Editing Trepanning (section)

== Tools and methods ==
In ancient times, trepanation instruments were less complex, and were commonly made out of flint, obsidian, or harder material such as stone knives, and later with metal such as bronze and copper.<ref name=":1">{{Cite journal|last=Verano|first=John W.|date=2017-12-01|title=Reprint of-Differential diagnosis: Trepanation|journal=International Journal of Paleopathology|language=en|volume=19|pages=111–118|doi=10.1016/j.ijpp.2017.03.004|pmid=29198392|issn=1879-9817|doi-access=free}}</ref> Additionally, the procedure was done by practitioners utilizing ''[[tumi]]'' (ceremonial knife in early Peru), sharpened seashells (South Pacific), a trephine drill, bronze knife, etc.<ref name=":1" /> The Greeks and [[Surgery in Ancient Rome|Romans]] were the first to design medical instruments to penetrate the skull.<ref name=":2">{{Cite journal|last=Faria|first=Miguel A.|date=2013-04-05|title=Violence, mental illness, and the brain – A brief history of psychosurgery: Part 1 – From trephination to lobotomy|journal=Surgical Neurology International|volume=4|page=49|doi=10.4103/2152-7806.110146|issn=2229-5097|pmc=3640229|pmid=23646259 |doi-access=free }}</ref> Such instruments includes the ''terebra serrata'', made to perforate the cranium by positioning the instrument's pointed end against the cranium and manually rolling the instrument's shaft back and forth between the surgeon's two hands.<ref name=":2" /> By the Renaissance period, when trepanation was routinely performed, a range of instruments were developed to accommodate the demand.

As many as five main methods were found for trephination: 
# Rectangular intersecting cuts
# Scraping utilizing an abrasive instrument such as flint
# Circular grooving
# Boring and cutting by a circular trephine or crown saw
# Burr hole done by drilling several circle holes closely to create a space and then cut/chisel the bone between the hole.<ref>{{Cite web|url=https://thereader.mitpress.mit.edu/hole-in-the-head-trepanation/|title=A Hole in the Head: A Complete History of Trepanation|date=2019-08-29|website=The MIT Press Reader|language=en|access-date=2020-04-28}}</ref><!-- this citation applies to all 5 items -->
The scraping method was found to be the most common in prehistoric times.<ref name=":1" /> The differences in method vary in the amount and depth of bone being removed. The trepanation surgical procedure includes exposure of the dura mater without damaging the underlying blood vessels, [[meninges]], and brain. Over time, the skin will reform over the puncture site, but the hole in the skull will remain.

The location of the trepanation on the skull varies by geographical region and period, common locations are the [[Frontal bone|frontal]] and the [[Occipital bone|occipital]] bones.<ref name=":3">{{Cite journal|last1=Kushner|first1=David S.|last2=Verano|first2=John W.|last3=Titelbaum|first3=Anne R.|date=June 2018|title=Trepanation Procedures/Outcomes: Comparison of Prehistoric Peru with Other Ancient, Medieval, and American Civil War Cranial Surgery|journal=World Neurosurgery|volume=114|pages=245–51|doi=10.1016/j.wneu.2018.03.143|issn=1878-8769|pmid=29604358|hdl=10150/628576|s2cid=4484348|hdl-access=free}}</ref> In most cases, trepanation was a one-off operation, with only a small percentage of the trepanned skulls having undergone more than one surgery. In those with multiple openings, the extent of bone remodelling helps identify whether the opening was done at around the same time or at different times during the individual's life.<ref name=":3" />