Paresis of the vocal cords: causes, symptoms, diagnosis

Speech in human society is the main means of communication, contributing to the development of higher mental functions: thinking, attention, memory, etc. From infancy, we learn to understand and reproduce sounds, words, phrases. These common signals and their configurations facilitate communication between people. A modern person does not even think about how you can express your thoughts, relationships, emotions in other ways, so that they are understandable to others and help build relationships. It is not surprising that any pathology of the vocal apparatus (for example, paresis of the vocal cords), depriving a person of the possibility of normal verbal (speech) communication, today is a serious problem, and not only of a medical nature.

A bit of anatomy

It's no secret that speech is an important feature of a person that distinguishes him from other representatives of the animal world. His speech apparatus is a complex structure, which includes organs related to various functional systems. The speech apparatus consists of 2 sections: central and peripheral. The peripheral department includes:

• a hearing aid (outer, middle and inner ear), which enables us to hear sounds and speech,
• a speech apparatus (breathing, vocal and articulatory apparatus) with the help of which we can make different sounds, form various sound combinations and words.

The central part of the speech apparatus includes the speech zones of the brain and nerve fibers that transmit impulses from the central nervous system to the peripheral respiratory and speech organs involved in sound production, as well as in the opposite direction. This gives us the opportunity not only to pronounce individual sounds, but also to control their pronunciation, analyze and form certain chains of sounds (words) with which we designate a particular object, action, characteristic, etc.  [1]

The basis of the vocal apparatus is the larynx, which consists of cartilage and muscles, and is covered with a mucous membrane. In the upper part of the larynx, which, in principle, is a sound generator, its inner shell forms 2 folds, consisting of muscle and fibrous connective tissue. The connective tissue parts of the folds are called the vocal cords, although most often this term refers to the vocal folds, i.e. M muscle, and their connective tissue part.

Thanks to movements in the joints of the larynx, the presence of elastic muscles and nerve fibers that innervate them, the tissue of the vocal folds can contract and stretch. As a result, the tension of the vocal cords and the size of the gap between them change, under the influence of a stream of exhaled air, vibration of the vocal cords (both of their entire mass and individual parts) occurs and a sound of different tonality is formed.

The vocal cords change their position and tension under the influence of nerve impulses coming from the central part of the speech apparatus. The impulses go along the nerve fibers. It is clear that any damage to the nerves connecting the central nervous system and the vocal apparatus will certainly affect the quality of sound pronunciation.

Epidemiology

And although according to statistics, most often people whose profession is associated with the need to speak a lot: teachers, dispatchers, announcers, etc., turn to people about a lost or hoarse voice , it is important to understand that a heavy load on the vocal cords is far from the only reason for the violation. Voice formation. Moreover, in this case we are talking about a simple reversible type of paresis associated with a violation of blood supply (due to overstrain of the ligaments, small capillaries can burst, nutrition of nearby soft tissues deteriorates, the tone of the muscles of the larynx and vocal folds decreases). 

According to studies, 60% of paresis of the vocal cords are associated with neoplasms in the larynx, esophagus or thyroid gland and surgical operations of the same localization. And in the first place are operations on the thyroid gland. Idiopathic paresis of uncertain etiology is diagnosed in 20% of cases, and usually the real cause of the disease is a viral infection. Paresis due to nerve damage during neurosurgical operations and neurological pathologies occurs in 5% of cases. Infectious and inflammatory diseases of the brain, throat, respiratory system cause disruption of the vocal apparatus in 4-5%. [2],  [3], [4]

Benninger et al. Calculated that bilateral vocal cord paralysis may be associated with surgical trauma in 44% of cases, malignant neoplasms in 17% of cases, secondary to tracheal intubation in 15% of cases, neurological disease in 12% of patients, and idiopathic causes in 12 cases. % of cases. [5]

Thus, it becomes clear that paresis of the vocal cords is a multifactorial pathology that requires a thorough examination and identification of the causes of the disease. Only in this way can the doctor understand the mechanism of the phonation disorder (sound production) that has arisen and prescribe the appropriate treatment (symptomatic and aimed at eradicating the cause of the disease) .

