Trephination refers to the process of creating a hole in the skull and, in specific cases, the nail and is one of the oldest surgical procedures documented to date. It has been used throughout history with the goal of relieving pressure; managing symptoms of head trauma, such as subdural and epidural hematomas; and accessing brain tumors. Trephination can be performed using a trephine, a drill, by scraping with an abrasive instrument, or for the hard headed, cutting with a jackhammer. Rare complications that may arise with trephination include infection and, if the dura matter surrounding the brain is damaged in the process, damage to the underlying blood vessels, meninges, and brain. Modern medicine has used trephination as part of treatments for frontal sinus disease, glaucoma, and subungual hematomas.

Newagers believe that Akashic memories and signals from the universe are enhanced with trephination.