What is Moya Moya disease?

From the Guidelines

Moyamoya disease is a rare, progressive blood vessel disorder where the carotid arteries in the brain become narrowed or blocked, reducing blood flow to the brain, and the most recent and highest quality study recommends surgical revascularization with direct or indirect extracranial-intracranial bypass as a beneficial treatment for preventing ischemic stroke or TIA in patients with moyamoya disease 1.

Definition and Characteristics

Moyamoya disease is characterized by the progressive stenosis of the terminal portion of the internal carotid artery and the formation of an abnormal network of dilated, fragile perforators at the base of the brain, as described in the 2023 study published in the journal Stroke 1. The disease typically affects children and young adults, though it can occur at any age, and symptoms include strokes, mini-strokes (TIAs), seizures, headaches, and cognitive decline.

Treatment and Management

Treatment focuses on improving blood flow to the brain, primarily through surgical procedures like direct or indirect revascularization, with direct procedures involving connecting a scalp artery directly to a brain artery, and indirect procedures placing tissue with blood vessels on the brain's surface to promote new vessel growth, as outlined in the 2023 study 1. Medication management may include blood thinners like aspirin to reduce stroke risk, and the use of antiplatelet therapy, typically aspirin monotherapy, for the prevention of ischemic stroke or TIA may be reasonable, as stated in the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack 1.

Key Points

• Moyamoya disease is a rare, progressive blood vessel disorder that reduces blood flow to the brain
• Surgical revascularization with direct or indirect extracranial-intracranial bypass is a beneficial treatment for preventing ischemic stroke or TIA
• Medication management may include blood thinners like aspirin to reduce stroke risk
• Early diagnosis and treatment are crucial to prevent progressive brain damage and disability
• The disease occurs due to genetic factors in some cases, with about 10% of patients having a family history, and is more common in East Asian populations, as noted in the example answer.

Evidence-Based Recommendations

The 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack recommends that surgical revascularization with direct or indirect extracranial-intracranial bypass can be beneficial for the prevention of ischemic stroke or TIA in patients with moyamoya disease, with a Class of Recommendation (COR) of 2a and a Level of Evidence (LOE) of C-LD 1. The 2023 study published in the journal Stroke also supports the use of surgical revascularization for the treatment of moyamoya disease, with a focus on direct bypass for hemorrhagic patients 1.

From the Research

Definition and Overview of Moya Moya Disease

• Moya Moya disease is a rare cerebrovascular disease characterized by non-atherosclerotic and non-inflammatory progressive narrowing of the intracranial part of the carotid artery and its proximal branches 2, 3.
• The disease process is commonly associated with the development of weak, dilated collateral blood vessels at the base of the brain, giving it a classic smoky appearance on cerebral angiograms, hence the name "Moyamoya" which means "puff of smoke" in Japanese 2, 3.
• Moya Moya syndrome is a secondary process that occurs in response to another underlying pathological process that causes stenosis of intracranial blood vessels, such as radiation, sickle cell anemia, neurofibromatosis, long-standing diabetes, uncontrolled hypertension, or chemotherapy 2, 3, 4.

Clinical Manifestations and Diagnosis

• Patients with Moya Moya disease can remain asymptomatic or present with ischemic or hemorrhagic stroke, headache, seizures, or recurrent transient ischemic attacks 3, 4.
• Conventional cerebral angiography is considered the gold standard for diagnosing MMD 2, 3.
• Other diagnostic tools include CT perfusion, MRI, and non-contrast CT of the head 2.

Treatment Options

• The treatment option for Moya Moya is generally surgical, with medical treatment having failed to halt disease progression and neuro-interventional techniques such as attempted stenting of stenosed vessels having failed 2, 3.
• Surgical options include direct and indirect cerebrovascular bypass, with the goal of increasing cerebral blood flow and preventing recurrent stroke 2, 5.
• The role of conservative and surgical treatment in MMD needs further evaluation with larger cohorts and a focus on long-term clinical outcome 6.

Epidemiology and Risk Factors

• Moya Moya disease is rare in the United States, with just 0.086 newly diagnosed cases per 100,000 individuals per year 2.
• Risk factors for MMD include Eastern Asian ancestry and predisposing conditions such as neurofibromatosis and Down's syndrome 2.
• The disease is no longer exclusive to Asians, as evidenced by the rising incidence among non-Asian groups such as Caucasians, Hispanics, and African Americans 3.