Distinguish between the clinical features of communicating and non-communicating hydrocephalus. Define the indications for external ventricular drains (EVD), ventriculo-peritoneal shunts and lumbar drains. Explain the practical aspects of EVD management in intensive care. Hydrocephalus, derived from the Greek words hydro (water) and kephalos (head), describes a congenital or acquired condition in which there is an excessive accumulation of cerebrospinal fluid (CSF) within the head. There is a wide range of causes, most of which involve obstructed CSF circulation or impaired absorption. 1