Stereotactic surgery is a

minimally invasive Minimally invasive procedures (also known as minimally invasive surgeries) encompass Surgery, surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by d ...

form of

surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

intervention that makes use of a three-dimensional

coordinate In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is sign ...

system to locate small targets inside the body and to perform on them some action such as

ablation Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosion, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft materi ...

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dise ...

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classif ...

, injection, stimulation, implantation, radiosurgery (SRS), etc. In theory, any organ system inside the body can be subjected to stereotactic surgery. However, difficulties in setting up a reliable frame of reference (such as

bone A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provid ...

landmarks, which bear a constant spatial relation to soft tissues) mean that its applications have been, traditionally and until recently, limited to

brain surgery 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 peri ...

. Besides 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 v ...

, biopsy and surgery of the

breast The breast is one of two prominences located on the upper ventral region of a primate's torso. Both females and males develop breasts from the same embryological tissues. In females, it serves as the mammary gland, which produces and sec ...

are done routinely to locate, sample (biopsy), and remove tissue. Plain X-ray images (

radiographic Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...

mammography), computed tomography, and magnetic resonance imaging can be used to

guide A guide is a person who leads travelers, sportspeople, or tourists through unknown or unfamiliar locations. The term can also be applied to a person who leads others to more abstract goals such as knowledge or wisdom. Travel and recreation Ex ...

the procedure. Another accepted form of "stereotactic" is "stereotaxic". The word roots are '' stereo-'', a prefix derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

word στερεός (''stereos'', "solid"), and ''-taxis'' (a suffix of

New Latin New Latin (also called Neo-Latin or Modern Latin) is the revival of Literary Latin used in original, scholarly, and scientific works since about 1500. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy ...

and ISV, derived from Greek ''taxis'', "arrangement", "order", from ''tassein'', "to arrange").

Uses

The surgery is used to treat various brain cancers, benign, and functional disorders of the brain. This is sometimes combined with

whole brain radiotherapy Whole brain radiotherapy (WBRT) is a palliative option for patients with brain metastases that alleviates symptoms, decreases the use of corticosteroids needed to control tumor-associated edema, and potentially improves overall survival. Usage ...

, and a 2021 systematic review found this combination led to the greatest improvement of survival for those with single brain metastasis. Amongst the malignant brain disorders are: brain metastasis and

glioblastoma Glioblastoma, previously known as glioblastoma multiforme (GBM), is one of the most aggressive types of cancer that begin within the brain. Initially, signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality ch ...

. The benign brain disorders are: meningioma,

cerebral arteriovenous malformation A cerebral arteriovenous malformation (cerebral AVM, CAVM, cAVM) is an abnormal connection between the arteries and veins in the brain—specifically, an arteriovenous malformation in the cerebrum. Signs and symptoms The most frequently observed ...

vestibular schwannoma A vestibular schwannoma (VS), also called acoustic neuroma, is a benign tumor that develops on the vestibulocochlear nerve that passes from the inner ear to the brain. The tumor originates when Schwann cells that form the insulating myelin sheath ...

, and

pituitary adenoma Pituitary adenomas are tumors that occur in the pituitary gland. Most pituitary tumors are benign, approximately 35% are invasive and just 0.1% to 0.2% are carcinomas. Functional disorders are:

trigeminal neuralgia Trigeminal neuralgia (TN or TGN), also called Fothergill disease, tic douloureux, or trifacial neuralgia is a long-term pain disorder that affects the trigeminal nerve, the nerve responsible for sensation in the face and motor functions such as ...

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

, and

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

Procedure

Stereotactic surgery works on the basis of three main components: * A stereotactic planning system, including

atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...

