Moyamoya disease is a chronic, progressive cerebrovascular disorder in which the large arteries supplying blood to the brain gradually narrow or become blocked without a clear cause. It develops when problems arise at the end of the internal carotid artery, located at the base of the brain, and in the circle of Willis, the arterial branches connected to it. In place of the blocked vessels, thin and weak blood vessels abnormally tangle and grow nearby. Because this shape resembles "puffs of smoke rising" on cerebral angiography, Japanese professor Jiro Suzuki named it "moyamoya." Although classified as a rare, intractable disease, it has a notably high incidence in East Asia, including Korea, Japan, and China, making it relatively familiar to Koreans.
The number of moyamoya disease diagnoses in Korea is increasing each year. According to statistics from the Health Insurance Review and Assessment Service, the number of patients treated for moyamoya disease has more than doubled over the past 10 years. Unlike other cerebrovascular diseases, which mainly occur in middle age or later, moyamoya disease appears frequently in children around age 10 and in relatively young adults in their 30s and 40s. While the cause has not yet been clearly identified, a certain genetic predisposition common among East Asians is known to be involved in its onset. As the prevalent age groups suggest, moyamoya disease can cause a stroke at the most active period of social life or at a young age when one is still growing. A cerebral infarction, in which a brain vessel suddenly becomes blocked, or a brain hemorrhage, in which a vessel ruptures, can leave lifelong aftereffects from just a single occurrence. Therefore, detecting the disease early and preparing in advance is most important of all.
The symptoms of moyamoya disease are largely divided into ischemic symptoms, which arise from insufficient blood flow to the brain, and hemorrhage, which occurs when a weak vessel ruptures. In children, ischemic symptoms are common, such as sudden weakness in one arm or leg, slurred speech, or reduced sensation on one side. These symptoms tend to appear especially in situations where breathing becomes rapid, such as crying, blowing on hot food to cool it, inflating a balloon, or strenuous exercise. When the brain's demand for blood flow changes rapidly, the brain vessels regulate by dilating and constricting. However, unlike normal vessels, moyamoya vessels have poor coping ability, so blood flow to the brain temporarily becomes insufficient. Frequent headaches or temporary paralysis symptoms that appear and then disappear should also raise suspicion of moyamoya disease. In adults, the disease is sometimes discovered through a sudden brain hemorrhage when a slightly enlarged vessel ruptures, which can be life-threatening or leave serious disability. The biggest problem is that it can easily be overlooked because it resembles an ordinary headache or simple fatigue. In children, repeated ischemic symptoms can lead to reduced intelligence or developmental delay, making diagnosis easy to delay.
Fortunately, the diagnostic process is not particularly difficult. Suspicious findings can be confirmed with brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), and cerebral angiography can accurately assess the degree of vessel narrowing and the development pattern of collateral vessels. The current standard treatment for moyamoya disease is bypass surgery, which supplements the insufficient blood flow to the brain. It is largely divided into "direct bypass surgery," which connects a vessel leading to the scalp directly to a brain vessel, and "indirect bypass surgery," which attaches tissue rich in blood flow to the surface of the brain to induce the growth of new vessels. Depending on the patient's age, vessel condition, and symptoms, direct or indirect bypass surgery is performed alone or in combination. In pediatric patients, new vessels often grow well with indirect bypass surgery alone, yielding good results. Performing surgery before the disease progresses can effectively prevent future strokes, and surgical outcomes are steadily improving.
However, surgery is only a means to prevent stroke by supplementing insufficient blood flow; it is not a fundamental treatment that halts the progression of the disease itself. The fact that there is still no drug treatment to supplement or replace surgery remains a long-standing challenge in the medical field. Moreover, the very cause of vessel narrowing in moyamoya disease has not been clearly identified. This is why I personally devote myself to basic research to uncover the fundamental cause and progression mechanism of moyamoya disease beyond surgery, and to find a treatment.
There is still no way to prevent the onset of moyamoya disease itself. However, it is clear that detecting the disease early can prevent a major incident. If neurological symptoms such as unexplained headaches, temporary paralysis, or language disorders recur, I recommend not hesitating and seeing a neurosurgeon. Greater caution is needed for those around age 10 or in their 30s and 40s, when the early onset of moyamoya disease is most common. Moyamoya disease is a cerebrovascular disorder that is not at all rare among Koreans. Remembering the name of the disease and not missing suspicious signs can be considered the first step toward rapid diagnosis and treatment.
