Acute acoustic trauma: causes, symptoms, diagnosis, treatment

Causes of acute acoustic trauma. Acute acoustic trauma occurs as a result of the impact of powerful impulse noise of more than 160 dB on the hearing organ, often in combination with a sharp increase in barometric pressure during an explosion. A shot from a pistol or a hunting rifle near the auricle, as a rule, leads to either temporary hearing loss (depending on the distance from the muzzle of the barrel to the external auditory canal), or to severe persistent hearing loss, which can be established immediately or after some time.

Pathological anatomy. Mild, moderate and severe degrees of hearing loss from impulse noise are distinguished. Mild degrees result in traumatic impact with subsequent partial degeneration of the outer hair and supporting cells of the SpO; moderate degrees result in damage to the outer hair supporting cells and partially to the inner hair cells; severe degrees result in destructive processes in all receptor cells involving the spiral ganglion and nerve fibers, with hemorrhages of varying intensity usually observed in the ear labyrinth, including in the vestibule structures.

In case of an explosive injury (mine, artillery shell, explosive + package, explosive device, etc.), in addition to acoustic injury, there is a barometric injury of the middle and inner ear, which leads to rupture of the eardrum, destruction of the chain of auditory ossicles, dislocation of the base of the stapes, rupture of the membrane of the round window and destruction of the structures of the membranous labyrinth. With such an injury, as a rule, a contusion neurological syndrome occurs (prostration, loss of consciousness, temporary dysfunction of other analyzers, etc.).

Symptoms of acute acoustic trauma. When acute acoustic trauma occurs, sudden unilateral or bilateral hearing loss of varying degrees occurs, all surrounding sounds instantly “disappear”, a syndrome of deafness occurs, which, in addition to hearing loss, is characterized by a sharp ringing in the ears, dizziness (not always), and pain in the ear. Blast trauma may cause bleeding from one or both ears and from the nose. Endoscopically, a ruptured eardrum is detected.

When examining hearing in both purely acoustic and explosive trauma, only loud speech or screaming is perceived in the first minutes and hours. When examining threshold tonal hearing between acoustic and explosive (with damage to the sound conduction system) trauma, some differences are observed: in acoustic trauma, the bone conduction curve merges with the air conduction curve, while in explosive (baroacoustic) trauma, a bone-air gap is observed at low and medium frequencies.

The evolution of acute acoustic trauma is determined by the severity of the lesion. In mild cases, hearing usually returns to its original level even without treatment. In moderate cases, even after intensive treatment (see the previous section), residual perceptual hearing loss (the presence of FUNG) remains, which, due to the reduced tolerance of the cochlear hair apparatus to incoming pathogenic factors (infection, intoxication, constant noise, etc.), can subsequently contribute to the development of more pronounced and progressive sensorineural hearing loss than in the case where there was no acute acoustic trauma in the anamnesis.

The treatment is not fundamentally different from that for chronic acoustic trauma. For anatomical damage to the middle ear, the treatment described in the subsection " Aerotitis " is used.

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