Neuropathic laryngeal paresis is a disease that manifests itself in weakness of the internal muscles of the larynx, which is associated with a violation of innervation. As is known, a unilateral type of neuropathic laryngeal paresis is usually accompanied by a hoarse voice, as well as a violation of the patient’s vocal function. If we talk about bilateral neuropathic paresis of the larynx, then this type of disease is usually expressed by a violation of the respiratory process, the development of hypoxia, which can even cause asphyxia. All measures aimed at diagnosing this disease will include, first of all, X-ray examination of the larynx, chest organs and esophagus. The study also includes CT of the larynx, CT and MRI of the brain, mandatory ultrasound of the thyroid gland and heart. Treatment of neuropathic laryngeal paresis is, first of all, the elimination of the factor causing damage to the nerves that innervated the larynx. Also, the treatment involves the use of neuroprotectors, further restoration of voice function with the help of phonopedic, as well as vocal exercises.
The content of the article:
Causes of neuropathic laryngeal paresis
Symptoms of neuropathic laryngeal paresis
Diagnosis of neuropathic laryngeal paresis
Treatment of neuropathic laryngeal paresis
Neuropathic laryngeal paresis
Usually, innervation of the internal muscles of the larynx occurs through the branches of the vagus nerve. As you know, the upper laryngeal nerve innervates the ring-thyroid muscle, while the rest of the laryngeal muscles innervate the recurrent nerves. It is because of various injuries, as well as a special pathological condition of the vagus nerve, that peripheral neuropathic laryngeal paresis develops. In case of lesion of the vagus nerve nucleus, a neuropathic central laryngeal paresis is formed in the cortical centers or in the brain stem.
It should be said that neuropathic laryngeal paresis is a common type of laryngeal paresis. This type is associated with the pathology of the larynx itself, as well as with other diseases of the nervous system and the pathological processes occurring in the thoracic cavity. Thus, the examination and treatment of patients with this disease is entrusted not only to an otolaryngologist, but also to a neurologist and specialists in thoracic surgery.
Causes of neuropathic laryngeal paresis
The peripheral type of neuropathic laryngeal paresis is very often caused by pathology of the left or right recurrent nerves. Precisely because of the large length of the recurrent nerve, as well as because of the entrance to the larynx from the thoracic cavity and possible contact with various anatomical structures, nerve damage is possible in a variety of areas. As a rule, the left recurrent nerve, bending around the aortic arch, can squeeze it with a characteristic aneurysm. Usually, the right recurrent nerve can pass close to the upper part of the right lung. It can also be transmitted by pleural adhesions in this area. The main cause of damage to the recurrent nerve with the further development of neuropathic paresis of the larynx may be trauma to the larynx. Other main causes include: pleurisy, pleural tumor, pericarditis, lymphadenitis, mediastinal cyst, an increase in the size of the thyroid gland (this usually occurs in the case of diffuse toxic goiter, as well as autoimmune thyroiditis and all possible iodine deficiency diseases and tumors). The cause of the occurrence and development of neuropathic laryngeal paresis can also be thyroid cancer, diverticula, various benign tumors, esophageal cancer, enlarged lymph nodes and tumors in them.
Interestingly, peripheral neuropathic laryngeal paresis may also be of toxic origin. The disease can occur as a result of toxic neuritis of the recurrent nerves in the case of poisoning with alcohol, nicotine, lead and even arsenic. The development of the disease due to diabetes mellitus, diphtheria, typhus (abdominal and rash), tuberculosis and intoxication is not excluded. Neuropathic laryngeal paresis is observed during damage to the recurrent nerve during various operations on the thyroid gland. The latter include: hemithyroidectomy, thyroidectomy and subtotal resection.
Usually, the central type of neuropathic laryngeal paresis occurs when, for example, the brain stem is damaged, which causes bulbar paralysis, as well as with tumors, polio, syringomyelia, neurosyphilis, botulism. The disease can also occur due to severe atherosclerosis of the cerebral vessels, with hemorrhage into the brain stem itself, which occurs during a hemorrhagic stroke.
Interestingly, neuropathic laryngeal paresis, if its nature is of central origin, is observed due to pathological processes that can affect important pathways going to the cerebral cortex. Usually, cortical neuropathic laryngeal paresis can accompany brain tumors, can occur with ischemic and hemorrhagic strokes, with severe types of traumatic brain injuries. It should also be noted that the cortical type of neuropathic laryngeal paresis in any case has a bilateral character. This is due to an incomplete intersection of the pathways to the place where the entrance to the brain stem begins.
