Topical Diagnosis

Topical Diagnosis, diagnosis of the location of pathological processes. T.d. has received special development in relation to diseases of the nervous system and can be brought here to extreme fineness due to the high morphological and functional differentiation of the nervous system. The practical significance of T.d. follows primarily from the importance of determining the place to which therapeutic intervention should be applied, especially when it comes to surgical intervention. The flourishing of modern neurosurgery is largely associated with major successes in T.d. of the nervous system. On the other hand, T.d. plays no small role in elucidating the very nature of the pathological process—its histological features, etiology, pathogenesis, and nosographic characteristics. Many infections, intoxications, blastomatoses, and abiopathies are characterized by a more or less typical localization for each of these processes—either in the form of a primary focus or in the form of the most pronounced local manifestation of the general disease of the organism. T.d. is based primarily on the use of the method of functional investigation. Noting pathological changes in the functions of the body, occurring either spontaneously or under the influence of artificial stimulation, one concludes about the lesion of that organ (resp. that part of it), with the normal activity of which the given function is predominantly associated. Such conclusions presuppose the accumulation of sufficiently deep knowledge of normal and pathological physiology. At the initial stages of its development, T.d. relied mainly on the empirical experience of correlating pathological syndromes with pathological-anatomical findings discovered at autopsy (the so-called clinical-anatomical parallels). However, the doctrine of syndromes and their correlation with the topography of the process continues to improve (cf., for example, the doctrine of syndromes of various lobes of the brain, in particular certain areas of the right hemisphere, earlier considered 'silent') and not only retains its independent significance for T.d. in the future, but also provides rich material for restructuring T.d. on a more solid physiological foundation. The success and specific forms of T.d. are most closely related to the depth of resolution of the topographical localization problem. Despite the influence of idealistic and mechanistic approaches, in modern neurology there is a growing understanding that the nervous system (and the entire organism) functions as a single whole with a differentiated distribution of roles between its histological parts; that not only the occurrence, but any change in the activity of these parts depends both on the simultaneous activation of other parts and on the activity of the entire organism and nervous system as a whole (and moreover, both at a given moment and at past stages of development of the organism). Under such circumstances, the evaluation of one symptom or another from the point of view of T.d. sometimes turns out to be very complex. Far from always is a symptom a direct expression of a given pathological focus. Due to the connection between different functions, a violation of one of them leads to a violation of others without this involving a lesion of the most important parts of their substrate. Thus, with a lesion of cortical field 40 (according to Brodmann), not only apraxia arises, but sometimes certain phenomena of optical agnosia. And conversely, optical agnosia caused by a lesion of the occipital lobe can lead to peculiar disorders of praxis, which creates in such cases a false impression of an apparently additional focus in the parietal lobe. Similar relationships are also brought about by the development of diaschisis. Furthermore, as for more complex functions (for example, reading or writing), they are disturbed with very different localization of the pathological process in brain tissue. Only with careful analysis, taking into account especially the history of development of this function, can one reveal the peculiar structure of the disorder and thereby approach the correct topical diagnosis. Thus, functional T.d. stands at the present level of our knowledge before great difficulties in a number of cases, and these difficulties are sometimes aggravated by the very nature of the pathological process. Thus, in brain tumors, one often has to deal with the so-called 'distant symptoms' due to disorders of cerebral circulation and cerebrospinal fluid circulation or due to reactive phenomena in the areas of tissue adjacent to the tumor. Under such circumstances, along with functional T.d., other methods of establishing a topical diagnosis acquire great importance, allowing, in case of their success, to directly detect the pathological focus. Most of these direct methods can be designated as biophysical. These include, along with percussion and auscultation, primarily radiography with its increasingly diverse modifications (encephalo-, myelo-, arteriography, etc.), further exploratory puncture of the organ' (in particular puncture of brain tissue), various types of instrumental observation' over the organ in vivo, up to vital microscopy (for example, cystoscopy, ventriculoscopy, capillaroscopy). Together with the growth of technology, the number and perfection of these methods of T.d. are constantly increasing. In each individual case, especially in case of diagnostic difficulty, it is necessary to involve all available methods of both functional and direct (biophysical) T.d. and determine the localization of the process only on the basis of the entire set of data obtained.