Causes of the paresis of the vocal cords

Paresis is a partial loss of the functions of the vocal apparatus, which can be considered as an independent disease or occur against the background of other pathologies. Most often, such a violation of phonation is observed against the background of diseases of the larynx of an inflammatory nature:

• Laryngitis - inflammation of the larynx due to the negative effects of infection, irritation of the laryngeal mucosa by inhaled chemicals or acids entering the oral cavity (from there they can enter the initial sections of the larynx) with reflux disease, overstrain of the vocal folds during loud conversation, screaming, during vocal lessons... The causes can also be traumatic injuries, the spread of the inflammatory process from the lower or upper respiratory tract to the laryngeal mucosa, tumors in the neck and mediastinum, age-related decrease in muscle tone, as a result of which food enters the respiratory tract and can provoke inflammation. [6]
• Laryngotracheitis is an inflammation of the mucous membrane of the larynx and the initial sections of the trachea adjacent to it. Usually it has an infectious nature (more often viral, less often bacterial) and occurs as a complication of infectious and inflammatory diseases of the nose, throat, bronchi, and lungs. Although the allergic nature of the disease cannot be ruled out.

Inflammation is always accompanied by metabolic disorders (tissue edema), hyperemia (reddening of the mucous membrane due to circulatory disorders) and, as a result, a decrease in the tone of the muscles of the larynx. It is not surprising that with the above pathologies, there is a coarsening or hoarseness of the voice, a decrease in its strength, and if you do not take care during an illness, then a complete absence of a voice or a whispering speech. [7]

• Chondroperichondritis of the cartilage of the larynx with paresis of the vocal cords is an inflammatory disease of the cartilage tissue of the main organ of phonation. The most susceptible to the disease are the cricoid and arytenoid cartilages, to which the vocal cords are attached. [8] Voice changes in this case are observed in parallel with the violation of the act of swallowing. An infection is called the cause of the disease. It can be opportunistic and pathogenic bacteria, viruses that penetrate and are activated in the tissues of the larynx as a result of stab and gunshot wounds, burns, respiratory diseases, internal infections (tuberculosis, syphilis, pneumonia, typhus), erysipelas. Sometimes chondroperichondritis of the larynx develops after blunt trauma to the throat, as a complication after surgery and therapeutic manipulations (intubation, bronchoscopy, tracheotomy, bougienage of the esophagus, etc.). [9] In some cases, the disease was provoked by radiation therapy for cancer, which reduced the body's resistance to infection. [10] If the disease is started, the voice may not be restored on its own. 

Risk factors

Any respiratory infectious disease (ARVI, influenza, sore throat, bronchitis, inflammation and pulmonary tuberculosis, diphtheria), as well as infections of the brain (meningitis, meningoencephalitis) and spinal cord (poliomyelitis) can be considered risk factors for complications such as paresis of the vocal cords.

Sound production disorders can be diagnosed with certain infectious pathologies of the gastrointestinal tract (for example, when the respiratory tract is affected by the causative agent of typhoid fever, voice changes are noted, it becomes hoarse, muffled, nasal nasal is often observed with botulism), typhus, serious cranial injuries, the formation of local voids in spinal cord and brain (syringobulbia), syphilitic infection, cerebral palsy.

With a neuromuscular autoimmune pathology called myasthenia gravis, paresis of the vocal cords can occur due to strong tension in the muscles of the larynx (prolonged or loud conversation, eating, etc.). With severe poliomyositis (inflammatory lesion of the striated muscles), the soft tissues of the neck and larynx can become inflamed, which is accompanied by a partial violation of their functionality (weakening, decreased tone).

Violation of the functionality of the muscles of the vocal cords can be associated with vascular disorders of the brain (atherosclerosis of the vessels of the brain, cerebral stroke), tumor processes in it (near the speech centers and the passage of the nerves responsible for the innervation of the larynx) and neurosurgical operations (for example, with partial damage nuclei of the vagus nerve). Paresis of the vocal cords after surgery caused by damage to the vagus nerve (its nuclei and branches) is a rare complication that occurs in 5-6 patients out of 100.

