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Functional examination of the larynx

 
, medical expert
Last reviewed: 17.06.2019
 
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In the clinical study of larynx functions, first of all, changes in respiration and voice formation are considered, as well as the use of a number of laboratory and functional methods. A number of special methods are used in phoniatrics - the section of laryngology, which studies the pathological states of the voice function.

The study of the voice function begins already during a conversation with the patient when assessing his voice and sound phenomena that occur when the respiratory function of the larynx is disturbed. Afonium or dysphonia, stridorous or noisy breathing, distorted timbre of voice and other phenomena can indicate the nature of the pathological process. Thus, with volumetric processes in the larynx, the voice is compressed, muffled, the characteristic individual timbre of it is lost, often the conversation is interrupted by a slow deep inspiration. On the contrary, in the "fresh" paralysis of the narrowing of the glottis, the voice, as it were, exhales almost soundlessly through the gaping vocal chasm, the patient lacks air for pronouncing the whole phrase, so his speech is interrupted by frequent breaths, the phrase is fragmented into separate words, during a conversation, hyperventilation of the lungs occurs breathing pauses. In a chronic process, when there is compensation for the voice function due to other larynx formations, and in particular the folds of the vestibule, the voice becomes rough, low, with a hint of hoarseness. If there is a polyp, fibroma, or papilloma on the voice fold , the voice becomes as if fractured, trembling with the impurities of additional sounds arising from the jitter of the formation on the voice fold. Stenosis of the larynx is recognized by the stridorous sound that occurs during inspiration.

Special studies of the lantern function become necessary only in those cases when a person whose larynx is the "working organ" is subject to examination, and voice and speech are the "product" of this organ. At the same time, dynamic parameters of external respiration (pneumography), flash excursions of vocal folds ( laryngostroboscopy, electroglottography, etc.) become objects of research . Using special methods, the kinematic parameters of the articulatory apparatus that form the sounds of speech are examined. With the help of special sensors, the aerodynamic expiratory indices of singing and talking are studied. In addition, in special laboratories, spectrographic studies of the tonal structure of the voice are performed by professional singers, determine the timbre coloration of their voices, study phenomena such as voice flight, singing formants, voice immunity, etc.

Methods of visualization of laryngeal motor function

As noted above, with the invention of the method of indirect laryngoscopy in a short period of time, almost all the most common disorders of laryngeal motor function were detected. However, as it turned out, using this method it is possible to detect only the most gross violations of the mobility of the vocal folds, while the researcher eluded those violations that can not be registered with the naked eye. In the future, various devices were used to study the motor function of the larynx, first, lighting, based on stroboscopy, then with the development of electronics - rheoglobotography, electronic stroboscopy, etc. The drawback of laryngostroskonium is the need to introduce a recording optical system into the epiglottium space, vocal folds during speech articulation, free singing, etc. These drawbacks are devoid of methods that record the vibration of the goth anion or resistance change to high-frequency electric current (rheoglobotography) during phonation.

Vibrometry is one of the most effective methods for studying the laryngeal function of larynx. Accelerometers are used for this purpose, in particular, the so-called maximum accelerometer, which measures the moment when the measured frequency of the fibrillating body reaches a given frequency of sound or maximum acceleration in the range of the frequencies to be phoned, i.e., the vibration parameters. When recording the vibration of the larynx, a piezoelectric sensor is used that generates an electrical voltage with a frequency of its constriction equal to the frequency of oscillations of the vocal folds. The sensor is attached to the outer surface of the larynx and allows measuring accelerations from 1 cm / s 2 to 30 km / s 2, i.e., within 0.001-3000 g (g is the acceleration of the free fall of the body, equal to 9.81 m / s 2 ) .

Rheography of the larynx

The rheography of the larynx was first performed by the French scientist Philippe Fabre in 1957. He called it a glotography, it was widely used in the study of various functional disorders of the larynx in the 60-70s of the XX century. This method is based on the same principle as REG, and is intended for changes in resistance to metric current that arise in living tissues under the influence of biophysical processes taking place in them. If in the REG they measure the changes in resistance to electric current that occur when the pulse wave passes through the brain tissue (change in the blood filling of the brain), then during a glotography, the resistance to the electric current of the vocal folds, changing its length and thickness during phonation, is measured. Therefore, with rheolaryngography, the change in resistance to electric current occurs synchronously with the phantom vibration of the vocal folds, during which they come into contact with the frequency of the produced sound, as well as the change in their thickness and length. The rheogram is recorded with a rheograph consisting of a power unit, a low-current generator (10-20 mA) of high frequency (16-300 kHz), an amplifier amplifying the current passed through the larynx, a recording device and electrodes applied to the larynx. The electrodes are placed so that the tissues in question are located between them, i.e., in the electric current field. In glaetography, according to Fabre, two electrodes with a diameter of 10 mm, lubricated with an electrode paste or coated with a thin felt felt impregnated with isotonic sodium chloride solution, are fixed with an elastic bandage on the skin on both sides of the larynx in the area of the projection of the thyroid cartilage plates.

The shape of the rheolaryngogram reflects the state of the motor function of the vocal folds. With quiet breathing, the rheogram looks like a straight line, slightly undulating in time to the respiratory excursions of the vocal folds. During phonation, oscillograms of the glotogram appear, similar in shape to the sinusoid, whose amplitude correlates with the loudness of the sound produced, and the frequency is equal to the frequency of this sound. Normally, the parameters of the glotogram are characterized by high regularity (constancy) and resemble the oscillations of the microphone effect of the cochlea. Often a glotogram is recorded together with a phonogram. Such a study is called phonoglottography.

In diseases of the laryngeal locomotor apparatus, manifested by the unobstructed vocal cords, their stiffness, paresis, or mechanical impact on them by fibroids, papillomas and other formations, corresponding changes in the glotogram are recorded, correlating to the existing lesions in varying degrees. When analyzing the results of a glotographic study, one should keep in mind that the parameters of the glotogram depend not only on the degree and time of the closure of the vocal folds, but also on the change in their length and thickness.

Functional X-ray tomography

Is a method of choice in the study of motor function of the larynx. The essence of the method lies in layered frontal images of the larynx during the singing and singing of vowels of different tones. The method allows to study the motor function of vocal folds in normal and in voice disorders associated with fatigue of the vocal apparatus, as well as with various organic diseases of the larynx. Take into account the symmetry of the position of the right and left halves of the larynx, the uniformity of convergence or divergence of the vocal folds, the width of the glottis, etc. So, in normal with the phonation of the "and" sound, the closest convergence of the vocal folds and the symmetry of the excursion of the radiopaque laryngeal formations are observed.

A variety of functional X-ray tomography of the larynx is roentgenographic imaging, at which time-frame shooting of excursions of mobile elements of the larynx is carried out with subsequent analysis of all criteria of these excursions. The advantage of this method lies in the fact that it is possible to observe the "work" of the voice device in dynamics while still obtaining information about the larynx as a whole, visualizing its deep structures, the degree and symmetry of their participation in the lantern and respiratory processes.

It is important to know!

Paralysis of the larynx is characterized by the immobility of one or both halves of the larynx. Violation of innervation entails serious morphofunctional changes - respiratory, defensive and voice-forming functions of the larynx suffer. Read more..

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