https://www.ahajournals.org/doi/pdf/10.1161/STR.0000000000000375

2021 Guideline for the Prevention of Stroke in Patients With Stroke and Transient Ischemic Attack: A Guideline From the American Heart Association/American Stroke Association

The characteristics of moyamoya disease (spontaneous occlusion of the circle of Willis, cerebrovascular ``moyamoya'' disease) on cerebral angiography were reported for the first time in 1957,8) and the concept of moyamoya disease as a separate disease entity was established in the 1960s.1–3,6,7) Pathologically, moyamoya disease is characterized by chronic progressive stenosis of the terminal portion of the bilateral internal carotid arteries, which leads to the formation of an abnormal vascular network composed of collateral pathways at the base of the brain (moyamoya vessels at the base of the brain) (`moyamoya' is the Japanese term for a ``puff of smoke,'' which has been used to describe the appearance of these collateral vessels on cerebral angiograms6)). Eventually, with bilateral internal carotid artery occlusion, the moyamoya vessels at the base of the brain derived from the internal carotid arteries disappear, and the entire brain is perfused by the external carotid artery system and the vertebrobasilar artery system.1–3,5–7) This disease is included in the list of diseases for Research on Measures for Intractable Diseases and the Specified Disease Treatment Research Program specified by the Ministry of Health, Labour and Welfare. Currently, the diagnostic criteria for moyamoya disease (spontaneous occlusion of the circle of Willis) laid down by the research committee are as follows.4)

Moyamoya Disease (Spontaneous Occlusion of the Circle of Willis)

Importance Although spontaneous intraparenchymal hemorrhage (IPH) accounts for less than 20% of cases of stroke, it continues to be associated with the highest mortality of all forms of stroke and substantial morbidity rates. Observations Early identification and management of IPH is crucial. Blood pressure control, reversal of associated coagulopathy, care in a dedicated stroke unit, and identification of secondary etiologies are essential to optimizing outcomes. Surgical management of hydrocephalus and space occupying hemorrhage in the posterior fossa are accepted forms of treatment. Modern advances in minimally invasive surgical management of primary, supratentorial IPH are being explored in randomized trials. Hemorrhagic arteriovenous malformations and cavernous malformations are surgically excised if accessible, while hemorrhagic dural arteriovenous fistulas and distal/mycotic aneurysms are often managed with embolization if feasible. Conclusions and relevance IPH remains a considerable source of neurological morbidity and mortality. Rapid identification, medical management, and neurosurgical management, when indicated, are essential to facilitate recovery. There is ongoing evaluation of minimally invasive approaches for evacuation of primary IPH and evolution of surgical and endovascular techniques in the management of lesions leading to secondary IPH.

Cerebral Intraparenchymal Hemorrhage: A Review.

Although the pathogenesis of moyamoya disease (MMD) has not been fully elucidated, the effectiveness of surgical revascularization in preventing stroke has been addressed by many studies. The main mechanism of surgical revascularization is augmenting the intracranial blood flow using an external carotid system by either direct bypass or pial synangiosis. This can improve resting cerebral blood flow as well as vascular reserve capacity. For direct revascularization, the superficial temporal artery is used as the donor artery in most cases, although the occipital artery may be used in limited cases. Usually, the cortical branch of the middle cerebral artery is selected as the recipient of direct anastomosis. As for indirect revascularization, various techniques using different kinds of connective tissues have been introduced. In some cases, reinforcing the anterior cerebral artery and the posterior cerebral artery territories can be considered. The effectiveness of surgical revascularization for preventing ischemic stroke had been generally accepted by many studies. However, for preventing hemorrhagic stroke, new evidence has been added by a recent randomized controlled trial. The incidence of peri-operative complications such as stroke and hyperperfusion syndrome seems to be high due to the nature of the disease and technical demands for treatment. Preventing and adequately managing these complications are essential for ensuring the benefits of surgery.

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Moyamoya Disease: Treatment and Outcomes

Moyamoya disease (MMD) is a rare cerebrovascular disease which is characterized by bilateral progressive steno-occlusion of basal cerebral arteries with emergence of coexisting abnormal net-like vessels.1 MMD is most frequent in Asian countries with an incidence ≤0.94/100 000, but an increase in incidence has been reported in non-Asian countries with some ethnic differences in disease characteristics.2–4 MMD shows worldwide a bimodal age distribution with a peak each in childhood and adulthood2–4; thus, it is one of the leading causes of stroke in children and young adults. The most frequent initial symptom of MMD adults in Asians and whites is intracranial hemorrhage because of fragile blood vessels and ischemic events, respectively.2,3 Children with MMD worldwide frequently experience ischemic events.2–4

The diagnostic workup includes magnetic resonance angiography or digital subtraction angiography and hemodynamic assessments using (semi) quantitative techniques, such as SPECT or PET.2 Historically, disease severity has been classified by the angiography-based Suzuki classification. This classification, however, neither correlates with disease severity nor allows therapeutic risk stratification and thus, has not been applied in routine clinical setting. As a consequence, the Berlin Moyamoya Grading has been established using standard diagnostic tools: magnetic resonance imaging and functional cerebrovascular assessment of hemodynamic impairment.5 This novel grading system correlates with disease severity and more importantly, allows to stratify the individual risk of surgical therapy. Only recently, the Berlin Moyamoya Grading has been validated on an independent Japanese data set.6

Cerebral hemodynamic impairment and repeat ischemic symptoms have to date been the main indications for treatment.2 However, because asymptomatic moyamoya is a progressive disease with an annual stroke rate of ≤13.3%,7,8 treatment indications for asymptomatic patients are currently revisited by the prospective AMORE trial.8 For …

Surgical Management of Moyamoya Disease.

Background and purpose About one half of those who develop adult-onset moyamoya disease experience intracranial hemorrhage. Despite the extremely high frequency of rebleeding attacks and poor prognosis, measures to prevent rebleeding have not been established. The purpose of this study is to determine whether extracranial-intracranial bypass can reduce incidence of rebleeding and improve patient prognosis. Methods This study was a multicentered, prospective, randomized, controlled trial conducted by 22 institutes in Japan. Adult patients with moyamoya disease who had experienced intracranial hemorrhage within the preceding year were given either conservative care or bilateral extracranial-intracranial direct bypass and were observed for 5 years. Primary and secondary end points were defined as all adverse events and rebleeding attacks, respectively. Results Eighty patients were enrolled (surgical, 42; nonsurgical, 38). Adverse events causing significant morbidity were observed in 6 patients in the surgical group (14.3%) and 13 patients in the nonsurgical group (34.2%). Kaplan-Meier survival analysis revealed significant differences between the 2 groups (3.2%/y versus 8.2%/y; P=0.048). The hazard ratio of the surgical group calculated by Cox regression analysis was 0.391 (95% confidence interval, 0.148-1.029). Rebleeding attacks were observed in 5 patients in the surgical group (11.9%) and 12 in the nonsurgical group (31.6%), significantly different in the Kaplan-Meier survival analysis (2.7%/y versus 7.6%/y; P=0.042). The hazard ratio of the surgical group was 0.355 (95% confidence interval, 0.125-1.009). Conclusions Although statistically marginal, Kaplan-Meier analysis revealed the significant difference between surgical and nonsurgical group, suggesting the preventive effect of direct bypass against rebleeding. Clinical trial registration url http://www.umin.ac.jp/ctr/index.htm. Unique identifier: C000000166.

Fumihiko Nisimura

Papers

Effects of Extracranial–Intracranial Bypass for Patients With Hemorrhagic Moyamoya Disease: Results of the Japan Adult Moyamoya Trial