II. Definitions

  1. Moyamoya
    1. Noninflammatory progressive Occlusion of the intracranial carotid arteries, triggering CVA findings, typically in children
    2. Results from arterial wall thickening, endothelial hyperplasia and fibrosis either with associated conditions (MMS) or genetic/idiopathic (MMD)
    3. Carotid Stenosis with secondary formation of collateral arteries from the Circle of Willis in a netlike configuration
    4. Netlike appearance on angiogram is described as a "Puff of Smoke", or in Japanase Moyamoya
  2. Moyamoya Disease (MMD)
    1. Idiopathic (and with possible defined gene defect), Moyamoya Disease (MMD) is without the associated conditions typical for MMS
  3. Moyamoya Syndrome (MMS)
    1. Associated with other conditions (e.g. Trisomy 21, Neurofibromatosis, Sickle Cell Anemia)

III. Epidemiology

  1. Primarily onset in children, presenting with Ischemic CVA or TIA in 80% of cases
    1. Less commonly may have onset in adulthood, often with hemorrhagic presentations

IV. Mechanism

  1. Noninflammatory progressive Occlusion of the intracranial carotid arteries, triggering CVA findings, typically in children
    1. Results from arterial wall thickening, endothelial hyperplasia and fibrosis either with associated conditions (MMS) or genetic/idiopathic (MMD)
    2. Internal Carotid Artery Stenosis progresses to affect the anterior cerebral arteries and middle cerebral arteries
  2. Secondary formation of collateral arteries from the Circle of Willis in a netlike configuration (appears as "Puff of Smoke", or in Japanase Moyamoya)
    1. Collateral vessels expand at the lenticulostriate, leptomeningial, thalamoperforating and dural arteries over the course of years into adulthood
    2. Collateral vessels are fragile and more prone to rupture

V. Associated Conditions: Moyamoya Syndrome (MMS)

VI. Imaging

  1. CT Head and CTA Head and Neck
    1. Often the initial imaging study in acute Cerebrovascular Accident in the first 24 hours
  2. MRI Brain and MRA Head and Neck
    1. Preferred in Moyamoya, especially in children if no delay
  3. Digital Subtraction Angiography
    1. Gold standard, and used during intervention
    2. Significant radiation exposure and largerly replaced by CTA and MRA for diagnostic purposes

VII. Presentations

  1. Cerebrovascular Accident (CVA)
    1. Transient Ischemic Attacks and CVAs represent 80% of Moyamoya presentations in children
    2. Events often provoked by hypocapnea induced vasonconstriction (e.g. straining, Hyperventilation)
  2. Cerebral Aneurysm formation and Hemorrhagic CVA or Intracranial Hemorrhage
    1. Typical presentation in adults with Moyamoya, due to rupture of fragile collateral vessels
    2. Rupture is most common in the Basal Ganglia and Hypothalamus, but other aneurysmal rupture sites occur

VIII. Staging

  1. Stage 1: Carotid fork narrowed
  2. Stage 2: Moyamoya initiation
    1. Large and obscure carotid fork
    2. Enlarged main arterial vessels without collaterals
  3. Stage 3: Moyamoya intensify
    1. Main intracerebellar artery changes, with some arterial replacement with Moyamoya
  4. Stage 4: Moyamoya minimization
    1. Internal Carotid ArteryOcclusion up to the Posterior Communicating Artery junction
    2. Rough, poor Moyamoya network
  5. Stage 5: Moyamoya reduced
    1. Disappearance of Internal Carotid Artery branches, and minimization of other vessels
    2. Increased collateral flow
  6. Stage 6: Moyamoya disappear
    1. Disappearance of main Moyamoya-involved vessels at brain base
    2. Vertebral arteries and external carotid arteries maintain flow, but other major vessels have all been replaced by collaterals

IX. Management

  1. No medical management reverses or prevents Moyamoya progression
    1. However, revascularization improves cerebral perfusion and reduces complication risk
    2. Refer all Moyamoya patients to neurosurgery
    3. Direct and indirect bypass methods are used depending on patient's age and staging
  2. Ischemic CVA or TIA is typically treated with Antiplatelet Therapy (Aspirin, Clopidogrel)
    1. However, increases risk of Hemorrhagic CVA complications
  3. Intracranial Hemorrhage
    1. Neurosurgical management
    2. Obstructive Hydrocephalus may require ventricular drain

