Introduction

Childhood arterial ischemic stroke (AIS) has received increasing attention as a cause of morbidity and mortality in the pediatric population. Several population based studies in the USA have demonstrated an incidence of childhood AIS at 0.63–1.2 cases per 100,000 children per year [1,2]. Of the estimated 83,000,000 children in the USA [3], nearly 1,000 will suffer an AIS this year. Extrapolating from the 2012 world population of 2,314,000,000 children [4], approximately 28,000 children will experience an AIS this year worldwide. Despite these increasingly recognized large numbers of childhood AIS cases, the pathogenesis, risk factors and outcomes of childhood AIS have only recently been explored. International networks, such as the International Pediatric Stroke Study (IPSS), have initiated large multicenter series demonstrating the natural history of this disease. Treatment trials, however, are still lacking. As a result, specific prevention and treatment strategies for childhood AIS remain largely unclear in all subtypes except sickle-cell related AIS. The purpose of this chapter is to review the current understanding of childhood AIS by stroke subtype, with a focus upon epidemiology, risk factors, pathophysiology, treatments and outcomes. Particular emphasis will be made on the hematologic risk factors for this disease, with special sections for sickle cell disease thrombotic risk factors.

Epidemiology

Most population-based estimates of childhood-onset AIS are over 20 years old, with the initial estimate coming from a 10-year cohort of children in Rochester Minnesota [1], and the second from the Cincinnati metropolitan area [2]. With the increased availability of magnetic resonance imaging (MRI) with diffusion-weighted imaging in pediatric hospitals, these previous estimates of incidence (0.63–1.2/100,000 children per year [1,2] may actually underestimate the disease. Childhood AIS clearly occurs in males more often than females, with one series of 1,187 children finding that 59% of their cohort was male [5]. Interestingly, known trauma accounts for some of this disparity, as 75% of patients with traumatic dissection are male. Males are over-represented in cases without trauma as well; making it unclear if the gender disparity is the result of known trauma and unrecognized trauma, or if an alternative mechanism is invoked.