Moyamoya disease is a chronic arteriopathy described for the first time in Japan at the 1957, without explained origin, resulting in progressive stenosis of the terminal portion of the internal carotid arteries, the proximal segment of the middle and anterior cerebral arteries. Commonly applied in clinical practice, recent brain vessel imaging techniques, such as CT (computed tomography) angiography, provide more efficient screening to detect asymptomatic cases of this disease. Therefore, knowledge of the radiological signs has a significant influence on the management of patients with Moyamoya disease.

Young patient, 23 years old, referred to radiology for intermittent headache assessment. Medical interrogation revealed regressive right hemiplegia that occurred 2 years ago. The clinical examination didn’t reveal any sensorimotor deficit. He was referred for CT-angiography looking specifically to find a vascular explanation (Figure 1).

Figure 1: CT angiography with MIP reconstructions of Willis circle reveals bilateral middle cerebral artery (MCA) narrowing (arrows); Hypervascular vessels are seen on (a) axial and (b) coronal reconstructions corresponding to Moyamoya collaterals. This CT angiography revealed non-symptomatic Intraventricular hemorrhage (arrow heads).

MoyaMoya disease is a chronic arteriopathy described for the first time in Japan in 1957, resulting in progressive stenosis of the terminal portion of the internal carotid arteries, the proximal segment of the middle and anterior cerebral arteries. The cause remains unknown poorly described. The genetic origin is frequently suggested, as in 15% of cases the disease involves other members of the family [1]. Studies by Mineharu have reported that the 17q 25 locus has a causal relationship with the disorder [2]. Some studies suggesting an association with sickle cell disease, neurofibromatosis type 1 (NF 1), fibromuscular dysplasia, Down syndrome and the use of oral contraceptive. When Moyamoya disease is associated with any of the above etiologies, it is considered "Moyamoya syndrome". Patients with this condition have a risk of subsequent stroke up to 10% per year [3]. Thrombotic alterations in the collateral circulation vessels may occur, causing ischemic lesions. Increased blood flow in the small collateral microaneurysms vessels, is the probable cause of intracranial haemorrhages. CT angiographic imaging modalities, which are commonly available, can at least provide indications for preliminary diagnosis and evaluation and offer the possibility of early diagnosis, especially in asymptomatic patient [4]. It’s provides an analysis of cerebral vascularization, demonstrates steno-occlusive disease, and looks for possible associated aneurysms. Its shows the disease-specific small vessels extending from the suprasellar cistern to the peri-thalamic basal nuclei, called Moyamoya vessels [5]. The typical "puff of smoke" appearance is due to the opacification of all these collateral vessels. They are ectasic or microaneurysmal and therefore brittle, with a high risk of rupture, responsible for intracerebral and intraventricular hemorrhages [6]. Transscleral anastomoses develop between the superficial temporal artery and the middle meningeal artery or the optic artery and the anterior or middle cerebral artery, perforating the dura mater [7].

MoyaMoya is a chronic pathology with a severe prognosis, for which brain imaging is at the forefront of the diagnostic and therapeutic strategy. No single imaging modality can perfectly assess this pathology on its own.

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