Neuromuscular dysfunction of the larynx: causes, symptoms, diagnosis, treatment

The larynx is the functional center of the upper respiratory tract, finely reacting to minor disturbances of its innervation, endocrine dysfunctions, various kinds of psychogenic factors and occupational and household hazards.

In this article, we will focus on those pathological conditions of the larynx, in which the most prominent manifestations of certain neuromuscular disorders of the larynx.

[1], [2], [3], [4], [5]

Sensitive laryngeal dysfunction

These dysfunctions include hyperesthesia, paresthesia and hypoesthesia of the mucosa, which can occur for a variety of reasons - local inflammatory and neoplastic processes, endocrine dysfunctions, secondary complications of a number of common infectious diseases, neuroses and hysteria.

Hyperesthesia and paresthesia of the larynx in the overwhelming majority of cases occurs in inflammatory diseases of the mucous membrane and its lymphoid apparatus, as well as in malignant and benign tumors and dorsal dryness crises. As a rule, such changes in the sensitivity of the mucous membrane of the larynx are accompanied by similar symptoms from the side of the larynx and the trachea. A sign of hyperesthesia of the larynx is the increased sensitivity of these anatomical formations to a variety of factors that normally do not cause any unpleasant sensations. These symptoms include pain, itching, perspiration, caused by factors coming in from outside (with inhaled air, drinks, beggars), and from the inside, when these factors get through the mucous membrane of the upper respiratory tract and gastrointestinal tract. External factors may include dry or wet, hot or cold air, insignificant content of smoke particles or vapors of various volatile substances in it, a number of aromatic compounds and many others. The irritation with these substances provokes a painful dry cough. The endogenous factors, along with substances dissolved in lymph and blood, include mucus, secreted by the mucous glands of the upper respiratory tract and containing antigen-like substances that enter it from the blood and lymph, which is especially characteristic for attacks of bronchial asthma.

Paresthesia of the larynx

Paresthesia of the larynx is characterized by the appearance of atypical sensations in the larynx, which differ from the pain or itching, arising not only and not so much from the influence of any substances, but more often as "genuinely," spontaneously in the form of a lump in the throat, sensation of stenosis, or, on the contrary, "free pipes, "that is," a sensation in which there is no sensation "of the passage of air through the upper respiratory tract. Most often such paresthesias occur in hysteroid individuals or with certain mental illnesses. Discomfort, a feeling of stiffness and objective difficulties in phonation, as well as the paresthesia noted above, are noted in secondary amyloidosis of the larynx, which appears as a complication of pulmonary tuberculosis, bronchiectasis and other chronic purulent and specific processes in the body.

Hypes- tesia and laryngeal anesthesia are rare and are associated with interruption or inadequate conductivity of the overlying nerve, for example, when the tumor is pressurized or wounded. More often these sensitivity disorders arise when the nucleus of this nerve or its supernuclear pathways and corresponding sensitive cortical zones are affected.

Paralysis and paresis of the larynx

Paralysis and paresis of the larynx relate to neuromuscular diseases of this organ. They can arise as a result of organic lesions of motor nerves, innervating the internal muscles of the larynx, and be functional in various neuropsychic disorders.

Paralysis and paresis of the larynx are divided into myogenic, neurogenic and psychogenic. Miogenic or myopathic paralysis of the larynx, depending only on pathological changes in the muscles, are very rare and can be caused by certain helminthiases (trichinosis), infectious diseases (tuberculosis, typhoid fever), and banal chronic inflammation, congenital myopathy, fatigue as a result of a voice load and etc.

Myopathic paresis of the larynx

Myopathic paresis, as a rule, is bilateral, affecting only the muscles that cause vocal folds. This lesion can be combined with weakness of other muscles, for example, respiratory (diaphragm, intercostal muscles). Among the myopathic lesions of the musculature of the larynx, paresis is mm. Vocales stands in the first place in the frequency of occurrence. This paresis during the phonation between the vocal folds creates an oval slit. This form of the gap arises because the retaining muscles retain their function, which, in phonation, bring the vocal arms of the arytenoid cartilages closer together, as a result of which the posterior ends of the vocal folds approach, while the vocal muscles do not take part in this process because of their flabbiness.

Myopathic paresis of the vocal muscles is manifested by the hoarseness and weakness of the voice with the loss of its individual timbre coloration. When trying to force a voice, the phenomenon of "blowing" of the larynx arises, consisting in excessive consumption of the stock of air in the lungs for phonation. When talking, patients are forced more often than usual to interrupt their speech for a new inspiration.

