What Is Moyamoya Disease?
Moyamoya disease is a rare, progressive, genetic disease that causes blockage of the primary blood vessels that supply the brain as they enter the skull.
Moyamoya disease is mainly seen in Japan and other Asian countries. "Moyamoya" is a Japanese word that means "puff of smoke," which describes the abnormal, tangled, and hazy appearance of the vascular collateral network (small blood vessels) that forms to compensate for the blocked blood vessels.
What Are Symptoms of Moyamoya Disease?
Moyamoya disease symptoms may be different in adults and children.
In adults, symptoms of Moyamoya disease include:
- Bleeding in the brain (hemorrhagic strokes)
- Vision problems
- Blurred vision
- Loss of vision in one eye
- Diminished vision in both eyes
- Inability to recognize objects
- Weakness, numbness, or paralysis on one side of the face, arm, or leg
- Cognitive problems
In children, symptoms of Moyamoya disease may include those seen in adults as well as:
What Causes Moyamoya Disease?
The cause of Moyamoya disease is unknown but it is believed to be genetic, along with possible immune abnormalities.
Other possible causes of Moyamoya disease include:
- Heart surgery
- Neurofibromatosis (genetic disorder of the nervous system)
- Procedures such as X-rays of the skull
Moyamoya syndrome may occur as a secondary disorder in association with other conditions, such as:
- Infections such as leptospirosis and tuberculosis
- Autoimmune conditions such as Lupus and thyroid disorders
- Heart disease
- High blood pressure (hypertension)
- Vascular disease
- Hardening of the arteries (atherosclerosis)
- Blood disorders such as sickle cell disease or beta thalassemia
- Connective tissue disorders such as von Recklinghausen disease (neurofibromatosis type 1) or tuberous sclerosis
- Metabolic diseases
- Graves’ disease
- Chromosome disorders
- Head trauma
- Radiation therapy of the brain
- Brain tumors
- Congenital disorders such as Down syndrome, Williams syndrome, Marfan syndrome, Turner syndrome, Hirschsprung disease
How Is Moyamoya Disease Diagnosed?
Along with a history and physical, Moyamoya disease is diagnosed using imaging tests to help find the location of the vascular blockage:
- Magnetic resonance imaging (MRI) of the brain or spine
- Cerebral angiogram
- Computerized tomography (CT) scan
- Single photon emission computerized tomography (SPECT)
- Electroencephalography (EEG)
- Transcranial Doppler ultrasound
Laboratory studies may be indicated and include:
What Is the Treatment for Moyamoya Disease?
The goals of treatment for Moyamoya disease are focused on reducing symptoms with attempts to decrease intracranial pressure, improve blood flow in the blood vessels of the brain, and control seizures. There is no cure for Moyamoya disease.
Revascularization surgery is the preferred treatment option for Moyamoya disease to repair narrowed arteries, improve blood flow, and reduce the risk of stroke. Moyamoya disease is a progressive condition, and without surgery, patients suffer cognitive decline and multiple strokes.
There are several types of revascularization procedures:
- EDAS (encephaloduroarteriosynangiosis)
- EMS (encephalomyosynangiosis)
- External carotid to internal carotid (EC-IC) bypass
- Direct arterial bypass, also called STA-MCA (superficial temporal artery-middle cerebral artery) bypass
- Omental transposition/transfer
- Dural inversion
- Angioplasty and stenting may be used to widen a narrowed artery
Medications may be used to treat Moyamoya disease if surgery is not an option, such as:
What Are Complications of Moyamoya Disease?
Complications of Moyamoya disease include:
- Cognitive impairment
What Is the Staging for Moyamoya Disease?
There are 6 stages of Moyamoya disease, called Suzuki stages. Each stage refers to a finding from the imaging of blood vessels (angiographic finding):
- Stage 1: Narrowing of carotid arteries
- Stage 2: Initial appearance of basal Moyamoya with dilatation of all main cerebral arteries
- Stage 3: Intensification of Moyamoya vessels together with reduction of flow in the middle and anterior cerebral arteries
- Stage 4: Minimization of Moyamoya vessels; the proximal portions of the posterior cerebral arteries become involved
- Stage 5: Reduction of Moyamoya vessels and absence of all main cerebral arteries
- Stage 6: Disappearance of Moyamoya vessels; the cerebral circulation is supplied only by the external carotid system
What Is the Life Expectancy for Moyamoya Disease?
About 10% of adults with Moyamoya disease will die, and about 4.3% of children. Death is usually due to bleeding in the brain (hemorrhage).
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