423 lines
27 KiB
Markdown
423 lines
27 KiB
Markdown
---
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title: "Moyamoya"
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docid: "c820f6bf-ddb6-4e75-b0ca-61263ed63b21"
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authors:
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- key: "5cff4116-3654-4b3a-bb75-5ebe0b8c9850"
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value: "Anne G. Osborn, MD, FACR"
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breadcrumbs:
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-
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name: "Brain"
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slug: "brain"
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treeNodeId: "6d8829f1-14d7-45af-8675-255189aa526a"
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-
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name: "Diagnosis"
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slug: "diagnosis"
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treeNodeId: "51c00394-446e-4a38-94af-d3b1d14d34e8"
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-
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name: "Pathology-Based Diagnoses"
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slug: "pathology-based-diagnoses"
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treeNodeId: "d9d3a8ed-f21b-4831-8c77-591a3500ef77"
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-
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name: "Stroke"
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slug: "stroke"
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treeNodeId: "12307683-f1ff-4823-a7d3-b10b40f9fd82"
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name: "Nonatheromatous Vasculopathy"
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slug: "nonatheromatous-vasculopathy"
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treeNodeId: "ed2d2a03-ebd6-4a72-8608-effc92deb342"
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-
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name: "Moyamoya"
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slug: "moyamoya"
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treeNodeId: null
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category: "Brain"
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cmeTopicId: "6d619830-666a-4fbd-8e1c-9768a7d22b02"
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documentVersionId: "61b569aa-0c21-432e-9ddc-9990f9d19651"
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imageCount: 18
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lastUpdated: "10/08/20"
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pageDescription: "Moyamoya"
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pageKeywords: "Brain, Diagnosis, Pathology-Based Diagnoses, Stroke, Nonatheromatous Vasculopathy, Moyamoya"
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pageTitle: "Moyamoya | STATdx"
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enhancedTitle: "Moyamoya"
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type: "DX"
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references: true
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breadcrumbs:
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- "Brain"
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- "Diagnosis"
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- "Pathology-Based Diagnoses"
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- "Stroke"
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- "Nonatheromatous Vasculopathy"
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- "Moyamoya"
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---
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# KEY FACTS
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- ## Terminology
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- Progressive narrowing of distal ICA/proximal circle of Willis (COW) vessels with secondary collateralization
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- Collateral vessels → cloud-like "puff of smoke" (moyamoya) at angiography
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- Moyamoya disease (MMD) = primary (idiopathic) moyamoya
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- Marked East-West gradient (more common in Japan, Korea)
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- Moyamoya pattern of collaterals = secondary to many etiologies
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- ## Imaging
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- Best diagnostic clue: Attenuated COW with multiple tiny basal ganglia flow voids on MR
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- Best imaging tool
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- T1 MR C+/MRA
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- DSA for delineating vascular details
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- ## Pathology
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- MMD
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- RNF213 polymorphism in 95% of familial East Asian population, 79% of sporadic
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- Correlated with early onset, severe form of MMD
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- Secondary moyamoya (many causes)
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- Syndromic (e.g., NF1), inflammatory states, prothrombotic states, premature aging, congenital mesenchymal defects, suprasellar irradiation in childhood
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- ## Clinical Issues
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- Bimodal age peaks
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- 5-10 years and 2nd peak during 4th decade
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- Most frequent cause of stroke in Asian children
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- Presentation
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- Children: Recurrent transient ischemic attacks (TIAs); hemorrhage rare
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- Adults: TIAs, infarcts, hemorrhage (20%), migraines
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# TERMINOLOGY
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- ## Abbreviations
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- Moyamoya disease (MMD)
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- ## Synonyms
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- Idiopathic progressive arteriopathy of childhood, spontaneous occlusion of circle of Willis (COW)
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- ## Definitions
