- 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 progressing arterial narrowing permits development of collateral channels. However, cerebral perfusion is gradually decreased to the borderline and ischemic symptoms appear for minutes usually with hyperventilation episodes such as crying with or without emotional upset, eating hot food with blowing, inflating balloons, or playing woodwind instruments.
- 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 lung injury in children with Moyamoya Disease, a cerebral infarction may occur because of hyperventilation caused by chest injury. The site of infarction is mainly in watershed areas of the brain. The cerebellum is not involved in the ischemia or infarction.
- 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: Headache reflects compensatory vasodilatation of cerebral arterial trees with chronic or compensated cerebral ischemia. It typically has characteristics of aggravation in the morning, frontal location, occasional orbital pain, possible provocation with hyperventilation and poor response to 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 at the basal ganglia or around the foramen of Monro.
- Involuntary movements: Some patients show involuntary movement. It seems related to the brain ischemia and is relieved after revascularization surgery.
Patterns of Evolution
- Natural Course: The natural course of Moyamoya Disease is progressive bilateral complete or near complete occlusion of internal carotid arteries and branches (middle and anterior cerebral arteries). Frequently 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 intracranial major vessels slowly occlude, extracranial anastomotic channels develop and cover almost total cerebral perfusion requirement. During this process, shortage of 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 present with developed moyamoya: Even though the angiographic staging is helpful for understanding of natural course of Moyamoya Disease, the typical presentation is Suzuki III-IV (moyamoya easily visualized on angiography with an increasing abnormal appearance and beginning disappearance of arterial branches of circle of Willis distal to moyamoya (53), 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 manifestation is 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 by 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 tool for the initial evaluation.
Intervention at Presentation
- 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.
- Fluids: Normovolemia is maintained with intravenous infusions and the intake of po fluids encouraged.
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