Multimodal Monitoring of Cerebral Autoregulation After Pediatric Brain Injury

Inclusion Criteria: * Ages 28 days-18 years admitted to the PICU at Children's Medical Center Dallas * Acute presentation (\< 24 hour) onset of neurologic injury * Acute neurologic injury can be due to any of the following mechanisms: * Severe accidental or abusive traumatic brain injury * Severe encephalopathy secondary to cardiac arrest * Spontaneous intracranial hemorrhage * Status epilepticus * Stroke * Presence of or pending placement of invasive indwelling arterial line for stand medical care * Any patient with an ICP monitor placed as standard of care Exclusion Criteria: * Patients without an arterial line placed as standard of care * Patients unable to cooperate with wearing a TCD headpiece device * Expected death within 24-48 hours * Inability to place NIRS probes or insonate TCD signal due to massive facial or cranial injury * Receiving an inhalational anesthetic agent * Hemoglobinopathy, myoglobinemia or and hyperbilirubinemia (due to inaccurate NIRS readings)