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- Progressive bilateral stenosis or occlusion of terminal internal carotid artery (ICA)/proximal COW with abnormal vascular network at base of brain
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- Compensatory development of collateral vascular network = "puff of smoke" (hazy network of basal collaterals)
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- Primary (idiopathic) moyamoya = MMD
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- More common in Japan, Korea
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- Secondary (acquired) moyamoya
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- Cranial radiation
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- Atherosclerosis
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- Neurofibromatosis (NF)
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# IMAGING
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- ## General Features
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- Best diagnostic clue: Attenuated COW with multiple tiny basal ganglia (BG) flow voids on MR
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- Location: Supraclinoid ICA/COW; anterior > > posterior circulation
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- Size: Large vessel occlusion
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- Morphology: "Puff of smoke" (moyamoya in Japanese)
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- Cloud-like lenticulostriate and thalamostriate collaterals on angiography
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- ## CT Findings
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- ### NECT
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- Children: 50-60% show anterior > posterior atrophy
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- Can present with stroke (children) or intracranial (IC) hemorrhage (more common in adults)
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- CECT
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- Enhancing dots (enlarged lenticulostriate arteries) in BG
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- Abnormal net-like vessels at base of brain
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- CTA: Abnormal COW and net-like collaterals
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- CT perfusion
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- Depicts penumbra, infarct core in ischemic MMD
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- Can quantify effect of revascularization therapies
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- ## MR Findings
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- T1WI: Multiple dot-like flow voids in BG
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- T2WI
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- ↑ signal in small vessel cortical and white matter infarcts
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- Collateral vessels = net-like filling defects in basal cisterns
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- FLAIR
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- Bright sulci = leptomeningeal ivy sign
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- Slow-flowing engorged pial vessels, thickened arachnoid membranes
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- Correlates with ↓ cerebral vascular reserve
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- T2* GRE
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- Hemosiderin if prior hemorrhage
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- Asymptomatic microbleeds occasionally seen in adults
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- DWI: Very useful for "acute on chronic" disease
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- T1WI C+
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- Lenticulostriate collaterals → enhancing "dots" in BG and net-like thin vessels in cisterns
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- Leptomeningeal enhancement (contrast-enhanced ivy sign) ↓ after effective bypass surgery
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- MRA: Narrowed distal ICA and proximal COW vessels, ± synangiosis
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- MRV: Some vasculopathies may also involve veins
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- MRS: Lactate in acutely infarcted tissue
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- NAA:Cr and Cho:Cr ratios frontal white matter improve/↑ after revascularization
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- pMR: ↓ perfusion in deep hemispheric white matter, relative ↑ perfusion in posterior circulation
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- Can also be helpful in evaluation of MMD following revascularization
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- ## Ultrasonographic Findings
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- Grayscale: Reduction of ICA lumen size
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- Pulsed Doppler
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- Doppler spectral waveforms in ICA show no flow (occluded) or high resistance (stenotic) flow pattern
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- ↑ end-diastolic flow velocity, ↓ vascular resistance in external carotid artery (ECA) collaterals
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- Color Doppler: Aliasing suggests stenoses
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- Power Doppler: Contrast injection improves visualization of slow-flow stenotic vessels and collaterals
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- ## Angiographic Findings
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- Conventional
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- Predominantly (not exclusively) anterior circulation
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- Narrow proximal COW and ICA (earliest)
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- Lenticulostriate and thalamoperforator collaterals (intermediate)
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- Transdural and transosseous extracranial (EC)-IC collaterals (late)
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- Dilatation of anterior choroidal artery + branches predicts adult hemorrhagic events
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- ## Nuclear Medicine Findings
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- PET: ↓ hemodynamic reserve capacity
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- SPECT I-123-iomazenil: Neuronal density preserved if asymptomatic, ↓ if symptomatic
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- ## Imaging Recommendations
