250 mL/h isotonic crystalloid; maintain euvolemia; target urine output >0.5 mL/kg/h; AVOID hypovolemia (reduces perfusion through collaterals)	Heart failure (reduce rate); pulmonary edema	Fluid balance; urine output; BMP q12h; avoid overhydration	STAT	STAT	-	STAT
Aspirin	PO	Antiplatelet therapy for ischemic moyamoya; reduces thrombus formation in stenotic vessels and fragile collaterals	81 mg daily; 325 mg daily :: PO :: :: 81-325 mg PO daily; 81 mg preferred for long-term; 325 mg may be used acutely; continue indefinitely unless hemorrhagic presentation	Active hemorrhage; hemorrhagic moyamoya presentation; allergy; severe bleeding risk	Signs of bleeding; platelet function if concerns	STAT	STAT	ROUTINE	STAT
Blood pressure management — AVOID HYPOTENSION	IV/PO	CRITICAL: Permissive hypertension in acute ischemic moyamoya; collateral-dependent flow is pressure-sensitive; hypotension → watershed infarction	Target BP varies :: IV/PO :: :: Acute ischemic: allow SBP up to 180-200 (unless hemorrhage or post-tPA); AVOID aggressive BP lowering; chronic: target ~10-20% above patient's baseline; NO specific BP target — individualize	Avoid antihypertensives acutely unless SBP >220 or hemorrhagic; DO NOT use IV nitroglycerin or nitroprusside (steal phenomenon)	Continuous BP monitoring; neuro checks q1h; avoid BP fluctuations	STAT	STAT	ROUTINE	STAT
Nicardipine (if BP too high with hemorrhage)	IV	BP reduction ONLY if hemorrhagic presentation with SBP >180; or hypertensive emergency with end-organ damage	5 mg/h titrated :: IV :: :: Start 5 mg/h; increase by 2.5 mg/h q5-15min; target SBP 140-160 for hemorrhagic moyamoya; AVOID dropping below 140	Severe aortic stenosis	Arterial line preferred; avoid over-lowering; neuro checks q1h	STAT	STAT	-	STAT

3B. Symptomatic Treatments¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Acetaminophen	PO, IV	Headache (common in moyamoya due to collateral dilation); safe first-line analgesic; avoid NSAIDs (bleeding risk)	650-1000 mg q6h :: PO :: :: 650-1000 mg PO/IV q6h PRN; max 3000 mg/day; AVOID NSAIDs and aspirin combinations (GI bleed)	Severe hepatic impairment	LFTs if chronic use	STAT	STAT	ROUTINE	STAT
Levetiracetam	PO, IV	Seizure treatment/prophylaxis; seizures occur in 20-30% of moyamoya patients; broad-spectrum; no hepatic metabolism	500 mg BID; 750 mg BID; 1000 mg BID :: PO :: :: Start 500 mg BID; increase by 500 mg/day q1-2wk; max 3000 mg/day; IV loading 1000 mg over 15 min if needed	Hypersensitivity; renal dosing	Psychiatric effects; renal function	STAT	STAT	ROUTINE	STAT
Verapamil	PO	Headache prevention in moyamoya (calcium channel blocker may improve collateral flow); migraine-like headache is common	80 mg TID; 120 mg TID :: PO :: :: Start 80 mg TID; increase by 80 mg q1wk; target 120 mg TID; max 480 mg/day; extended-release preferred	Second/third-degree AV block; severe LV dysfunction; concurrent beta-blocker	HR; BP; ECG; constipation; avoid in hypotension	-	ROUTINE	ROUTINE	-
Iron supplementation (if deficient)	PO	Iron deficiency anemia correction; anemia worsens cerebral ischemia in moyamoya; optimize before surgery	325 mg ferrous sulfate daily :: PO :: :: 325 mg (65 mg elemental iron) PO daily on empty stomach; may increase to BID if tolerated; target ferritin >50	Hemochromatosis; iron overload	Ferritin, iron studies q3 months until replete	-	ROUTINE	ROUTINE	-

