From Big Medical Encyclopedia

PRESBYACUSIS (presbyacusis; Greek presbys an old age + akousis hearing) — the private manifestation of aging of an organism consisting in age decrease in hearing. Idea of P. as about senile relative deafness is not absolutely right since the first signs sometimes find it in persons at the age of 30 — 40 years. It is noted that at men hearing decreases in a little bigger degree and earlier, than at women. The factors promoting early manifestations of P. consider action of noise and the postponed diseases of an ear.

Early studies of P. were conducted at the end of 19 century by H. Zwaardemaker, and then P.'s studying was widely adopted as at us in the country, and abroad.

Patol. changes at P. are found throughout everything acoustic analyzer (see). In a snail and a cochlear ganglion (a spiral node of a snail) as a result of dystrophic and atrophic processes the number of sensory cells and neurons decreases. In a predoor membrane (a predoor wall of a cochlear channel, T.; membrana vestibularis s. Reissneri) is noted vacuolation. The atrophy and a necrosis of kernels are characteristic of the centers of an acoustical way, up to an acoustical zone of a cerebral cortex. In an acoustical nerve (see. Eighth cranial nerve ) the number of bunches and fibers decreases. The atrophy of vessels, especially in a spiral sheaf, a vascular stripe and nervous educations develops. The number of neurons in the central departments of the analyzer decreases much quicker, than number of sensory cells in spiral body (see. Kortiyev body ). Also structural changes of the sound carrying out device are observed middle ear (see): viscosity of synovial fluid increases and properties of tissues of nakovalnemolotochkovy and nakovalnestremenny joints change.

At P. hearing preferential on high frequencies decreases, perception of short tones worsens, disorder of ability to localize sources of a sound in space is noted, stage of latency of distinguishing of acoustical information, etc. is extended. Deterioration in legibility of the speech at P. exceeds disturbance of perception of true tones. Deterioration in perception of the filtered and discontinuous speech, and also the speech at noise is especially noticeable.

According to Gatsek (R. A. Gacek, 1968), it is possible to allocate 4 types P.: the touch type which is shown at mature age a hearing impairment on high tones as a result of an atrophy of voloskovy and supporting cells of spiral body; the nervous type which is characterized by hl. obr. disturbance of legibility of the speech owing to reduction of number of neurons in a cortical part of the analyzer; the metabolic type differing in uniform increase in tone thresholds in all frequency range with insignificant disturbance of legibility of the speech and connected with an atrophy of a vascular stripe; the mechanical type caused not gistol. changes, and aberrations of physical properties of elements of an inner ear.

For diagnoses Items apply audiometriya (see). The most precursory symptoms age hearing disorder (see) reveal by means of an audiometriya in expanded frequency range, including 12, 16 and 18 kHz. In the USSR the standard on age changes of hearing is accepted (GOST 12.4. 062 — 78). At P. audiometric curves have the descending configuration, on the steepness of their decrease judge depth of relative deafness.

Treatment symptomatic, antiatherosclerotic, with use of the means warning a senilism of an organism. At the expressed relative deafness it is shown hearing aid (see).

Forecast depends on time of emergence of the first signs of P. and speed of progressing of process.

See also Relative deafness .

Bibliography: Sagalovich B. M. The changes of hearing caused by age in book: Relative deafness, under the editorship of N. A. Preobrazhensky, page 197, M., 1978; Temkin Ya. S. Deafness and relative deafness, M., 1957; Arentsschild O. Das alternde Ohr, funktionelle Aspekte, H.N.O., Bd 20, S. 108, 1972.

B. M. Sagalovich.