**6. Clinical features**

The pathological changes in cerebral arteries lead to cerebrovascular events in Moyamoya disease. Two peaks have been identified, at around ten years and 30–40 years. The peak occurs later in women than in men [24].

The symptoms can be classified in the following four main heads (**Figure 1**) [13].

Transient ischemic attacks [TIA] and infarct may present as a variety of symptoms- motor paresis, sensory disturbance, speech disturbances, alteration of consciousness [25]. Whereas these symptoms present acutely, mental decline, dyskinesias tend to progress over the years. Dilated collateral vessels in basal ganglia have been implicated in the development of choreiform movements [26]. Bilateral disease is associated with cognitive deficits. Hemorrhagic type is more common in adults >40 years of age and most commonly present with impaired consciousness. Irrespective of the primary pathology [ischemic/hemorrhagic], the symptoms tend to be recurrent and usually a single pathology predominates in each individual. Headache is another common symptom generally seen in children <14 years old [27]. Dilated transdural collaterals stimulate dural nociceptors precipitating migraine-like headaches. Headache may also be a manifestation of chronic hypoxemia.

The symptoms are triggered by hyperventilation, such as blowing/crying due to decreased cerebral blood flow secondary to CO2 washout. Worsening is also seen

**Figure 1.**

*Clinical symptoms of Moyamoya disease.*

*Moyamoya Disease Worldwide-Global Burden East and West DOI: http://dx.doi.org/10.5772/intechopen.96137*

with infection of the upper respiratory tract. Hypertension and aging often contribute to hemorrhage, which may occur at repetitive intervals. Massive bleeding may even lead to death. Epilepsy, as a manifestation of the disease, is usually seen in children less than ten years of age [28].

The clinical features also tend to vary from East to West. The ischemic manifestations are more predominant in the US [United States] than in other eastern countries. The rate of hemorrhagic disease in adults in Asian countries is higher [42%] than in those of Asian descent residing in the US [29]. The disorder's overall spectrum remains constant worldwide, with ischemic manifestations as the main presenting feature in children and both ischemia and hemorrhage in adults.
