Pseudobulbar Paralysis

PSEUDOBULBAR PARALYSIS (false bulbar paralysis), loss of function of the tongue, chewing, facial, pharyngeal, and laryngeal muscles, and sometimes the corresponding eye movements, due to lesions of the central, corticonuclear pathways of the motor nuclei of the medulla oblongata, in contrast to bulbar paralysis, which results from lesions of the motor nuclei of the medulla oblongata. Therefore, the terms "cerebrobulbar paralysis" and "supranuclear bulbar paralysis" are also used as synonyms for P. p. Thus, P. p. can be characterized as a central paralysis of the aforementioned group of muscles, whereas bulbar paralysis represents a peripheral (nuclear) paralysis of the same group of muscles. As is known, the cortical innervation of the lip, tongue, pharyngeal, and laryngeal muscles is bilateral, i.e., the cortex of each hemisphere innervates both the right and left groups of nuclei of the nerves corresponding to the aforementioned muscles (V, VII, IX, X, XII). Therefore, unilateral lesions of the cortex or corticonuclear pathways of these nerves do not cause significant disturbances in the function of the aforementioned muscles. For the development of the picture of P. p., bilateral lesions of the corticonuclear pathways are necessary. There are, however, indications that in exceptionally rare cases, the picture of P. p. developed with unilateral disease of the brain; however, the validity of such cases was disputed on the grounds that with insufficiently thorough examination, the second focus of lesion could remain unnoticed. In any case, as a rule, the basis of P. p. consists of bilateral lesions of the corticobulbar pathways. Lesions of the corticobulbar pathways leading to the picture of P. p. can be localized at various levels of the course of these pathways from the cerebral cortex to the nuclei of the medulla oblongata. Most often, the pathological anatomical basis of P. p. consists of multiple small cavities localized in the area of the ganglia and extending to the internal capsule. Such cavities develop either as a result of miliary hemorrhages and softening or as a result of the breakdown of nerve tissue adjacent to sclerosed vessels ("desintegration lacunaire"). Often, the picture of P. p. is caused by circulatory disorders in the brainstem. In recent times, the view is becoming increasingly established that the picture of P. p. can be caused not only by lesions of the corticobulbar pathways but also by lesions of the striatum; at the same time, the hypothesis is put forward that the corpus striatum, namely the putamen, represents the center of automatic movements also in phonation and swallowing, which is confirmed by the frequent presence of disorders of swallowing, phonation, and chewing in Parkinsonian syndromes. However, there is a difference between the striatal (akinetic) and corticobulbar (paralytic) forms of P. p.: in the first case, it is only a matter of insufficiency of motor initiative in the corresponding musculature without phenomena of actual paresis or paralysis; only the automatic ease of performing swallowing and phonatory movements is lost. On the contrary, in the corticobulbar form of P. p., there is an actual loss of elementary movements. In addition, in the corticobulbar form, there are phenomena of central paresis in the limbs, which is explained by the involvement of the corticospinal pathways in the pathological process, lying along their entire course adjacent to the corticobulbar ones. The question of the existence of the striatal form of P. p. has rather theoretical interest. Practically, combinations of striatal and corticobulbar lesions are most often observed, which is already evident from the aforementioned frequency of simultaneous lesions of the striatum and internal capsule as a cause of P. p. Pseudobulbar paralysis occurs in various diseases; among them, the main place belongs to sclerosis of cerebral vessels, leading to repeated lesions of brain tissue of thrombotic, hemorrhagic, or disintegrative (see above) nature. This explains the fact that P. p. is observed predominantly in old age. The cause of P. p., observed in middle age, is most often also vascular lesions, specifically syphilitic endarteritis. P. p. in childhood is observed as one of the symptoms of the so-called cerebral palsy in cases of bilateral lesions of the corticobulbar pathways. The clinical picture of P. p. consists of symptoms of paresis of the articulatory, phonatory, and swallowing musculature. Speech disorders occupy the main place in the picture of the disease: in mild cases, they manifest as indistinct pronunciation of consonants with satisfactory pronunciation of vowels; speech becomes monotonous, somewhat slow, and acquires a nasal tint; usually there is more or less marked scanning and insufficient loudness of speech. This speech disorder, denoted