One of the most common causes of paresis of the vocal cords are tumor processes in the neck and mediastinum, which compress the nerves that conduct impulses to the peripheral part of the vocal apparatus, and laryngeal injury when the vagus nerve or its branches are damaged: the recurrent and lower laryngeal nerve. Most often, we are talking about damage to the recurrent nerve of the larynx, which is possible with surgical interventions on the thyroid gland, intubation, blockade of the brachial plexus by the ladder method, external trauma of the larynx. [11]

Compression and degeneration of the recurrent nerve is possible with various diseases of the chest organs. The branches of the vagus nerve, going in the opposite direction (from the chest organs to the pharynx and larynx), are in direct contact with many vital organs (heart, lungs, esophagus, mediastinum, thyroid gland). Any pathological formations and processes in the tissues of these organs can:

• press on the nerve (aortic aneurysm, inflammation of the membranes or enlargement of the lower chambers of the heart, tumors, goiter, pneumonia with their enlargement, exudative and cicatricial processes in the pleura)
• or cause its destruction (oncological diseases: esophageal cancer, malignant processes in the thyroid gland, mediastinum, etc.).

The recurrent nerve can also be compressed by enlarged lymph nodes (cervical, peribronchial, mediastinal). [12]

An increased load on the vocal cords and inhalation of cold air through the mouth provoke inflammatory diseases of the tissues of the pharynx and larynx, in which their blood supply and functionality are disrupted. An identical situation is observed when inhaling highly dusty air, smoke, corrosive chemicals, as well as with severe intoxication of the body. In this case, laryngitis is diagnosed, which has a complication in the form of paresis of the vocal cords.

Since the peripheral part of the speech apparatus is directly related to the activity of the central nervous system, any disturbances in its work can negatively affect the process of sound production. Paresis of the vocal cords can be observed with psychopathy, hysterical attacks, neuroses (for example, astheno-neurotic syndrome), neurocirculatory dystonia (it is also vegetative-vascular or VSD). Sometimes the voice of people disappears or is greatly weakened by nervousness as a result of stress or a strong psycho-emotional shock. [13]

Another extremely rare cause of bilateral recurrent laryngeal nerve palsy is Guillain-Barré syndrome (GBS), the most common acquired demyelinating neuropathy. Although Guillain-Barré syndrome classically presents as a loss of deep tendon reflexes with ascending muscle paralysis, cranial nerves can be affected in addition to peripheral nerves. GBS can also present with respiratory distress syndrome requiring mechanical ventilation, the development of cardiac arrhythmias, and hemodynamic instability. [14]

Pathogenesis

At the heart of the  pathogenesis of the  disease, called paresis of the vocal cords, is precisely the violation of the conduction of nerves (the vagus nerve and its branches), along which impulses go to the tissues of the larynx, including the muscle tissue of the vocal folds. That is, we are talking about a violation of the innervation of the vocal apparatus, which is the reason for a decrease in the tone of its muscles and is reflected in the strength, sonority, timbre of the voice. These violations in speech therapy are combined under one name - dysphonia, and in the case of a complete absence of voice, they speak of aphonia. [15], [16]

Vocal cord paresis and its consequences have no gender or age preference. This pathology can occur with equal probability in men, women, children. [17]

Symptoms of the paresis of the vocal cords

Given the fact that paresis of the vocal cords is a multifactorial impairment of the functionality of the speech apparatus, it can be suspected that the combinations of symptoms in different types of pathology may differ markedly. In fact, if we discard the symptoms of the underlying disease (and after all, the weakening of the musculo-ligamentous apparatus of the larynx is often observed against the background of already existing health disorders), in all cases a specific clinical picture is visible.

The first signs of paresis of the vocal cords are usually changes in the voice (its sonority, timbre, tonality) and breathing problems. These symptoms can be expressed in varying degrees. With unilateral paresis of the ligaments, unpleasant voice transformations come to the fore. He becomes unusual, more hoarse, deaf, hoarse. Coarsening of the voice, unusual rattling of sounds during a conversation is often noted.

Rapid fatigue, when it is necessary to speak a lot, associated with tension during exhalation (the sound is formed on exhalation), is explained by the same changes in the voice. The formation of sounds and words in a person is carried out at the reflex level. Having learned to speak, we no longer think about how to reproduce this or that sound. But with paresis, the sounds change, their sound becomes unusual, so a person has to strain the vocal apparatus harder in order to return the sonority to the voice and pronounce sounds and words correctly. This leads to rapid fatigue, discomfort in the larynx region, and sometimes to a spasm of its muscles.

