Transient ischemic symptoms: Temporary symptoms such as motor weakness or speech disturbance are common in children older than 2-3 years. Complaints of transient sensory symptoms are less frequent. Slowly progressive arterial narrowing permits the development of collateral channels. However, cerebral perfusion is gradually decreased to a borderline state and transient ischemic symptoms appear, typically lasting for minutes. These episodes are usually associated with behavior such as crying, with or without emotional upset, blowing while eating hot foods, inflating balloons, or playing woodwind toys.
Permanent neurological deficits due to infarct:Repeated transient ischemic symptoms may lead to cerebral infarction in old children. Alternatively, in patients with Moyamoya Disease a cerebral infarction may occur without preceding transient ischemic attacks, especially in younger children (> 3 years old). In cases of chest trauma with an associated lung injury, children with Moyamoya Disease may experience a cerebral infarction due to the hyperventilation caused by the injury. The site of infarction is mainly in watershed areas of the brain. The cerebellum is not involved in the ischemia or infarction seen in Moyamoya Disease.
Seizures: These are caused by cerebral infarction, hemorrhage or chronic ischemia. Seizure may aggravate cerebral hemodynamics and lead to cerebral infarction and vice versa.
Headache: Headaches in children with Moyamoya Disease reflect a compensatory vasodilatation of cerebral arterial trees when there is a chronic or compensated cerebral ischemia. It typically has the characteristics of being worst in the morning, having a frontal location, occasional being associated with orbital pain, possibly being triggered by hyperventilation and not being relieved by usual analgesic medication.
Hemorrhage: Bleeding is more frequent in adolescents or adults than in children. The areas of bleeding are usually dilated collateral moyamoya vessels in the basal ganglia or around the foramen of Monro.
Involuntary movements: Some patients show involuntary movement. This is apparently related to ischemia within the brain and is relieved after revascularization surgery.
Patterns of Evolution
Natural course: The natural course of Moyamoya Disease is a progressive, bilateral complete or near complete occlusion of the internal carotid arteries and their middle and anterior cerebral arteries branches. Frequently, the posterior cerebral arteries are also involved.
Angiographic staging: In 1969 Suzuki and Takaku described six angiographic stages outlining the natural course of Moyamoya Disease, starting with I and progressing to VI (53). As the brain’s major arterial intracranial slowly occlude, extracranial anastomotic channels develop to a degree that almost meets the total cerebral perfusion requirement. During this process, any short-fall in cerebral perfusion causes cerebral infarction. The goal of surgical revascularization is to protect the brain from stroke by creating an alternative blood supply, such that infarction is prevented, even though the patient exhibits continued progression of the moyamoya over time.
Nearly all patients are in Stage 3 or 4: Even though the angiographic staging is helpful for understanding of natural course of Moyamoya Disease, the typical presentation is Suzuki III-IV, and most decision making is dependent on clinical status coupled with other radiographic data (such as cerebral perfusion).
Time of Evolution
Slow progression: The symptoms may progress slowly in cases with headache, and transient ischemic episodes. It can be difficult to predict the course of disease progression in children.
Sudden manifestation, rapid progression, recurrence: The manifestations are sudden in cases of cerebral infarction, seizure or hemorrhage. The neurologic deficits caused by infarction or hemorrhage show gradual improvement over time, identical to neurological deficits caused by other brain insults. However, additional new deficits, due to recurrent cerebral infarction in the ipsilateral or contralateral cerebral hemispheres, may follow within a few months, especially in young children (22)
Evaluation at Presentation
History: Presence of preceding transient ischemic symptoms, cerebral infarction, headache, seizure or cerebral hemorrhage are important clues for diagnosis as well as presence of family history and associated conditions for quasi Moyamoya Disease: neurofibromatosis, cranial radiation, sickle cell anemia, etc.
Screening of daily activities: School performance and emotional stability are valuable information source of functional status of brain.
Physical Examination: Sometimes systemic hypertension is associated by chronic cerebral ischemia or accompanying renal artery stenosis. Usually carotid pulsation in the neck reveals no diagnostic information. Searching stigmata of neurofibromatosis type I may be valuable.
Neurological Examination: The patient may asymptomatic between the transient ischemic attacks.Imaging: MRI and MRA are the best imaging tools for the initial evaluation.
Child younger than 3 years: Urgent management should be considered if the patient is younger than 3 years or the if patient demonstrates symptoms and signs of cerebral infarction, seizure or suffer from hyperventilation-associated TIA. In some cases, it can be difficult to coordinate surgery if the child is experiencing repeated clusters of strokes.
Avoidance of ischemia:Hyperventilation, hypovolemia, anemia, hypotension should be avoided.
Maintain blood pressure: Control of hypertension, if present, should be moderate to avoid lowering the pressure too much and consequently increasing the risk of stroke from relative hypotension.
Hydration: Active hydration is encouraged to prevent hypotension, particularly if the child is at risk of dehydration (fever, diarrhea, hot weather, etc.).
VS: Normal blood pressure is maintained.
IVF: Normovolemia is maintained and the intake of PO fluids is encouraged.