From the Guidelines
Moyamoya disease is a rare, progressive cerebrovascular disorder characterized by narrowing or blockage of the carotid arteries at the base of the brain, leading to reduced blood flow, as defined by the most recent guidelines from the American Heart Association/American Stroke Association in 2023 1.
Definition and Characteristics
Moyamoya disease is a stenotic-occlusive condition that affects 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 a scientific statement from the American Heart Association/American Stroke Association in 2023 1. The term "moyamoya" means "puff of smoke" in Japanese, which refers to the hazy, smoke-like appearance of the tiny blood vessels that develop at the base of the brain to compensate for the narrowed main arteries.
Symptoms and Diagnosis
This condition can affect both children and adults, causing symptoms such as:
- Stroke
- Transient ischemic attacks (mini-strokes)
- Seizures
- Headaches
- Cognitive decline Moyamoya can be either primary (genetic) or secondary to other conditions like Down syndrome, sickle cell disease, or prior radiation therapy.
Treatment and Management
Treatment typically involves surgical revascularization procedures to restore blood flow to the brain, such as:
- Direct bypass surgery (connecting a scalp artery directly to a brain artery)
- Indirect procedures that encourage new blood vessel formation 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, as recommended by the American Heart Association/American Stroke Association in 2021 1. Without treatment, moyamoya disease progressively worsens over time, increasing the risk of multiple strokes and neurological deterioration. Early diagnosis and intervention are crucial to prevent permanent neurological damage and improve long-term outcomes.
Ongoing Research and Debates
There remains ongoing debate as to the optimal revascularization strategy, with some studies suggesting a potential relative benefit of direct over indirect bypass in hemorrhagic moyamoya 1. However, there is a lack of randomized data regarding revascularization strategy in ischemic moyamoya, and most meta-analyses and their source studies have several limitations. Further research is needed to better understand the natural history of moyamoya disease, examine the efficacy of medical management options, and determine the most effective surgical intervention for moyamoya disease 1.
From the Research
Definition and Characteristics of Moyamoya Disease
- Moyamoya disease is an uncommon cerebrovascular disease characterized by progressive stenosis of the terminal portion of the internal carotid artery and its main branches 2.
- The disease is associated with the development of dilated, fragile collateral vessels at the base of the brain, which are termed moyamoya vessels 2.
- Moyamoya disease is a type of cerebrovascular disease characterized by occlusion of the distal end of the internal carotid artery and the formation of collateral blood vessels 3.
Clinical Features and Diagnosis
- The incidence of moyamoya disease is high in east Asia, and familial forms account for about 15% of patients with this disease 2.
- Moyamoya disease has several unique clinical features, which include two peaks of age distribution at 5 years and at about 40 years 2.
- Most pediatric patients have ischemic attacks, whereas adult patients can have ischemic attacks, intracranial bleeding, or both 2.
- Catheter angiography is a diagnostic method of choice, while magnetic resonance angiography and computed tomography angiography are noninvasive diagnostic methods 4.
- High-resolution vessel-wall magnetic resonance imaging also helps in diagnosing moyamoya disease by revealing concentric vessel-wall narrowing with basal collaterals 4.
Treatment and Outcomes
- Extracranial-intracranial arterial bypass, including anastomosis of the superficial temporal artery to the middle cerebral artery and indirect bypass, can help prevent further ischemic attacks 2.
- Surgical revascularization such as extracranial-intracranial bypass is the preferred procedure for moyamoya disease patients presenting with ischemic stroke 4.
- Procedure-related cerebral infarction and hyperperfusion syndrome are potential complications that can lead to neurological deterioration 4.
- Revascularization surgery remains the primary treatment for moyamoya disease largely because of the lack of effective in vivo and in vitro models 3.