Chapter 552

Stroke denotes the sudden onset of a focal neurologic deficit and most often includes the abrupt appearance of weakness. Interruption of blood flow to a part of the central nervous system (CNS) usually underlies the resultant weakness. Because most strokes in children are related to focal cerebral involvement, the most common clinical manifestation is the abrupt appearance of hemiparesis. Less frequently, the cause of stroke involves the brainstem, cerebellum, or spinal cord. The functional consequences always reflect the neuroanatomic features of the affected CNS region. Either focal cerebral ischemia or hemorrhage may cause the clinical manifestations of stroke. Further, ischemic stroke in children is attributable to either arterial ischemic stroke (AIS) or to cerebral sinovenous thrombosis (CSVT). This chapter addresses these causes of focal cerebral injury in children. First, epidemiologic features of stroke in children will be presented. Consideration will then be directed to the occurrence of pediatric cerebrovascular disease in neonates as well as in older children. Emphasis will be placed on the pathogenetic, clinical, diagnostic, and therapeutic aspects of the varied causes of strokes in children.

Stroke in children follows a biphasic pattern of occurrence. Its occurrence is highest among newborns and occurs less frequently in children greater than 30 days of age. Among neonates, studies indicate an occurrence of stroke that approximates a frequency of 1 in 4000 births.1-3 Arterial ischemic stroke accounts for 80% of these occurrences, although 20% are due tocerebral sinovenous thrombosis (CSVT) and hemorrhage (excluding intraventricular and subarachnoid hemorrhages).4,5

Several studies of stroke in children older than age 1 month, performed over the last three decades have reported an occurrence of stroke at a rate of approximately 2 in 100,000 per year.6-8 However, recent studies suggest that the frequency may be greater and as high as 13 in 100,000 per year.5,9 Strokes occur more often in males than in females and more frequently in African Americans and Caucasians.

Ischemic injury to the brain occurs as a result of one of three different mechanisms: embolism, thrombosis, or diminished systemic perfusion. Embolic damage to the brain occurs when material formed at a site in the vascular system proximal to the brain lodges in a blood vessel, blocking cerebral perfusion. Emboli originate most commonly from the heart, arising from clots on cardiac chamber walls or from vegetations on valve leaflets. Congenital heart disease that includes right-to-left shunt predisposes to such embolus formation. Artery-to-artery emboli are composed of clot or platelet aggregates that originate in vessels proximal to the brain but ultimately come to rest and to occlude flow in vessels critical for cerebral perfusion. Intravascular embolus formation is promoted by some forms of thrombophilia (see below). Thrombosis denotes vascular occlusion resulting from a localized process within a blood vessel or vessels. Although atherosclerosis underlies most thrombotic processes affecting adults, it is a very uncommon cause of thrombosis in children. Localized luminal clot formation occurs in ...

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