Surgical management of Moyamoya disease and syndrome: Current concepts and personal experience

In this focus, we review, in the light of the recent literature, the modalities and indications of surgical cerebral revascularization for Moyamoya (MM) disease or syndrome. We also report our experience in the surgical management of adult MM. In symptomatic forms, with presence of severe disturbances of perfusion or cerebrovascular reactivity on multimodal imaging work-up, the risks of recurrent ischemic or hemorrhagic stroke is high (respectively 10-13%/yr and 2-7%/yr). The objective of treatment is to augment cerebral perfusion (in ischemic forms) or to reduce lenticulo-striate neovessel overload (in hemorrhagic forms), by initiating the development of a cortical neovascularization and/or by directly increasing cerebral blood flow. The risk of immediate postoperative death or stroke is similar between indirect and direct or combined techniques and respectively 0-0.5% and 3-6%, provided a strict perioperative anesthetic management is applied (normocapnia, normoxia and controlled hypertension). Indirect techniques (i.e. encephalo-duro-arterio-myo-periosteo-synangiosis or multiple burr-holes) are technically easy, allow wide cortical revascularization and are very efficient in children: absence of clinical recurrence in more than 95% of cases and presence of a good neovascularization in 83%. However, their effect is delayed for several months, the impact on the hemorrhagic risk is moderate and the global response is uncertain in adults. Direct (superficial temporal artery to middle cerebral artery bypass) or combined techniques improve cerebral blood flow immediately and significantly. They are associated with a higher rate of stroke-free survival at 5 years (95% vs 85%). A recent randomized study has proven that they could reduce the hemorrhagic risk by 2- to 3-fold in comparison with conservative treatment alone. However, their feasibility in children is limited by the very small size of vessels. We present also our results in the surgical management of 12 adult MM patients (mean age 41.3, sex ratio=1) operated between 2009 and 2014 (14 revascularization procedures: EDAMS 2, multiple burr-holes 1, combined revascularization procedures 11). MM types according to clinical presentation were the following: ischemic 8, hemorrhagic 2, combined 2. All patients were recently symptomatic, with recurrent ischemic/hemorrhagic events (2/3) or crescendo neurological deficit (1/3) in association with severe alterations of cerebral blood flow. Mean clinical and radiological follow-up was 22 months. Postoperative mRS at 6 months was improved or stable in 92%. None of the patients suffered recurring stroke. In conclusion, surgical treatment should be discussed quickly in symptomatic forms of MM (progressive or recurring) because of their poor outcome. Indirect techniques are favored in pediatric patients due to their simplicity and good clinical results. Direct, or preferentially combined techniques would be more effective in adult patients to prevent the recurrence of ischemic or hemorrhagic stroke.