Trepanning

Trepanning, also known as trephination, trephining or making a burr hole is a surgical intervention in which a hole is drilled or scraped into the human skull.

The word derives from the verb trepan via Old French and therefrom via Medieval Latin from the Greek noun of relevant meaning trypanon, literally "(a) borer, (an) auger".

In Medieval times it was used by doctors to ‘treat health problems related to intracranial diseases’, like migraine, epileptic seizures and mental disorders!  Wherever there was thought to be pressure, they bored a hole to let the pressure out.  The instrument used for cutting out the round piece of skull bone is called a trephine.

So much for doctors. 

Now we need to look back in time.  Evidence of trepanation has been found in prehistoric human remains from Neolithic times onward. Cave paintings indicate that people used trepanation then and in those days the bone that was trepanned was kept by the prehistoric people and 'may have been worn as a charm'. 

The reason for doing it was totally different from that employed by our esteemed medical profession – it derived from the belief that it would help in spiritual experience – by enabling the energy to flow in and out of the crown chakra more easily.

Do not try this at home. [Sorry - a joke]