Moyamoya is a rare cerebrovascular disease that involves the enlargement of lenticulostriate and thalamoperforating arteries. Its name is derived from a Japanese term meaning “puff of smoke” due to how it appears on imaging.

 

Moyamoya origins

Like takotsubo cardiomyopathy (ie, broken-heart syndrome), which means “octopus pot” in Japanese and refers to the shape of the left ventricle on imaging, moyamoya disease is also named for its appearance on imaging.

Moyamoya refers to the compensatory enlargement of lenticulostriate and thalamoperforating arteries seen near the top of the internal carotid on angiography.

First described by Japanese investigators in 1957, moyamoya is a chronic, progressive cerebrovascular disease. Adults with this condition continue to manifest additional cognitive and neurological deficits over time. The death rate in adults is nearly double that of children (10% vs 4.3%, respectively).

 

Incidence of moyamoya

Publishing in Computational Intelligence and Neuroscience, Chinese researchers estimated that the incidence of moyamoya disease is 4%, with 1.5% exhibiting family history.

Zhao L, Li T, Xue B, et al. Influence of autologous bone marrow stem cell therapy on the levels of inflammatory factors and Conexin43 of patients with moyamoya disease. Comput Intell Neurosci. 2022;2022:7620287.

Its etiology is unknown.

 

In children, the first symptom is usually stroke or transient ischemic attacks, along with muscle weakness and hemiparesis. Other symptoms resulting from artery blockage include seizures, headaches, alterations in consciousness, visual problems, and involuntary movements. Although adults may experience similar symptoms, they often initially present with a hemorrhagic stroke.

Moyamoya disease. NIH. Updated July 25, 2022.

 

The continuous thickening of the walls of the internal carotid occurs progressively throughout the disease’s six stages (I to VI), which reflect progressive stenosis. In stage VI, the moyamoya vessels disappear and there is total arterial blockage.

Diagnosis of moyamoya is supported by computed tomography angiography, brain MRI, and catheter angiography to determine the stage of the disease, collateralization, and the dimensions of potential donor vessels.

 

Treatment strategies

Thanks to medical advances, moyamoya can be diagnosed early and treated over time.

Treatment consists of anticoagulants to decrease stroke risk and various types of surgery to revascularize the brain by unblocking narrowed arteries. Bypass is another option. Revascularization is often more successful in children than adults. Some patients experience no recurrence of the disease or associated symptoms following surgery.

Bypasses include direct or indirect, as well as combined extracranial-to-intracranial (EC-IC). Indirect bypass is performed without direct anastomosis; this type of bypass moves vascularized tissue to the brain’s surface to facilitate angiogenesis via burr holes or dural inversion. Although indirect bypass obviates proposed damage from hyperperfusion, it takes several months to a year for new blood vessels to grow and blood flow to be re-established.

“Controversy remains as to which surgical procedure is superior due to heterogeneous techniques and outcome measures used,” wrote the authors of a review published in Frontiers in Surgery.

Nguyen VN, Parikh KA, Motiwala M, et al. Surgical techniques and indications for treatment of adult moyamoya disease. Front Surg. 2022;9:966430.

 

“Prior studies have shown improved functional and symptomatic outcomes, angiographic revascularization, recurrent stroke, and decreased hemorrhage rates when utilizing direct bypass compared to indirect bypass for revascularization in the setting of moyamoya disease,” the authors added.

Pioneered in 1969, EC-IC is a common intervention in adult patients with moyamoya disease. It involves a direct anastomosis between a donor and recipient artery (eg, superficial temporal and middle cerebral arteries). Combined bypass strategies allow for immediate improvements in cerebral bypass and later collateralization stemming from an indirect bypass.

 

Stem cell approach studied

An intriguing potential treatment for moyamoya disease involves the use of autologous bone marrow stem cells (ABMSC). In the study published in Computational Intelligence and Neuroscience, Chinese researchers compared the outcomes of ABMSC with bypass in 52 moyamoya patients.

“Our study suggests that the treatment of [ABMSC] was beneficial to balance the inflammatory response of disorders, reduce the damage of vascular tissue in the brain, and regulate tissue repair by co-acting with various inflammatory factors as compared to traditional surgery,” the authors wrote.

We also have found that the risk factors of intracranial infection after [ABMSC transplantation] were less as compared to those after conventional surgery.