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- Best imaging tool: T1 C+ MR/MRA
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- DSA for mapping collaterals, grading
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- Protocol advice
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- Contrast improves detection: Synangiosis, collaterals
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- Catheter angiography defines anatomy of occlusions prior to bypass
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- Diagnostic criteria: MR/MRA or catheter angiography
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- Stenosis/occlusion of terminal ICA or proximal anterior cerebral artery (ACA) and middle cerebral artery (MCA)
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- Abnormal vascular network/flow voids in BG
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- Bilateral
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- Unilateral findings in MCA = rete MCA anomaly
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# DIFFERENTIAL DIAGNOSIS
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- ## Ivy Sign
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- Leptomeningeal metastases, subarachnoid hemorrhage, meningitis, ↑ inspired oxygen
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- ## Punctate Foci in Basal Ganglia
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- Cribriform lacunar state: No enhancement
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- ## Severely Attenuated Circle of Willis
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- Subarachnoid hemorrhage, meningitis, tumor encasement
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- ## Rete Middle Cerebral Artery Anomaly
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- Unilateral, not bilateral
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- Weblike rete anomaly of MCA
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- Twig-like horizontal MCA + branches
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- May occur with aneurysm (50%)
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- Occurs predominantly in Asians
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# PATHOLOGY
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- ## General Features
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- ### Etiology
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- MMD
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- Ring finger protein 213 polymorphism in 95% of familial East Asian population, 79% of sporadic
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- Correlated with early-onset, severe form of MMD
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- Also recently reported in non-MMD disorders
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- RNF213 vasculopathy spectrum (IC atherosclerosis, peripheral pulmonary artery stenosis, and rental artery stenosis)
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- Secondary moyamoya
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- Down syndrome, tuberous sclerosis, sickle cell disease, connective tissue disease, progeria, NF1
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- NF1 with suprasellar tumor and radiation is disastrous
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- Morning glory syndrome; syndromes with aneurysms, cardiac and ocular defects
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- Inflammatory: CNS angiitis (of childhood), basal meningitis, atherosclerosis, head and neck infections
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- Vasculopathies and prothrombotic states: XRT, Kawasaki, anticardiolipin antibody, factor V Leiden, polyarteritis nodosa, Behçet, SLE
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- Epidemiology: MMD
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- Incidence in Japan: 1:100,000
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- Incidence in North America, Europe: 0.1:100,000
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- 10-15% familial
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- ## Staging, Grading, & Classification
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- Staging criteria (after Suzuki)
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- Stage 1: Narrowing of ICA bifurcation
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- Stage 2: ACA, MCA, posterior cerebral artery (PCA) dilated
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- Stage 3: Maximal basal collaterals; small ACA/MCA
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- Stage 4: Fewer collaterals (vessels); small PCA
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- Stage 5: Further ↓ collaterals; absent ACA/MCA/PCA
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- Stage 6: Extensive ECA-pial collaterals
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- ## Gross Pathologic & Surgical Features
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- ↑ perforating (early) and ECA-ICA (late) collaterals in atrophic brain
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- Hemorrhage (subarachnoid, intraventricular > parenchymal) adults
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- ↑ saccular aneurysms (especially basilar in adults)
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- ## Microscopic Features
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- Intimal hyperplasia, medial layer thinness
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- Excessive infolding, "waving" of internal elastic lamina
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- Progressive narrowing, eventual obliteration of vessel lumen
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- Periventricular pseudoaneurysms (cause of hemorrhage)
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# CLINICAL ISSUES
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- ## Presentation
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- ### Most common signs/symptoms
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- Children: Transient ischemic attacks (TIAs), alternating hemiplegia (exacerbated by crying), headache
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- Adults: TIAs, cerebral infarct, or hemorrhage
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- Hemorrhagic presentation more common in Asian adults
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- ### Other signs/symptoms
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- Children: Developmental delay, poor feeding, chorea
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- ### Clinical profile
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- Children more likely to have TIAs and to progress; adults more likely to infarct (but slower progression)
