A cranial drill, also known as a craniotome, is a tool for drilling simple burr holes (trepanation) or for creating larger openings in the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

. This exposes the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

and allows operations like

craniotomy A craniotomy is a surgery, surgical operation in which a bone flap is temporarily removed from the Human skull, skull to access the Human brain, brain. Craniotomies are often critical operations, performed on patients who are suffering from brain ...

and craniectomy to be done. The

drill A drill is a tool used for making round holes or driving fasteners. It is fitted with a drill bit for making holes, or a screwdriver bit for securing fasteners. Historically, they were powered by hand, and later mains power, but cordless b ...

itself can be ''manually'' or ''electrically'' driven, and primarily consists of a handpiece and a

drill bit A drill bit is a cutting tool used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In orde ...

, which is a sharp tool that has a form similar to

Archimedes' screw The Archimedes' screw, also known as the Archimedean screw, hydrodynamic screw, water screw or Egyptian screw, is one of the earliest documented hydraulic machines. It was so-named after the Greek mathematician Archimedes who first described it ...

; this instrument must be inserted into the drill chuck to perform holes and remove materials. The trepanation tool is generally equipped with a

clutch A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...

which automatically disengages once it touches a softer tissue, thus preventing tears in the dura mater. For larger openings, the craniotome is an instrument that has replaced manually pulled saw wires in craniotomies from the 1980s.

History

Cranial drill

The oldest evidence of a hole being applied on a human's brain with a drill dates from c. 4000 B.C. The oldest cranial drilling instrument was found in France, and subsequent use was evidenced by the Ancient Romans, Egyptians, and in Trepanation in Mesoamerica. The practice of

trepanning Trepanning, also known as trepanation, trephination, trephining or making a burr hole (the verb ''trepan'' derives from Old French from -4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, ...

is also evidenced in Ancient

Greece Greece, officially the Hellenic Republic, is a country in Southeast Europe. Located on the southern tip of the Balkan peninsula, it shares land borders with Albania to the northwest, North Macedonia and Bulgaria to the north, and Turkey to th ...

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

and the

Far East The Far East is the geographical region that encompasses the easternmost portion of the Asian continent, including North Asia, North, East Asia, East and Southeast Asia. South Asia is sometimes also included in the definition of the term. In mod ...

. The conceivable reasons why ancient humans developed the technique of drilling the head could be religious, ritual or medical factors. The first trepanning procedure consisted of different types of tools and techniques: at the beginning the only material that was available for use, it was a sharp and carved rock. The development of The

Hippocratic Corpus The Hippocratic Corpus (Latin: ''Corpus Hippocraticum''), or Hippocratic Collection, is a collection of around 60 early Ancient Greek medical works strongly associated with the physician Hippocrates and his teachings. The Hippocratic Corpus cov ...

, written in the fifth century B.C., is the first written source that can be found about trepanning. The aim of the procedure described in "On Wounds in the Head" was to allow the stagnant blood to escape from the head through a hole. The drill that was used at the time is similar to modern ones but was operated by hand rotation. In the 15th century, people began to believe that drilling was a cure for mental problems due to a magical '' stone of madness'' or ''stone of folly'' in the head, which had to be removed. Paintings that portray this practice exist, the most significant ones include ''The Extraction of the Stone of Madness'' c. 1488–1516 by

Hieronymus Bosch Hieronymus Bosch (; ; born Jheronimus van Aken ; – 9 August 1516) was a Dutch people, Dutch painter from Duchy of Brabant, Brabant. He is one of the most notable representatives of the Early Netherlandish painting school. His work, gene ...

and ''A Surgeon Extracting the Stone of Folly'' by Pieter Huys. Hieronymus Bosch 053 detail

From the Renaissance ages, cranial drilling continued to evolve and surgical practice was used less due to the high mortality rate. It was used only for some interventions, such as the treatment of hemorrhages, depressed fractures and penetrating the head. Also, the name for the surgery changed from trepanning to craniotomy. In the late 1860s, the archaeologist E.G. Squier discovered a skull in an ancient Inca cemetery. This specific skull was anticipated to be of the

pre-Columbian era In the history of the Americas, the pre-Columbian era, also known as the pre-contact era, or as the pre-Cabraline era specifically in Brazil, spans from the initial peopling of the Americas in the Upper Paleolithic to the onset of European col ...

. The

exhibited a large rectangle-shaped hole on the top. The skull was brought it back to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, and his findings were presented to the

New York Academy of Medicine The New York Academy of Medicine (the Academy) is a health policy and advocacy organization founded in 1847 by a group of leading New York metropolitan area physicians as a voice for the medical profession in medical practice and public health r ...

. Squier argued that the brain was injected with a tool called a ''burin'' which was used on woods and metals before. Traces showed human hand prints. He concluded that the skull and brain evidenced recovery from prehistoric brain surgery, potentially prolonging the patient's life.

Metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the ...

was a technique that allowed the use of saws and

scalpels A scalpel or bistoury is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, podiatry and various handicrafts. A lancet is a double-edged scalpel. Scalpel blades are usually made of hardened and tempered ste ...

. Other cultures came about experimenting through the usage of glass.

Application

A cranial drill is currently used for

neurosurgery Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the specialty (medicine), medical specialty that focuses on the surgical treatment or rehabilitation of disorders which affect any portion of the nervous system ...

operations. The procedure of trepanning is applied to patients who suffer, for example, a

traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity ranging from mild traumatic brain injury (mTBI/concussion) to severe traumati ...

or a

stroke Stroke is a medical condition in which poor cerebral circulation, blood flow to a part of the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemor ...

. In these cases, it might be necessary to drill a hole in the skull to be able to access the dura mater or the brain itself, and to relieve brain pressure or blood clots. With the use of modern types of cranial drills, surgeons are able to create holes in the bone structure without traumatizing underlying brain tissue. The drill's working tooltip consists of a spiral blade that is framed by a guard device with an angled cranium guide that rests against the inner layer of the skull bone. The dura guard pushes the dura mater downward while the craniotome is moved forward thus preventing dural tearing.

Types and design

A cranial drill is an essential instrument used by surgeons to drill into the skull bone. Various types of drills are used by surgeons for the craniotomy, or oral surgeries. The cranial drill can be differentiated by the examinations of what kind of surgery have to be performed. They can be manually operated, operated by electricity, or by

pneumatic motor A pneumatic motor (air motor), or compressed-air engine, is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed-air energy to mechanical work through either linear or rotary ...

Manual cranial drill

The rotating crank is typically connected to several cogs that set pressure on the skull. This specific drill is not connected to any external power and is used very little in today's operations. The manual cranial drill is the most used and predominant type of drill in

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

, and performs manually. It has an adjusted stopper based on the setting and where the bone is thickest to prevent plunging. Surgeons use this drill manually without any other procedures, and can require substantial upper-body strength.

Electric cranial drill

The electric cranial drill is powered either by a battery or by

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

via wall sockets.

Pneumatic cranial drill

The

is known for its great speed, which makes surgery much easier and faster. It is driven by expanding compressed air. The use of this kind of mechanism has many advantages such as the ease of use through high peak velocities. Thanks to superior torque, this system has great performance and it is essential for complex revision operations. The surgical procedure is shorter than usual, so patients spend less time under

anesthesia Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...

. Pneumatic high-speed craniotomes usually run at 40,000 to 80,000 rpm and have greatly facilitated intracranial approaches in

. They are also employed to temporarily remove the

vertebral arch Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

laminotomy A laminotomy is an orthopaedic neurosurgery, neurosurgical procedure that removes part of the lamina of the vertebral arch, lamina of a vertebral arch in order to relieve pressure in the vertebral canal. A laminotomy is less invasive than conve ...

Scientific progress

Technological progress to reduce

time and minimize risks for patients during

have been introduced in the field of cranial drills, primarily from

machining Machining is a manufacturing process where a desired shape or part is created using the controlled removal of material, most often metal, from a larger piece of raw material by cutting. Machining is a form of subtractive manufacturing, which util ...

CAD/CAM

CAD/CAM stands for ''computer-aided design/computer-aided manufacturing''. In the medical field, as well, it is used by surgeons to simplify and ease surgeries: in the case of trepanning, a processor collects information from 2D images and then turns them into 3D images. The processor codifies this information so that the drill can, without any trouble, pierce the correct portion of the skull.

Photo gallery

File:Brace and bit cranial trephine, Germany, 1701-1800 Wellcome L0058144.jpg, Manual drill during the 18th century File:Edinburgh Skull, trepanning showing hole in back of skull Wellcome M0009393.jpg, Edinburgh Skull, showing trepanning hole in back of skull File:A human skull showing signs of Trepanning. Wellcome L0035690.jpg, A human skull showing signs of trepanning File:KMH - Trepanation.jpg, Human skull with trepanation, Celtic museum in Hallein (Salzburg) File:Peter Treveris - engraving of Trepanation for Handywarke of surgeri 1525.png, Engraving by Peter Treveris of a trepanation. From Heironymus von Braunschweig's ''Handywarke of surgeri'' File:Trepanation illustration France 1800s.jpg, Trepanation illustration France 1800s File:Cranial trephine with two bits, Europe, 1601-1800 Wellcome L0058141.jpg, Cranial trephine with two bits, Europe, 1601–1800 File:Decompressive Craniectomy.png, Decompressive Craniectomy

References

{{Surgical instruments, state=autocollapse Hole making Medical equipment Surgical instruments