With an isolated bilateral paralysis of the lateral perforochermal punctate muscles, the vocal cavity takes the form of an irregular rhombus. Normally, these muscles close the vocal folds along the midline along their entire length and thereby block the laryngeal lumen. When they are paralyzed, the voice slit, while trying to make a background, remains gaping, which makes the symptom of the "purging" of the larynx especially pronounced, the voice loses its sonority, and patients, due to significant consumption of pulmonary air, are forced to turn to whisper speech.

When paralysis of a single unpaired muscle - the transverse arytenoid muscle - during the phonation in the posterior section of the vocal cicle, the lumen is coiled in the form of a small isosceles triangle at the level of the vocal appendages of the arytenoid cartilages, while the remaining parts of the vocal folds are completely closed. This form of paralysis is the most favorable for both the voice and respiratory function of the larynx.

With the paralysis of the vocal muscles and the transverse arytenoid muscle during phonation, a picture appears remotely resembling an hourglass and is a combination of variants.

When paralysis of individual fibers of the posterior pericardium muscles, which ensure the tension of the vocal folds during the phonation, their uncomforting and flotation of the free edges occurs, the voice becomes jarring at the same time, loses its timbre color and the ability to intonate high sounds. This phenomenon is well defined by stroboscopy.

In the case of a one-sided paralysis of the posterior cricoid muscle, which is the only paired muscle that widens the vocal cavity, the corresponding vocal fold occupies the middle position by inhaling the adductor muscles; with the bilateral paralysis of this muscle, the obstruction of the glottis arises as a result of the fact that both vocal folds occupy the middle position.

With the paralysis of all the laryngeal adducts, the vocal folds under the influence of the traction of the posterior pericumperial muscles occupy the position of the extreme lead, and phonation is practically impossible, breathing excursions of the vocal folds are absent.

Neurogenic paralysis of the internal muscles of the larynx

Neurogenic paralysis of the internal muscles of the larynx is divided into peripheral ones, caused by the defeat of the corresponding motor nerves, and the central ones that arise when the bulbar nuclei of these nerves, the superior conducting paths and centers are affected.

Peripheral neurogenic paralysis of the internal muscles of the larynx is caused by the defeat of the vagus nerve, in particular their branches - recurrent nerves. The latter, as is known, innervate all the internal muscles of the larynx except for the anterior metacarpal muscles, which stretch the vocal cuff and divert the vocal folds. The considerable extent of recurrent nerves, their direct contact with many anatomical formations that can be influenced by various pathological conditions and surgical interventions, reversing their course from the chest cavity to the larynx - all this negatively affects their protection, which increases the risk of their damage. The causes of these injuries can be: for the left recurrent nerve - an aneurysm of the aortic arch, which this nerve circumscribes, pleural adhesions on the tip of the right lung (for the right nerve), exudative and cicatricial processes in the pericardium and pleura, tumors and hyperplasia of the mediastinal lymph nodes, tumors of the esophagus , goitre, thyroid cancer, tumors and lymphadenitis of the cervical lymph nodes (for both nerves).

Neuritis of the recurrent nerve can develop as a result of intoxication with a number of infectious diseases (diphtheria, typhus) and poisoning with alcohol, nicotine, arsenic, lead, etc. Sometimes the recurrent nerve is damaged by a strumectomy.

With paralysis of the recurrent nerve, the first posterior pericardium muscles, which remove the vocal folds and expand the vocal cleft (the risk of acute respiratory obstruction of the larynx and asphyxia), first cease to function, and after a while the other internal muscles of the larynx are immobilized, and only then the vocal folds (with unilateral nerve damage - one fold) occupy a cadaverous position - an intermediate between the full ghost and the outermost lead.

This sequence of switching off the internal muscles of the larynx, which is observed in the lesion of one or both return nerves and known as the Rosenbach-Semion law, is of great clinical significance, since with simultaneous damage to both recurrent nerves, the first occurrence of vocal folding leads to a sharp disruption of breathing, an emergency tracheotomy. With a unilateral paralysis of the recurrent nerve, the vocal fold first occupies the middle position, remaining stationary. At phonation, a healthy fold adjoins it, and the voice sounds relatively satisfactory. Breathing remains free at rest and with little physical exertion. With the spread of the pathological process to the muscles that lead the muscles, the vocal fold departs from the midline, concavity appears on it and then it assumes a cadaveric position. There is hoarseness of the voice. Only later, after a few months, when compensatory hyperaddition of the healthy fold appears and it begins to fit tightly against the fixed crease, the voice acquires a normal sound, however, the vocal function is practically impossible.

