Thought is was 6, but here:
"insert a shunt into the ventricle to drain cerebrospinal fluid (to treat hydrocephalus)
insert a deep brain stimulator (DBS)
insert an intracranial pressure (ICP) monitor.
remove a sample of tissue cells (needle biopsy)
drain a blood clot (hematoma aspiration)
insert an endoscope to remove tumors."
sorry if this doesn't help or is not the answer you were looking for. good day mate!