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- Children more likely to have ipsilateral anterior plus posterior circulation involvement
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- ## Demographics
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- ### Age
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- Bimodal age peaks (5-10 years and 2nd peak during 4th decade)
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- Japan, Korea: 6 years > 35 years
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- North America, Europe: 35 years > 6 years
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- ### Sex
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- M:F = 1:1.8; in familial cases, M:F = 1:5
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- Most frequent cause of stroke in Asian children
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- ## Natural History & Prognosis
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- Progressive narrowing, collateralization, and ischemia
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- Prognosis depends on etiology, ability to form collaterals, age/stage at diagnosis
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- Pediatric cases usually advance to stage 5 within 10 years of onset
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- Infantile moyamoya progresses faster
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- Pediatric cases present with stroke
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- Hemorrhagic moyamoya more common in older patients with large collateral vessels
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- Has poorer outcome
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- ## Treatment
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- MMD
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- Indirect bypass: Encephaloduroarteriomyosynangiosis (EDAMS) more effective in children
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- 5-year risk of ipsilateral stroke post encephaloduroarteriosynangiosis (EDAS) = 15%
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- Direct bypass: Superficial temporal artery-MCA (STA-MCA) more common in adults
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- Combined EDAMS, STA-MCA
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- Anticoagulation; correct/control prothrombotic states and inflammatory etiologies
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- Hypertransfusion for sickle cell-related moyamoya
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- Perivascular sympathectomy or superior cervical ganglionectomy (adults)
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# DIAGNOSTIC CHECKLIST
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- ## Consider
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- Seek secondary causes of moyamoya
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- ## Image Interpretation Pearls
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- Enhanced asymmetric atrophy found on childhood CT, look for abnormal vascular pattern
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- Adult moyamoya can present with IC hemorrhage
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- ## Reporting Tips
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- Successful revascularization = ↓ basal collaterals, ↑ flow in MCA branches, ↑ caliber of STA (direct bypass)
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16877c2f-bb02-4c68-afaf-2bfadf0fb33f
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## References
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# Selected References
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1. [Han Q et al: Quantitative analysis of revascularization in ischemic moyamoya disease via whole-brain computed tomography perfusion: a retrospective single-center study. Medicine (Baltimore). 99(7):e19168, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32049846%5Bpmid%5D)
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1. [Ravindra VM et al: Preoperative computed tomography perfusion in pediatric moyamoya disease: a single-institution experience. J Neurosurg Pediatr. ePub, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=31978885%5Bpmid%5D)
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1. [Terrell D et al: Cerebral revascularization for moyamoya syndrome associated with sickle cell disease: a systematic review of the literature on the role of extracranial-intracranial bypass in treating neurologic manifestations of pediatric patients with sickle cell disease. World Neurosurg. 137:62-70, 2020](http://www.ncbi.nlm.nih.gov/pubmed/?term=32014541%5Bpmid%5D)
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1. [Bang OY et al: Moyamoya disease and spectrums of RNF213 vasculopathy. Transl Stroke Res. 11(4):580-9, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31650369%5Bpmid%5D)
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1. [Boulouis G et al: Nontraumatic pediatric intracerebral hemorrhage. Stroke. 50(12):3654-61, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31637968%5Bpmid%5D)
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1. [Goyal P et al: Neuroimaging of pediatric arteriopathies. J Neuroimaging. 29(3):287-308, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30920080%5Bpmid%5D)
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1. [Li J et al: Imaging of moyamoya disease and moyamoya syndrome: current status. J Comput Assist Tomogr. 43(2):257-63, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30589721%5Bpmid%5D)
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1. [Liu ZW et al: Collateral circulation in moyamoya disease: a new grading system. Stroke. 50(10):2708-15, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31409266%5Bpmid%5D)
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1. [Ravindran K et al: Surgical outcomes for pediatric moyamoya: a systematic review and meta-analysis. J Neurosurg Pediatr. 1-10, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31518973%5Bpmid%5D)
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1. [Soun JE et al: Central nervous system vasculopathies. Radiol Clin North Am. 57(6):1117-31, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=31582039%5Bpmid%5D)
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1. [Acker G et al: Surgical management of moyamoya disease. Stroke. 49(2):476-82, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29343587%5Bpmid%5D)
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1. [Cho KC et al: Rete middle cerebral artery anomalies: a unifying name, case series, and literature review. J Neurosurg. 131(2):453-61, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=30074465%5Bpmid%5D)
