Trephination: Unlocking the Mysteries of Ancient Brain Surgery

Long before operating rooms, anesthesia, or even a basic understanding of brain anatomy, ancient humans were performing surgery on the skull. Trephination – the practice of deliberately drilling, scraping, or cutting a hole into the skull – is one of the oldest surgical procedures ever recorded, with evidence stretching back over 8,000 years. It sounds extreme, but the archaeological record tells a surprisingly nuanced story: patients survived, practitioners improved their technique over centuries, and the procedure laid early groundwork for what would eventually become modern neurosurgery and neuropsychology.

What is trephination? 🔗

The word “trepanation” comes from the ancient Greek trypanon, meaning “borer” or “auger.” The procedure – also referred to as trepanning, trephining, or simply making a burr hole – involved creating an opening in the skull using sharp instruments. Prehistoric cultures used tools like flint, obsidian, and early metal instruments to perform this operation. Crucially, unlike the modern craniotomy where the removed bone segment is replaced, trephination left a permanent hole in the skull.

The goal was to expose the dura mater – the tough membrane covering the brain – without damaging the underlying blood vessels, brain tissue, or meninges beneath. Five main methods have been identified archaeologically: scraping, grooving, cutting and intersection, drilling circular burr holes, and sawing. Of these, scraping appears to have been most common in prehistoric times.

How old is the evidence? 🔗

Evidence of trepanning appears in 5-10% of all Neolithic (8,000-3,000 BC) skulls found across Europe, Scandinavia, Russia, North and South America, and China. The oldest confirmed trepanned skull from China dates to around 5,000 years ago, found in Shandong, and shows smooth bone edges suggesting the individual survived the procedure and lived for some time afterward.

Perhaps the most significant archaeological record comes from South America. Archaeologists have uncovered over 10,000 trepanned skulls in Peru alone, making it the single richest site of this practice in the world. It was a Peruvian skull that first forced 19th-century Western scientists to take ancient neurosurgery seriously – when American archaeologist Ephraim George Squier presented a trepanned Inca skull to the New York Academy of Medicine in 1865, the audience refused to believe that anyone could have survived a procedure carried out without modern surgical standards. Their skepticism was partly informed by the fact that in leading Western hospitals of that era, survival from trephination rarely reached 10% – largely due to hospital-acquired infections.

Why was trephination performed? 🔗

The motivations behind trephination were mixed, spanning medical, neurological, and spiritual domains. Understanding these reasons offers a window into how ancient peoples conceptualized the relationship between the brain and behavior.

Traumatic head injuries 🔗

The most medically grounded reason was physical trauma. Trephination was most commonly conducted on individuals with head injuries – allowing surgeons to remove shattered bone fragments and drain blood pooling under the skull. Hunting accidents, falls, animal attacks, and weapons such as clubs and sling stones were frequent causes of these injuries. The procedure appears to have been most common in cultures where weapons capable of producing skull fractures were widely used – a pattern consistent with battlefield medicine rather than purely ritual practice.

Epilepsy and psychiatric conditions 🔗

Hippocrates, writing around 400 BC, believed trephination could relieve seizures in people who had suffered traumatic head injuries. This early association between skull surgery and neurological behavior is significant – it represents one of the earliest recorded attempts to intervene in what we now call brain function to alter behavioral or cognitive outcomes. Trepanning was also used to treat mental health conditions such as epilepsy, a practice that continued into the 18th century. The logic, while not grounded in modern anatomy, was not entirely unreasonable: if behavior seemed disordered, perhaps the skull itself was the source of pressure or imbalance.

Spiritual and religious beliefs 🔗

In some ancient societies, trepanning was performed on individuals whose behavior was considered abnormal, under the belief that it released evil spirits thought to be causing the condition. In China, twelve shaman corpses in a tomb were found with trephined skulls, reflecting a connection between cranial surgery and communication with spiritual forces. In ancient Peru, illness was believed to arise when a person became spiritually separated from their body, and trepanation was part of restoring that balance. Bone discs removed from skulls were sometimes kept and worn as charms, suggesting that the procedure held symbolic as well as physical significance.

Survival rates: more impressive than expected 🔗

One of the most striking findings from modern analysis of ancient trepanned skulls is how often patients survived. Archaeologists have established that cranial operations using different techniques have a history of at least 7,000 years, and the bone evidence tells us a great deal about patient outcomes. When new bone forms around a wound’s edge – showing calcium deposits and new tissue growth – it confirms the patient lived for months after the procedure. Skulls with no biological activity around the site suggest near-immediate death. Skulls showing partial healing indicate survival of weeks.