Symptoms in acute bilateral reversal of the recurrent nerves are typical: the patient sits motionless on the bed, leaning his hands on her edge, on his face - an expression of extreme fright, the breath of rare stridiform, supraclavicular fossa and epigastric region on inspiration sink, with exhalation protrude, lips cyanotic, pulse frequent . The slightest physical effort leads to a sharp deterioration in the patient's condition. Only then, when the vocal cords take a cadaveric position, and this occurs no earlier than in 2-3 days and a gap not exceeding 3 mm forms between them, the respiratory function improves somewhat, but the physical load still causes phenomena of general hypoxia.

Central paralysis of the larynx

Central paralysis of the larynx is caused by bulbar nuclear and supranuclear conductor lesions and can occur with a variety of diseases and brain lesions.

Bulbar paralysis of the larynx occurs with progressive muscular atrophy, multiple sclerosis of cerebral vessels, syringomyelia, dorsal sucking, progressive bulbar paralysis, hemorrhages, tumors and gums of the medulla oblongata and other diseases associated with damage to the nuclear formations of the brain stem, as well as cortical centers of the pyramidal system and somatotopically organized cortical-bulbar pathways. In the latter case, the organic cortical paralysis of the vagus nerve is two-sided because of the incomplete intersection performed by these nerve pathways before they enter the nuclei of the corresponding motor nerves. These cortical paralysis are caused by hemorrhages, infarct softening, tumors arising in the cortical-bulbar pathways and corresponding motor zones of the cerebral cortex, providing arbitrary movements of the internal muscles of the larynx.

[6], [7], [8], [9], [10]

Syndromal paralysis of the larynx

Syndromal paralysis of the larynx occurs usually with various myopathic syndromes, congenital hypoplasia of neuromuscular synapses, McDurdle syndrome, spastic paralysis, in some forms of myotonia, etc.

Myasthenic syndromes resemble the classical form of myasthenia gravis. They are due to the pathological state of the neuromuscular synapse, i.e., a violation of the transfer of excitation from the nerve fiber to the cholinergic structures of the muscle. From this state it is necessary to distinguish miastenopodobnye state, not associated with a violation of the synaptic transmission of nervous excitation and caused by organic lesions of the brain, endocrine glands, as well as a violation of carbohydrate and mineral metabolism. Despite the fact that in recent cases, the positive effect of the administration of anticholinesterase drugs (proserine, galantamine, physostigmine, etc.) is sometimes observed, this fact does not indicate a true myasthenia, in which administration of these drugs gives a significant, albeit temporary, benefit.

Myasthenic Lambert-Eaton syndrome occurs with bronchogenic carcinoma, thyroid damage and is characterized by a significant disruption of acetylcholine release from the vesicles in the presynaptic department, although the amount of this mediator in numerous vesicles is even excessive. The syndrome is more common in men after 40 years and may precede the development of the underlying disease. Symptoms of this syndrome are muscle weakness and muscle atrophy, reduction or loss of deep reflexes, pathological fatigue, mainly of the legs, less often of the hands. Groups of muscles innervated by cranial nerves suffer less often, however, when they are involved in the pathological process, one or another paresis and paralysis, including extraocular and intralaryngeal muscles, can be observed. In the latter case, speech becomes quiet and indistinct due to the weakness of the articulatory apparatus. Incidentally, it should be noted that many "unexplained" cases of hyperacia occur precisely because of myasthenic lesions of the muscles of the tympanum.

Congenital aplasia of the neuromuscular synapse, manifested by the myasthenic syndrome, is clearly seen in electron microscopy: synapses in such cases resemble synapses of embryonic muscles. Clinically, pronounced hypotension of the muscles, often a decrease or loss of tendon reflexes. The disease is more common in women. The use of proserine or galantamine produces a positive effect. The voice of such patients is usually weakened, a loud speech or cry does not work out or is possible only for a short time.

