Trephination is absolutely still used today, though you won’t hear most surgeons call it that. The ancient practice of drilling a hole through the skull has evolved into what neurosurgeons now call a “burr hole” procedure, and it remains one of the most common operations in brain surgery. Beyond neurosurgery, trephination also plays a role in eye surgery and veterinary medicine.
From Ancient Practice to Modern Burr Holes
Trephination is one of the oldest known surgical procedures, with archaeological evidence stretching back thousands of years. The word itself comes from a term meaning “borer,” and it became interchangeable with “trephination” because of a French instrument called the tres fines, meaning “three ends.” The core concept hasn’t changed: create an opening through bone to access what’s underneath.
What has changed dramatically is the precision, safety, and purpose. Ancient trephination was likely performed for head injuries, seizures, or spiritual reasons using sharpened stones. Modern burr holes are drilled with engineered tools, guided by imaging technology, and performed under sterile conditions for well-defined medical reasons. A modern craniotomy, the larger skull-opening procedure used for major brain surgery, is actually performed by connecting a series of individual burr holes. So trephination isn’t just surviving in modern medicine. It’s foundational to it.
Why Surgeons Still Drill Through the Skull
Burr holes serve a surprisingly wide range of purposes in neurosurgery. The most common reason is to relieve dangerous pressure on the brain when fluid, typically blood, builds up and compresses brain tissue. According to Johns Hopkins Medicine, the specific conditions treated with burr holes include:
- Acute subdural hematoma: a sudden collection of blood between the brain and its outer covering, often from trauma
- Chronic subdural hematoma: a slower bleed that develops over weeks, more common in older adults
- Epidural hematoma: bleeding between the skull and the brain’s outer membrane
- Hydrocephalus: excess fluid buildup inside the brain’s ventricles
- Brain abscesses: pockets of pus that form around the brain’s protective layers
- Certain brain cancers
Beyond draining fluid, burr holes also serve as access points. When doctors need to monitor pressure inside the skull after a traumatic brain injury, they drill a small hole and thread a monitoring device through it into the brain’s fluid-filled chambers. The same approach is used for external ventricular drains, which allow excess fluid to flow out of the brain through tubing.
Brain Biopsies Through a Single Hole
One of the more precise modern applications of trephination is the stereotactic brain biopsy. When a tumor or abnormal mass is spotted on imaging but doctors need a tissue sample to determine what it is, they can take that sample through a single small burr hole rather than opening the skull widely. The surgeon marks the spot on the skull using coordinates calculated from brain scans, drills the hole, and passes a biopsy needle through it to reach the target deep inside the brain. This can be done with a rigid frame mounted to the patient’s head, frameless navigation systems, or even robotic assistance.
Emergency Trephination in Trauma
In emergency settings, trephination can be lifesaving. Epidural hematomas, where blood collects rapidly between the skull and the brain’s outer layer, can become fatal within hours. Surgical evacuation is recommended when the blood collection exceeds about 30 milliliters, and outcomes worsen sharply when the delay between a patient’s loss of consciousness and surgery stretches beyond two hours.
In hospitals with full neurosurgical teams, this is handled in the operating room with advanced tools. But in remote or resource-limited settings where definitive neurosurgical care isn’t immediately available, a burr hole evacuation can serve as a temporary measure to buy time. The core logic is the same as it was thousands of years ago: relieve the pressure before the brain is permanently damaged.
How Well It Works
For chronic subdural hematomas, burr hole drainage is effective but not always a one-and-done fix. Recurrence rates across studies range from 5% to 26%, meaning some patients will need a repeat procedure. In a study comparing outcomes by age, patients under 80 had a cure rate of about 63% after the initial surgery, with cumulative cure rates climbing to 76% by the one-year mark. Patients 80 and older had lower cure rates (33% initially, reaching 59% at one year) but still benefited substantially. Complication rates were low in both groups, around 4% to 5%.
A larger single-center study of over 1,200 patients found a recurrence rate of 10% and an overall postoperative complication rate of 27.2%, though that figure includes minor complications. The procedure is generally considered safe relative to more extensive skull surgeries, which is part of why it remains a first-line approach for many conditions.
Modern Tools vs. Ancient Ones
The instruments used for trephination have changed beyond recognition. The hand-cranked Hudson brace, a twist drill that a surgeon manually turned, was widely used until the late twentieth century. It has largely been replaced by powered drills with automatic safety features. Disposable cranial perforators now attach to electric drills and include an automatic release mechanism: the drill only spins while the surgeon applies pressure, and it stops the moment it breaks through the inner layer of skull bone. This dramatically reduces the risk of accidentally piercing the delicate membrane covering the brain.
Different perforator designs offer tradeoffs. Some have blunt tips and smooth blades for a more controlled cut, while others feature sharp tips and curved blades that cut through bone faster but carry a slightly higher risk of damaging the underlying membrane at certain angles. Surgeons choose based on the location and purpose of the hole. For surgeries near the back of the skull, different drill systems may be preferred than for holes drilled elsewhere.
Trephination Outside the Brain
The principle of using a circular cutting tool to remove a disc of tissue isn’t limited to the skull. In corneal transplant surgery, ophthalmologists use a device called a trephine to cut a full-thickness circle from the patient’s damaged cornea, then replace it with a matching disc from a donor. The donor tissue is typically cut 0.25 to 0.5 millimeters larger than the opening in the patient’s eye to ensure a secure fit. This procedure, called penetrating keratoplasty, is one of the most common types of corneal transplant.
In veterinary medicine, trephination is still performed on horses to treat sinus disease. Horses have large, complex sinus cavities that can become infected or filled with fluid, and drilling through the bone of the face gives veterinarians direct access to flush and drain these spaces. While minimally invasive approaches through the nasal passages are becoming more common, classical trephination and bone flap techniques remain in regular use for equine sinus problems.
Why the Name Changed but the Procedure Didn’t
If trephination is so widely practiced, why do so few people realize it still exists? Largely because the terminology shifted. Calling it a “burr hole procedure” sounds modern and clinical. Calling it “trephination” conjures images of prehistoric skulls with rough-edged holes. But the underlying concept, removing a small disc of bone to access a cavity underneath, is identical. The tools are safer, the indications are evidence-based, and the outcomes are tracked with rigorous data. But a neurosurgeon drilling a burr hole in 2025 is performing the same fundamental operation that humans figured out thousands of years ago.