3C. Medical Management (Long-term)¶

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Aspirin (long-term antiplatelet)	PO	Long-term antiplatelet therapy for all moyamoya patients with ischemic presentation; reduces ischemic events; continue post-surgery	81 mg daily :: PO :: :: 81 mg PO daily indefinitely; hold 7 days before surgery then resume 24-48h post-op per neurosurgical guidance	Active hemorrhage; hemorrhagic moyamoya without ischemic history; allergy	GI bleeding; platelet function	-	ROUTINE	ROUTINE	-
Atorvastatin	PO	Vascular risk factor optimization; pleiotropic effects (endothelial function, anti-inflammatory); may benefit even with non-atherosclerotic disease	20 mg daily; 40 mg daily :: PO :: :: Start 20-40 mg daily; target LDL <70 given high vascular risk; monitor LFTs	Active liver disease; pregnancy	LFTs at baseline and 3 months; CK if myalgia; lipid panel q6 months	-	ROUTINE	ROUTINE	-
Cilostazol	PO	Antiplatelet with vasodilatory properties; may improve collateral development; studied in moyamoya as adjunct to aspirin	50 mg BID; 100 mg BID :: PO :: :: Start 50 mg BID; increase to 100 mg BID if tolerated; take 30 min before or 2h after meals	Heart failure (PDE3 inhibitor); hemorrhagic moyamoya	Headache (common, usually transient); HR; bleeding signs	-	ROUTINE	ROUTINE	-

3D. Surgical Revascularization¶

Treatment	Route	Indication	Dosing	Pre-Treatment Requirements	Contraindications	Monitoring	ED	HOSP	OPD	ICU
STA-MCA bypass (direct revascularization)	Surgical	Most effective surgical option: Direct anastomosis of superficial temporal artery to middle cerebral artery branch; immediate flow augmentation; preferred in adults	N/A — surgical procedure :: Surgical :: :: Microsurgical anastomosis; STA donor to M4 cortical MCA branch; provides immediate blood flow augmentation; most evidence in adults	Complete presurgical workup: DSA, perfusion imaging, neuropsych; optimize Hgb >10; hold aspirin per surgeon; adequate STA caliber on CTA/ultrasound	Inadequate donor (STA) or recipient vessels; active infection; severe medical comorbidities precluding craniotomy; recent large infarct (<6 weeks)	Post-op: ICU 24-48h; BP strictly controlled (avoid hypo- and hypertension); TCD daily; CT if deficit; hydration; avoid hyperventilation; aspirin resume 24-48h	-	ROUTINE	ROUTINE	STAT
EDAS (encephaloduroarteriosynangiosis — indirect)	Surgical	Indirect revascularization; STA laid on brain surface to promote neoangiogenesis over weeks-months; combined with direct bypass in adults; primary technique in pediatrics	N/A — surgical procedure :: Surgical :: :: Dissected STA branch sutured to dural edges overlying cortex; new collateral formation occurs over 3-6 months; may be combined with direct bypass (combined approach)	Same as STA-MCA bypass	Same as direct bypass; less technically demanding; longer time to full benefit	Same as direct bypass; follow-up angiography at 6-12 months to assess new collateral formation	-	ROUTINE	ROUTINE	STAT
EMS (encephalomyosynangiosis — indirect)	Surgical	Indirect revascularization using temporalis muscle; often combined with EDAS or direct bypass; additional blood supply source	N/A — surgical procedure :: Surgical :: :: Temporalis muscle dissected and laid on cortical surface; promotes collateral growth; less effective alone than EDAS or direct bypass	Same presurgical requirements	Same as EDAS	Same as EDAS; follow-up imaging	-	ROUTINE	ROUTINE	STAT
Combined direct + indirect revascularization	Surgical	Preferred approach in adults: Direct bypass (immediate flow) + indirect (EDAS/EMS for additional long-term collateral development); maximizes revascularization	N/A — combined procedure :: Surgical :: :: STA-MCA bypass + EDAS or EMS in same operative session; provides immediate + delayed revascularization; bilateral surgery staged 1-3 months apart	Complete presurgical evaluation; bilateral procedures staged (contralateral side 1-3 months later after recovery)	Same as individual procedures; hemodynamic instability	ICU post-op; staged bilateral procedures; repeat perfusion imaging between stages	-	ROUTINE	ROUTINE	STAT
Multiple burr holes (indirect)	Surgical	Alternative indirect technique when STA inadequate or in regions not covered by standard bypass; promotes neoangiogenesis through dural openings	N/A — surgical procedure :: Surgical :: :: Multiple burr holes placed over ischemic territory; dura opened at each site; promotes collateral ingrowth; less invasive; may supplement other techniques	Less effective than direct bypass; used when other options limited	Same general surgical risks	Follow-up perfusion imaging at 6-12 months	-	ROUTINE	ROUTINE	-

