Disorders and Treatments
The greatest risk of moyamoya disease is stroke, but it can cause a wide range of neurological symptoms, including:
- Headache or dizziness
- Weakness or paralysis in a limb or on one side of the body
- Problems with speech — inability to speak or recall words
- Sensory or cognitive impairment
- Involuntary movements
- Seizures or loss of consciousness
- Vision problems
Noteworthy, these symptoms are commonly related to exercise, exertion, increased respiratory rate, or dehydration.
At NewYork-Presbyterian, our experienced pediatric neurosurgeons with expertise in cerebrovascular surgery evaluate children showing symptoms of moyamoya disease. Your child will have a neurological exam followed by imaging tests that allow a view into the cause of the symptoms. These may include:
- Magnetic resonance imaging (MRI) produces detailed visualization of brain tissue and accurately detects acute and chronic strokes. MRI can also be used to rule out tumors or other causes of neurological symptoms. A MR perfusion study can be used to evaluate the difference in blood flow between the two hemispheres of the brain.
- Computed tomography angiograms (CTA) and magnetic resonance angiograms (MRA) are non-invasive vascular studies that create three-dimensional images of the blood vessels in the brain.
- Digital-subtracted cerebral angiogram (DSA) produces the most detailed images of the blood vessels of the brain. It is the definitive test used to diagnose moyamoya disease.
- Single-photon emission computerized tomography (SPECT) scan shows the areas of the brain that are being deprived of oxygen.
Types of Moyamoya
Moyamoya disease is when the disorder exists in isolation of other aliments or known diagnoses.
Moyamoya syndrome is when the disorder is secondary to a known or identified predisposition including sickle cell anemia, neurofibromatosis, past cranial radiation therapy, and Down syndrome.
Once moyamoya disease is diagnosed, an experienced pediatric neurosurgeon will evaluate your child and make a treatment recommendation. Surgery is the only treatment that has been shown to prevent future strokes and neurological deterioration, but a doctor may recommend some immediate nonsurgical options, such as blood-thinning drugs or blood pressure medications to reduce the risk of stroke. Patients who have suffered neurological deficits from moyamoya may need speech or physical therapy to restore functioning.
If surgery is the recommended treatment, extracranial-intracranial bypass surgery, or cerebral revascularization, restores blood flow to the brain by diverting blood from a vessel in the scalp or nearby muscles to the oxygen-starved brain. The brain is then able to produce new blood vessels – a process called angiogenesis — from the graft to take advantage of the new source of blood supply. The surgery, called encephaloduralarteriosynangiosis (EDAS), involves isolation of the donor's vessel in the scalp and suturing of the graft onto the brain surface. Like any brain surgery, revascularization carries with it some risk of bleeding or stroke, but when the surgery is performed by an experienced neurosurgeon those complications are rare. The surgery usually has good outcomes with excellent protection against further strokes, especially in children and young adults.
Arteriovenous Malformations (AVMs)
An arteriovenous malformation (AVM) is an abnormal tangle of blood vessels that can occur anywhere in the body. When it occurs in the brain, an arteriovenous malformation is known as a cerebral (or brain) AVM. It can occur deep in the brain (in the thalamus, basal ganglia, or brainstem), or on the brain’s surface.
Although many AVMs are congenital (present at birth), they may not cause any symptoms until early adulthood or middle age, after years of increased pressure against vessel walls.
Symptoms of AVMs
The most frequent — and serious — signs of a brain AVM are the symptoms of an intracerebral hemorrhage, or bleeding in the brain, which is a neurological emergency that requires immediate care. These symptoms commonly start with a sudden-onset headache, often described as "the worst headache in my life," the sudden onset of seizures, and may also include:
- Loss of consciousness or diminished alertness
- Weakness and/or numbness in part of the body
- Aversion to bright light
- Double vision, vision loss, or other vision changes
- Confusion or irritability
- Neck and shoulder pain, or a stiff neck
- Nausea and vomiting
Many patients who are diagnosed with an AVM only find out about their condition in the emergency room after a rupture. Others are diagnosed when the AVM is seen on a CT scan or MRI, which may have been performed after an accident or injury or may have been ordered by a neurologist to investigate the cause of a patient’s headaches or other symptoms.
- Computerized tomography (CT) and magnetic resonance imaging (MRI) scans are noninvasive procedures that produce images of brain or spine structures and detect bleeding. CT scans use X-rays and MRI scans use magnetic fields to create images of the brain or spine. CT and MR scans detect the AVM but are not precise enough to see the details of an AVM’s structure and location, which are best seen on cerebral angiography.
- Cerebral angiography, also called cerebral arteriography, is a minimally invasive procedure that provides a detailed image of blood flow in the brain. An angiogram is a gold standard for diagnosing and evaluating AVMs. Angiography can detect any associated aneurysms that can co-exist with AVMs.
Sometimes an AVM is found “incidentally,” meaning that it hasn’t caused any symptoms but is found during a CT or MRI scan performed for another reason (for example, after an accident or injury). Owing to the natural history of AVMs in children, adolescents and young adults, treatment is almost always needed.
The decision to treat a cerebral AVM depends on its location, the risk of future complications if it is left untreated, and the risk of neurological deficits that may be associated with its treatment.
We use a variety of surgical techniques, alone or in combination, for the treatment of AVMs. Some AVMs will require just one of these therapies and others will require a combination:
Stereotactic Radiosurgery: Stereotactic radiosurgery for an AVM consists of highly targeted radiation beams directed at the AVM from multiple angles. The radiation, once delivered, produces a slow narrowing of the abnormal blood vessels over one to three years, until the AVM is obliterated. The appeal is the noninvasive nature of the treatment but balanced by the delay in hemorrhagic risk reduction (2-3 yrs) and the risks of radiation to the brain.
Endovascular Embolization: This involves the insertion of a catheter, or small plastic tube, through an artery in the upper leg or wrist. The tube is guided up the circulatory system to the site of the AVM, where it delivers a liquid “glue" that embolizes or blocks blood flow to the malformed vessels. In most cases, embolization alone is not enough to cure an AVM, but it is very useful to reduce the size of an AVM before surgery. In some cases it may reduce a large AVM enough to make radiosurgery a viable option, thus avoiding the need for surgical resection. Frequently, embolization is staged, meaning sequential treatments are used to reduce the risk of contrast dye load.
Microsurgical Resection: Microsurgical resection of an AVM is open surgery in which the neurosurgeon removes part of the skull to gain access to the abnormal vessels, which are then separated from the brain and removed. For accessible AVM’s surgical removal is the best form of treatment since the benefits are immediate and the results are usually lifelong.
Following this procedure, close monitoring and strict control of blood pressure are required, as well as a high-quality angiogram to determine that the AVM has been completely removed. At NewYork-Presbyterian we employ intra-operative angiography to confirm the completeness of removal right then and there during surgery, thereby eliminating the need for additional anesthesia or surgery. There are risks involved in any brain surgery, including infection and seizures, but a successful surgical resection that completely removes an AVM virtually eliminates the risk of a future rupture.
After Treatment: Ongoing Monitoring
After surgery, radiosurgery, or embolization, your medical team will monitor your/your child’s progress and conduct tests to evaluate the success of your therapy. While recurrence of AVMs in children is infrequent, continued surveillance until adulthood is usually mandated.