Hello, Oldgoaly. Here is the older version of trepanning. I thought that I had seen the word before, as in older trepanning tools. Regards, Lou
Trepanning, also known as trepanation, trephination, trephining or making a burr hole (the verb trepan derives from Old French via Medieval Latin, from the Greek noun of trypanon, literally "borer, auger")[1][2] is a surgical intervention in which a hole is drilled or scraped into the human skull, exposing the dura mater to treat health problems related to intracranial diseases or release pressured blood buildup from an injury. It may also refer to any "burr" hole created through other body surfaces, including nail beds. It is often used to relieve pressure beneath a surface. A trephine is an instrument used for cutting out a round piece of skull bone.