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Ontology: Moyamoya Disease (C0026654)

Definition (NCI) A rare inherited vascular disorder characterized by constriction of arteries at the base of the brain, resulting in the formation of collateral circulation in order to compensate for the constriction. The name "moyamoya" in Japanese means "puff of smoke" and derives from the characteristic radiographic appearance of the collateral vessels.
Definition (MSH) A noninflammatory, progressive occlusion of the intracranial CAROTID ARTERIES and the formation of netlike collateral arteries arising from the CIRCLE OF WILLIS. Cerebral angiogram shows the puff-of-smoke (moyamoya) collaterals at the base of the brain. It is characterized by endothelial HYPERPLASIA and FIBROSIS with thickening of arterial walls. This disease primarily affects children but can also occur in adults.
Concepts Disease or Syndrome (T047)
MSH D009072
ICD9 437.5
ICD10 I67.5
SnomedCT 69116000, 89142007
Swedish Moyamoyasjukdom
English Moyamoya Disease, CEREBROVASCULAR MOYAMOYA DIS, MOYA MOYA DIS, MOYAMOYA DIS, Spontaneous occlusion of the circle of Willis, Moyamoya disease (diagnosis), Disease, Moya-Moya, Moya Moya Disease, Moya-Moya Disease, Progressive Intracranial Occlusive Arteropathy (Moyamoya), Cerebrovascular Moyamoya Disease, Moyamoya Syndrome, Moyamoya Disease [Disease/Finding], moya-moya disease, moyamoya, moyamoya disease, disease moya moya, moyamoya syndrome, disease moyamoya, moya disease, moya moya disease, Moyamoya, Moyamoya syndrome, Moyamoya disease, Progressive intracranial arterial occlusion, Moyamoya disease (disorder), Progressive intracranial arterial occlusion (disorder), disease (or disorder); moyamoya, moyamoya; disease
Japanese モヤモヤビョウ, ウィリスドウミャクリンヘイソクショウ, Moyamoya病, もやもや病, ウィリス動脈輪閉塞症, ウィリス大脳動脈輪閉塞症, モヤモヤ病, 脳底部異常血管網症, 西本病, Willis動脈輪閉塞症, ウイリス動脈輪閉塞症, ウイリス大脳動脈輪閉塞症
Czech moyamoya nemoc, Spontánní okluze Willisova kroužku, Moyamoya nemoc, onemocnění moya-moya, moya-moya nemoc
Spanish Oclusión espontánea del polígono de Willis, enfermedad de Moyamoya (trastorno), enfermedad de Moyamoya, oclusión arterial intracraneal progresiva (trastorno), oclusión arterial intracraneal progresiva, Enfermedad de Moyamoya, Artereopatía Oclusiva Intracraneal Progresiva (Moyamoya), Enfermedad de Moyamoya Cerebrovascular
French Occlusion spontanée du cercle de Willis, Maladie de Moya-Moya, Artériopathie de Moya-Moya, Syndrome de Moya-Moya
Dutch spontane occlusie van cirkel van Willis, aandoening; mojamoja, mojamoja; aandoening, Mojamoja-ziekte, ziekte van Moyamoya, Cerebrovasculaire Moymoya-ziekte, Moyamoya-ziekte, Progressieve intracraniale occlusieve arteropathie, Ziekte, Moyamoya-
Portuguese Oclusão espontânea do polígono de Willis, Doença de Moya-Moya, Arteropatia Oclusiva Intracraniana Progressiva (Moyamoya), Doença Cerebrovascular de Moyamoya, Doença de Moyamoya
German spontane Okklusion des Circulus arteriosus Willisii, Moyamoya-Syndrom, Moyamoya Krankheit, Moyamoya-Krankheit, Progressive intrakranielle okklusive Arteriopathie (Moyamoya), Zerebrovaskuläre Moyamoya-Krankheit
Italian Occlusione spontanea del circolo di Willis, Malattia di Moyamoya
Finnish Moyamoya-tauti
Korean 모야모야 병
Polish Choroba Moyamoya
Hungarian Moyamoya-betegség, Willis-kör spontán elzáródása
Norwegian Moyamoya, Progredierende intrakranial okkluderende arteriopati