Symptoms of neuropathic laryngeal paresis
The first symptom of the appearance and development of neuropathic paresis of the larynx is a characteristic decrease in the mobility of the vocal cords, which manifests itself in a violation of phonation (or vocalization) and in violation of respiratory function. The involvement of the internal muscles of the larynx in the pathological process with neuropathic paresis of the larynx occurs sequentially. At the first stage, there is a violation of the function of the posterior cricoid muscle, which, meanwhile, is responsible for the ability to expand the glottis and divert the vocal folds. After that, weakness begins to develop and paralysis of the laryngeal adductors occurs, which can narrow the larynx and reduce the vocal cords. The latter has its own name — the law of Rosenbach and Semon. This law explains why, with neuropathic paresis of the larynx, the vocal cord, as a rule, occupies its median position. This happens because of the preserved operability of adductors, which are observed at the beginning of the disease. After a certain time, there is an increase in the weakness of the adductors, which is why the vocal cord can move to an intermediate position.
It should be said that neuropathic paresis of the larynx is usually characterized at the beginning of its manifestation by the preservation of normal phonation, due to the adjunction of a healthy vocal cord to the ligament of the affected side, which occupies the middle position. In the first stages, breathing remains normal. Shortness of breath can manifest itself only with strong physical exertion. In the future, the development of this disease is accompanied by the involvement of all kinds of laryngeal adductors, as well as the vocal cord, which occupies an intermediate position. Due to the latter, there is a final closing of the glottis during phonation. This leads to hoarseness of the voice, which is already a characteristic symptom of neuropathic laryngeal paresis. After a couple of months, the patient begins to develop hyperadduction of the vocal cords, but already on the healthy side, which is why it fits more tightly to the paretic ligament. As a result, we observe the restoration of a normal voice, but at the same time, the violation of vocal functions in a sick patient still persists.
If we talk about bilateral laryngeal paresis, then in the initial period it is accompanied by characteristic disorders of the respiratory system, which can lead up to asphyxia. The latter is due to the location of the vocal cords, which have a median position and can be completely closed, thereby preventing the passage of air through the respiratory tract. As for the clinical manifestations of bilateral neuropathic paresis of the larynx, first of all, it should be said about the presence of noisy breathing with possible retraction of the supraclavicular pits, as well as the epiglottis and even intercostal spaces both on inspiration and exhalation. A patient suffering from bilateral neuropathic laryngeal paresis is forced to be in a sitting position, leaning on a sofa or chair. The facial expression in neuropathic laryngeal paresis reflects, as a rule, fright, and his skin has the appearance of cyanotic coloration. With any physical exertion, even minor, there is a deterioration in the human condition. Two or three days after the clinical manifestations of this disease, the vocal cords become in an intermediate position, which is why a gap forms between them. Over time, respiratory function improves, but when performing any physical activity, symptoms characteristic of hypoxia occur.
Diagnosis of neuropathic laryngeal paresis
The main purpose of the diagnosis of neuropathic laryngeal paresis is, first of all, to identify the cause of this paresis. A patient with suspected neuropathic laryngeal paresis is referred to a neurosurgeon, an otolaryngologist, a thoracic surgeon, a neurologist and an endocrinologist. The examination of the patient includes a large list of necessary studies: X-ray of the larynx, CT of the larynx, studies of vocal functions (for example, stroboscopy, phonetography, electroglottography, and others), as well as electrocardiography of the laryngeal muscles. Be sure to conduct research to determine the state of the thyroid gland. To do this, the thyroid gland is examined using ultrasound. In case of suspicion of damage to the recurrent nerve in various pathological processes, an X-ray of the chest organs, ultrasound of the heart, an X-ray of the esophagus, and so on are also prescribed.
Treatment of neuropathic laryngeal paresis
First of all, the treatment of neuropathic laryngeal paresis consists in eliminating the cause of the disease, that is, in the treatment of infectious diseases, pericarditis, thyroiditis, pleurisy, in the treatment of the consequences of stroke. Also, the treatment consists in removing possible tumors and diverticula in the esophagus, as well as mediastinal tumors. If necessary, doctors also perform thyroid resection.
In order to quickly restore the function of the damaged nerve, doctors prescribe to the patient the use of neuroprotectors, the use of B vitamins and, in some cases, reflexotherapy.
