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DIFFERENTIAL DIAGNOSTICS OF Hearing Aid

By hearing loss is understood the difficulty of verbal communication and perception of sounds. Distinguish between conductive (sound-conducting), perceptual (sound-perceiving) and mixed types of hearing loss.

The most important condition for the supply of sound energy to the hair cells of the spiral organ is the normal morphological state, the functional mobility of the sound-conducting apparatus from the outer ear to the organ of Corti. For good sound transmission, normal air pressure in the tympanic cavity and ear lymph in the maze is necessary. Violation of mechanical sound conduction at any level leads to conductive hearing loss, the causes of which are diseases, primarily the middle and then the outer and inner ears.

Mixed hearing loss often represents a transitional stage to perceptual hearing loss, when there are changes in the hydrodynamics of the ear lymph and an increase in its pressure. It is more often observed in Meniere's disease and in the cochlear form of otosclerosis.

Perceptual hearing loss implies a violation of not only the perception of sounds by the receptor cells of the Corti's organ, but also the pathology of the entire auditory sensory tract, therefore it is better to call it sensorineural hearing loss.

The degree of hearing loss is determined by speech and tonal thresholds of hearing. On a tonal audiogram, special attention is paid to speech frequencies. In the table. 1.9.1 the characteristic of degrees of hearing loss according to G.V. Kovtun is given (cited. According to Kozlov M.Ya .., Levin A.L., 1989).



Table 1.9.1

Degree of hearing loss



The clinical diagnosis of hearing loss should consist of two parts - morphological and functional. For example, right-sided adhesive otitis media with conductive hearing loss of the II degree or bilateral post-influenza sensorineural hearing loss of I degree on the right and II degree on the left ear.

Of particular importance in the differential diagnosis of hearing loss are non-purulent ear diseases with a whole eardrum, which include chronic tubo-otitis, adhesive otitis media, otosclerosis, Meniere's disease and sensorineural hearing loss. Tubootitis, adhesive otitis media and stage I otosclerosis are characterized by conductive hearing loss. In Meniere's disease, mixed hearing loss with a sensorineural component is noted. The progression of otosclerosis gradually leads to mixed hearing loss, and its late cochlear form is characterized by impaired sound perception. It must be borne in mind that conductive hearing loss that has existed for several years can progress to mixed and sensorineural hearing loss. Sensoneural hearing loss is cochlear (receptor), radicular (with neuroma of the VIII nerve) and central genesis.

Violation of the mechanism of sound conduction in the middle and inner ear is characterized by certain signs that are generally different from sensorineural hearing loss (Table 1.9.2). There is a low-frequency, less often mid-frequency subjective ear noise. Conversation is often perceived worse than whispering, as it contains lower sound frequencies. The duration of the perception of predominantly low-frequency tuning forks decreases. Lateralization of sound in Weber's experiment in a sore ear with a one-sided and worse hearing ear - with bilateral conductive hearing loss. The tuning fork experiments of Rinne, Federichi, Bing are negative. The experience of Jelle is negative with otosclerosis, so it is its pathognomonic symptom. However, with severe tympanosclerosis, adhesive otitis media, the Jelle experiment can also be negative. The duration of bone conduction in the Schwabach experiment is elongated on the affected side or worse than the hearing ear. An improvement in hearing acuity in whispering speech after blowing the ear through the Politzer or through a catheter indicates conductive hearing loss with tubootitis. The restriction or lack of mobility of the tympanic membrane when examining a Siegle pneumatic funnel is characteristic of adhesive otitis media.

Conducted hearing loss is characterized by an increase in tonal thresholds of air conduction, mainly in the low-frequency region (up to 50-60 dB) with a slight increase in bone conduction thresholds in the low-frequency region (up to 20 dB). There is always a bone-air interval of more than 20 dB. Sometimes there may be an increase in tonal thresholds of bone conduction to 40 dB due to blockade of both windows of the labyrinth, which entails a deterioration in the hydrodynamics of the inner ear.