The syndrome of McArdle occurs with hereditary glycogenosis (Girke's disease), a disease defined by a peculiar disorder of carbohydrate metabolism leading to a disruption of reversible glycogenolysis and glycogenesis processes with simultaneous disruption of protein and lipid metabolism. The disease is congenital, extremely rare. Clinical petitions begin already in childhood and are expressed in the fact that after a minor physical exertion there is pain in the muscles, their rapid fatigue and weakness, myoglobinuria, late muscular dystrophy, heart failure, often weakness of smooth muscles. The syndrome is caused by a deficiency of phosphorylase in the muscle tissue, thereby delaying the cleavage of glycogen, which accumulates in excess in muscle.

Myotonia

This type of disease of the motor system is characterized by a violation of the contractile function of the musculature, expressed in a special condition of the musculature, in which the contracted muscle hardly returns to a state of relaxation. The phenomenon is more often observed in the striated muscle, but can take place in the smooth muscles. An example of such a phenomenon can serve as a symptom of the tonic pupil, which is part of the Eddie syndrome caused by selective degeneration of the ganglia of the posterior roots of the spinal cord and the ciliary ganglion. The disease manifests itself at the age of 20-30 years sluggish reaction of the pupil to light and darkness, a decrease or a complete absence of tendon reflexes, moderate hypericotropism. The symptom of the tonic pupil is characterized by the fact that its expansion or constriction after the change of illumination is kept unusually long.

Myotonia of arbitrary musculature in its pure form is observed with a special disease called congenital myotonia, or Thomsen's disease. The disease is a kind of hereditary myopathy with an autosomal type of inheritance. In this disease, there are no morphological changes in the central nervous system and the peripheral nervous system. In the pathogenesis of this type of myotonia, permeability of cell membranes, the ionic and mediator exchange in the "calcium-troponin-actomyosin" link are important, as well as the increased sensitivity of tissues to acetylcholine and potassium. The disease begins usually at school age, sometimes the first signs of it appear immediately after birth, and by 4-5 months there are signs of muscle hypertrophy. The flow is slow, progressing in the early years with subsequent stabilization; It is often first diagnosed during the passage of a military medical commission upon admission to military service.

The main symptom of the phenomenon of myotonia is a disturbance of the movements, which consists in the fact that after a severe contraction of muscles the subsequent relaxation of them is difficult, but with repeated repetition of this movement it becomes more and more free and, finally, normal. After a short rest, the phenomenon of myotonia repeats itself with the same intensity. Myotonic phenomena can extend to the muscles of the face, in which in this case an expression remains inadequate for long, on the masticating and swallowing muscles and internal muscles of the larynx; in the latter cases, there are difficulties in chewing, swallowing and phonation. Chewing movements become slow, swallowing is done with difficulty, and a sudden sharp cry leads to prolonged closure of the glottis, which slowly opens only after a few seconds. Signs of the disease increase with cooling of the body or its individual parts, with physical exertion and mental stress.

Objectively, the muscles are hypertrophic, the patients have an athletic build (a symptom of Hercules), but the strength of the muscles relative to their volume is reduced.

Functional paralysis of the larynx

Functional paralysis of the larynx occurs with neuropsychiatric disorders, hysteria, neurasthenia, traumatic neurosis. The main sign of functional paralysis of the larynx is the "imaginary" aphonia, in which the voice with laughter, coughing, crying remains sonorous, conversational speech becomes possible only in a whisper. Functional paralysis of the larynx is more common in women and appears as a manifestation of a hysterical fit or severe emotional stress. Often, aphonia, which occurs with acute laryngitis in a neurotic, continues in the form of functional aphonia for a long time and after the disappearance of all manifestations of inflammation, which should be taken into account by practical doctors. In these cases, the patient must be referred to a therapist. Functional aphonia, suddenly arising, just as suddenly can disappear. Usually this happens after a strong long sleep, a violent experience of some joyful event, a sudden fright. Sensitivity of the mucous membrane of the pharynx and larynx with functional aphonia, as a rule, is reduced, as well as in the majority of persons with an hysterical mentality.

Treatment of neuromuscular dysfunction of the larynx

Treatment of neuromuscular dysfunction of the larynx is determined by their nature; each of them requires careful diagnosis, sometimes at the level of genetic research methods, complex biochemical methods, studies of metabolic processes, etc. Only after an accurate recognition of the disease based on the establishment of its etiology and pathogenesis is the patient directed to the appropriate specialist or to a number of specialists. With regard to violations of the larynx, the treatment with them is symptomatic.