Moyamoya Disease: Treatment and Outcomes

Abstract

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.

Keywords: Cerebral revascularization; Moyamoya disease; Treatment outcome.

Figure 1.

This line charts demonstrates the change in the number of revascularization surgeries from 2009 to 2013 in Korea. The number of indirect revascularization surgeries is constant over this period while the number of direct revascularization surgeries gradually increases.

Figure 2.

Post-operative angiography of the external carotid artery. Black arrowheads indicate the superficial temporal artery (donor artery). The tip of the black arrow is the anastomosis site to the angular artery (recipient artery). The middle cerebral artery is supplied from the superficial temporal artery with a reverse direction (white arrowheads).

Figure 3.

The quantitative magnetic resonance angiography shows intact bypass flow through the superficial temporal artery.

Figure 4.

Intraoperative photos show the surgical procedure of encephalo-duro-arterio synangiosis (EDAS). (A) The formation of the arterial flap containing the parietal branch of the superficial temporal artery (STA) and surrounding galea tissue as a cuff shape. Under the flap, the cortex is exposed through the ovoid craniotomy and durotomy. (B) Completed suture with dural margin. The proximal and distal end of the STA is kept connected without cutting (white arrowheads=the parietal branch of the STA; black arrowheads=the dural margin being sutured with the cuff of flap water-tightly; asterisk=the temporalis muscle split vertically and reflected).

Figure 5.

Post-operative single-photon emission computed tomography showing improved vascular reserve in the Diamox study comparing the pre-operative status.