Moyamoya disease: symptoms, causes and treatment.

A rare cerebrovascular disease affecting the internal carotid arteries.

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

But although it is perhaps our most important organ, it would not be able to function and would even die within a short time if it did not receive a constant supply of oxygen and nutrients. These reach it through the cerebrovascular system, the neurons being irrigated by different Blood vessels.

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

Moyamoya disease

It receives the name of Moyamoya disease to a rare but dangerous alteration of the rare but dangerous alteration of cerebrovascular type, characterized by acharacterized by a progressive occlusion or stenosis of the internal carotid arteries (generally it happens in both at the same time) and its main branches in its terminal parts inside the skull.

This narrowing in turn causes an extensive secondary network of smaller vessels to form and strengthen, allowing blood to continue to flow in, forming a circuit whose shape in neuroimaging is reminiscent of cigarette smoke. whose shape in neuroimaging is reminiscent of cigarette smoke. (this is what is referred to by the term Moyamoya, which in Japanese refers to smoke).

Although in many cases it may remain silent and asymptomatic, the fact is that as the narrowing of the carotid artery progresses it causes the blood that reaches it to travel at high speed, which is compounded by the fact that the secondary network does not have sufficient capacity to carry a sufficient supply of oxygen and nutrients.

This can have important repercussions for the subject, who may experience dizziness and mental slowing, malaise, irritability, impaired vision or speech, weakness or paralysis of one or other side of the body.The symptoms are usually more noticeable when exertion is made, and can even lead to ischemic strokes or even cerebral hemorrhages if a vessel ruptures (something that is more common in this disorder since the secondary network is much more fragile than the carotid), something that can lead to loss of physical or mental abilities (depending on the affected area) or even death. Symptoms are usually more noticeable when exerting oneself.

Although it can appear in people of any age, it is much more frequent in children between five and nine years of age, to whom it could cause problems and developmental delays or even intellectual disability. Another peak of cases has also been observed in adults over 45 years of age. In terms of gender appears in both males and femalesalthough it is more predominant in the latter.

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

With respect to prognosis it can vary greatly depending on when it is detected and the application of treatment. The mortality associated with this disease is around 5% in adults and 2% in children, mostly due to stroke.

Stages

As we have indicated, Moyamoya disease is a progressive disorder that worsens over time, with different stages or degrees depending on the severity of the disease. different stages or degrees depending on the stenosis.. In this sense, there are six grades.

Grade 1

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

Grade 2

A more advanced grade occurs when the collateral vessels or secondary network that give the disorder its name begin to develop.

Grade 3

At this point in the disease, the collateral vessels begin to intensify and a progressive narrowing of the carotid artery is observed. progressive narrowing of the internal carotid artery and middle cerebral artery, depending to a large extent on the vascularThe disease is characterized by a progressive narrowing of the internal carotid and middle cerebral arteries, depending to a great extent on collateral vascularization.

Grade 4

The network of collateral vessels originating in the internal carotid begins to weaken and become less functional, while flow increases and circuits are generated at the level of the external carotid (outside the skull).

Grade 5

The collateral vessel network develops and intensifies from the external carotid artery, while in the internal carotid artery the collateral network is greatly reduced.

Grade 6

The internal carotid artery is completely closed and the collateral network of the internal carotid artery also eventually disappears, the initial secondary circuit ceases. The blood supply becomes dependent on the external carotid and vertebral artery.

Causes

Moyamoya disease does not have a fully defined cause, being an idiopathic disease. In spite of this the existence of genetic influence has been observed.It has been studied chromosomes 3, 6 and 17 and it has been observed that it is more frequent in the population of Asian descent and in people with relatives who have suffered from it. This aspect is also taken into consideration because it is sometimes associated with genetic disorders.

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

Treatment

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

Other methods include surgery, through which revascularization surgery can be performed, which will improve circulation, although the vessels will tend to narrow again (although the treatment usually slows down the symptoms and their progression). It is also possible to use very specific anticoagulants and other substances to regulate the behavior of the blood, although this is done in adults but not in children because of the risk of hemorrhage after strokes.

Also complications that may arise, such as learning delays and intellectual disabilities, should be addressed.educational guidelines and support should be offered when needed. Speech and/or physical therapy may be useful in cases with speech or movement impairment, as well as occupational therapy and psychoeducation of the family.

Bibliographic references:

• Acuña, A.R. and de Godoy, C.O. (2010). Moya-Moya disease. Pediatr. (Asuncion), 37 (1).
• Bretón, A., Gómez, J., Ramos, R., Martín, V., Pérez, J. and Alayón, A. (1999). Moya-Moya disease. Case report and review of the literature. 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.