Having a stroke is often the first sign of a rare but potentially lethal condition that causes narrowing of blood vessels that supply the brain. Dr Chen Min Wei, Consultant, Neurosurgery, National Neuroscience Institute shares more about moyamoya disease, the treatment and how it got its unusual name.
Every minute, the adult brain needs to receive about 700ml of blood so it can function well – that’s similar to the amount in two cans of cola. To get to the brain, blood travels through blood vessels, and the two arteries on either side of the neck are a major supply route: the left common carotid artery and the right common carotid artery. These arteries split to form the internal carotid artery which brings blood to the brain, and the external carotid artery which brings blood to the face.
Moyamoya disease is a medical condition that happens when the inner wall of either or both the left or right internal carotid artery thickens. This results in narrowing which restricts blood flow to the brain. To compensate, tiny blood vessels develop to try to supply the brain with enough blood. These tiny blood vessels resemble a puff of smoke on an angiogram brain scan, hence the name ‘moyamoya’, which means ‘puff of smoke’ in Japanese, due to the condition first being reported in Japan in the late 1950s.
The dangers of moyamoya disease
Over time, the artery wall can narrow so much that it blocks blood flow to the brain, resulting in an ischaemic stroke. The tiny blood vessels that create the ‘puff of smoke’ appearance can also bleed, causing a haemorrhagic stroke.
“Because moyamoya disease develops silently, someone may only know they have it when they are hospitalised for a stroke or other symptoms,” says Dr Chen.
Symptoms of moyamoya disease include:
- Most common: stroke
- Bleeding in the brain
- Headaches
- Problems with learning and development in children
- Seizures
- In rare cases, vision impairment
Who is at risk of moyamoya disease?
Moyamoya disease is a rare condition, with NNI neurosurgeons treating around eight to 10 cases a year. It is more common in females and East Asians, such as those of Chinese, Japanese, and Korean descent and is usually diagnosed during childhood and in adults in their 40s. Research suggests that the condition may be passed down through families, as around 20 to 30 per cent of patients who are diagnosed with moyamoya disease have the RNF213 gene.
Diagnosis of moyamoya disease
The following tests may be conducted to check for moyamoya disease:
Magnetic Resonance Imaging (MRI)
These non-invasive scans use magnetic fields and radiofrequency waves to look for strokes or bleeding in the brain, which are usually the first signs of the disease. Specialised MRI scans can even potentially see if the blood vessel narrowing is caused by moyamoya disease or other possible reasons instead.
Cerebral Angiogram
This procedure involves inserting a catheter (a long and flexible plastic tube) up a vessel in the groin, and through the blood vessels to the arteries in the neck. A special dye is then passed through the catheter so that doctors can take detailed images of blood vessels of the brain under X-ray scans without any other body organs obstructing the view.
Magnetic Resonance Angiography (MRA) Vessel Wall Imaging
This non-invasive scan focuses on blood vessels and blood flow. MRA vessel wall imaging gives doctors a better understanding of what is happening in the blood vessels of the brain.
How is moyamoya disease managed?
If a patient has had a stroke caused by moyamoya disease, surgery is usually the only treatment option. This involves by-passing the narrowed internal carotid artery by connecting a branch of the external carotid artery found at the side of the face to a healthy blood vessel in the brain to restore blood flow.
Once discharged from hospital, patients may need to return for a follow-up scan one year later to check on and ensure that blood flow to the brain has improved. Patients can go back to living a normal life but should continue to monitor their health in case moyamoya disease starts causing symptoms in untreated areas of the brain.
“This bypass surgery carries significant risk, therefore it is only recommended for patients who have major symptoms such as stroke and not as a preventive measure. In patients who suffer stroke, antiplatelet drugs such as aspirin may be given as a form of primary prevention,” says Dr Chen.
Did you know?
Moyamoya syndrome is not the same as moyamoya disease. The key difference between the two is the reason for the narrowing of the internal carotid artery. Moyamoya disease happens when the internal carotid artery narrows naturally. If the vessel narrows due to other underlying reasons in the body such as fatty plaque build-up in the vessel or brain tumours, it is defined as moyamoya syndrome because the growth of tiny blood vessels resembles moyamoya disease.
Tags:
;
Public;
;
;
News Article;
;
National Neuroscience Institute;
;
;
;
;
;
;
Patient Care
