Moyamoya is a rare vascular-occlusive (blockage of blood vessels) disease that affects the intracranial carotid artery. The stenosis, narrowing and thickening of the artery, is non-artherosclerotic, meaning it is not caused by fatty deposits on the blood vessel walls and cannot be treated with angioplasty or stenting. Instead Moyamoya disease is a progressive disease that causes permanent blockage to a vascular cerebral artery; it most often occurs in children and adolescents.
When the narrowed and occluded arteries at the base of the brain can no longer deliver oxygen-rich blood to the brain, in the case of Moyamoya, tiny new blood vessels form in an attempt to move oxygenated blood through the brain. These fragile new vessels, which can easily tear and create bleeding in the brain, create a tangle or net, which when viewed with medical imaging can look similar to a “puff of smoke”—the Japanese term is moyamoya. Moyamoya was first diagnosed in Japan, but can affect many ethnicities.
Moyamoya syndrome has many of the characteristics as the disease, but often develops secondarily to another disorder such as Down syndrome, neurofibromatosis, sickle cell disease, or after brain radiation therapy.
Causes and Symptoms of Moyamoya
Often time the cause of Moyamoya is unknown and cannot be determined. Sometimes the cause appears to be genetic and other times a traumatic injury is indicated. Although the pathogenesis (disease’s development) of the Moyamoya syndrome is sometimes an underlying disorder as mentioned above.
Many symptoms of Moyamoya in children and adolescents are similar to those in adults:
repeated transient ischemic attacks (TIAs or “mini-strokes”) — more common in children and young adults
muscle weakness or paralysis (often on just one side)
seizures or convulsions
slurred speech or other communication problems
vision issues such as blurred vision
intracranial hemorrhage — more likely to occur in adults
How Is Moyamoya Diagnosed?
Sometimes the “puff of smoke” characteristic of Moyamoya will show up on a CT (computerized tomography) scan or during magnetic resonance imaging (MRI).
However, if Moyamoya is suspected, then several techniques can provide detailed imaging:
A cerebral angiogram uses a special contrast agent and a fluoroscope (a camera that uses x-ray imaging) to view the blood vessels.
A computed tomography angiography (CTA) scan provides detailed images of blood vessels and soft tissues within the brain using x-rays. A contrast dye is injected into the bloodstream and non-invasive x-rays are used to provide imaging.
A single photon emission computed tomography (SPECT) test uses nuclear imaging to see how the blood circulates in the brain.
Other tests can be used to view blood circulation in the brain such as a PET (positron emission tomography) or a transcranial Doppler ultrasonography (TCD).
What Are the Treatments for Moyamoya at NSPC?
Moyamoya left untreated can develop into successive hemorrhagic events and cause neurological impairment. Medical management of Moyamoya can include anti-clotting drugs and calcium channel blockers, which reduce blood pressure in the hopes of limiting the risk of a stroke. However, these only slow the progression of the symptoms, and surgery is the only long-term solution.
Surgical treatment of Moyamoya involves diverting the blood around the vascular occlusion in the artery. This revascularization can be direct or indirect. Neurological Surgery, P.C. (NSPC) employs a multidisciplinary medical team approach to complex cases. With board certified neurosurgeons who specialize in pediatric neurosurgery and complex neurosurgery, NSPC has experienced doctors who provide world-class treatment in the Long Island and NY tri-state region for serious brain conditions such as Moyamoya.
Cerebral bypass surgery reestablishes blood flow to the brain, similar to a coronary bypass for the heart.
Direct revascularization: STA-MCA Bypass is considered a direct extracranial–intracranial bypass (EC-IC bypass). During this procedure, one end of the superficial temporal artery (STA, also called the donor artery) is detached from the scalp and is reattached to the middle cerebral artery (MCA), returning blood flow to the ischemic (having insufficient blood) part of the brain. Since the donor artery comes from outside the skull (extracranial) and is attached inside the skull (intracranial), a small hole or craniotomy is made in the skull.
Indirect revascularization procedures:
An EDAS (encephaloduroarteriosynangiosis) procedure, sometimes called pial synangiosis, also detaches the superficial temporal artery from the scalp, similar to an STA-MCA. But instead of attaching the donor blood vessel directly to another artery, it is sutured onto the surface of the brain. This allows new vessels to form in the brain.
EMS (encephalomyosynangiosis) is a microsurgical procedure that takes a small portion of the temporalis muscle from the side of the head and places it on the surface of the brain to increase blood circulation.
Omental Transposition uses part of the omentum (a section of the peritoneum, or membrane lining the abdominal cavity and organs) as a graft onto the surface of the brain to increase blood flow.
A Dural Inversion reverses the flaps of fibrous dural tissue on the meningeal vessel of the skull. The inverted blood vessels give additional oxygenated blood to the surface of the brain.
Our team of leading Long Island physicians specialize in cerebrovascular and endovascular conditions, including brain aneurysms, arteriovenous malformations (AVM) and carotid stenosis such as Moyamoya. As one of New York City area’s premier neurosurgical groups, NSPC offers patients the most advanced treatments of brain and spine disorders at our centers. Talk with one of our Moyamoya surgery specialists to see what the best treatment option is for you or your child.