, multimodality image matching tools, coordinates calculator, etc. * A stereotactic device or apparatus * A stereotactic localization and placement procedure Modern stereotactic planning systems are computer based. The stereotactic atlas is a series of cross sections of anatomical structure (for example, a human brain), depicted in reference to a two-coordinate frame. Thus, each brain structure can be easily assigned a range of three coordinate numbers, which will be used for positioning the stereotactic device. In most atlases, the three dimensions are: latero-lateral (), dorso-ventral () and rostro-caudal (). The stereotactic apparatus uses a set of three coordinates (, and ) in an orthogonal frame of reference ( cartesian coordinates), or, alternatively, a

cylindrical coordinates A cylindrical coordinate system is a three-dimensional coordinate system that specifies point positions by the distance from a chosen reference axis ''(axis L in the image opposite)'', the direction from the axis relative to a chosen reference d ...

system, also with three coordinates: angle, depth and antero-posterior (or axial) location. The mechanical device has head-holding clamps and bars which puts the head in a fixed position in reference to the coordinate system (the so-called zero or origin). In small laboratory animals, these are usually

landmarks which are known to bear a constant spatial relation to soft tissue. For example, brain atlases often use the

external auditory meatus The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about in length and in diameter. Str ...

, the inferior orbital ridges, the median point of the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

between the incisive teeth. or the

bregma The bregma is the anatomical point on the skull at which the coronal suture is intersected perpendicularly by the sagittal suture. Structure The bregma is located at the intersection of the coronal suture and the sagittal suture on the superi ...

(confluence of sutures of frontal and parietal bones), as such landmarks. In humans, the reference points, as described above, are intracerebral structures which are clearly discernible in a

radiograph Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeut ...

or tomograph. In newborn human babies, the "soft spot" where the coronal and sagittal sutures meet (known as the fontanelle) becomes the bregma when this gap closes. Guide bars in the , and directions (or alternatively, in the polar coordinate holder), fitted with high precision

vernier scale A vernier scale, named after Pierre Vernier, is a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation, thereby increasing resolution and reducing measurement unce ...

s allow the neurosurgeon to position the point of a probe (an

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...

, a

cannula A cannula (; Latin meaning 'little reed'; plural or ) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. In simple terms, a cannula can surround the inner or outer surfaces ...

, etc.) inside the brain, at the calculated coordinates for the desired structure, through a small trephined hole in the skull. Currently, a number of manufacturers produce stereotactic devices fitted 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 ...

in humans, for both brain and spine procedures, as well as for animal experimentation.

Types frame systems

# Simple orthogonal system: The probe is directed perpendicular to a square base unit fixed to the skull. These provide three degrees of freedom by means of a carriage that moved orthogonally along the base plate or along a bar attached parallel to the base plate of the instrument. Attached to the carriage was a second track that extended across the head frame perpendicularly. # Burr hole mounted system: This provides a limited range of possible intracranial target points with a fixed entry point. They provided two angular degrees of freedom and a depth adjustment. The surgeon could place the burr hole over nonessential brain tissue and utilize the instrument to direct the probe to the target point from the fixed entry point at the burr hole. # Arc-quadrant systems: Probes are directed perpendicular to the tangent of an arc (which rotates about the vertical axis) and a quadrant (which rotates about the horizontal axis). The probe, directed to a depth equal to the radius of the sphere defined by the arc-quadrant, will always arrive at the center or focal point of that sphere. # Arc-phantom systems: An aiming bow attaches to the head ring, which is fixed to the patient's skull, and can be transferred to a similar ring that contains a simulated target. In this system, the phantom target is moved on the simulator to 3D coordinates. After adjusting the probe holder on the aiming bow so that the probe touches the desired target on the phantom, the transferable aiming bow is moved from the phantom base ring to the base ring on the patient. The probe is then lowered to the determined depth in order to reach the target point deep in the patient's brain.

Treatment

Stereotactic radiosurgery

Stereotactic radiosurgery utilizes externally generated

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

to inactivate or eradicate defined targets in the head or spine without the need to make an incision. This concept requires steep dose gradients to reduce injury to adjacent normal tissue while maintaining treatment efficacy in the target. As a consequence of this definition, the overall treatment accuracy should match the treatment planning margins of 1–2 mm or better. To use this paradigm optimally and treat patients with the highest possible

accuracy and precision Accuracy and precision are two measures of ''observational error''. ''Accuracy'' is how close a given set of measurements ( observations or readings) are to their ''true value'', while ''precision'' is how close the measurements are to each oth ...

