Fact-sheet: Moyamoya disease


Updated on 07/21/2025 at 6:29 PM

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Definition

Stenosing intracerebral vasculopathy.
"Moya" can be translated as "haze," "smoke cloud," or "puff of smoke" in Japanese.
It is characterized by stenosis of the cerebral arteries of the circle of Willis, particularly the terminal internal carotid arteries.

Two forms are distinguished:

  • Moyamoya disease: primary (congenital) form
  • Moyamoya syndrome: secondary form (sickle cell disease, NF1, T21, progeria, post-infectious, inflammatory diseases, hemostasis disorders, post-radiotherapy)

Population: preferential involvement of children ++ and the Asian population

Clinical features

  • Stroke
  • Subarachnoid hemorrhage
  • Headaches
  • Seizures
  • Cognitive impairment

CT

  • CT angiography of the Circle of Willis
  • Perfusion CT after acetazolamide injection:
    CBF study: evaluation of vascular reserve
  • CBV study: decreased

MRI

3T MRI preferred.

  • 3D TOF MRA
  • T1 Gadolinium: vascular enhancement in the lenticulostriate nuclei, and linear enhancement within the white matter
  • FLAIR: vessels showing spontaneous hyperintensity due to vascular dilation, "ivy sign" (hyperintensity of the cortical sulci)
  • Perfusion: increased perfusion in the posterior territory and decreased perfusion in the anterior territory
  • Diffusion: detection of recent ischemic lesions

Vascular intervention

  • X-Ray Angiography: "puff of smoke" appearance of the collateral network

Management

  • Medical treatment: antiplatelet agents / anticoagulants
  • Surgical treatment: dural-encephalic anastomoses

Classification

Suzuki grades:

  • Stenosis of the terminal internal carotid artery and of the origin of A1 and M1
  • Onset of collateral network formation:
    ICA stenosis, dilation of the anterior, middle, and posterior cerebral arteries distal to the steno-occlusive lesions
  • Intensification of the collateral network (involvement of the lenticulostriate and thalamostriate arteries, vascular rarefaction distal to the lesions)
  • Appearance of transdural anastomoses (between branches of the ECA and the pial network)
  • Reduction of the Moyamoya network, occlusion of the ICA, anterior, middle, and posterior cerebral arteries
  • Disappearance of the network: cerebral collateral supply provided by transdural anastomoses

Differential diagnosis

  • Arteriovenous malformation of brain