Speech audiometry reveals 100% speech intelligibility, but the sensitivity thresholds increase to 50 dB, while the speech intelligibility curve is shifted to the right of the normal curve and parallel to it.

When conducting suprathreshold audiometric tests, the level of uncomfortable volume (UDG) may exceed the maximum intensity of the audiometer, therefore, conductive hearing loss is characterized by a large dynamic range of the auditory field (DDSP). FUNG is negative. With Langenbeck noise audiometry, noise and tone are heard at the same intensity level.



Table 1.9.2

Differential diagnosis of hearing loss in non-purulent ear diseases



Legend: LF, MF, HF - low-, medium-, high-frequency subjective ear noise; + / 0 - a diagnostic sign occurs or is absent; ? e? iui o? eooii pathognomonic symptoms of diseases have been identified.

Auditory sensitivity to ultrasounds is normal, its lateralization is noted in the better hearing ear. The lower limit of perceived sound frequencies (UHF) is shifted to the right to 60-100 Hz. In the study of spatial hearing in otoclerosis, the determination of the localization of the sound source in the vertical plane is violated. Similar changes can be observed with adhesive otitis media and chronic suppurative otitis media due to impaired mobility of the foot plate of the stapes. With pronounced asymmetry of hearing, spatial hearing is disturbed in the horizontal plane.

Differentiated conductive hearing loss from sensorineural allows impedance audiometry. With the latter, the tympanogram is normal (type A), and the thresholds of the acoustic reflex of the stapes increase in proportion to hearing loss, there may be FUNG and the decay of the acoustic reflex. With conductive hearing loss, there are changes in tympanograms, often negative pressure in the tympanic cavity. The acoustic reflex of the stapes is not recorded due to the limited mobility of the sound-conducting apparatus. With adhesive otitis media, a tympanogram of type B is noted (very low compliance of the tympanic membrane, negative pressure in the middle ear or it is not determined), the stapes reflex is not recorded. Chronic tubo-otitis is characterized by a lesser restriction of the mobility of the eardrum against a background of reduced pressure in the tympanic cavity (type C tympanogram, the apex of which is shifted toward negative pressure). The acoustic reflex is positive. After blowing the ear, the pressure in the tympanic cavity is restored and the mobility of the tympanic membrane is normalized. Extensive movable scars of the tympanic membrane, its atrophy, defects of the auditory ossicles are manifested by a tympanogram of type D - hypertensibility of the tympanic membrane, the absence of a stapes reflex in case of an anvil defect. With otosclerosis, the compliance of the tympanic membrane is moderately reduced due to fixation of the foot plate of the stapes (tympanograms of the A1-A2 type) and there is no reflex of the stapes. With a gaping auditory tube, the tympanogram and stapes reflex are normal, but vibrations of the tympanic membrane are recorded synchronously with breathing.

With conductive hearing loss, not one of the types of otoacoustic emission is recorded, but there is an extension of the latent period of all components of short-latent auditory evoked potentials (VSWR). VSAP wave curves during air stimulation shift on the intensity scale, respectively, according to the degree of conductive hearing loss.

Mixed hearing loss is a transitional stage to sensorineural hearing loss when there are reversible changes in the receptor that are detected using suprathreshold tests. It is noted in Meniere's disease and stages II-III of otosclerosis, as well as in the progression of adhesive otitis media and tympanosclerosis.

On a tonal audiogram, the curves of air and bone conduction often go horizontally, thresholds can increase evenly in air conduction - up to 60 dB and bone - up to 40 dB.
There is a small gap between these curves (up to 15 dB). There are concave and descending audiograms with breaks in the high-frequency zone. Audiograms in individual areas may be similar to those with conductive, mixed, and sensorineural hearing loss. The sound-conducting component of hearing loss is noted in the low frequency region.

Often revealed FUNG. Unlike sensorineural, with mixed hearing loss (rock type), FUNG can be reversible with improved hydrodynamics in the inner ear. If it is present, 100% speech intelligibility is not always achieved, the level of uncomfortable volume (UDG) increases abruptly, the DSP is narrowed, the SISI test is 100%. Above-threshold tests often correlate with the level of hearing in bone conduction. Normal auditory sensitivity to ultrasounds is maintained, despite the sensorineural component of the audiogram. With speech audiometry, 100% speech intelligibility is achieved with a greater deviation of the audiogram to the right compared to conductive hearing loss.