, all errors, from image acquisition over treatment planning to mechanical aspects of the delivery of treatment and intra-fraction motion concerns, must be systematically optimized. To assure quality of patient care the procedure involves a multidisciplinary team consisting of a

radiation oncologist A radiation oncologist is a specialist physician who uses ionizing radiation (such as megavoltage X-rays or radionuclides) in the treatment of cancer. Radiation oncology is one of the three primary specialties, the other two being surgical and ...

medical physicist A medical physicist is a health professional with specialist education and training in the concepts and techniques of applying physics in medicine and competent to practice independently in one or more of the subfields (specialties) of medical phys ...

, and radiation therapist. Dedicated, commercially available stereotactic radiosurgery programs are provided by the irrespective

Gamma Knife Radiosurgery is surgery using radiation, that is, the destruction of precisely selected areas of tissue using ionizing radiation rather than excision with a blade. Like other forms of radiation therapy (also called radiotherapy), it is usually u ...

, CyberKnife, and Novalis Radiosurgery devices. Stereotactic radiosurgery provides an efficient, safe, and minimal invasive treatment alternative for patients diagnosed with

malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

benign Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...

and functional indications in the brain and spine, including but not limited to both primary and secondary tumors. Stereotactic radiosurgery is a well-described management option for most

metastases Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then ...

, meningiomas,

schwannoma A schwannoma (or neurilemmoma) is a usually benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. Schwannomas are homogeneous tumors, consisting only of Schwann cells ...

, among others. Irrespective of the similarities between the concepts of stereotactic radiosurgery and fractionated radiotherapy and although both treatment modalities are reported to have identical outcomes for certain indications, the intent of both approaches is fundamentally different. The aim of stereotactic radiosurgery is to destroy target tissue while preserving adjacent normal tissue, where fractionated radiotherapy relies on a different sensitivity of the target and the surrounding normal tissue to the total accumulated radiation dose. Historically, the field of fractionated radiotherapy evolved from the original concept of stereotactic radiosurgery following discovery of the principles of

radiobiology Radiobiology (also known as radiation biology, and uncommonly as actinobiology) is a field of clinical and basic medical sciences that involves the study of the action of ionizing radiation on living things, especially health effects of radiation. ...

: repair, reassortment, repopulation, and reoxygenation. Today, both treatment techniques are complementary as tumors that may be resistant to fractionated radiotherapy may respond well to radiosurgery and tumors that are too large or too close to critical organs for safe radiosurgery may be suitable candidates for fractionated radiotherapy. A second, more recent evolution extrapolates the original concept of stereotactic radiosurgery to extra-cranial targets, most notably in the lung, liver, pancreas, and prostate. This treatment approach, entitled stereotactic body radiotherapy or SBRT, is challenged by various types of motion. On top of patient immobilization challenges and the associated patient motion, extra-cranial lesions move with respect to the patient's position due to respiration, bladder and rectum filling. Like stereotactic radiosurgery, the intent of stereotactic body radiotherapy is to eradicate a defined extra-cranial target. However, target motion requires larger treatment margins around the target to compensate for the positioning uncertainty. This in turn implies more normal tissue exposed to high doses, which could result in negative treatment

side effects In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

. As a consequence, stereotactic body radiotherapy is mostly delivered in a limited number of fractions, thereby blending the concept of stereotactic radiosurgery with the therapeutic benefits of fractionated radiotherapy. To monitor and correct target motion for accurate and precise patient positioning prior and during treatment, advanced image-guided technologies are commercially available and included in the radiosurgery programs offered by the CyberKnife and Novalis communities.

