Have you been lately suffering from vision problems and speech difficulties? Watch out, for you might be having a condition called Moyamoya which can cause intracerebral hemorrhage or even stroke in advanced stages. Get detailed information about this disorder, including its causes, symptoms, diagnosis and treatment.

What is Moyamoya?

It is considered to be one of the uncommon forms of occlusive cerebrovascular disease. In this rare vascular disorder, the blood vessels at the core of the brain become slender in shape. This in turn blocks the flow of blood and causes severe oxygen deficiency in the brain. The body, in response to the blockage, builds up a number of tiny vessels to encourage the flow of blood and oxygen into the nervous system.

Moyamoya ICD9 Code

The ICD9 code for this disease is 437.5.

Moyamoya Incidence

This disease mainly affects children although it also afflicts adults in a few cases. In Japan, this disease is generally observed in children aged between 5 and 15 years. Adults affected by this disorder are generally between 30 to 40 years of age. In the US, the condition occurs in 1 out of every 1000000 individuals.  Inhabitants of Australia, Europe and Africa have also been diagnosed with this syndrome.

Picture of Moyamoya

Picture 1 – Moyamoya

This condition is more common in women than in men.

Moyamoya Causes

This medical condition is associated with the q25.3 on chromosome 17. Naturally, the disease is considered to arise due to hereditary factors. The real cause of this syndrome is, however, not known. There are a number of diseases that are linked with this ailment. In a few cases, this disease can be found in patients suffering from sickle cell disease, neurofibromatosis type I and Down’s syndrome. Patients, who have undergone radiotherapy test in the past, are more prone to this disease.

Moyamoya Symptoms

A mild stroke, also known as Transient Ischemic Attack, is the main warning sign of this medical condition. This hemorrhagic stroke occurs as a consequence of obstruction of blood flow to the brain. The various symptoms that indicate the presence of this disorder, apart from Ischemic stroke, are:

  • Mini stoke
  • Weakness in arms or legs
  • Headaches
  • Cognitive Learning
  • Problem in speaking or uttering
  • One side of the body paralyzed
  • Seizures

An analysis of the above symptoms can help a doctor to get a complete idea about the condition as well as its intensity.

Moyamoya Diagnosis

A number of diagnostic procedures help a doctor to confirm the presence of this disease as also determine its severity. Diagnostic imaging tests are done to determine the distinctiveness of collateral blood vessels and arterial slandering of this disease.  Some of these diagnostic tests involve:


MRI (Magnetic Resonance Imaging) scan is one of the effective tests for this condition. It uses radio-frequency waves along with a magnetic field and generates a detailed imaging of the soft tissues located near the brain. Magnetic Resonance Angiogram is conducted during this noninvasive diagnostic test, by infusing a contrast agent in the blood level, in order get a clear view of the arteries of the brain.


Computed Tomography (CT) imaging is done to determine the flow of blood inside the brain. Doctors need to analyze the quantity of blood reaching the brain. Hence, they infuse a contrast agent in the blood line. The process also helps physicians to analyze which specific areas of the brain are more vulnerable to strokes. During this CT imaging, Diamox (acetazolamide), a type of medication is given to the patient to open the arteries. This particular medication is considered to be a type of stress test for the mind and is quite analogous to anxiety tests used for the heart.


In this procedure, a catheter is injected into the artery and then run directly into the brain through the blood vessels. After the catheter is in position, a contrast agent is infused in the blood stream and X-ray images are taken. This particular test analyzes all the prime blood vessels catering to the brain, such as vertebral, external carotid and the internal carotid arteries. The images are quite significant, since they are used to point out which pre-existing collateral vessels would not be disturbed if surgery is conducted.

Cerebral blood flow studies

Studies such as PET- Positron Emission Tomography, TCD- Transcranial Doppler Ultrasonography, SPECT- Single Photon Emission Computed Tomography and xenon-enhanced CT also help diagnose this disease. These also assist doctors provide the right kind of treatment to patients suffering from this hereditary syndrome.


Computed Tomography Angiography (CTA) scan helps a doctor to get the detail pictures of the anatomical compositions of the brain. This diagnostic procedure includes infusing of a contrasting dye in the blood line, in order to make the arteries visible. Such a procedure provides a clear image of the soft tissues and the blood vessels.

Moyamoya Differential Diagnosis

A differential diagnosis helps isolate the condition from a number of other disorders can be detected, such as:

Connective tissue diseases

This involves disorders like SLE- Systemic Lupus Erythematosus.


This involves infectious conditions, like:

  • Post-varicella vasculitis
  • Teberculous meningitis
  • Bacterial leptomeningitis

Haematological disorders

These include conditions like:

  • Aplastic anaemia
  • Sickle cell disease
  • Anti phospholipid disease

Moyamoya Treatment

There is no medicine available in the market that can prevent the narrowing of the artery. The cure is focused on minimizing the risk of frequent strokes by supplying blood to those parts of the brain which got affected. The series of repeated strokes can also be reduced by an arterial bypass surgery.

Image of Moyamoya

Picture 2 – Moyamoya Image


Medicines such as Asprin, minimize the risk of TIA stroke among patients. However, according to medical researchers, Asprin alone is unsuccessful in curing moyamoya.


A surgical cure is advised to patients with progressive strokes. Operative techniques prevent stroke by re-supplying the flow of blood to the areas of the brain affected by this disease. The types of surgeries recommended for patients of this syndrome include:

  • Cerebral bypass procedure
  • EMS Procedure
  • Omental transposition procedure
  • Encephalo-Duro-Arterio-Synangiosis
  • Multiple burr holes procedure

Moyamoya Prognosis

In the absence of surgery, most individuals suffering from this syndrome can become more vulnerable to strokes and mental retardation (as the arteries tend to become narrower). Unless proper treatment is adminsitered, Moyamoya can prove to be life-threatening by causing intracerebral hemorrhage. This disease can also give rise to a number of transient ischemic attacks (mini-strokes) and strokes.

Moyamoya is a progressive disease which is followed by a series of mild strokes. If any member of your family shows the symptoms of this disorder, call your health provider immediately. The condition can give rise to various other complications in the body. Hence, it should be treated in time and with utmost care.



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