What is the creation of an opening into a brain ventricle called?

The surgical creation of an opening into a brain ventricle is called as Ventriculostomy. It is a neurosurgical procedure which involves making a hole in the cerebral ventricle for the purpose of drainage. The procedure involves the penetration of the skull, the dura mater and the brain so as to access the brain ventricle by inserting a tube into the hole. It is also known as ventricular catheter or the external ventricular drain. Its main purpose is to drain the cerebrospinal fluid externally. It is done for patients who suffer head trauma and hydrocephalus. Also, for brain surgeries and administration of medicines.