Parkinson's disease

Frame for Stereotactic Thalamotomy on display at the Glenside Museum

Functional neurosurgery comprises treatment of several disorders such as

hyperkinesia Hyperkinesia refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. Hyperkinesia is a state of excessive restlessness which is featured in a large variet ...

, disorder of muscle tone, intractable pain, convulsive disorders and psychological phenomena. Treatment for these phenomena was believed to be located in the superficial parts of the CNS and PNS. Most of the interventions made for treatment consisted of cortical extirpation. To alleviate extra pyramidal disorders, pioneer Russell Meyers dissected or transected the head of the

caudate nucleus The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia in the human brain. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's d ...

in 1939, and part of the

putamen The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal ...

and

globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It consists of two adjacent segments, one external, known in rodents simply as the globus pallidus, and one internal, known in rod ...

. Attempts to abolish intractable pain were made with success by transection of the

spinothalamic tract The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory co ...

at spinal medullary level and further proximally, even at mesencephalic levels. In 1939-1941 Putnam and Oliver tried to improve Parkinsonism and hyperkinesias by trying a series of modifications of the lateral and antero-lateral cordotomies. Additionally, other scientists like Schurman, Walker, and Guiot made significant contributions to functional neurosurgery. In 1953, Cooper discovered by chance that ligation of the anterior chorioidal artery resulted in improvement of Parkinson's disease. Similarly, when Grood was performing an operation in a patient with Parkinson's, he accidentally lesioned the

thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...

. This caused the patient's tremors to stop. From then on, thalamic lesions became the target point with more satisfactory results. More recent clinical applications can be seen in surgeries used to treat Parkinson's disease, such as

Pallidotomy Pallidotomy is a neurosurgical procedure. It is used to treat Parkinson's disease and some other conditions, often as an alternative to deep brain stimulation. It involves placing a tiny electrical probe in the globus pallidus, one of the basal g ...

Thalamotomy Thalamotomy ( el, θάλαμος, thalamus, lit =chamber; el, τομή , tomē, lit=cut, slice) is a surgical procedure in which an opening is made into the thalamus to improve the overall brain function in patients. First introduced in the 1950 ...

(lesioning procedures), or

Deep Brain Stimulation Deep brain stimulation (DBS) is a neurosurgical procedure involving the placement of a medical device called a neurostimulator, which sends electrical impulses, through implanted electrodes, to specific targets in the brain (the brain nucleus ...

(DBS). During DBS, an electrode is placed into the thalamus, the pallidum of the subthalmamic nucleus, parts of brain that are involved in motor control, and are affected by Parkinson's disease. The electrode is connected to a small battery operated stimulator that is placed under the collarbone, where a wire runs beneath the skin to connect it to the electrode in the brain. The stimulator produces electrical impulses that affect the nerve cells around the electrode and should help alleviate tremors or symptoms that are associated with the affected area. In

, a needle electrode is placed into the thalamus, and the patient must cooperate with tasks assigned to find the affected area- after this area of the thalamus is located, a small high frequency current is applied to the electrode and this destroys a small part of the thalamus. Approximately 90% of patients experience instantaneous tremor relief. In

, an almost identical procedure to thalamotomy, a small part of the pallidum is destroyed and 80% of patients see improvement in rigidity and hypokinesia and a tremor relief or improvement comes weeks after the procedure.

History

The stereotactic method was first published in 1908 by two British scientists,

Victor Horsley Sir Victor Alexander Haden Horsley (14 April 1857 – 16 July 1916) was a British scientist and professor. He was born in Kensington, London. Educated at Cranbrook School, Kent, he studied medicine at University College London and in Berlin, G ...

, a physician and neurosurgeon, and Robert H. Clarke, a physiologist and was built by Swift & Son; the two scientists stopped collaborating after the 1908 publication. The Horsley–Clarke apparatus used a Cartesian (three-orthogonal axis) system. That device is in the Science Museum, London; a copy was brought to the US by

Ernest Sachs Ernest Sachs (January 25, 1879 – December 2, 1958) was an American neurosurgeon. The grandson of Goldman Sachs's founder, he became Professor of Neurosurgery at the Washington University School of Medicine in St. Louis, Missouri in 1919. He was ...

and is in the Department of Neurosurgery at

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...

