**5. Conclusions**

Moyamoya disease is more prevalent than previously thought because many patients go undiagnosed. Once diagnosed, asymptomatic patients may already harbour a cognitive decline long before cerebrovascular events take place. The only effective treatment is surgical revascularization, which should be undertaken as soon as any clinical deterioration sign occurs. Many posit that preventive surgical treatment should be recommended to asymptomatic patients, particularly in the paediatric age group.
