Ventriculostomy is a neurosurgical procedure that involves creating a hole (stoma) within a cerebral ventricle for drainage.
When catheter drainage is temporary, it is commonly referred to as an external ventricular drain (EVD).
EVD ventriculostomy (catheter within the lateral ventricle with tip at the foramen of Monro) is done primarily to monitor the intracranial pressure as well as to drain cerebrospinal fluid (CSF), primarily, or blood to relieve pressure from the central nervous system (CNS).
For example, a "third ventriculostomy" is a neurosurgical procedure that creates a hole in the floor of the third ventricle and usually has no indwelling objects.
Other types of ventriculostomy include ventriculocisternostomy developed by the Norwegian doctor Arne Torkildsen.