Breathing problems with paresis of the vocal cords are explained by the narrowing of the glottis as a result of a decrease in the tone of the muscles of the folds. The fact is that the trachea is not only a phonation organ, but also a part of the respiratory system. When we are silent, they are open and air can circulate freely in the respiratory tract. The vocal folds close only during a conversation. If their tone is reduced as a result of a weakening of central control or a violation of tissue trophism, the folds remain closed or do not open completely even during the process of silence, which is an obstacle to the air flow.

With unilateral paresis of the vocal cords, which occurs when their innervation is disturbed on the one hand, there are no special breathing problems. A normally functioning vocal fold allows the formation of a gap sufficient for free passage of air and sound production, even if somewhat distorted. After a few months, the defects in sound pronunciation become less noticeable, since the lost function of the affected fold is compensated for due to the normal functioning of the healthy fold, which now works for two.

But when it comes to bilateral paresis, the situation is somewhat different. Narrowing of the glottis on both sides is already a serious problem for breathing, inhalation and exhalation are difficult for a person. This is especially noticeable during physical exertion, when shortness of breath occurs, or during a lively conversation (a person speaks with a breath, makes frequent stops to take in air, inhalation and exhalation are unusually noisy).

In addition, with weak vocal cords, it becomes impossible to pronounce most, and sometimes even all, speech sounds. In this case, the patient either speaks in a whisper or expresses himself with gestures (aphonia). True, the complete absence of phonation during paresis is extremely rare, in contrast to paralysis of the vocal cords, when the possibilities of sound pronunciation and breathing completely depend on the position that the affected ligaments retain. So bilateral paralysis with closed ligaments can lead to sudden asphyxia and death of the patient.

Despite the fact that the larynx is not an organ of the digestive system, many patients with paresis of the vocal cords in the immediate vicinity of the pharynx have difficulty swallowing food. If the weakening of the functionality of the vocal cords is combined with a violation of the innervation of the epiglottis, which blocks the entrance to the larynx during meals, the risk of food entering the respiratory tract: the larynx and trachea increases, which can also cause asphyxia.

Unilateral paresis of the vocal cord can be accompanied by a decrease in the functionality of other nearby organs (tongue, lips) and dysphagia  (impaired swallowing), as a result of damage to the nerves responsible for the innervation of various organs of the head and neck. So the vagus nerve (or rather a pair of nerves) conducts impulses from the brain to the abdominal cavity, and its branches are responsible for the innervation of not only the articulatory apparatus, but also other areas of the head, neck, chest, and abdominal cavity. This nerve contains both motor and sensory fibers, so its damage can be accompanied by both a violation of the motor function of organs and a decrease in their sensitivity (numbness).

If the vagus nerve and its branches are damaged, the central nervous system partially or completely loses control over the functioning of a separate part of the body (in particular, the larynx and oral organs), therefore, conscious volitional efforts do not allow to correct the process of sound production in a short time.

With functional paresis that occurs in people with an unstable psycho-emotional state, the clinical picture may be somewhat different. In it, nonspecific symptoms appear, which are often subjective. In the overwhelming majority of cases, these symptoms are much weaker than the patients describe them. Patients may complain of perspiration and sore throat, a tickling or burning sensation in it, the appearance of a lump in the throat, etc., as well as headaches, sleep disturbances, increased anxiety, which are not typical directly for paresis.

Forms

A variety of reasons causing paresis of the vocal cords made it necessary to classify paresis depending on the factors causing them. So disturbances in sound production (dysphonia) are usually divided into organic and functional. Organic cases include cases of dysfunction of the vocal apparatus caused by inflammatory diseases, neoplasms in the area of the vocal folds and movement disorders (paresis and paralysis of the muscles of the larynx and vocal cords in particular).

If there are no signs of inflammation, the shape and color of the vocal cords are normal, but there is voice dysfunction, otolaryngologists talk about functional dysphonia caused by an incorrect relationship between the processes of excitation and inhibition in the brain or functional psychogenic disorders.

