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BACKGROUND

Stroke refers to acute vascular events involving the brain, brainstem, or spinal cord. Subtypes of stroke in the pediatric population include arterial ischemic stroke (AIS), cerebral sinovenous thrombosis (CSVT) with or without venous infarction, and hemorrhagic stroke (HS). By age, stroke subtypes can be further subdivided into perinatal (occurring from 20 weeks of gestation to 1 month of age by the broadest definition) and childhood stroke (occurring from 1 month to 18 years).1 AIS is defined as an acute neurological deficit of any duration consistent with focal brain ischemia conforming to an arterial distribution (Figure 121-1) and evidence of infarction on neuroimaging. A transient ischemic attack (TIA) is defined as focal deficit(s) in a vascular territory lasting less than 24 hours; we include the absence of infarction on neuroimaging (restriction of water diffusion) in this definition. CSVT involves thrombosis of the superficial or deep dural venous sinuses. If thrombosis sufficiently impedes venous drainage, both ischemic and hemorrhagic infarction can occur. Hemorrhagic stroke is comprised of nontraumatic intracerebral hemorrhage (ICH) which can be intraparenchymal (IPH) and/or intraventricular (IVH) and subarachnoid hemorrhage (SAH).

FIGURE 121-1.

MRA showing normal arterial anatomy. A. Right internal carotid artery. B. Right middle cerebral artery. C. Left anterior cerebral artery. D. Left vertebral artery. E. Basilar artery. F. Left posterior cerebral artery. Anterior and posterior communicating arteries are not easily visible.

Stroke incidence in the pediatric population is estimated at about 2.3 per 100,000 per year in developed countries, and unlike in adults, for whom about 85% are arterial ischemic, in children about half of all strokes are hemorrhagic.2 Boys are affected more commonly than girls, and in the United States, African Americans have a higher incidence than children of other races, findings not entirely explained by sickle cell anemia or trauma.2 The perinatal period is a time of particularly high risk with an incidence of 1 in 4000 live births.3 Stroke is among the top ten causes of death among US children.1 Case fatality rates are estimated at 2% to 5% for AIS, 5% to 10% for CSVT, and 5% to 25% for ICH/SAH. Some deaths, however, may be due to comorbid disease rather than the stroke and its secondary consequences. Among survivors, two-thirds or more may have permanent neurological deficits.

PATHOPHYSIOLOGY AND RISK FACTORS

ARTERIAL ISCHEMIC STROKE

Arterial ischemic stroke results when blood flow is obstructed or diminished by occlusion of an artery (Figure 121-2) (Table 121-1). This may be due to a thromboembolic mechanism that begins at a local (artery-to-artery embolus) or distal (cardioembolic or paradoxical) source, inflammatory or non-inflammatory steno-occlusive disease intrinsic to the arterial wall (arteriopathy or vasculopathy), or an extrinsic process that results in vessel wall compression (mass lesion, trauma, or cerebral edema). Ischemia deprives neurons ...

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