The lateralization of sound in Weber's experience is often of an indefinite nature, depending on the predominance of impaired sound conduction or sound perception in the ear. Usually there is lateralization of sound in the direction of the better hearing ear, and ultrasound - in the direction of the worse hearing ear. Hydrops of the labyrinth in Meniere's disease is confirmed by a positive glycerol test, characterized by a decrease in tonal hearing thresholds of more than 10 dB. The UHF is shifted to 60-70 Hz. Disturbed spatial hearing in the horizontal and vertical planes.

With electrocochleography, the amplitude of the summation potential (SP) and the ratio of its amplitude to the amplitude of the action potential (AP) - SP / PD increase to 0.5. Normal and in patients with sensorineural hearing loss of another etiology, SP / PD is 0.25.

With a mixed form of otosclerosis, the tonal audiogram begins to acquire a descending character, often with a lack of a bone-air interval, similar to sensorineural hearing loss, but all indicators of an audiological study are characteristic of conductive hearing loss. There is a violation of spatial hearing in the vertical plane.

The cochlear form of otosclerosis (with a descending tonal audiogram without a bone-air interval) is audiologically more difficult to distinguish from sensorineural hearing loss, however, in addition to the descending curves of the audiogram, other audiological tests indicate the conductive nature of hearing impairment. In such cases, the totality of all clinical manifestations of the disease, as well as the results of radioimmunological diagnostics by the nature of the distribution of the radiopharmaceutical in the bones of the skull and parenchymal organs, which differ in otosclerosis and primary sensorineural hearing loss, must be taken into account.

The main audiological signs of the diagnosis of non-purulent diseases of the ear are given in table. 1.9.3.

Sensoneural hearing loss is quite easily differentiated from conductive hearing loss using tuning fork tests. The lateralization of sound during Weber's experience is noted in the best-heard ear. The experiences of Rinne and Federichi are positive. The perception of bone conduction in the Schwabach experiment is shortened. Bing’s experience, designed to diagnose impaired sound conduction, is positive. Also, a violation of the mobility of the foot plate of the stapes is not detected using the Jelle experiment.

Table 1.9.3

Audiological diagnosis of non-purulent ear diseases



It is rather difficult to differentiate receptor (cochlear), radicular and central sensorineural hearing loss.

According to tonal audiometry, receptor and radicular hearing loss is characterized by a descending type of curve without a bone-air interval. The pathology of the Corti's organ is often accompanied by a break in the curves (especially bone conduction) in the high frequency region. With stem hearing loss, there is a predominant increase in tonal thresholds for high and low frequencies with a parabolic form of an audiogram, but there may be an increase in thresholds only for high frequencies.

Speech audiogram with receptor hearing loss is deviated to the right of the standard curve. Speech intelligibility does not reach 100% or even worsens with increasing speech intensity. Already at an early stage of the eighth neuroma, the intelligibility of speech is violated while maintaining tonal hearing (tonal-speech dissociation). Tonal-speech dissociation is even more pronounced with central sensorineural hearing loss. With small shifts in tonal thresholds, speech intelligibility is sharply disturbed.

All types of sensorineural hearing loss are characterized by a deterioration in speech intelligibility against the background of noise.

With receptor hearing loss, the level of discomfort volume (UDM) is normal, the dynamic range of the auditory field is narrowed. UDH is reduced in neuroma of the VIII nerve. With central sensorineural hearing loss, the level of UDH is normal.

The phenomenon of accelerated increase in volume (FUNG) is positive in the case of damage to the receptor cells of the organ of Corti and the auditory centers of the brain and is not detected when the root of the VIII nerve is damaged.

The lower limit of perceived sound frequencies (UHF) for all types of sensorineural hearing loss is normal and corresponds to 20-40 Hz.

