Hemorrhagic Moyamoya Disease : A Recent Update

Moyamoya disease (MMD) is a progressive cerebrovascular disease with unknown etiology, characterized by bilateral stenoocclusive changes at the terminal portion of the internal carotid artery and an abnormal vascular network formation at the base of the brain. MMD has an intrinsic nature to convert the vascular supply for the brain from internal carotid (IC) system to the external carotid (EC) system, as indicated by Suzuki’s angiographic staging. Insufficiency of this ‘IC-EC conversion system’ could result not only in cerebral ischemia, but also in intracranial hemorrhage from inadequate collateral anastomosis, both of which represent the clinical manifestation of MMD. Surgical revascularization prevents cerebral ischemic attack by improving cerebral blood flow, and recent evidence further suggests that extracranial-intracranial bypass could powerfully reduce the risk of re-bleeding in MMD patients with posterior hemorrhage, who were known to have extremely high re-bleeding risk. Although the exact mechanism underlying the hemorrhagic presentation in MMD is undetermined, most recent angiographic analysis revealed the characteristic angio-architecture related to high re-bleeding risk, such as the extension and dilatation of choroidal collaterals and posterior cerebral artery involvement. We sought to update the current management strategy for hemorrhagic MMD, including the outcome of surgical revascularization for hemorrhagic MMD in our institute. Further investigations will clarify the optimal surgical strategy to prevent hemorrhagic manifestation in patients with MMD.

Hemorrhagic Moyamoya Disease : A Recent Update

Moyamoya disease (MMD) is a progressive cerebrovascular disease with unknown etiology, characterized by bilateral stenoocclusive changes at the terminal portion of the internal carotid artery and an abnormal vascular network formation at the base of the brain. MMD has an intrinsic nature to convert the vascular supply for the brain from internal carotid (IC) system to the external carotid (EC) system, as indicated by Suzuki’s angiographic staging. Insufficiency of this ‘IC-EC conversion system’ could result not only in cerebral ischemia, but also in intracranial hemorrhage from inadequate collateral anastomosis, both of which represent the clinical manifestation of MMD. Surgical revascularization prevents cerebral ischemic attack by improving cerebral blood flow, and recent evidence further suggests that extracranial-intracranial bypass could powerfully reduce the risk of re-bleeding in MMD patients with posterior hemorrhage, who were known to have extremely high re-bleeding risk. Although the exact mechanism underlying the hemorrhagic presentation in MMD is undetermined, most recent angiographic analysis revealed the characteristic angio-architecture related to high re-bleeding risk, such as the extension and dilatation of choroidal collaterals and posterior cerebral artery involvement. We sought to update the current management strategy for hemorrhagic MMD, including the outcome of surgical revascularization for hemorrhagic MMD in our institute. Further investigations will clarify the optimal surgical strategy to prevent hemorrhagic manifestation in patients with MMD.

Genetics and Biomarkers of Moyamoya Disease: Significance of RNF213 as a Susceptibility Gene / 대한뇌졸중학회지

Moyamoya disease is characterized by a progressive stenosis at the terminal portion of the internal carotid artery and an abnormal vascular network at the base of the brain. Although its etiology is still unknown, recent genome-wide and locus-specific association studies identified RNF213 as an important susceptibility gene of moyamoya disease among East Asian population. A polymorphism in c.14576G>A in RNF213 was identified in 95% of familial patients with moyamoya disease and 79% of sporadic cases, and patients having this polymorphism were found to have significantly earlier disease onset and a more severe form of moyamoya disease, such as the presentation of cerebral infarction and posterior cerebral artery stenosis. The exact mechanism by which the RNF213 abnormality relates to moyamoya disease remains unknown, while recent reports using genetically engineered mice lacking RNF213 by homologous recombination provide new insight for the pathogenesis of this rare entity. Regarding biomarkers of moyamoya disease, moyamoya disease is characterized by an increased expression of angiogenic factors and pro-inflammatory molecules such as vascular endothelial growth factors and matrix metalloproteinase-9, which may partly explain its clinical manifestations of the pathologic angiogenesis, spontaneous hemorrhage, and higher incidence of cerebral hyperperfusion after revascularization surgery. More recently, blockade of these pro-inflammatory molecules during perioperative period is attempted to reduce the potential risk of surgical complication including cerebral hyperperfusion syndrome. In this review article, we focus on the genetics and biomarkers of moyamoya disease, and sought to discuss their clinical implication.