From Big Medical Encyclopedia
Fig. 1. Localization of the damages of a cerebral cortex causing apraxias (on Lipmanna): 1 — akrokinetichesky (motor) apraxia; 2 — ideokinetichesky apraxia; 3 — ideatorny apraxia.

APRAXIA (grech, apraxia inaction) — disturbance of irregular shapes any (and first of all purposeful) actions at safety of elementary force, accuracy and co-ordination of movements, arising at focal defeats of bark of big cerebral hemispheres. Phenomena And. were for the first time described by Lipmann (H. Lipmann, 1900) who defined And. as inability to carry out the reasonable movement in the absence of paresis, an ataxy or disturbance of a muscle tone. Lipmann connected Ampere-second by defeat of parietal and nizhnetemenny area of a cerebral cortex (fig. 1) and distinguished motor (akrokinetichesky) And., at a cut of the patient accurately represents the movements which it shall execute, but does not find motive ways for its performance; ideatorny And., at a cut of the patient does not imagine what movement it shall execute, and ideokinetichesky And., taking the intermediate place. Special form A., described by Lipmann (1905), is And. the left hand, arising owing to disturbances of conduction paths of a corpus collosum therefore the nervous impulse formulating a problem of the movement does not reach nizhnetemenny departments of the right hemisphere. It leads to difficulty of performance of the necessary movement by the left hand at preservation of an opportunity to carry out the movements by the right hand.

Further development of the doctrine about And. it was connected with works of Zittiga (O. Sittig, 1931), Kleysta (K. Kleist, 1934) and Denny-Brown (D. Denny-Brown, 1952, 1958). The most significant progress in the doctrine about And. were reached by the Soviet neurologists who tried to approach the phenomena of Ampere-second of the point of view of the general mechanisms of the motive act which are in detail studied by N. A. Bernstein (1947) and the all-psychological doctrine about structure of human activity (L. S. Vygotsky, 1956, 1960; A. N. Leontyev, 1957, etc.).

On modern representations And. differs from such forms of disturbance of movements as paresis, an ataxy, dystonias markedly, and arises when one of the components necessary for implementation of difficult autokinesia is broken. According to localization of defeat in a cerebral cortex various mechanisms which are the cornerstone of difficult autokinesia can be broken, and And. can take the unequal forms.

Afferent (kinaesthetic) apraxia it is shown by disturbance of kinaesthetic bases of the movement, i.e. disturbance of feelings of situation or direction of the movement of this or that part of a body, especially hands without which accurate addressing of motive impulses loses the definiteness, and the movement becomes uncontrollable. This form A., close to akrokinetichesky and ideokinetichesky apraxia of Lipmann, it is expressed in impossibility to find the necessary movement on the basis of kinaesthetic feelings, and the patient can make this movement only under constant visual control. At afferent And. defeat of postcentral departments of bark of a dominant hemisphere is noted (left at right-handed persons).

Oral apraxia represents a special look And. organs of articulation, at a cut the difficulties of the motor speech taking the forms of afferent (kinaesthetic) motor develop aphasias (see). The patient cannot find the positions of organs of articulation necessary for pronouncing the corresponding sounds — artikuly, and the syndrome which includes mixing of relatives on an articulation of sounds in the expressional speech, peculiar disturbances of the letter, etc. forms. Defeat at oral And. it is localized in the lower sites of postcentral (kinaesthetic) departments of bark of a dominant hemisphere (left at right-handed persons).

Fig. 2. Disturbance of movements during the writing of letters at the patient with space apraxia as a result of wound of the left parietooccipital area. The first and third ranks — samples of a font, the second and fourth ranks — writing of these letters by the patient.

Space apraxia right — left is shown by disturbance of orientation of the patient in the space directions, first of all in the direction. The patient cannot draw the image oriented in space, cannot hit the necessary nail of space, and also construct a figure of matches or design some space scheme (constructive And.). By the letter of the patient makes space mistakes, being not able to correlate correctly parts of difficult constructed letters and showing signs of the mirror letter, and all system of movements is broken on the expressed space type (fig. 2). The described disturbances arise at defeats of parietooccipital departments of bark of big hemispheres.

Fig. 3. Disturbance of movements during the drawing and the letter at the patient with kinetic apraxia as a result of defeat of the left premotorny zone. «122», «101», «Circle», «Square» — the task offered for writing and a sketch (at the top of its execution). In the bottom of the drawing — an example of handwriting of the patient during the writing of the letter (repetitions of letters are emphasized).

Kinetic, or efferent, apraxia it is expressed that finding of the necessary movements and their space organization remain safe, but smooth transition from one link of the difficult movement to the following is unavailable. Movement skills break up, each element of difficult movement skill requires a special impulse, smoothness of the letter is broken. Similar disturbances arise at defeat of premotorny departments of bark of big hemispheres, preferential dominant hemisphere (left at right-handed persons). As is well-known from a number of researches, in particular Fulton (F. Fulton, 1935), premotorny departments of bark of big cerebral hemispheres are in close connection with subcrustal kernels and are directly involved in processes of automation of difficult autokinesias, in formation of smooth movement skills. Efferent And. it is characterized by pathological inertness of movements and motive perseverations (repetition of the same movements) which the patient realizes, but cannot detain randomly. Similar defects are often shown also in the letter (fig. 3). At this form A. defeat is located in deep departments of premotorny areas and leads to disturbance of normal bonds of a premotorny zone with subcrustal kernels.

Similar form A. it can be shown in disturbance of speech processes that leads to efferent (kinetic) aphasias (see). The patient without effort finding the necessary articulation is not able to switch easily from one articulation to another, and pronouncing the whole word and the more so whole phrase becomes unavailable. It occurs at damage of lower parts of a premotorny zone of a dominant hemisphere (left at right-handed persons) — Brock's zone.