by the term "dysarthria," reaches in individual cases various degrees of development; in severe cases, it leads to complete paralysis of the articulatory musculature; patients completely lose the ability to pronounce articulate sounds and attempts at speech are limited to unarticulated moaning sounds (anarthria). Disorders of swallowing (dysphagia) manifest primarily as choking when eating, leakage of liquid food through the nose, and insufficient intensity of chewing movements; due to flabbiness of the lip musculature and insufficient swallowing of saliva, there is a tendency to drooling. In severe cases, due to weakness of the tongue and chewing musculature, pushing the food bolus to the pharynx becomes so difficult that food remains in the buccal-oral cavities and patients are forced to extract it and push it to the pharynx with their fingers. The entry of food particles into the respiratory tract is often a cause of pneumonia. Due to the always present bilateral paresis of the facial musculature, the face in P. p. takes on a mask-like character. Along with the paretic weakness of the facial musculature, which is evident in voluntary movements, the emotive-mimetic innervation of it is not only not weakened but appears abnormally increased, which manifests in the so-called forced laughing and crying: patients burst into uncontrollable laughter or crying at the slightest provocation. The origin of this symptom is attributed to the disinhibition of automatic mechanisms of subcortical ganglia (thalamus, striatum). Since the symptom complex of P. p. is caused in most cases by significant sclerotic lesions, which usually also involve changes in the brain, patients usually have symptoms from the psyche, manifesting as weakening of memory, difficulty in thinking, increased affectivity, etc. Often the picture of P. p. is combined with the picture of senile dementia. On objective examination, phenomena of muscular weakness of the swallowing, facial, and articulatory musculature are found: patients do not protrude the tongue sufficiently, cannot voluntarily contract the mimetic musculature with sufficient intensity; the soft palate does not rise during phonation or the elevation occurs only to a slight degree. The paresis of the bulbar musculature has a central character: it is not accompanied by either atrophy nor fibrillary contractions nor reaction of degeneration. Particularly characteristic is the increase in deep and superficial reflexes in the area of the chewing and facial musculature - a symptom that also serves as a differential diagnostic sign for distinguishing P. p. from bulbar paralysis. The totality of reflexes showing a clear increase in P. p. can be denoted by the general term "oral" or "sucking" reflexes. These include: Fressreflex (Oppenheim), consisting of sucking and swallowing movements when touching the lips or tapping on them (symptom Toulouse-Vurpas). The nasolabial reflex (Astvatsaturov) is also sharply increased in P. p., consisting in a trunk-like closure of the lips when tapping on the root of the nose; the jaw reflex is also always increased in P. p. Rott and others described cases of P. p., in which movements of the eyes to the sides were difficult (paralysis of gaze). In some cases, patients were able to follow the movement of a finger with their eyes, but could not voluntarily look in one direction or the other.

Since, according to the nature and localization of the lesions causing P. p., along with corticobulbar conductors, corticospinal (pyramidal) conductors are always to a greater or lesser degree involved in the process, patients with P. p. always have more or less pronounced symptoms of central tetraparesis: muscle weakness in the limbs, increased tendon reflexes, weakening or loss of abdominal reflexes, pathological reflexes (Babinski, etc.), characteristic stooping and limited mobility of the trunk, a shuffling gait (microbasia). - In terms of differential diagnosis, one should mainly keep in mind various forms of bulbar paralysis, neuritis of the bulbar nerves, myasthenia gravis, parkinsonism. The distinction of these forms from P. p. is based on the characteristic features of the latter: increased oral reflexes, combination with pyramidal symptoms, absence of atrophy, etc. - The prognosis in P. p. depends on the nature of the underlying process. Cases dependent on arteriosclerosis and disintegration, observed in old age, represent a progressive disease and give an unfavorable prognosis. Cases of P. p., developing in connection with syphilitic lesions, give a relatively favorable prognosis provided timely application of antisyphilitic treatment. P. p., sometimes observed as a phenomenon accompanying cerebral palsy in children, is most often due to encephalitis and usually does not have a progressive nature (see Children's paralyses, forms of cerebral palsy).