A 2018 study analyzing 800 trepanned skulls from Peru found that long-term survival rates ranged from 40% in early periods (400-200 BC) to as high as 91% during the period 1000-1400 AD, with an average rate of 75-83% during the Inca Empire. By comparison, the mortality rate from cranial surgeries during the American Civil War was 46-56%. The Inca’s success is attributed to performing procedures outdoors (reducing hospital-acquired infections), using herbal medicines, and employing single-use tools.

This stands in stark contrast to 18th-century European hospitals, where trephination reached nearly 100% fatality – not because the operation itself was fatal, but because rampant infection in hospital environments killed patients postoperatively. Ancient Peruvian practitioners, working in open air with plant-based medicines and careful technique, outperformed European surgeons by a significant margin.

Techniques and tools used 🔗

Ancient practitioners were not working randomly. Roman physician Celsus, writing between 25 and 35 AD, provided careful and precise instructions on trephination methodology in his work De Medicina, advising the procedure for head wounds with explicit guidance on how to avoid damaging the dura. Greek physicians including Hippocrates, Galen, and Heliodorus all recommended trephination for specific categories of skull fractures.

Persian and Islamic physicians in the Middle Ages, including Rhazes, Avicenna, Avenzoar, and Albucasis, further advanced the technical knowledge of trephination. Albucasis (936-1013 AD) documented the use of drills and emphasized the importance of not penetrating the dura membrane – a refinement that directly improved patient safety. A circular trephine or crown saw, featuring a retractable central pin and a transverse handle, has remained relatively unchanged from ancient times to today, demonstrating the enduring practicality of the basic design.

Trephination’s place in the history of neuropsychology 🔗

Trephination is significant not just as a medical curiosity but as an early chapter in humanity’s effort to understand the brain’s role in thought, emotion, and behavior. The very act of drilling into the skull to relieve a psychiatric condition or control seizures reflects a dawning – if imprecise – recognition that the brain matters. These ancient practitioners did not have words for neuropsychology, but they were asking neuropsychological questions: Why does this person behave strangely? Why do they have seizures? Can we fix it by intervening in the head?

By the late 19th century, neurologist Hughlings Jackson’s study of focal seizures helped the medical community understand localized brain function, building directly on centuries of observation that followed ancient skull surgery. Trephining remains in use in modern neurosurgical medicine – not only as a therapeutic procedure but for exploratory diagnosis, relieving intracranial pressure from hematomas, debriding penetrating wounds, and gaining access to the brain for stereotactic procedures. The instrument used today is recognizably descended from the one used 7,000 years ago.

The prefrontal leucotomy – a precursor to the lobotomy – involved cutting a hole in the skull to access and alter the brain’s frontal lobe, a procedure used well into the 20th century. In that sense, trephination was not merely a historical footnote; it was the technical ancestor of some of the most consequential (and controversial) interventions in the history of psychiatry and neuroscience.

From ritual to science: what trephination tells us 🔗

Trephination captures a pivotal tension in the history of medicine: the line between spiritual interpretation and empirical observation was not always clear, and yet practical knowledge accumulated anyway. Ancient surgeons who operated on skull fractures were learning – through trial, error, and observation of healing – what worked. Their spiritual framing did not prevent them from developing real surgical skill. In many ways, trephination illustrates how early humans used the tools and concepts available to them to address problems we still grapple with today: how to treat brain injury, how to manage neurological disease, and how the brain shapes the person.

What do you think? Given that ancient Peruvian surgeons achieved survival rates that outperformed 19th-century European hospitals, what does that suggest about the relationship between cultural context and medical success? And does the fact that trephination was used for both physical trauma and psychiatric conditions tell us something meaningful about how early humans understood the brain’s role in behavior?

References

1. https://www.medicalnewstoday.com/articles/326281
2. https://medcardia.com/ancient-brain-surgery-trepanation-history/
3. https://en.wikipedia.org/wiki/Trepanning
4. https://www.historyhit.com/ancient-neurosurgery-what-is-trepanning/
5. https://thereader.mitpress.mit.edu/hole-in-the-head-trepanation/
6. https://www.epilepsy.com/stories/surgery-epilepsy-trephination-innovation
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC3876527/
8. https://www.facs.org/for-medical-professionals/news-publications/news-and-articles/bulletin/2022/november-december-2022-volume-107-issue-11/from-the-archives/
9. https://www.science20.com/recreational_number_theory/ancient_brain_surgery