. Clarke used the original to do research that led to publications of primate and cat

brain atlas A brain atlas is composed of serial sections along different anatomical planes of the healthy or diseased developing or adult animal or human brain where each relevant brain structure is assigned a number of coordinates to define its outline or vol ...

es. There is no evidence it was ever used in a human surgery. The first stereotactic device designed for the human brain appears to have been an adaptation of the Horseley–Clarke frame built at Aubrey T. Mussen's behest by a London workshop in 1918, but it received little attention and does not appear to have been used on people. It was a frame made of brass. The first stereotactic device used in humans was used by

Martin Kirschner Martin Kirschner (28 October 1879 – 30 August 1942) was a German surgeon. Kirschner was born in Breslau, the son of Margarethe Kalbeck (sister of Max Kalbeck) and Judge Martin Kirschner (1842–1912), who later served as city councillor ...

, for a method to treat

by inserting an electrode into the trigeminal nerve and ablating it. He published this in 1933. In 1947 and 1949, two neurosurgeons working at Temple University in Philadelphia, Ernest A. Spiegel (who had fled Austria when the Nazis took over) and Henry T. Wycis, published their work on a device similar to the Horsley–Clarke apparatus in using a cartesian system; it was attached to the patient's head with a plaster cast instead of screws. Their device was the first to be used for brain surgery; they used it for psychosurgery. They also created the first atlas of the human brain, and used intracranial reference points, generated by using medical images acquired with contrast agents. The work of Spiegel and Wycis sparked enormous interest and research. In Paris, Jean Talairach collaborated with Marcel David, Henri Hacaen, and

Julian de Ajuriaguerra Julian de Ajuriaguerra (born January 7, 1911 at Bilbao (Spain) and died at Villefranque (Pyrénées-Atlantiques) on March 23, 1993) was a Spanish-French neuropsychiatrist and psychoanalyst of Spanish Basque origin. He is one of the pioneers of " ...

on a stereotactic device, publishing their first work in 1949 and eventually developing the

Talairach coordinates Talairach coordinates, also known as Talairach space, is a 3-dimensional coordinate system (known as an 'atlas') of the human brain, which is used to map the location of brain structures independent from individual differences in the size and overa ...

. In Japan, Hirotaro Narabayashi was doing similar work. In 1949,

Lars Leksell Lars Leksell (1907–1986) was a Swedish physician and Professor of Neurosurgery at the Karolinska Institute in Stockholm, Sweden. He was the inventor of radiosurgery. Life and career Lars Leksell was born in Fässberg Parish, Sweden on Nove ...

published a device that used

polar coordinates In mathematics, the polar coordinate system is a two-dimensional coordinate system in which each point on a plane is determined by a distance from a reference point and an angle from a reference direction. The reference point (analogous to th ...

instead of cartesian, and two years later he published work where he used his device to target a beam of radiation into a brain. Leksell's radiosurgery system is also used by the

device, and by other neurosurgeons, using

linear accelerator A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear ...

s, proton beam therapy and neutron capture therapy. Lars Leksell went on to commercialize his inventions by founding

Elekta Elekta is a global Swedish company that develops and produces radiation therapy and radiosurgery-related equipment and clinical management for the treatment of cancer and brain disorders. Elekta has a global presence in more than 120 countries, w ...

in 1972. In 1979, Russell A. Brown proposed a device, now known as the

N-localizer The N-localizer is a device that enables guidance of stereotactic surgery or radiosurgery using tomographic images that are obtained via computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). The N-local ...

, that enables guidance of stereotactic surgery using tomographic images that are obtained via medical imaging technologies such as

X-ray computed tomography An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 ...

(CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). The N-localizer comprises a diagonal rod that spans two vertical rods to form an N-shape that allows tomographic images to be mapped to physical space. This device became almost universally adopted by the 1980s and is included in the Brown-Roberts-Wells (BRW), Kelly-Goerss, Leksell, Cosman-Roberts-Wells (CRW), Micromar-ETM03B, FiMe-BlueFrame, Macom, and Adeor-Zeppelin stereotactic frames and in the Gamma Knife radiosurgery system. An alternative to the N-localizer is the Sturm-Pastyr localizer that is included in the Riechert-Mundinger and Zamorano-Dujovny stereotactic frames. Other localization methods also exist that do not make use of tomographic images produced by CT, MRI, or PET, but instead conventional radiographs. The stereotactic method has continued to evolve, and at present employs an elaborate mixture of

image-guided surgery Image-guided surgery (IGS) is any surgical procedure where the surgeon uses tracked surgical instruments in conjunction with preoperative or intraoperative images in order to directly or indirectly guide the procedure. Image guided surgery systems u ...

that uses computed tomography, magnetic resonance imaging and stereotactic localization.

History in Latin America

In 1970, in the city of Buenos Aires, Argentina, Aparatos Especiales company, produced the first Stereotactic System in Latin America. Antonio Martos Calvo, together with Jorge Candia and Jorge Olivetti through the request of neurosurgeon Jorge Schvarc (1942-2019), developed an equipment based on the principle of Hitchcock Stereotactic System. The patient was seated in an adapted chair with two telescopic arms attached at it base, which fixed the stereotactic frame preventing the patient’s movement. A double radiopaque ruler attached to the side of the frame made it possible to obtain the antero-posterior and latero-lateral X-ray images without the need of moving the radiopaque ruler. The thermal coagulation lesion was performed using tungsten monopole electrodes of 1,5mm of diameter (without temperature control) with a 3mm active tip, utilizing an electrical bipolar coagulator. The lesion size was previously determined by testing the electrode in egg albumin. Coagulation size was the result of the electrical coagulator power regulation and the application time of the radiofrequency. The first surgery performed with this system was a Trigeminal Nucleotractothomy. Jorge Schvarcz performed more than 700 functional surgeries until 1994 when, due to health problems he stopped exercising his profession. But the equipment developed kept improving on a neurosurgery history. Jorge Schvartz

This was the beginning of the developing of technology to produce stereotactic devices in Latin America. This was the beginning of the first stereotactic manufacturer of Latin America – The Brazilian Micromar. File:Equipamento Estereotaxico ETM01-B (Teixeira-Martos, Hitchcock modificado).png File:Equipamento Estereotáxico Teixeira-Martos TM-02B.png File:Equipamento Estereotáxico Teixeira-Martos TM-03B.png

Research

Stereotactic surgery is sometimes used to aid in several different types of animal research studies. Specifically, it is used to target specific sites of the brain and directly introduce pharmacological agents to the brain which otherwise may not be able to cross the blood–brain barrier. In rodents, the main applications of stereotactic surgery are to introduce fluids directly to the brain or to implant

cannulae A cannula (; Latin meaning 'little reed'; plural or ) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. In simple terms, a cannula can surround the inner or outer surfaces ...

and

microdialysis Microdialysis is a minimally-invasive sampling technique that is used for continuous measurement of free, unbound analyte concentrations in the extracellular fluid of virtually any tissue. Analytes may include endogenous molecules (e.g. neurotra ...

probes. Site specific central microinjections are used when rodents do not need to be awake and behaving or when the substance to be injected has a long duration of action. For protocols in which rodents’ behaviors must be assessed soon after injection, stereotactic surgery can be used to implant a cannula through which the animal can be injected after recovery from the surgery. These protocols take longer than site-specific central injections in anesthetized mice because they require the construction of cannulae, wire plugs, and injection needles, but induce less stress in the animals because they allow for a recovery period for the healing of trauma induced to the brain before injection. Surgery can also be used for microdialysis protocols to implant and tether the dialysis probe and guide cannula.