Previously, it was customary to divide the paresis of the vocal cords and larynx into 2 types:

• myogenic (myopathic)
• neurogenic (neuropathic).

Myogenic included changes in the inner layers of the muscle tissue of the larynx, provoked by the acute and chronic course of the inflammatory process, overstrain of the vocal apparatus, intoxication, etc. Disorders of blood supply and muscle nutrition. Paresis caused by weakness of the muscles of the vocal cords due to a violation of their innervation (compression, damage, dysfunction of the nerves) are considered neuropathic. [18]

Today, some scientists attribute myopathic paresis of the vocal cords to functional dysphonia of the hypotonic type and consider it as a temporary violation of phonation, which is restored by local action on the muscles. And directly paresis of the larynx is considered only those pathological conditions that are associated with a violation of the activity of the vagus nerve and its branches, i.e. Neurogenic pathologies.

Neuropathic forms of paresis can be both organic and functional, i.e. Arising from neuropsychic disorders. Organic disorders are divided into pathologies of central and peripheral origin.

Paresis of central origin, caused by diseases of the brain and operations on it, account for only 10% of the total. These include: damage to the cerebral cortex, cortical-nuclear pathways (bundles of nerve fibers that transmit impulses to the motor nuclei of the cranial nerves, in this case we are talking mainly about the fibers going to the nerve centers of the vagus nerve) or directly themselves the nuclei of this nerve, located in the medulla oblongata. They arise as a result of cerebral ischemia, tumors in it, serious head injuries, infectious and inflammatory processes in the brain and spinal cord. Functional weakness of the vocal cords can be diagnosed with cerebral palsy, multiple sclerosis, or be the result of errors during neurosurgical interventions.

Paresis of peripheral origin occurs as a result of damage to the nerves that transmit information from the brain to the ligaments and vice versa. The branches of the vagus nerve are just such nerves. Causes: trauma to the nerve, its compression by various neoplasms and enlarged organs of the chest, lymph nodes, germination of metastases of cancerous tumors, etc.

There are also congenital and acquired paresis. In the first case, the pathology is provoked by a violation of the formation of various parts of the speech apparatus in the prenatal period (infection, intoxication, vitamin deficiency of a pregnant woman in the early stages, fetal injury) or birth trauma, which led to a violation of the innervation of the peripheral part of the speech apparatus in an infant. Acquired weakness of the vocal apparatus is the consequences or complications of other pathological processes or the result of overstrain of the vocal apparatus, although in most cases we are talking about the effect of several provoking factors at the same time, for example, active conversation and inhalation of cold air, overstrain of the muscles of the vocal cords against the background of an existing violation of the central nervous system and etc.

Paresis of the vocal cords can be either unilateral (considered the most common and is characterized by damage to the right or left vocal cord), and bilateral,  [19] when both vocal folds are affected. Despite all the variety of causes and factors that can cause paresis of the left or right vocal cord,  [20] unilateral pathology is considered less dangerous, since it is mainly a violation of phonation and associated psychological problems. 

With bilateral weakening of the ligaments, which develops as a complication after operations on the neck and thyroid gland, against the background of trauma, intubation, neurodystrophic and neuromuscular diseases, we are not talking about a simple violation of sound production, but also about the pathology of respiratory function, which is considered a life-threatening situation...

Complications and consequences

Human speech is an opportunity for full-fledged, thorough communication with other representatives of his species, an opportunity to convey his thought in an understandable form and receive useful information from other people. People with phonation disorders (for various reasons) do not show a decrease in understanding of someone else's speech, but the inability to express their thoughts clearly and understandably definitely becomes a serious psychological problem. This is especially noticeable if a person's professional activity makes demands on sound production.

It is difficult for a teacher with a hoarse voice to speak and hold the attention of students, which entails a violation of discipline and the comprehensibility of the material presented. A speech therapist without a clear pronunciation of sounds cannot properly teach his wards to speak. A singer with dysphonia does not have the right to start work at all, which is accompanied by a certain discontent from the authorities and sponsors. Thus, paresis of the vocal cords and the resulting impairment of vocal function not only limits the possibilities of normal communication, but can also cause a person's disability, especially in the case of nerve dysfunction associated with damage (dystrophic processes, careless resection), which often have irreversible character.

