Pediatric Stroke Syndromes

Arterial blood reaches the brain via the anterior (internal carotid) and posterior (vertebrobasilar) circulations, converging at the circle of Willis. Strokes involve the middle cerebral artery (MCA) territory more frequently than either the anterior or posterior cerebral arteries. AIS is the focal brain infarction that results from occlusion of these arteries or their branches. AIS is a leading cause of acquired brain injury in children, with the perinatal period carrying the highest risk (see later).

In children the diagnosis of stroke is frequently delayed or missed. This is due to subtle and nonspecific clinical presentations, a complicated differential diagnosis (Chapter 594.4) and a lack of awareness by primary care pediatric physicians. The acute onset of a focal neurologic deficit in a child is stroke until proven otherwise. The most common focal presentation is hemiparesis but acute visual, speech, sensory, or balance deficits also occur. Children with these presentations require urgent neuroimaging and consultation with a child neurologist as emergency interventions may be indicated. AIS is a clinical and radiographic diagnosis. CT imaging can demonstrate larger mature AIS and exclude hemorrhage, however MRI identifies early and small infarcts and is therefore required to exclude ischemic stroke. Diffusion weighted MRI (DWI) can demonstrate AIS within minutes of onset, and MR angiography can confirm vascular occlusion and suggest arteriopathy as the underlying cause (Fig. 594-1).

Figure 594-1 Arterial ischemic stroke. A healthy 3 yr old boy experienced the sudden onset of left-sided weakness. Examination also demonstrated left-sided hemisensory loss and neglect. Diffusion weighted MRI shows focal increased signal in the right temporal-parietal region in the territory of the middle cerebral artery (MCA, A). Apparent diffusion coefficient map confirms restricted diffusion consistent with infarction (ischemic stroke) (B). MR angiogram shows no occlusion or stenosis and decreased flow in the MCA (C). Follow-up MRI at 3 mo shows atrophy and gliosis in the same region (D).

Most etiologies for AIS are well-established; some represent only potential associations (Tables 594-1 and 594-2). AIS often remains idiopathic although most children have identifiable, frequently multiple risk factors. Three main categories of etiology should be considered: arteriopathic, cardiac, and hematological; full investigation often reveals multiple risk factors in a given individual.

Table 594-1 COMMON RISK FACTORS FOR ARTERIAL ISCHEMIC STROKE IN CHILDREN

Arteriopathy refers to disorders of the cerebral arteries and has emerged as the leading cause of childhood AIS, present in >50% of children. Idiopathic arterial stenosis has been termed focal cerebral arteriopathy (FCA), and may be more specfically identified as transient cerebral arteriopathy (TCA) or postvaricella angiopathy (PVA). These diseases likely represent focal, localized, unilateral vasculitis. More diffuse or bilateral vasculitis may be primary or associated with systemic inflammatory conditions (Table 594-3). Arterial dissection can be spontaneous or post-traumatic and can affect extracranial internal carotid or vertebral arteries, or intracranial arteries. Moyamoya disease may be idiopathic or associated with other conditions (NF-1, trisomy 21, sickle cell anemia, radiation therapy) and demonstrates progressive occlusion of the distal internal carotid arteries (Table 594-4, Fig. 594-2). Congenital malformations of the craniocervical arteries, including PHACES syndrome, may predispose to AIS.

From Roach ES, Golomb MR, Adams R, et al: Management of stroke in infants and children, Stroke 39:2644–2691, 2008, Table 5, p 8.

Table 594-4 RISK FACTORS FOR MOYAMOYA DISEASE

Other syndromes, 1 patient each: Reye (remote), Williams, Alagille, cloacal exstrophy, renal artery fibromuscular dysplasia, and congenital cytomegalic inclusion virus infection (remote). Two patients had unclassified syndromic presentations. There were 4 blacks, 2 of whom had sickle cell disease.

From Roach ES, Golomb MR, Adams R, et al: Management of stroke in infants and children, Stroke 39:2644–2691, 2008, Table 6, p 11.

Figure 594-2 Cerebral angiogram showing idiopathic supraclinoid–internal carotid arteriopathy with classic moyamoya collaterals (arrow).

Cardioembolic stroke comprises about 25% of childhood AIS with embolism occurring either spontaneously, or during catheterization or surgical repair. AIS complicates 1 in 185 pediatric cardiac surgeries, and re-operation increases the risk. Complex congenital heart diseases are the most frequent cause for AIS, however acquired conditions including arrhythmia, cardiomyopathy, and infective endocarditis should also be considered. The presence of a patent foramen ovale provides the possibility of paradoxical venous thromboembolism. All children with suspected AIS require thorough cardiovascular examination, electrocardiogram, and echocardiogram.

Hematologic disorders include iron deficiency anemia and sickle cell anemia (SCA). In SCA the risk of AIS is increased 400-fold. Coagulation disorders are also frequently identified in AIS. They include hereditary (e.g., factor V Leiden) and acquired (e.g., antiphospholipid antibodies) prothrombotic states and prothrombotic medications,