Cerebrovascular Disorders

Chapter 36

Cerebrovascular Disorders

Stroke is defined as a neurologic deficit persisting for more than 24 hours. Stroke may be caused by either cerebral ischemia or intracranial hemorrhage. The estimated annual incidence of stroke in children ranges from 2 to 13 per 100,000 person years and is among the top 10 causes of death in childhood.1

The presentation of stroke in children is sometimes heralded by the abrupt onset of a focal neurologic deficit, but often, especially in infants and young children, the symptoms are nonspecific and the diagnosis of stroke is frequently delayed. Although many children who have had a stroke recover completely, more than 75% will have a perceptible persistent neurologic deficit, and more than 40% will have major neurologic sequelae.2

Unlike adults, in whom hypertension, diabetes, smoking, and hypercholesterolemia are frequently identified as risk factors for the development of stroke, cerebrovascular arteriopathy, vascular anomalies, aneurysms, congenital heart disease, sickle cell disease, and hematologic abnormalities are among the most common predisposing conditions in children.1 More than half of all strokes in children are ischemic, caused either by an intrinsic vasculopathy or emboli from a remote source.2 Vascular malformations, aneurysms, and venous sinus thrombosis are the most common causes of hemorrhagic stroke. This chapter focuses on intrinsic vascular abnormalities as causes of ischemic and hemorrhagic pediatric stroke.


Ischemic stroke in children has an annual incidence of between 2 and 3 per 100,000 children in the United States.3 The causes of ischemic stroke in children are diverse and include a variety of cerebrovascular entities in approximately 70% of children, such as arterial dissection, moyamoya disease or syndrome, sickle cell disease, isolated angiitis of the central nervous system or vasculitis, coagulopathy, or other known source; the remainder of cases are idiopathic in origin. More than one risk factor may be present. Twenty-five percent of children with ischemic stroke have coexistent cardiac disease.2 Metabolic disorders, such as mitochondrial diseases and hyperhomocysteinemia, should be considered in the differential diagnosis of ischemic stroke in children, especially if the distribution of the infarction does not conform to an arterial territory.

The most common symptoms of ischemic stroke in children are hemiplegia, seizures, fever, dysphagia, headache, and altered level of consciousness. Headache and seizures are especially common in chronic ischemic conditions such as moyamoya disease.4

Imaging: The imaging features of ischemic stroke in children are variable and depend on the underlying cause. In acute arterial dissection, an end arterial distribution infarction is often present on computed tomography (CT) or magnetic resonance imaging (MRI). By contrast, in proximal, chronic steno-occlusive disease such as moyamoya disease (Fig. 36-1), infarctions may be absent, conform to an arterial territory, or lie within the border zones between the major vascular territories. In chronic multivessel steno-occlusive disease, there may be a shift in the location of the vascular border zones because of differential involvement of the various branches of the circle of Willis.

Noninvasive vascular imaging such as computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) typically shows an abrupt vascular cutoff with dissection and thromboembolic stroke. In moyamoya disease, stenosis or occlusion of the supraclinoid segment of the internal carotid and proximal middle or anterior cerebral artery is usually present, with numerous collateral vessels in the basal ganglia at certain stages of the disorder.5 Vasculitis causes irregular narrowing of medium or small vessels and is inconsistently demonstrated on CTA or MRA.6 Catheter angiography remains the gold standard for the imaging diagnosis of cerebrovascular disease in children and should be considered whenever a small vessel vasculitis is suspected or when surgical treatment is contemplated.

Vascular Anomalies

Vascular anomalies are disorders of vascular development. Although congenital, they may only become symptomatic many months or years after birth. Intracranial vascular malformations are classified according to the vascular channels involved and the hemodynamics of the lesion (high-flow vs. low-flow).7

High-Flow Vascular Anomalies

High-flow vascular anomalies occur when there is an abnormal connection between an artery and a vein that bypasses the normal arteriolar-capillary network. In arteriovenous fistula (AVF), the supplying artery communicates directly with the draining vein through a macroscopic fistula. In arteriovenous malformation (AVM), the supplying artery connects with the draining vein through a plexiform network of abnormal vessels, termed the nidus. Both AVF and AVM are further subdivided, on the basis of anatomic location, into dural, subarachnoid (vein of Galen malformation), pial, or parenchymal (Figs. 36-2, 36-3, and 36-5; e-Fig. 36-4).7,8

High-flow vascular malformations may produce symptoms and signs in several ways.7,9,10 The presence of an abnormal connection between a supplying artery and a draining vein allows for potentially rapid blood flow through the anomaly. In the absence of venous outflow obstruction, the malformation may cause high-output cardiac failure due to the lack of regulation of blood flow through the normal arteriolar and capillary network. The lower resistance through the malformation may result in diversion of blood away from the normal brain parenchyma (“steal” phenomenon), producing cerebral ischemia. High-flow malformations also expose the draining veins to arterial pressure, which may cause progressive stenosis of the vein, termed high-flow venopathy. High-flow venopathy may be a cause of seizures or cerebral atrophy due to impaired tissue perfusion from a diminished arterial-venous pressure gradient. Hydrocephalus can develop from increased venous pressures, that result in impaired resorption of cerebrospinal fluid (CSF) (see Fig. 36-3, A). Elevated venous pressure can also result in the development of a varix that predisposes to hemorrhage.

Dural High-Flow Anomalies

Dural AVF or AVM comprise a meningeal arterial supply with dural venous sinus drainage and often present in the prenatal or immediate postnatal period as a cause of fetal or neonatal heart failure (see Fig. 36-2).7,10,11 The anomalies may include a single or multihole fistula or complex malformation. The abnormal connections are frequently located either in the vicinity or in the torcular herophili or involve dural venous sinuses that drain into the torcular herophili.

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Dec 20, 2015 | Posted by in PEDIATRIC IMAGING | Comments Off on Cerebrovascular Disorders

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