Acute acoustic trauma: causes, symptoms, diagnosis, treatment

Causes of Acute Acoustic Injury. Acute acoustic trauma occurs as a result of the impact on the hearing organ of a powerful impulse noise of more than 160 dB, often in combination with a sharp increase in the barometric pressure in the explosion. A shot from a pistol or a hunting rifle near the auricle usually leads to either temporary hearing loss (depending on the distance from the muzzle trunk to the external auditory canal) or to a pronounced hearing loss that can be established immediately or after a while.

Pathological anatomy. There are light, medium and severe degrees of hearing impairment from impulse noise. At an easy degree to a traumatic influence with the subsequent partial degeneration the external hair and support cells СпО are exposed, at an average weight external hair support, and also partially internal hair cells are amazed; at a severe degree, destructive processes occur in all receptor cells involving the spiral node and nerve fibers, while, as a rule, there are different intensities of hemorrhage in the ear maze, including in the structures of the vestibule.

In the case of explosive trauma (mine, artillery shell, burst-burst, explosive device, etc.), in addition to acoustic trauma, a barometric trauma of the middle and inner ear arises that leads to rupture of the tympanic membrane, destruction of the auditory ossicles, dislocation of the base of the stapes, rupture the membrane of the round window and the destruction of the structures of the membranous labyrinth. With such trauma, as a rule, there is a contusion neurological syndrome (prostration, loss of consciousness, temporary disruption of the functions of other analyzers, etc.).

Symptoms of acute acoustic trauma. At the time of acute acoustical injury, sudden, one-sided or bilateral hearing loss of various degrees occurs, all surrounding sounds instantly "disappear," and a deafness syndrome occurs, in addition to hearing loss, a sharp ringing in the ears, dizziness (not always), and pain in ear. In an explosive trauma, bleeding from one or both ears and nose may occur. Endoscopically, the rupture of the tympanic membrane is determined.

When examining a hearing, both in purely acoustic and in explosive trauma, in the first minutes and hours only loud speech or scream is perceived. When studying threshold hearing between acoustic and explosive injuries (traumas), there are some differences: in the case of acoustic trauma, the bone conduction curve merges with the air conduction curve, while in the explosive (baroacoustic) trauma at low and medium frequencies, air rupture.

The evolution of acute acoustic trauma is determined by the severity of the lesion. With a mild degree of hearing, as a rule, returns to the initial level even in the absence of treatment. At moderate severity, even after intensive treatment (see the previous section), the residual deafness phenomena of the perceptive type (the presence of FUNG) persist, which in the future, due to a lower tolerance of the cochlear hair device to incident pathogenic factors (infection, intoxication, constantly acting noise, etc.) may contribute to the development of more pronounced and progressive sensorineural hearing loss than if there was no acute acoustic trauma in the anamnesis.

Treatment in principle does not differ from that in chronic acousular trauma. For anatomical injuries of the middle ear, the treatment described in the sub-section " Aerotitis " is used.

[1], [2], [3], [4], [5], [6], [7]