Moyamoya Disease Screening: Who Should Be Tested and How
Moyamoya disease is an extremely rare cerebrovascular disorder characterized by the progressive narrowing or blockage of arteries at the base of the brain, particularly the internal carotid arteries. Due to its low incidence rate—estimated at fewer than 1 in 100,000 people in Western countries—it is not included in routine medical screening protocols. However, early detection can be life-saving, especially for individuals with a family history of the condition.
Understanding the Genetic Link in Moyamoya Disease
Although moyamoya disease is considered sporadic in many cases, research has shown a significant genetic component, particularly in familial cases. If one family member has been diagnosed with the condition, other relatives may carry genetic predispositions that increase their risk. Studies suggest that up to 10–15% of patients in certain populations have affected relatives, highlighting the importance of targeted screening within high-risk families.
Non-Invasive Initial Screening Methods
For individuals with a family history or presenting symptoms such as transient ischemic attacks (TIAs), seizures, or unexplained neurological deficits, non-invasive imaging techniques are typically the first step. Two primary tools are used:
Transcranial Doppler (TCD) Ultrasound
Transcranial Doppler is a painless, radiation-free test that measures blood flow velocity in the brain's major arteries. Abnormal flow patterns, such as elevated velocities due to stenosis, can raise suspicion of moyamoya disease. While TCD alone cannot confirm the diagnosis, it serves as an effective preliminary tool for identifying individuals who need further evaluation.
Brain MRI and MRA (Magnetic Resonance Angiography)
MRI with MRA provides detailed images of both brain tissue and blood vessels. It can reveal characteristic signs of moyamoya, including narrowed internal carotid arteries and the development of tiny collateral vessels that resemble a "puff of smoke"—the origin of the disease's name, which means "moyamoya" in Japanese. This imaging modality is highly sensitive and widely accessible, making it ideal for initial diagnostic assessment.
Confirmatory Diagnosis: The Role of Cerebral Angiography
If initial tests suggest moyamoya disease, the gold standard for confirmation is cerebral angiography. This invasive procedure involves injecting contrast dye into the blood vessels and using X-ray imaging to visualize the vascular architecture in real time. It offers the most detailed view of arterial stenosis and collateral circulation, allowing neurologists and neurosurgeons to classify the stage of the disease and plan appropriate treatment.
Who Should Consider Screening?
While general population screening is not recommended due to the rarity of the disease, the following groups should consider evaluation:
- First-degree relatives (parents, siblings, children) of a diagnosed patient
- Individuals experiencing recurrent headaches, strokes, or TIAs without a clear cause
- Patients of Asian descent, as the condition is more prevalent in East Asian populations
- Children or adults with unexplained cognitive decline or seizures
Early identification through proper screening can lead to timely interventions such as revascularization surgery, which significantly reduces the risk of stroke and improves long-term outcomes.
Conclusion: Proactive Monitoring Saves Lives
Although moyamoya disease remains rare, awareness and targeted screening for at-risk individuals can make a critical difference. Combining non-invasive imaging like TCD and MRA with definitive angiographic confirmation allows for accurate diagnosis and effective management. If you or a loved one has a family history of unexplained strokes or known moyamoya disease, consult a neurologist to discuss whether screening is appropriate.