4. OTHER RECOMMENDATIONS¶

4A. Referrals & Consults¶

Recommendation	ED	HOSP	OPD	ICU
Cerebrovascular neurosurgery consultation with moyamoya expertise for all patients; early surgical referral improves outcomes	URGENT	URGENT	ROUTINE	URGENT
Neurology consultation for acute stroke management, medical optimization, and long-term monitoring	STAT	STAT	ROUTINE	STAT
Neuropsychological testing baseline before surgery and at 6-12 months post-surgery to assess cognitive outcomes	-	-	ROUTINE	-
Anesthesiology pre-operative consultation with emphasis on: AVOID hyperventilation (reduces PaCO2 → vasoconstriction → ischemia); maintain normotension; avoid dehydration; ketamine caution	-	ROUTINE	ROUTINE	-
Hematology referral if sickle cell disease, thrombophilia, or polycythemia contributing to moyamoya syndrome	-	ROUTINE	ROUTINE	-
Genetics counseling if bilateral moyamoya disease (familial screening recommended; RNF213 in East Asian populations; ACTA2 for systemic vascular moyamoya)	-	-	ROUTINE	-
Physical therapy for stroke rehabilitation; occupational therapy for ADL adaptation; speech therapy if aphasia	-	ROUTINE	ROUTINE	-
Ophthalmology referral for retinal vascular assessment (moyamoya can affect retinal vessels)	-	-	ROUTINE	-

4B. Patient Instructions¶

Recommendation	ED	HOSP	OPD
STAY WELL HYDRATED at all times; dehydration is the most dangerous trigger for ischemic events in moyamoya — drink at least 2-3 liters of fluid daily; increase during illness, exercise, or hot weather	ROUTINE	ROUTINE	ROUTINE
Return to ED immediately if new weakness, numbness, vision changes, speech difficulty, severe headache, or any new neurologic symptom — do not wait to see if it improves	STAT	STAT	ROUTINE
AVOID hyperventilation: Do not blow up balloons, play wind instruments, blow-dry hair on hot settings prolonged, or perform breathing exercises that involve forced deep breathing — hyperventilation causes cerebral vasoconstriction and can trigger stroke	-	ROUTINE	ROUTINE
Avoid excessive crying in children; teach older patients to avoid Valsalva maneuvers (heavy straining, breath-holding) as these can reduce cerebral perfusion	-	ROUTINE	ROUTINE
Take aspirin daily as prescribed; do not stop without consulting neurologist; carry a medication list at all times	-	ROUTINE	ROUTINE
Avoid extreme temperature exposure (hot baths, saunas, cold exposure) which can trigger hemodynamic changes and ischemic events	-	ROUTINE	ROUTINE
Inform all physicians and dentists about moyamoya diagnosis before any procedure; anesthesia requires special precautions; avoid vasoconstrictive medications (triptans, ergotamines, decongestants with pseudoephedrine)	-	ROUTINE	ROUTINE
Wear medical alert identification indicating moyamoya disease and "avoid hyperventilation"	-	ROUTINE	ROUTINE

4C. Lifestyle & Prevention¶

Recommendation	ED	HOSP	OPD
Maintain adequate hydration (2-3 L/day minimum); carry water bottle; increase fluids during illness or physical activity	-	ROUTINE	ROUTINE
Regular low-to-moderate intensity exercise encouraged for cardiovascular health; avoid competitive or extreme sports; avoid activities with significant dehydration risk	-	-	ROUTINE
Iron-rich diet or supplementation to maintain adequate hemoglobin; anemia worsens ischemic symptoms	-	-	ROUTINE
Avoid smoking and secondhand smoke (vascular damage; reduces oxygen-carrying capacity)	-	ROUTINE	ROUTINE
Blood pressure management: avoid both hypertension AND hypotension; individualized BP targets; home BP monitoring twice daily	-	ROUTINE	ROUTINE
Family screening with MRA recommended for first-degree relatives, especially in East Asian populations with bilateral disease (10-15% familial)	-	-	ROUTINE