Frontal apraxia. At frontal And. a peculiar type of disturbance of autokinesias and actions is noted. In these cases both kinaesthetic and space, and the kinetic organization of movements can remain safe, but the patient has gross violations in subordination of all movements to the known intention, programming of the difficult, consistently proceeding motive acts and control over the autokinesias is broken. As a result of it the difficult movements submitting to the instruction given to the patient or his own intention lose purposeful character and are replaced or the movements which are repeating the movements of the doctor (ekhopraksiya), or the arisen inert stereotypes which the patient does not notice and does not correct. Defeat is found in frontal (prefrontal) departments of a brain that indicates a role of frontal lobes in the organization of difficult intelligent motive acts. However the types of disturbance of a praksis described above remain the same in these cases. The exception is made by only pure forms ideatorny And., at which the patient loses an opportunity to imagine the necessary movement, but is not excluded, as these rather exceptional cases have the unequal factors which are already described above in the basis.

Methods of a research of apraxiauntil recently were insufficiently developed and came down to the offer to repeat the movements of the doctor, to perform these or those operations with the real or imagined objects (e.g., to show how give some tea from a teapot as stir tea in a glass etc.). These methods allow to establish existence of this or that look And., but do not give yet the chance to allocate the factors which are the cornerstone of this or that look And., and consequently, also do not give the sufficient grounds to use symptoms And. for topical diagnosis of brain defeat.

In a crust, time this lack is met by introduction of a number of the receptions allowing to show what defects are the cornerstone of this or that form A. So, for the analysis kinaesthetic And. (or «And. poses») to the patient suggest to reproduce various provisions of fingers of a hand on a sample (e.g., to expose II and V fingers, to put fingers in a figure of a ring); at a research oral And. to give to language the provision of a tubule, to place it between teeth and an under lip, to whistle etc. The difficulties in performance of this test which were followed by unsuccessful searches give the grounds for ascertaining kinaesthetic And., what allows to think of defeat of certain departments of postcentral area of bark of big hemispheres.

For the analysis space And. to the patient suggest to give to the straightened palm horizontal, frontal or sagittal position or to correlate position of both hands in corresponding coordinates of space. Difficulties in performance of this test at easy performance of previous give the grounds to assume the center of defeat in nizhnetemenny or parietooccipital area of bark. Difficulties during the performance of test of Ged — reproduction of provisions of hands of the doctor sitting before the patient have similar value; braking tendencies to mirror reproduction of movements, to carry out the cross movements (e.g., touching with the right hand the left ear etc.).

For the analysis kinetic And. the patient is offered to execute the «kinetic melody» set to it demanding smooth switching from one element of movements to another (e.g., to tick on a sample or according to the speech instruction rhythms or to carry out test on reciprocal coordination of movements of both hands at the same time, putting fingers of one hand in a fist and straightening fingers of other hand, repeating this movement many times in a row). Disturbance of smooth performance of this of «a kinetic melody» with jamming on one of links of the movement can indicate defeat of premotorny departments of bark. Existence of rough motive perseverations (impossibility in time to stop the movement and inert repetition it in the form of violent movements) can indicate involvement in pathological process of deep departments of a premotorny zone and subcrustal motive kernels.

For the analysis of the phenomena frontal And. the patient is put in conditions under which it is offered to perform the conditional operation which is not corresponding to an evident signal (e.g., in response to the raised fist to raise a finger and to lower), or its the conditional action demanding the rhythmic scheme of answers is developed (e.g., in response to one knock to lift right, in response to two knocks — the left hand); this test repeats several times in a row with rhythmic alternation, and then this rhythmic order is broken. The tendency to replacement conditional (corresponding to the instruction) actions imitative or a tendency of reproduction of an inert stereotype, irrespective of a signal, is a sign of disturbance of the regulating function of frontal lobes of a brain and, therefore, a symptom frontal And.

Conducting the described tests allows to add the clinical description And. the pathophysiological analysis of the factors which are the cornerstone of it various forms and to differentiate And. as from more elementary disorders of the movements (paresis, an ataxy), and from the general inaktivnost of the movements arising at sharply expressed gipertenzionno-dislocation states.

Forecast and treatment. The forecast is defined by the nature of a disease, at Krom arises And. (in most cases it is vascular damages of a brain, the softening of certain departments of bark of big hemispheres is preferential, tumors, injuries, inflammatory and dystrophic processes are more rare). Treatment of a basic disease, and also special events — the occupations with the patient directed to improvement of autokinesias is carried out.

Bibliography: Bernstein N. A. About creation of movements, M., 1947; Luriya A. R. the Highest cortical functions of the person and their disturbance at local damages of a brain, M., 1969, bibliogr.; it, Bases of a neuropsychology, M., 1973; Tonkonogy I. M. Introduction to a clinical neuropsychology, page 106, L., 1973; De AJuriaguerra J. and. Tissot R. The apraxias, Handb. clin. neurol., ed. by P. J. Vinken a. G. W. Bruyn, v. 4, p. 48, Amsterdam — N. Y., 1969, bibliogr.; Lange J. Agnosien und Apraxien, Handb. Neurol., hrsg. v. O. Bum-ke u. O. Foerster, Bd 6, S. 807, B., 1936, Bibliogr.; Warrington E. K. Constructional apraxia, Handb. clin. neurol., ed. by P. J. Vinken a. G. W. Bruyn, v. 4, p. 67, Amsterdam — N. Y., 1969, bibliogr.

A. P. Luriya.