Dysphonia does not have the best effect on children, especially if such a disorder arose at an early age, when the child is just mastering speech. The sooner the problem is solved, the less consequences it will have. After all, the developed incorrect stereotypes of the pronunciation of sounds will subsequently be very difficult to alter, despite the restored vocal function. This will create difficulties in communication, and in understanding words, in comprehending the educational material. [21]

It is especially difficult for people whose voice disappears altogether. They become virtually dumb with preserved hearing and understanding of speech. This state is psychologically difficult for most patients: they withdraw, try to limit contacts, fall into depression.

Paresis caused by infectious-inflammatory diseases or neuropsychiatric disorders are usually reversible, and with appropriate treatment, the voice is quickly restored. However, patients do not always seek special help, expecting that the disease will go away by itself, and they trigger pathology. But the longer the vocal cords lack oxygen and nutrients, the harder it will be for them to recover from illness. [22]

Full treatment of neuropsychiatric disorders is impossible without the participation of specialists (psychologist, psychiatrist), and without stabilization of the central nervous system, the return of the voice can be expected for a very long time.

Diagnostics of the paresis of the vocal cords

Paresis of the vocal cords is a pathology that can have completely different, unrelated causes. Its external manifestations in the form of dysphonia (aphonia) can say little about those factors that led to impaired voice formation. Yes, and it is too early to make a diagnosis based on this alone, because weakness of the muscles of the vocal cords does not arise by itself. It should be considered as a complication of existing pathologies and functional changes in the functioning of organs caused by metabolic disorders, infection, intoxication, nerve damage during surgery, etc.

Those. Dysphonia, which is precisely the main symptom of ligament paresis, is considered an independent disease only in isolated cases. For example, with weakness of the vocal folds in newborns. But in this case, too, it is rather a distant consequence of intrauterine disorders that led to such anomalies in the development of the child.

In most cases, patients turn to doctors not so much about dysphonia itself (except that there is a pronounced form of it or the voice is used by a person as a working tool), but in connection with breathing and swallowing disorders, suspecting they have cardiopulmonary diseases, diphtheria, sore throat, croup (in a child), etc. In some cases, paresis of the vocal cords is diagnosed unexpectedly, in parallel with the underlying disease, about which one has to communicate with a doctor (this is often the case with respiratory diseases, endocrine pathologies, tumor processes, diseases of the heart, esophagus, etc.).

Whatever it was, but the diagnosis of impaired voice formation and the identification of the causes of this process begins with a visit to the doctor. First, patients turn to a therapist who decides whether he will be able to make a diagnosis on his own (for example, in case of dysphonia for infectious and inflammatory diseases of the throat and respiratory system) or will need the help of narrow specialists: an otolaryngologist, neuropathologist, neurosurgeon, psychiatrist, pulmonologist, endocrinologist, etc. Etc. If we are talking about dysphonia against the background of overstrain of the muscles of the vocal apparatus, it may be necessary to consult and help a phoniator, who is usually approached by people who are professionally engaged in vocal.

At the initial visit to a doctor, specialists are based on the patient's complaints, a visual examination of the throat, and a study of the anamnesis. Information about past and existing diseases, ongoing surgical interventions allow you to quickly navigate the situation and narrow the range of possible causes of dysphonia, respiratory failure and dysphagia, which are manifestations of paresis of the vocal cords. So the tendency to psychogenic pathologies suggests a functional paresis, and operations on the chest, mediastinum, heart, thyroid gland, esophagus, as well as neurosurgical interventions can be considered as a possible cause of organic damage to the vagus or recurrent nerve.

But this information is not enough. Laboratory tests also cannot reveal a clear picture of the pathology. With their help (blood test), one can only determine the presence of inflammatory processes in the body and some metabolic disorders (for example, increased glucose levels in diabetes mellitus).

Special tests prescribed for suspected malignant diseases (biopsy and histological examination of a biopsy) only make it possible to differentiate a malignant tumor from a benign one, but are not an indicator that it was the neoplasm that caused the dysfunction of the vocal cords and sound production.

