Acute ischemic stroke affects roughly 1 in 50,000 children every year and is one of the top ten causes of death in children. Currently, caregivers lay the affected child flat in hopes of increasing blood flow to the brain and reducing the volume of the brain which is damaged. However, there are currently no techniques to measure brain blood flow at the child's bedside and indicate if this treatment is effective. We will probe brain blood volume, oxygen saturation, and flow with red light to determine the efficacy of this intervention.

Arterial ischemic stroke (AIS) affects about 2 children per 100,000 per year and is one of the top 10 causes of mortality in children. After stroke, there is a disturbance in cerebral blood flow (CBF) autoregulation, and changes in head position may change CBF. Currently, practice at the Children's Hospital of Philadelphia (CHOP) is to keep the head of bed (HOB) of a child with AIS flat for 24 hours; however, there is no evidence that this practice is efficacious in children. Furthermore, maintaining a child supine for 24 hours is uncomfortable for the child and is often unenforceable in younger children. This study will use a noninvasive optical technique to measure CBF as HOB position is changed to assess the effectiveness of head of bed position in increasing CBF in children with acute arterial ischemic stroke.

The primary objectives are to determine the difference in CBF at HOB flat (0 degrees) and HOB at +30 degrees in healthy children and in children with AIS. The secondary objectives are to examine CBF in healthy children and in children with AIS at other HOB angles (0, +15, and +30 degrees) compared to the CBF at HOB 0 degrees and to determine if the position that maximizes CBF varies over time from stroke onset.

Inclusion Criteria Healthy Control Subjects

1. Subjects age 2-18 years inclusive
2. No history of congenital or acquired brain injury
3. No history of developmental delay, mental retardation, genetic or metabolic syndrome affecting the brain

Inclusion Criteria AIS Subjects

1. Subjects age 2-18 years inclusive
2. 72 hours or less from stroke onset
3. MRI or CT confirmation of AIS

Exclusion Criteria for All Subjects

1. Skull defect preventing application of probes
2. Moyamoya disease
3. Sickle cell anemia

Children (2-18 y.o.) presenting at the Children's Hospital of Philadelphia with a confirmed arterial ischemic stroke