Chickenpox and stroke in childhood - A study of frequency and causation

Background and Purpose - The purpose of this study was to determine whether infection with varicella is causal for arterial ischemic stroke (AIS) in c hildren. Methods - First, a prospective cohort study was conducted in young children (aged 6 months to 10 years) with AIS at 2 institutions (cohort study). The presence of varicella infection < 12 months before AIS was determined and compared with the published frequency of varicella infection in the healthy pediatric population. The clinical and radiographic features of AIS were c ompared between the varicella and nonvaricella study cohorts. Second, a lit erature search of varicella-associated AIS was conducted, and the clinical and radiographic features were compared with the study nonvaricella cohort. Results - In the cohort study, 22 (31%) of 70 consecutive children with AIS had a varicella infection in the preceding year compared with 9% in the he althy population. Children in the varicella cohort were more likely to have basal ganglia infarcts (P <0.001), abnormal cerebral vascular imaging (P < 0.05), and recurrent AIS or transient ischemic attacks (P <0.05) than those in the nonvaricella cohort. The pooled literature analysis of 51 cases of varicella-associated AIS showed similar findings to the varicella cohort. Conclusion - In young children with AIS, there is a 3-fold increase in prec eding varicella infection compared with published population rates, and var icella-associated AIS accounts for nearly one third of childhood AIS. Varic ella-associated AIS has characteristic features, including a 2-fold increas e in recurrent AIS and transient ischemic attacks. Varicella is an importan t risk factor for childhood AIS.