In the diagnosis of paresis of the vocal cords and larynx, instrumental diagnostics plays a decisive role. The simplest and most accessible method used by otolaryngologists is laryngoscopy - examination of the throat and larynx with instruments. For indirect laryngoscopy, such instruments are a mirror and a headlamp for illumination. Direct laryngoscopy is performed using a laryngoscope inserted into the patient's larynx (both diagnostic and therapeutic), which allows visualization of both the vocal folds and the inside of the larynx. [23]

Laryngoscopy allows you to identify inflammatory foci, changes in the laryngeal mucosa, small and large hemorrhages, which are invisible during a normal examination. It can be used to assess the state of the vocal folds: their position during breathing and phonation, pathological changes in movement, color, shape, size of the glottis.

An electronic stroboscope is used to determine the nature of the vibrations of the vocal cords. It allows you to assess the presence or absence of fluctuations of the vocal folds during sound reproduction, the uniformity and synchronism of the existing fluctuations in frequency and amplitude, to reveal incomplete closure of the ligaments, the shape of the glottis, etc.

For greater objectivity of the study, video laryngoscopy or video laryngostroboscopic examination can be prescribed, which allows displaying an enlarged image of the larynx on the monitor, fixing it, documenting information for subsequent discussion among specialists.

Glottography is a relatively new method for studying the phonation characteristics of the voice. A glottograph is a device that generates ultra-high frequency currents and measures the resistance as these currents pass through the larynx. By changing the current strength, one can judge the functionality of the vocal folds. On the monitor of the device, you can see a curve, which in healthy people is characterized by a pronounced cyclicality and uniformity of individual cycles. With various pathologies, the curve has certain deviations: the periodicity is violated, the oscillation phases are not determined, specific fragments with teeth appear. [24]

If the doctor detects non-closure of the vocal folds, restriction of the mobility of one of them (or both), other anomalies that suggest muscle tissue failure or insufficient nervous regulation, the patient is referred for additional examination. Methods are used to help assess the contractility of the muscles of the larynx (electromyography) and the features of neuromuscular transmission (electroneurography). True, electromyography does not provide sufficient information about the vibrations of the vocal folds and is indicative of paresis of the larynx, which can be combined with a weakening of the vocal cords, and neurography is relevant only in the case of the neurogenic nature of the pathology and is prescribed after consulting a neurologist. [25]

If a paresis of central origin is suspected (bulbar, associated with pathologies of the medulla oblongata, where the nucleus of the vagus nerve is located, or cortical, associated with damage to the cerebral cortex and its pathways), a thorough examination of the brain structures for the presence of tumors, hemorrhages, degenerative processes is required. Such a study is possible with the help of computed or magnetic resonance imaging of the brain, as well as scanning of brain structures (MSCT), carried out in trauma, to identify developmental abnormalities, acute hemorrhages. [26],  [27], [28]

If the doctor suggests peripheral paresis of the vocal cords, i.e. The one caused by the compression of the branches of the vagus nerve on the way to the vocal apparatus, an overview chest x-ray, tomography of the mediastinum or esophagus, ultrasound diagnostics of the heart, thyroid gland are prescribed.

X-ray and tomography of the larynx help to assess the general picture of the organ, but do not make it possible to determine the nature of the movements of the vocal folds, therefore, such studies are more relevant for detecting tumors and degenerative processes in the tissues of the larynx or near it. [29], [30]

If the examination of the patient does not show any morphological changes (the structure and shape of the vocal cords are normal, no organic disorders that can affect the sound pronunciation function are found in the body), the doctor concludes that the paresis is possible functional nature. In this case, it will not be superfluous to consult a psychologist and psychiatrist, conduct psychological testing with the diagnosis of possible psychoemotional disorders.

Differential diagnosis

Particular attention is paid to differential diagnosis, because it is much easier to diagnose paresis or paralysis of the vocal cords than to determine its cause. Stunning and hoarseness of the voice can be observed both in respiratory pathologies, which is a common situation and does not require specific treatment (often standard procedures are sufficient to treat a sore throat), and in neurological disorders, which can only be identified with the help of special instrumental studies. Therefore, in establishing the true cause and picture of pathology, the community of doctors of various directions plays an important role.

