STEREOTAXIC METHOD

From Big Medical Encyclopedia

STEREOTAXIC METHOD (Greek stereos firm, volume, space + taxis an arrangement) — a method of surgical impact on deeply located structures of a brain with use of intracerebral and cranial (ekstrakranialny) reference points. The possibility of achievement by a surgical instrument of a certain point of a brain with the minimum damages of other its sites is extremely important in neurosurgery and neurophysiology. Only thanks to S. m became available to diagnosis and to lay down. impacts of formation of a brain, directly adjacent to the kernels which are carrying out the vital functions. In pilot studies practically all stimulations, destructions and administrations of active agents in deeply located structures of a brain are carried out by means of S. by m.

The central problem of S. of m is definition of exact localization of the brain structures targets which are subject to studying or influence (assignment of electropotentials, electrostimulation, destruction). The solution of these tasks is connected with studying of stereotaxic topography of deep formations of a brain and their variability depending on specific features of a structure of a brain and the nature of its pathology (hydrocephaly, an atrophy, etc.).

In S. of m also the problem of physiological identification of the subcrustal structures which are subject to intervention and ways of their destruction is of great importance (mekhano-, himio-, krio-, thermodestruction, electrolysis).

During the determination of coordinates of structures of a brain two approaches are used: determination of coordinates of rather external (ekstrakranialny) reference points (outside acoustical passes, edges eye orbrgg, the sagittal plane etc.) and coordinates of rather intracerebral reference points revealed radiological (front and back commissures, cerebral cavities, the Turkish saddle etc.).

The kraniotserebralny topography is the cornerstone of use of ekstrakranialny reference points. Convenience of this approach is followed, however, in connection with individual variability of a structure of a brain, insufficient accuracy. Therefore cranial reference points serve in clinic preferential for the choice of access to necessary structures of a brain and are applied as the main only in pilot studies on animals.

Use of intracerebral reference points does not provide absolute accuracy during the determination of coordinates in view of individual variability of space ratios of position of structures of a brain too, but allows to obtain more exact data. As basic reference points for intracerebral system front and back commissures of a brain are recognized the most convenient. They rather well decide on the help of contrast agents, and the dispersion of coordinates of separate structures of a brain at the same time appears the smallest. Data on coordinates of structures of a brain contain in stereotaxic atlases, in to-rykh sets of photos and the planimetric drawings combined with them — schemes of cuts of a brain in the planes parallel to coordinate axes (planes) are presented. In drawings the grid of coordinates is put and the provision of a cut of rather sagittal or frontal plane is specified. The majority of stereotaxic atlases of a brain of the person is constructed in coordinate system, the beginning of coordinates in a cut is located on the middle of the line connecting front and back commissures.

For carrying out stereotaxic operation the system of coordinates chosen in the stereotaxic atlas is combined with system of coordinates of an individual brain. At the same time the roentgenograms containing the image of basic X-ray contrast reference points cannot be directly compared with coordinate system of the atlas since are not rectangular projections of a skull and brain, and the central projections, in to-rykh the sizes of the image of an object depend on situation between a X-ray tube and a film. Transition from the central projection to rectangular is carried out by mathematical calculations. Usually the problem is solved approximately, with use of auxiliary large-scale lattices and devices with very long distance between a tube and a film, and also using for transformation of projections and coordinates of the COMPUTER. Thanks to the electronic equipment became possible to apply simple diagnostic X-ray apparatus with one tube and to make stereotaxic operations in the usual operating room.

New perspectives in S.'s development by m opened in connection with development of the computing (computer) tomography allowing to receive without administration of contrast mediums images of structures, cerebral cavities, to distinguish gray matter of a brain and conduction paths and to solve thus a problem of the accounting of individual variations in position of structures (see. Tomography computer ).

Stereotaxic devices divide into two groups: devices, in to-rykh fix the head operated, and devices, to-rye fix on the head. In both cases the stereotaxic device is intended for ensuring orientation and the necessary movement of a surgical instrument of rather stereotaxic system of coordinates. The vast majority of devices for operations on animals, including the devices functioning on classical treats devices of the first group. to Horsley's scheme — Clark, and also a number of devices for carrying out stereotaxic operations on the person. These are the difficult constructions connected with the specialized stationary x-ray equipment. The stereotaxic devices expected the simplified techniques supplied with small-size X-ray tubes and allowing to make stereotaxic calculations on the COMPUTER concern to the second group.

S.'s use m on animals allows to obtain new data on the structurally functional organization of a brain and brain mechanisms of behavior. In S.'s neurosurgery of m it is used only for the solution of diagnostic and to lay down. tasks (see. Stereotaxic neurosurgery ). Researches of a possibility of use of S. of m for problem solving of functional prosthetics of touch and other systems of a brain are conducted.

