An external ventricular drain (a/k/a ventriculostomy or extraventricular drain), is a device drilled through the skull and into the ventricles (fluid-containing cavities where the cerebrospinal fluid (CSF) is produced) in the brain. An EVD is used in neurosurgery to treat hydrocephalus, i.e., when the normal flow of CSF is obstructed in order to relieve increased ICP.
External Ventricular Drain (EVD) medical expert witness specialties include neurosurgery.