Paralysis and Paresis

PARALYSIS AND PARESIS (from Greek paralyo- to relax; pariemi- to let go). In the general sense of the word, paralysis is understood as the loss of a certain function due to a disturbance of innervation. Thus, one can speak of paralysis of motor functions, of paralysis of sensitivity, of paralysis of a certain sense organ, etc. Usually, however, this term denotes specifically the loss of motor functions dependent on damage to the motor apparatus of the central or peripheral nervous system. Paresis is an incomplete paralysis, not the loss of motor functions, but only their weakening to a certain degree. Paralysis must be strictly distinguished from other motor disorders. The loss of movements may depend on damage to the bone-joint apparatus (ankylosing processes in the joints, Parrot's syphilitic pseudoparalysis due to damage to the epiphyses). In these cases, it is not a paralysis, because with the latter a disorder of movements must be conditioned by a disturbance of motor impulses from the nervous system. On the same basis, one cannot speak of paralysis where the loss of movement depends on primary damage to the muscles themselves (inflammatory processes, so-called myopathic paralyzes; in progressive muscular dystrophy, etc.). Often the disorder of movement is caused by pain: the patient does not move a certain limb in a certain direction because such movement is accompanied by a painful sensation (so-called pseudoparalysis, pseudoparesis, paralysie douloureuse in small children). Such states should be distinguished from true paralysis. Finally, there are many motor disorders conditioned by damage to the nervous system, which nevertheless do not fall under the concept of paralytic disorders. These are the phenomena of ataxia, in which the disorder of movement depends not on the impossibility of contracting the corresponding muscles with the necessary force, as happens in paralysis or paresis, but on an incorrect combination of contractions of the corresponding muscles. This is also apraxia, in which gross muscular strength is completely unaffected, and the disorder of motor functions is expressed by the loss of the ability to act (see Apraxia). These are hyperkineses, where motor function is disturbed and distorted due to the admixture of superfluous movements. These may be certain disturbances of tone, both towards hypertonia and towards atonia, which may hinder the correct execution of movements. Regarding these disturbances, it should be said, however, that they are usually closely connected with motor disorders of the paralytic type. The loss of innervation impulses conditioning the occurrence of paralysis or paresis may have an organic character, i.e., depend on an organic, anatomically confirmed damage to the innervation apparatus, central or peripheral. Then one speaks of organic paralysis or paresis. Reflex paralyzes also belong to this group, in which weakening of movements (usually in the hand or foot) occurs by reflex (local irritation after injuries, wounds), and which are accompanied by cyanosis, hypothermia, and often also trophic disorders. But the disturbance of innervation impulses may also have a purely dynamic character, depend on all kinds of psychogenic moments (suggestion, autosuggestion, imitation, emotion), and then one speaks of functional paralysis. Functional paralytic disorders are encountered mainly in hysteria (see). In essence, etiology, symptomatology, and course, both named types of paralysis are deeply different from each other. Within the organic paralysis, in turn, a number of groups can be distinguished. First of all, one can distinguish various types of paralysis according to differences in their distribution. Paralysis may be more or less total, i.e., affecting all limbs, facial musculature, etc. It may also be limited, i.e., spreading only to a certain "limited territory." In cases of hemiplegia, it is a matter of damage to one half of the body, for example, as is often the case, damage to the upper and lower limbs on one side, the lower branch of the facial nerve, and the hypoglossal nerve. In cases of diplegia, there is a combination of right-sided and left-sided hemiplegia. In paraplegia (see), both lower limbs are affected (so-called lower paraplegia) or, which occurs rarely, both upper limbs (so-called upper paraplegia). In the combination of upper and lower paraplegia, one speaks of quadriplegia or tetraplegia. In the combination of hemiplegia and paraplegia, triplegia arises. Where one limb is affected, one speaks of monoplegia: in the case of the upper limb, of upper monoplegia, in the case of the lower limb, of lower monoplegia. Where it is not a complete paralysis but a paresis, the terms hemiparesis, paraparesis, monoparesis are used accordingly. Paralysis and paresis can be classified further according to their symptomatic properties. For example, the division of paralyzes into flaccid paralyzes, spastic paralyzes (paraparesis spastica), etc., is generally used. The etiological principle is sometimes adopted as the basis for the classification of paralyzes. Thus, one speaks of traumatic paralyzes (e.g., luxation paralyzes after dislocations with compression of plexuses or nerve trunks, strangulation paralyzes with damage to the brachial plexus), of intoxication paralyzes, infectious paralyzes, of professional paralyzes (e.g., paralysis of the median nerve in carpenters, in locksmiths), etc. The greatest significance undoubtedly lies in the division of paralyzes based on the localization of the anatomical damage. In this sense, one must first distinguish peripheral and central paralyzes. In peripheral paralyzes, it is a matter of damage to the preneuron or peripheral neuron, i.e., damage to the motor cells of the anterior horns of the spinal cord, respectively nuclei of cranial nerves (nuclear paralyzes), or anterior roots, or damage to peripheral nerves. In central paralyzes, there is damage to central motor neurons. Since the central motor apparatus is constructed very complexly and consists of several systems, the concept of central paralysis is complex and includes various forms of motor disorders within its framework. To understand the character and essence of these disorders, it is necessary first of all to bear in mind that the functions of voluntary movements disturbed in this case are constructed very complexly and are amenable to dissection, respectively dissociation, in which one part of such a complex function is lost and the other remains preserved and undergoes certain changes. Such dissociation of complex functions usually occurs in central paralyzes; this is explained by the fact that these functions are anatomically localized in the central nervous system not simply, but multiply, so that the more elementary part of them is anatomically represented in the more phylogenetically and ontogenetically older parts of the central nervous system, while the more complex part of them is localized in the newer parts (e.g., the direct cortico-spinal or pyramidal system, which reaches great development only in primates and in man). However, there is one place in all vertebrates whose preservation is absolutely necessary for the integrity of all motor functions, however complex or elementary they may be. No matter how the motor function is constructed, its final realization necessarily involves the cells of the anterior horns of the spinal cord or cells of equal significance for motor function of the nuclei of cranial nerves. In other words, higher motor centers can exert their influence only through the medium of the peripheral neuron. Therefore, anatomical damage to the peripheral neuron (cells of the anterior horn or connecting these cells with the corresponding muscles peripheral nerves) entails the complete loss in the corresponding area of all motor functions as a whole without any dissociation. Peripheral paralysis is total; with it, complex motor functions are lost, but also such elementary functions as reflex functions. This is the most important property of peripheral paralysis in symptomatic terms, finding its clinical expression in the fact that the paralysis is accompanied by the extinction of reflexes and a fall in tone, i.e., it is a flaccid paralysis. The second characteristic feature of peripheral paralysis lies in its complete inability to compensate. This ganglionic accumulation is absolutely necessary for the function; no anatomical bypass paths can remedy the situation if this nucleus is dead. Thus, for example, paralysis of the biceps muscle of the arm will never smooth out or improve if its nucleus is destroyed. The function may, of course, improve partially due to compensatory strengthening of the function of synergists, i.e., muscles, 673