Moyamoya is a neurological disorder that occurs because of blocked arteries present at the base of brain. The name moyamoya has been derived from a Japanese word because this condition was first identified by Japanese. In this health condition, the blood vessels present in the brain starts to become narrow, which in turn creates blockage leading to stroke. Till date there is no medication available that can either stop or reverse the effect of moyamoya disease. Treatment for this problem is focused on maintaining normal blood flow in the brain for eliminating the risk of stroke.
What Is The ICD-10 Code For Moyamoya?
For reimbursement purpose, the disease is diagnosed with ICD-10 I67.5. This is the latest code which came into existence from October 2018.
The problem is diagnosed by a doctor after inquiring about the symptoms. If the doctor finds that the symptoms are of moyamoya then for reconfirmation he prescribes some tests. The list of tests includes:
- Magnetic Resonance Imaging
- Computed Tomography Angiography
- Computed Tomography Perfusion
After the problem is identified immediate treatment is initiated. If the problem is at an early stage then it can treated with effective medication but if the problem is become severe or complicated then surgery is prescribed. Doctors recommend that one should not leave the condition untreated for a prolonged period of time else it can have fatal effect.
For understanding moyamoya, it is very important to understand the circulatory system present in neck and head of an individual. The flow starts from the aorta, which is a carotid artery and then divides near the larynx into two parts i.e. internal and external carotid arteries. Internal arteries are responsible for maintaining required blood flow in the front and sides of the brain, whereas; eternal arteries are responsible for maintaining required blood flow in the face and scalp region.
Oxygenated blood is sent to the brain via two paired arteries, namely the vertebral arteries and the internal carotid arteries. After it has passed the skull region the arteries combine together and form a single basilar artery. The communication between both these arteries occur in a ring which is commonly known as Circle of Willis. To the face and scalp region blood is carried by paired external carotid arteries.
In moyamoya the internal carotid arteries starts narrowing at the place where the arteries bifurcate into anterior and middle cerebral arteries. The reason for narrow of arteries is the thickening of the outer wall of the arteries. If the process of narrowing continues then it ultimately results in blockage. Brain has an internal repair mechanism by which it compensates the narrowing of the arteries by creating collateral blood vessels. These vessels are responsible for transferring oxygenated blood to the blocked areas of the brain.
When these small collateral vessels are tracked on an angiogram, it gives a filmy and hazy appearance. As these are very small delicate collaterals it can eventually break and start bleeding in the brain, which can cause hemorrhage. Effect of moyamoya is not limited to any particular side of the brain, instead; it equally affects both the side of the brain. Based on the angiography findings, this progression of the neurological condition is divided in to different stages:
Stage 1 – Internal carotid arteries starts narrowing
Stage 2 – Moyamoya vessels starts to develop at the base of the brain.
Stage 3 – In this stage both internal carotid artery and moyamoya vessels start intensifying.
Stage 4 – Increase in the number of collateral vessels from scalp and decrease in the moyamoya vessel count.
Stage 5 – Moyamoya vessels completely disappear and significant increase in the collateral vessels.
Once the blockage triggers it continues rapidly. There is no medication found till date that can stop or reverse the process of blockage. If the patient undergo stroke or bleeding then he/she may suffer severe function loss, hence; it is very important that this condition is taken care very seriously.