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1. [Huang S et al: Etiology and pathogenesis of moyamoya disease: an update on disease prevalence. Int J Stroke. 12(3):246-53, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28381201%5Bpmid%5D)
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1. [Fujimura M et al: Moyamoya disease. Front Neurol Neurosci. 40:204-20, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=27960175%5Bpmid%5D)
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## Images
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### Selected Images
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*Coronal graphic shows severe tapering of both distal internal carotid arteries (ICAs) <img src='img/arrows/WS.png'/> and strikingly enlarged lenticulostriate arteries <img src='img/arrows/WO.png'/> coursing through basal ganglia. This is the puff of smoke (moyamoya) pattern.*
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*Coronal graphic shows severe tapering of both distal internal carotid arteries (ICAs) <img src='img/arrows/WS.png'/> and strikingly enlarged lenticulostriate arteries <img src='img/arrows/WO.png'/> coursing through basal ganglia. This is the puff of smoke (moyamoya) pattern.*
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*Axial T2WI MR shows curvilinear net-like filling defects <img src='img/arrows/BO.png'/> within the ambient (circummesencephalic) cistern corresponding to collateral moyamoya vessels. Note the asymmetric atrophy.*
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*Lateral internal carotid artery DSA in a 3-year-old child with moyamoya disease (MMD) shows near-total supraclinoid ICA stenosis <img src='img/arrows/BC.png'/>. Note innumerable tortuous enlarged collaterals <img src='img/arrows/BO.png'/> forming the puff of smoke appearance typical of MMD.*
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*Lateral DSA in the same patient shows the collaterals (moyamoya vessels) <img src='img/arrows/BO.png'/> are supplied primarily by thalamoperforating and medial choroidal branches.*
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*Axial T2WI MR in adult moyamoya shows attenuated, almost thread-like supraclinoid ICAs and middle cerebral arteries (MCAs) <img src='img/arrows/WS.png'/> with numerous tiny collateral vessels in the suprasellar cistern <img src='img/arrows/WC.png'/> and around the midbrain <img src='img/arrows/WO.png'/>. There is marked cortical atrophy along with enlarged temporal horns.*
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*Axial T1 C+ FS MR in the same patient shows contrast in innumerable small arterial collateral vessels in the basal ganglia and deep white matter <img src='img/arrows/WO.png'/>, creating a puff of smoke appearance. (Courtesy H. Els, MD.)*
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*Axial T2WI MR in a 23-year-old man with left hemisphere transient ischemic attacks (TIAs) shows the flow void of a normal right M1 MCA <img src='img/arrows/WS.png'/>. The left MCA appears very hypoplastic and twig-like <img src='img/arrows/WO.png'/>. There is an unusual web-like tangle of vessels seen within the sylvian fissure <img src='img/arrows/WC.png'/>.*
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*Submentovertex MR angiogram in the same patient shows a normal right MCA <img src='img/arrows/WS.png'/>. The left MCA is thread-like <img src='img/arrows/WO.png'/>, and its distal M3 and M4 branches <img src='img/arrows/WC.png'/> are attenuated compared to the normal right side.*
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*Oblique view of the left internal carotid MR angiogram shows a normal anterior cerebral artery (ACA) <img src='img/arrows/WC.png'/>, but the left MCA is severely attenuated <img src='img/arrows/WS.png'/> with reduced distal branches. A web of numerous small, tangled vessels <img src='img/arrows/WO.png'/> surrounds its M1 segment.*
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*Oblique view of the left internal carotid DSA in the same patient shows the tangled web of vessels <img src='img/arrows/BO.png'/> that surrounds the attenuated M1 MCA segment. This is thought to represent a rete MCA anomaly rather than segmental moyamoya.*
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### Additional Images
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*Axial FLAIR MR shows the ivy sign due to engorged vessels <img src='img/arrows/WS.png'/> within sulci in another patient with moyamoya. The sulcal signal is so striking that this FLAIR scan resembles a T2WI.*
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*Lateral view, selective internal carotid angiogram, shows severe stenosis of the supraclinoid ICA <img src='img/arrows/BS.png'/> with a puff of smoke appearance <img src='img/arrows/BO.png'/> from collateral lenticulostriate vessels.*
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*Lateral angiography, right ICA injection in the same patient, shows narrowing of the distal ICA and occlusion of the ACA and MCA with the puff of smoke appearance <img src='img/arrows/BC.png'/> of enlarged lenticulostriate collaterals. Note the additional network of collaterals more posteriorly <img src='img/arrows/BO.png'/>, likely thalamoperforators and posterior choroidal branches.*
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*Lateral DSA of the vertebrobasilar circulation in the same patient shows a striking puff of smoke appearance caused by innumerable dilated collateral branches <img src='img/arrows/BO.png'/> arising from the thalamostriate arteries.*
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*Axial MRA shows occlusion of both distal ICAs <img src='img/arrows/BS.png'/>, nonvisualization of MCAs and ACAs, and stenosis of posterior cerebral arteries (PCAs) <img src='img/arrows/BO.png'/> in an 8 year old with hemiparetic migraines in this case of idiopathic arteriopathy of childhood.*
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*Axial MRA in another patient with idiopathic progressive arteriopathy of childhood shows occluded supraclinoid ICAs <img src='img/arrows/WS.png'/>. Note the bilateral synangiosis <img src='img/arrows/BO.png'/>.*
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*Axial T1WI MR shows right frontal and left temporaoccipital atrophy <img src='img/arrows/WO.png'/> from remote ischemia. There are multiple small basal ganglia flow voids <img src='img/arrows/WS.png'/> from lenticulostriate collaterals.*
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*Axial T1WI C+ MR in the same patient shows multifocal white "dots" <img src='img/arrows/WS.png'/> due to slow flow in multiple, enlarged lenticulostriate collaterals with intravascular enhancement.*
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