The thresholds of perception of ultrasound with receptor hearing loss are increased or ultrasound is not perceived. The lateralization of ultrasounds in case of VIII neuroma in the healthy ear, while the lateralization of sound in the Weber experiment is absent. With a nuclear lesion of the auditory system and asymmetry of hearing, there is no lateralization of audible sounds, and ultrasound is lateralized in the best-heard ear.

Receptor hearing loss is accompanied by impaired spatial hearing in the vertical plane with hearing loss at frequencies above 4000 Hz. With severe asymmetry of hearing, spatial hearing is disturbed in a horizontal plane from the side of the affected ear. With symmetrical hearing loss of more than 50 dB, the ability to localize the sound source is significantly impaired or absent. For radicular and central lesions, spatial hearing impairment has not been adequately studied.

With impedance audiometry for all forms of sensorineural hearing loss, normal mobility of the sound-conducting apparatus of the middle ear is noted.

The thresholds of the acoustic reflex with receptor hearing loss increase towards high frequencies or are not detected. Neuroma of the VIII nerve and brain stem imperfection are characterized by the decay of the acoustic stirrup of the stapes. Stirrup reflex in neurinoma (ipsi and contralateral) may not be caused by stimulation of the affected side. Pathology of the brain stem at the level of the trapezoidal body leads to the loss of both contralateral reflexes of the stapes with safety - ipsilateral. Volumetric processes in the field of cross and one non-cross paths are distinguished by the absence of all reflexes, except for the ipsilateral on the healthy side.

When the auditory receptors are damaged, on the audiogram for auditory evoked potentials, the VSWP is clearly recorded, except for the first-order wave. With neuroma of the VIII nerve and the stem level of the lesion, lengthening of the I and V inter-peak intervals of VSWR is noted. With large tumors, CSWP are not caused.

Caused otoacoustic emission (UAE) with neurinoma and damage to the brain stem is not recorded on the side of the lesion.

Cortical hearing loss is characterized by tonal-speech dissociation, lengthening of the latent period of auditory reactions, deterioration in speech intelligibility against a background of noise, impaired spatial hearing in the horizontal plane. Binaural perception does not improve speech intelligibility. Patients often experience difficulties in perceiving radio broadcasts and telephone conversations. Afflicted with DVS. A drop or lack of potentials to sounds of different tonality and intensity is noted.

Neuroma of the VIII nerve and other diseases of the brain are diagnosed using computed and magnetic resonance imaging of the skull.

Military personnel with hearing loss of various genesis are examined according to Art. 40 of the order of the Ministry of Defense of the Russian Federation N 315 1995, taking into account the table of additional requirements for the state of health of citizens.
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DIFFERENTIAL DIAGNOSTICS OF Hearing Aid

  1. The experiments of Rinne, Weber, Schwabach in the differential diagnosis of hearing loss
    Experience of comparing air and bone conduction (Rinne experiment) Methodology: a sounding low-frequency (C 128) tuning fork is placed with a foot on the mastoid process. When the sound from it ceases to be perceived by the researched, the tuning fork is brought to the external auditory canal. With normal hearing and damage to the sound pickup device, the tuning fork will be heard for some time to come.
  2. Diagnosis of hearing loss
    Уточнение функции слухового анализатора предусматривает главным образом осуществление топической диагностики. Основной вопрос топической диагностики – различение поражений системы звукопроведения от поражения системы звукового восприятия. В дифференциальной диагностике поражений слухового анализатора особое значение приобретает распознавание центральных форм тугоухости. Тугоухость лечится
  3. Ключарева А.А. и соавт.. Диагностика и дифференциальная диагностика заболеваний печени у детей (Пособие для практических врачей), 2001

  4. Дифференциальная диагностика
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    При подозрении на реноваскулярную АГ проводят стандартную дифференциальную диагностику между АГ и вторичными формами АГ различного генеза, а при выявлении признаков, характерных для реноваскулярной АГ, целью дифференциальной диагностики является установление непосредственной причины патологического процесса, то есть установление этиологической формы реноваскулярной АГ. В большинстве случаев для
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