trepaning

Trepanation, or trepanning, is a surgical procedure in which a circular section of the skull bone is removed or a hole is drilled through the skull to expose the dura mater or relieve intracranial pressure. The term derives from the Latin trepanare, meaning to bore through, and the instrument used is a trepan, an auger-like drill or circular saw.

Evidence of trepanation appears in archaeological sites across Europe, the Americas, Africa, and the Pacific, with some skulls showing bone healing that indicates survival after the procedure. In ancient contexts, trepanation may have served medical purposes such as treating head injuries, relieving pressure, or removing damaged bone, as well as ritual or spiritual aims in various cultures. Techniques varied widely, using crude flint blades, bronze or iron tools, or later metal trepans to remove a bone fragment or create a hole.

In modern medicine, the term is largely historical, with contemporary procedures for accessing the brain evolving into craniotomy (removal of a bone flap to expose the brain) or craniectomy (temporary removal of bone to relieve pressure). Trepanation remains distinct from these procedures, but the basic idea—creating access through the skull—is shared. Risks include infection, bleeding, brain injury, swelling, and seizures; edges of the skull may heal if the bone is replaced.

Today, trepanation is not a routine medical procedure, and modern neurosurgical techniques, sterile methods, and postoperative care have largely superseded it. It is of interest primarily in historical, anthropological, and medical literature.