Capsular Warning Syndrome Leading to Acute Ischemic Stroke in a Pediatric Patient Secondary to Varicella Zoster Virus.

We report the case of a 3-year-old boy who presented with recurrent stereotyped transient episodes of left sided weakness consistent with capsular warning syndrome (CWS) which eventually progressed to acute ischemic stroke (AIS). He received thrombolytic therapy with tissue plasminogen activator. Workup was notable for positive CSF varicella (VZV) PCR, and positive CSF and serum VZV IgG and negative IgM. On further history, he was unvaccinated and had a rash consistent with VZV 5 months prior to presentation. This case highlights the importance of recognizing CWS given the increased risk of progression to AIS. In addition, it emphasizes the importance of considering VZV vasculopathy in pediatric AIS and inquiring about infectious history and immunization status despite high rates of vaccination in the United States.