Intracranial duplex Doppler: practical uses in pediatric neurology and neurosurgery.

The value of pulsed Doppler studies of the cerebral vessels of neonates, infants, and children having neurologic and neurosurgical problems is presented. In this study, Resistive Index--[(peak systolic velocity - end-diastolic velocity)/peak systolic velocity] x 100--was used in correlative studies of pediatric patients having hydrocephalus, extra-axial collections, shunt malfunctions, vascular malformations, and craniocerebral injuries. Age-related normal values for Resistive Index are defined, with special attention to the expected values in patients having normally functioning ventriculoperitoneal shunts. Correlations of Resistive Index with intracranial pressure in animal models, as well as a variety of pathologic pediatric neurosurgical conditions, emphasize the usefulness of pulsed Doppler studies in some conditions as well as limitations in others.