Vocal cord paresis must be distinguished from vocal cord paralysis. In the first case, we are talking about incomplete loss of functions of the nerves that innervate the vocal folds, i.e. About the weakening of their functionality. With paralysis of the vocal cords, innervation is absent, which can be seen with microlagingoscopy (displacement of the laryngeal mucosa due to low tone of the muscles of the vocal folds) and electroglottography.

The need to differentiate myopathic and neurogenic pathologies is associated with different approaches to the treatment of diseases of various etiologies. And in some cases, we are talking about a violation of the innervation not so much of the vocal cords, but of the articulatory apparatus. The causes of the pathology may be the same (damage or compression of the nerves), but in addition to the vagus nerve, in this case, the pathology of the glossopharyngeal and hypoglossal nerves (their peripheral parts and nuclei located in the medulla oblongata) is considered. There is also an incorrect pronunciation of certain sounds, a change in the strength and timbre of the voice.

Prevention

The diagnosis of "paresis of the vocal cords" sounds somehow menacing, so one might get the impression that we are talking about a severe, irreversible pathology of the speech apparatus. In fact, the prognosis of the disease and the approach to its treatment depends on the severity of the disorder.

Myopathic paresis, which develops as a complication of laryngitis and other infectious and inflammatory diseases of the respiratory tract, or as a result of excessive load on the vocal cords, are quite easy to treat with simple methods and pass without consequences. Functional disorders of the vocal apparatus arising from stress and nervous disorders are also not considered irreversible. The speech function is restored as the psycho-emotional state stabilizes (in some cases it goes away even without treatment).

In most cases of neurogenic paresis, the patient manages to return his voice and correct sound pronunciation, but the restoration of vocal abilities is no longer in question. Moreover, in some patients, pronunciation defects remain in the future, and some difficulties in owning their vocal apparatus are determined. In the case of severe organic disorders that are difficult to treat, a decrease in voice function is observed for a long time, which leads to atrophy of the muscles of the vocal cords and persistent phonation disorders. [31]

Prevention of violations of the work of the vocal folds is a careful attitude to your voice, prevention and timely treatment of infectious and inflammatory diseases of the throat and respiratory tract, maintaining normal nervous and endocrine systems.

In childhood, dysphonia usually occurs against the background of laryngitis, so parents should pay great attention to ensuring that the child does not overheat before going outside, does not drink ice water, does not try to use icicles as ice cream, talks less in the cold, etc. It is necessary from a young age in an intelligible form to explain to children how such carelessness can end, because only the awareness of the dangerous results of one's actions works better than simple teachings and punishments.

Adults are often reckless about the kind of air we breathe. Working in dusty conditions, at chemical plants, in laboratories, workshops do not always adhere to the requirements of breathing apparatus protection. But irritating substances can easily affect the functionality of both the respiratory and vocal apparatus, which will change the nature of speech and its capabilities. The requirement to wear respirators, cotton-gauze bandages and other protective equipment is due to the need to protect the respiratory system and voice formation, which are vital for a person. This is the prevention of many diseases, including paresis of the larynx and vocal cords, in which dysphonia or aphonia is noted.

People of certain professions, especially teachers, whose voice is a decisive factor in teaching and educating the younger generation, with all their desire, far from always succeed in maintaining the health of the vocal cords. In this case, the emphasis will have to be placed on the prevention of complications of paresis of the vocal cords, i.e. Dystrophic processes as a result of long-term dysfunction of the vocal apparatus. It is better to take care and talk less in the acute period of the illness, which will help the ligaments recover faster. Otherwise, the restoration of the voice can take a long time, and besides, you need to be prepared that it will subsequently have some unpleasant features.

Early diagnosis of a pathology called "vocal cord paresis" is the key to effective treatment of the vocal apparatus (as well as other related systems) and restoration of the voice. Therefore, a doctor should be consulted at the first signs of a phonation disorder: a change in the timbre and sonority of the voice, its strength, rhythm, especially if they occur in the postoperative period or against the background of organic brain diseases. But myopathic paresis also cannot be treated lightly, because dysfunction of the vocal apparatus for a long time, impaired respiration and nutrition of the tissues of the vocal apparatus in inflammatory diseases can provoke the development of degenerative processes that affect the quality of the voice, communication function and the patient's life as a whole.