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5. DIFFERENTIAL DIAGNOSIS¶

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Intracranial atherosclerosis	Older age; vascular risk factors (DM, HTN, smoking); unilateral preferred; no moyamoya collaterals; extracranial disease common	DSA (focal plaque vs progressive stenosis); CTA (calcification); risk factor profile; MRI (embolic pattern not watershed)
CNS vasculitis (PACNS)	Multifocal irregular narrowing of multiple vessel sizes; CSF pleocytosis/elevated protein; may respond to immunosuppression	CSF analysis (inflammatory); brain biopsy (gold standard); DSA (beading pattern); ESR/CRP; MRI (multifocal lesions)
Radiation-induced vasculopathy	History of cranial radiation (typically childhood); progressive stenosis years after treatment; unilateral more common	Radiation history; MRI (radiation changes); progressive stenosis in radiation field
Fibromuscular dysplasia (FMD)	Typically cervical/renal arteries; "string of beads" on angiography; not typically intracranial	CTA/MRA ("string of beads" in cervical ICA/renal arteries); spares intracranial vessels typically
Sickle cell vasculopathy	Known sickle cell disease; progressive ICA stenosis similar to moyamoya; moyamoya syndrome	Hemoglobin electrophoresis; sickle cell confirmed; management differs (chronic transfusion)
NF1-associated vasculopathy	Café-au-lait spots; neurofibromas; optic glioma; progressive intracranial stenosis	Clinical features of NF1; genetic testing; imaging of moyamoya pattern + NF1 features
Down syndrome vasculopathy	Trisomy 21; moyamoya pattern; may present with stroke in young patient	Karyotype; clinical features; imaging shows moyamoya pattern
Takayasu arteritis	Large vessel vasculitis; aorta and branches; may involve carotid → intracranial; systemic symptoms; elevated ESR	ESR/CRP markedly elevated; aortic arch imaging; systemic symptoms; younger women
Antiphospholipid syndrome	Recurrent thrombosis; pregnancy loss; livedo reticularis; progressive vascular occlusion can mimic moyamoya	aPL antibodies (lupus anticoagulant, anticardiolipin, anti-β2GP1); coagulation studies

6. MONITORING PARAMETERS¶

Parameter	Frequency	Target/Threshold	Action if Abnormal	ED	HOSP	OPD	ICU
Blood pressure	q1h acute; q4h stable inpatient; BID at home	Individualized; avoid hypotension; SBP 120-160 typically	Hypotension → fluid bolus, reduce antihypertensives; hypertension → cautious treatment (avoid over-lowering)	STAT	STAT	ROUTINE	STAT
Neurologic exam	q1h acute; q4h stable; each clinic visit	Stable or improving	New deficit → STAT imaging; OR evaluation if post-operative	STAT	STAT	ROUTINE	STAT
Hydration status (intake/output)	q4h inpatient; daily awareness outpatient	Euvolemia; urine output >0.5 mL/kg/h	Dehydrated → aggressive IV/PO hydration; urine output low → bolus	STAT	STAT	ROUTINE	STAT
CBC (hemoglobin)	Admission; q6-12h post-op; q3-6 months outpatient	Hgb >10 g/dL; avoid anemia	Anemia → transfuse if <7 or symptomatic; iron supplementation	STAT	STAT	ROUTINE	STAT
MRA head	Baseline; 6-12 months post-surgery; annually	Stable or improved flow; bypass patency	Progressive stenosis → repeat perfusion; surgical revision consideration	-	-	ROUTINE	-
Perfusion imaging (MR or CT perfusion)	Baseline; 6-12 months post-surgery; as indicated	Improved perfusion post-surgery; stable reserve	Worsening perfusion → re-evaluate for additional revascularization	-	-	ROUTINE	-
TCD (transcranial Doppler)	Post-op daily x 3 days; q6 months outpatient	MCA velocities stable; bypass flow adequate	Increasing velocities → progressive stenosis; absent flow → occlusion; asymmetric → surgical hemisphere assessment	-	STAT	ROUTINE	STAT
EEG (with hyperventilation)	Baseline; annually; if new symptoms	No re-buildup pattern (indicates adequate reserve)	Re-buildup present → impaired reserve → consider surgical referral	-	ROUTINE	ROUTINE	-

7. DISPOSITION CRITERIA¶

Disposition	Criteria
Admit to ICU	Acute stroke (ischemic or hemorrhagic); post-surgical revascularization (24-48h); refractory hypo/hypertension; seizures; large infarct with edema
Admit to floor (neuroscience unit)	TIA with new diagnosis; workup and surgical planning; stable post-ICU; medical optimization before surgery
Discharge home	Stable neurologic exam; adequate PO hydration demonstrated; BP at target; antiplatelet therapy started; follow-up arranged with cerebrovascular neurosurgery and neurology; patient/family educated on hydration and hyperventilation avoidance
Transfer to moyamoya center	Diagnosis confirmed but facility lacks cerebrovascular neurosurgery expertise for bypass surgery; complex bilateral disease
Outpatient follow-up	Neurology q3-6 months; neurosurgery per surgical timeline; MRA annually; perfusion imaging per protocol

