Body Schema

Body Schema. Sensations coming from one's own organism form the basis for the formation of synthetic spatial perception of one's body in the form of its schema. Under normal conditions, this perception appears not vivid*—one might even say vague—but any disturbance of the schema is painfully perceived by consciousness as a violation of the vital foundation of the organism. The body schema is at the same time a very stable formation, which is proven among other things by the phenomenon of phantom in amputees, where despite the absence of a limb, the subject continues to perceive the schema of the entire body, including the removed limb. The following manifestations of disturbance of the Body Schema are observed: changes in the shape, size, and weight of individual parts of the body, their disappearance, their separation (head and hands are felt but separately from the rest of the body), displacement of parts (head and shoulders have sunk, back is in front, etc.), enlargement, reduction, change in shape and weight of the entire body, doubling of the body (feeling of a double), disappearance of the entire body. Thus, we have transitions from partial somatotopically delimited to more general-total disturbances, approaching depersonalization. Disturbance in recognizing parts of one's body as a result of disturbance of its schema is called autotopagnosia (Pick), of which finger agnosia (Gerstmann) should be considered a partial manifestation. In autotopagnosia, the patient loses orientation in his own body (distinguishing right and left, hands and feet, etc.). The concept of Body Schema is closely connected, besides the already mentioned phantoms in amputees, with Babinski's anosognosia, when for example the patient does not perceive his hemiplegia, and Schilder's painful asymbolia (pain is felt but not connected with the Body Schema). Disturbances of the Body Schema are as a rule connected with various other sensory disorders. Most often this involves peculiar visual illusions in the form of metamorphopsias, i.e., geometric-optical disturbances, when the subject sees objects distorted, turned upside down, reduced or increased in volume, etc., polyopia (multiplication of objects in number), porropsia (disturbance of vision in depth—objects seem too distant or on the contrary). In other cases, disturbances of the Body Schema are accompanied by disorders of the common sense and vestibular symptoms. It is important to note that in disturbances of the Body Schema and in the mentioned optical and vestibular symptoms, the main factor is the disturbance of spatial schizoid perceptions, concerning both one's own body and the external world. The connection between these disturbances is quite constant. This last circumstance has served as the reason for attempts to isolate a separate syndrome, the so-called interparietal. Such a name is based on observations showing that disturbance of the Body Schema and corresponding optical symptoms occur with lesions of the cortex located in the depth of the posterior part of the interparietal sulcus. It should however be noted that the interparietal cortex is probably only the leading link of an extensive system having other links in other places of the cortex as well as in the visual thalamus, vestibular apparatus, etc., consequently the appearance of elements of the 'interparietal' syndrome is possible with lesions in various parts of the brain (especially in the visual thalamus); one can only assume on the basis of available literature data (Potzl and his school) that the presence of a complete interparietal syndrome with disturbance of the Body Schema, metamorphopsia, etc. is accessible to more definite localization in the specified area of the cortex. This is also confirmed by the circumstance that disturbance of the Body Schema is often accompanied by other lower parietal symptoms (apraxia, optical agnosia, alexia, acalculia, astereognosis, etc.). Disturbances of the body schema are usually accompanied by affective disorders (anxiety, fear, horror). Disturbances of the Body Schema are observed with various focal lesions: skull injuries (in the parietal area), tumors, arteriosclerosis, syphilis of the brain, etc. Most often these are left-sided lesions, but sometimes right-sided, and in general the question of the significance for this syndrome of the left and right hemispheres is not entirely clear. Disturbances of the Body Schema are possible in epilepsy, in circulatory disturbances (for example in angioneurosis) and finally in diffuse psychoses (for example in schizophrenia). In such cases the mentioned syndrome is often the starting point for the development of the most complex psychotic pictures, especially in the form of depersonalization phenomena and others. The course of disturbance of the Body Schema depends on the form of the underlying disease: in tumors the symptom is characterized by constancy, in epilepsy, angioneurosis its episodic appearance is characteristic (in epilepsy sometimes in the form of a special aura). In syphilis of the brain the symptom disappears after specific treatment. Interesting is the possibility of appearance of disturbance of the Body Schema in healthy people under special conditions: Parker and Schilder described this symptom when riding in an elevator (for example the sensation of elongation of legs when a descending elevator suddenly stops). Disturbance of the Body Schema has also been obtained experimentally by freezing or heating a defect in the skull in the parietal area (Neu, Potzl): patients during the experiment felt that their leg or arm disappeared, etc. Similar phenomena were also obtained in experiments with mescaline poisoning. The symptom of disturbance of the Body Schema, connected with new 'human' areas of the cortex, undoubtedly has significance in the structure of many neuropsychiatric diseases, and it is not without practical interest for the neurosurgeon in terms of establishing localization of the lesion, of course when compared with other phenomena.