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 is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

. This exposes the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

and allows operations like

craniotomy A craniotomy is a surgical operation in which a bone flap is temporarily removed from the skull to access the brain. Craniotomies are often critical operations, performed on patients who are suffering from brain lesions, such as tumors, blood clot ...

and craniectomy to be done. The drill itself can be ''manually'' or ''electrically'' driven, and primarily consists of a hand piece and a

drill bit Drill bits are cutting tools 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 order ...

which is a sharp tool that has the 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 hydraulic machines. Using Archimedes screws as water pumps (Archimedes screw pump (ASP) or screw pump) dates back ...

, this instrument must be inserted into the drill chuck to perform holes and remove materials. The trepanation tool is generally equipped with a clutch which automatically disengages once it touches a softer tissue, thus preventing tears in the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

. 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. 4,000 B.C. The oldest cranial drilling instrument was found in France, and subsequent use evidenced by the Ancient Romans, Egyptians, and in

Trepanation in Mesoamerica Trephination in Mesoamerica has been practised by a number of pre-Columbian cultures in the Mesoamerican region, dating from at least the Mesoamerican chronology, mid-Preclassic era (ca. 1500 Common Era, BCE), and continuing up to the late Postcla ...

. The practice of

trepanning Trepanning, also known as trepanation, trephination, trephining or making a burr hole (the verb ''trepan'' derives from Old French from Medieval Latin from Greek , literally "borer, auger"), is a surgical intervention in which a hole is drill ...

is also evidenced from Ancient

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...

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 or geography. Etymology The word ''north ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

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

Polynesia Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...

and the

Far East The ''Far East'' was a European term to refer to the geographical regions that includes East and Southeast Asia as well as the Russian Far East to a lesser extent. South Asia is sometimes also included for economic and cultural reasons. The ter ...

. 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 or tools and techniques: at the beginning the only material that was available for use 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/ Netherlandish painter from Brabant. He is one of the most notable representatives of the Early Netherlandish painting school. His work, generally oil on o ...

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

pre-Columbian era In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, ...

. 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 (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

, and his findings presented to the New York Academy of Medicine. 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 patients life. Metallurgy was a technique that allowed the use of saws and

scalpels A scalpel, lancet, or bistoury is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, podiatry and various arts and crafts (either called a hobby knife or an X-acto knife.). Scalpels may be single-use disposab ...

. 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 medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and pe ...

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 TBI/concussionto severe traumatic br ...

or a stroke. In these cases, it might be necessary to drill a hole in the skull to be able to access the

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 tool tip 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 in to the skull bone. Various types of drills are used by surgeons from 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

Vilebrequin - musée HCL - instruments chirurgicaux

The rotating crank is typically connected to several cogs that sets 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, and performs manually. It has an adjusted stopper based on the setting and where the bone is the most thickest to prevent plunging. Surgeons use this drill manually without any other procedures. Surgeons that use a hand-cranked drill often are required to employ a lot of 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 that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describ ...

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. 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 The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

in laminotomy.

Scientific progress

Technological progress to reduce surgery time and minimize risks for patients during surgery have been introduced in the field of cranial drills, primarily from machining.

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, Celtic museum in Hallein ( Salzburg ). Human skull with trepanation 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 Medical equipment Surgical instruments