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Moyamoya disease: symptoms, causes and treatment

Moyamoya disease: symptoms, causes and treatment

May 2, 2024

Our brain is a fundamental part of the organism , since it regulates the functioning and coordination of most of the body and allows us to be who we are: it controls from the vital signs to the higher processes such as reasoning or motivation, passing among others by perception and motor skills.

But even though it may be our most important organ, it could not work and it would even die in a short time if it did not receive a constant supply of oxygen and nutrients. These come to him through the cerebrovascular system, being the neurons irrigated by different blood vessels.

However, sometimes these vessels can suffer injuries or be affected by diseases that can cause blood to flood part of the brain or not reach the places where it should, which can have very relevant health effects. Among these problems we can find Moyamoya's disease , of which we will see the main characteristics throughout this article.

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The disease of Moyamoya

It receives the name of Moyamoya disease to a rare but dangerous alteration of cerebrovascular type , characterized by an occlusion or progressive stenosis of the internal carotids (usually occurs in both at the same time) and its main branches in their terminal parts of the inside of the skull.

This narrowing in turn provokes the formation and strengthening of an extensive secondary network of smaller vessels that allow the blood to continue to arrive, forming a circuit whose form in neuroimaging is reminiscent of the smoke of a cigarette (This is what the term Moyamoya refers to, which in Japanese refers to smoke).

Although in many cases it can remain silent and asymptomatic, the fact is that since there is progression of the narrowing of the carotid artery, it causes the blood that reaches it to travel at high speed, something to which the fact that the network secondary does not have enough capacity to carry a sufficient supply of oxygen and nutrients.

This can have important repercussions for the subject, being able to experiment from dizziness and mental retardation, discomfort, irritability, vision or language impairments, weakness or paralysis of either side of the body , convulsions and even to be able to provoke the appearance of ischemic strokes or even of cerebral haemorrhages if some glass arrives to break (something that in this disorder is more habitual since the secondary network is much more fragile than the carotid one), something that can take to the loss of physical or mental abilities (depending on the affected area) or even death. The symptoms are usually more noticeable when efforts are made.

Although it can appear in people of any age, the truth is that it is much more frequent in children between five and nine years of age, which could lead to problems and developmental delays or even intellectual disabilities. Another peak of cases has been observed in adults over 45 years of age. When it comes to sex appears in both men and women , although it is more predominant in the latter.

The disease of Moyamoya was discovered by the doctors Takeuchi and Shimizu in 1957, and originally it was thought to be exclusive to the Japanese population . However with the passage of time it has been discovered in people of different ethnicities, although it is still much more prevalent in the population of Asian origin).

With respect to the prognosis it can vary enormously depending on when it is detected and on the application of a treatment. Mortality associated with this disease is around 5% in adults and 2% in children, mostly derived from stroke.

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As we have indicated, Moyamoya's disease is a progressive alteration that gets worse over time, having established different stages or degrees depending on the stenosis . In this sense we find ourselves with six degrees.

Grade 1

Moyamoya disease is considered grade 1 when only observed a narrowing of the point where the internal carotid artery bifurcates .

Grade 2

A more advanced degree occurs when the collateral vessels or secondary network that give the disorder its name begin to be generated.

3rd grade

At this point of the disease, the collateral vessels begin to intensify at the same time that a Progressive narrowing of the internal carotid and the middle cerebral artery , depending largely on the collateral vascularization ..

Grade 4

The network of collateral vessels that originates in the internal carotid begins to weaken and have worse functionality, while increasing the flow and generate circuits at the level of external carotid (outside the skull).

Grade 5

The network of collateral vessels develop and intensify from the external carotid artery, while in the internal carotid artery the collateral network is greatly reduced.

Grade 6

The internal carotid artery is totally closed and the collateral network of this also ends up disappearing, the initial secondary circuit is stopped . The blood supply becomes dependent on the external carotid and the vertebral artery.


Moyamoya disease does not have a definite cause, being an idiopathic disease. Despite this the existence of genetic influence has been observed , having studied chromosomes such as 3, 6 and 17 and having observed that it is more frequent in the population of Asian descent and in people with relatives who have suffered it. This aspect is also taken into account because it is sometimes associated with genetic disorders.

In addition, in some cases it can be associated with infectious processes (in which case it would be a syndrome and not a disease, since it would be secondary to it).


Moyamoya's disease does not currently have a treatment that cures or reverses it, although it can treat the symptoms and have controlled the level of stenosis or possible damage to blood vessels .

Among other methods, the surgical technique stands out, through which revascularization surgery can be performed, which will improve circulation, although the vessels will have a tendency to narrow again (despite the fact that treatment usually restrains the symptomatology and its progression). It is also possible to use, although it is done in adults but not in children due to the risk of hemorrhages after bumps, use very specific anticoagulants and other substances that allow to regulate the behavior of the blood.

As well the complications that may arise, such as learning delays and intellectual disability, should be addressed , offering guidelines and educational supports when needed. Speech therapy and / or physiotherapy can be useful in cases with speech or movement impairment, as well as occupational therapy and psychoeducation to the family.

Bibliographic references:

  • Acuña, A.R. and from Godoy, C.O. (2010). Moya-Moya disease. Pediatr. (Asunción), 37 (1).
  • Bretón, A., Gómez, J., Ramos, R., Martín, V., Pérez, J. and Alayón, A. (1999). Moya-Moya disease. Case report and literature review. An.Esp.Pediatr., 50: 65-68.
  • Buller, E., Luzuriaga, C. and Soler, M.G. (2016). Moyamoya disease. Clinical Journal of Family Medicine, 9 (3). Albacete
  • Takeuchi, K. & Shimizu, K. (1957). Hypogenesis of bilateral internal carotid arteries. No To Shinkei, 9: 7-43.

Moyamoya disease diagnosis and treatment | Boston Children’s Hospital (May 2024).

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