In a number of foreign countries of S. of m it is applied for the purpose of elimination of the separate heavy mental disorders which are not giving in to other methods of treatment (an erotic deficiency of intellect, nek-ry forms of schizophrenia, epilepsy with the expressed mental disorders, severe forms of persuasive states, etc.). Depending on a wedge, pictures and dynamics of mental disturbances the stereotaxic tsingulotomiya (destruction of a zone crinkle), an amigdalotomiya, a gipotalamotomiya, a me-zovilotomiya (destruction of a knee of a corpus collosum), etc. can be carried out. Such operations often allow resistant positive to lay down. effect, including provide a certain recovery of structure of the identity of the patient. However in a number of the countries, including in the USSR, the relation to psychosurgeries remains negative in connection with danger of emergence of undesirable effects.

Main stages of stereotaxic operations: definition of the place of a craniotrypesis, anesthesia, contrasting of cerebral cavities, calculations of stereotaxic coordinates, rentgenol. control, functional control (i.e. a research of dynamics of displays of a disease by impact on a brain during operation — diagnostic electrostimulation of structures targets, use of a method of evoked potentials etc.) and as the most important stage of single-step stereotaxic operation — medical destruction of structures targets.

The accumulated experience allowed to select those structures of a brain, destruction to-rykh is, as a rule, capable to allow expected to lay down. effect (suppression of pain, elimination of hyperkinesias, etc.).

By means of S. the different types of influences which are carried out with the diagnostic purposes can be carried out by m (electrostimulation, temporary switching off by means of electropolarization, moderate cooling); for the purpose of destruction (chemical influence, napr, pure alcohol, electrolysis, electrothermic coagulation, stress rupture, freezing); for the purpose of removal (suction, mechanical removal, evaporation by laser radiation).

S.'s achievement of m is use of a method of implanted electrodes for the decision diagnostic and to lay down. tasks at patients with epilepsy, extrapyramidal frustration, a phantom pain syndrome, etc. In the USSR this method was for the first time applied by N. P. Bekhtereva in 1962. During stereotaxic operation on the calculations executed on the COMPUTER, electrodes enter into structures targets of one or both hemicerebrums for registration of activity of deep structures of a brain, for diagnostic and to lay down. electrostimulations, and then for to lay down. destructions of structures targets. Results of use of a method of implanted electrodes by neurosurgeons and neurophysiologists showed that this method expands diagnostic and to lay down. S.'s possibilities of m, and also gives valuable information on the structurally functional organization of a brain and the principles of its work.

The page of m is fundamentals of the stereotaxic neurology interpreting from stereotaxic positions neurologic symptoms and syndromes, their brain mechanisms, ways of their recognition and the description, and also data on diagnostic and their predictive value in nevrol. to practice. From positions of stereotaxic neurology stereotaxic symptoms and syndromes of hyperkinesias, muscular rigidity, asomatognostichesky and speech stereotaxic symptoms and syndromes, stereotaxic symptoms and syndromes of disturbances of a number of mental processes and mental states, including emotional and emotional and motivational are described. All these symptoms and syndromes have specific brain providing in the form of mechanisms of the emergency change of a functional condition of this stimulated structure, mechanisms of implementation of the corresponding effects, reactions and states, mechanisms of control which are weakening or which are urgently blocking the called reactions and states.



Bibliography: Abrakov L. V. Fundamentals of stereotaxic neurosurgery, L., 1975, bibliogr.; Bekhtereva N. P. Healthy and sore brain of the person, L., 1980; Vakolyuk N. I. Stereotaxic atlas of a brain of the person, Kiev, 1979, bibliogr.; Ivannikov Yu. G. Use of the COMPUTER at stereotaxic brain operations, JI., 1969, bibliogr.; Kandel E. I. Functional and stereotaxic neurosurgery, M., 1981, bibliogr.; M are and c A. M. and Spiritual N. P. Universal stereotaxic atlas of a brain of a dog, Chisinau, 1975; Smirnov V. M. Stereotaxic neurology, L., 1976; Afshar E., Watkins E. S. a. Yap J. Page of Stereotaxic atlac of the human brain stem and cerebellar nuclei (variability study), N.Y., 1978; Functional neurosurgery, ed. by T. Rasmussen a. R. Marino, N. Y., 1979; H a s s 1 e r R., Mundinger F. Riechert T. Stereotaxis in Parkinson syndrome, V. a. o., 1979, bibliogr.; J a with-q u e s S., S h e 1 d e n C. McCann G. A computerized microstereotactic method to approach, 3-dimensionally reconstruct, remove and adjuvantly treat small CNS lesions, Appl. Neurophysiol., v. 43, p. 176, 1980; Kelly P. J. a. Alker G. J. A method for stereotactic laser microsurgery in the treatment of deep-seated CNS neoplasms, ibid., p. 210; Matsui T. a. H i r a n about A. An atlas of the human brain for computerized tomography, N. Y., 1978; Mundinger F. Stereotaktische Operationen am Gehirn, Stuttgart, 1975; Schaltenbrand G. Wah-r e n W. Atlas for stereotaxy of the human brain, Stuttgart, 1977.


V. M. Smirnov, V. V. Usov

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