8. EVIDENCE & REFERENCES¶

Recommendation	Evidence Level	Source
Guidelines for diagnosis and treatment of moyamoya disease (2012)	Professional society guideline	Research Committee on Moyamoya Disease. Neurol Med Chir 2012
STA-MCA bypass effective in reducing stroke risk in adult moyamoya	Class II evidence (prospective cohort)	Miyamoto et al. Stroke 2014 (JAM Trial)
RNF213 as susceptibility gene for moyamoya disease	Class II evidence (GWAS)	Kamada et al. J Hum Genet 2011
Suzuki staging system for moyamoya angiographic progression	Class III evidence (descriptive)	Suzuki & Takaku. Arch Neurol 1969
Direct bypass superior to indirect in adults; combined approach recommended	Class II evidence (systematic review)	Jeon et al. J Neurosurg 2018
Hemorrhagic moyamoya management: surgical revascularization reduces rebleeding	Class I evidence (RCT)	Miyamoto et al. Stroke 2014 (JAM Trial)
Hyperventilation avoidance critical in moyamoya (cerebrovascular reactivity impaired)	Expert consensus; physiologic studies	Expert consensus; cerebrovascular physiology literature
Dehydration is major stroke trigger in moyamoya; hydration maintenance essential	Class III evidence; case series	Kim. J Korean Neurosurg Soc 2016
Cerebrovascular reserve testing (acetazolamide SPECT/PET) predicts surgical benefit	Class II evidence	Kuroda et al. Neurology 2001
Family screening recommended for first-degree relatives; 10-15% familial incidence	Class III evidence; cohort studies	Baba et al. J Neurosurg 2008

CHANGE LOG¶

v1.0 (January 31, 2026) - Initial template creation - Comprehensive moyamoya disease/syndrome management covering diagnosis, medical therapy, surgical revascularization (STA-MCA bypass, EDAS, EMS, combined approaches), and long-term monitoring - Emphasis on critical management principles: hydration, avoid hyperventilation, avoid hypotension

APPENDIX A: Suzuki Angiographic Staging¶

Stage	Angiographic Findings	Clinical Significance
I	Narrowing of carotid fork (ICA bifurcation)	Early disease; may be asymptomatic; screening finding
II	Initiation of moyamoya collaterals; dilated MCA/ACA branches	Early collateral formation; TIAs may begin
III	Intensification of moyamoya collaterals; MCA and ACA further narrowed	"Puff of smoke" appearance maximal; frequent TIAs/strokes
IV	Minimization of moyamoya collaterals; PCA involvement begins	Collaterals starting to fail; ECA collaterals develop; higher ischemic risk
V	Further reduction of moyamoya; increased ECA collaterals	Major cerebral arteries occluded; reliance on ECA supply
VI	Disappearance of moyamoya; complete ICA occlusion; ECA/vertebral supply only	End-stage; entirely dependent on external collaterals; most severe

APPENDIX B: Perioperative Management Checklist for Moyamoya Surgery¶

Pre-operative: - [ ] Adequate hydration (IV fluids starting night before) - [ ] Aspirin held per neurosurgical guidance (typically 7 days) - [ ] Hemoglobin optimized (>10 g/dL) - [ ] Baseline neuropsychological testing completed - [ ] Anesthesia briefed on: NO hyperventilation, maintain normocapnia (PaCO2 35-40), maintain normotension, adequate IV fluids, avoid hypothermia

Intra-operative: - [ ] PaCO2 35-40 mmHg (NEVER hyperventilate; avoid PaCO2 <35) - [ ] MAP maintained at or above patient's baseline (avoid hypotension) - [ ] Temperature 36-37°C (normothermia) - [ ] Adequate IV hydration (replace insensible + blood loss) - [ ] Avoid vasoconstrictive agents

Post-operative: - [ ] ICU for 24-48h minimum - [ ] BP strictly monitored (avoid hypo- AND hypertension; target ±10% of baseline) - [ ] Aggressive IV hydration (150-200 mL/h) - [ ] Pain control (avoid hyperventilation from pain-induced crying) - [ ] Neuro checks q1h x 24h - [ ] CT head if any new deficit - [ ] TCD daily x 3 days (bypass patency) - [ ] Resume aspirin 24-48h post-op per surgeon - [ ] Avoid fever (increases metabolic demand) - [ ] Encourage calm environment (minimize stress/agitation)