Deafness

Deafness is the most severe degree of hearing loss, in which a person is practically or completely unable to perceive sounds, including human speech. The audiological criterion for deafness is an increase in hearing thresholds above 90 decibels (dB).

The condition may be congenital or acquired at any age. Deafness is not only a medical problem, but also a serious social issue, as it significantly hinders verbal communication and integration into the society of hearing people.

Aetiology and pathophysiology

The causes of deafness can vary and affect different parts of the hearing organ.

• Sensorineural (neurosensory) deafness. This is the most common etiology. It is associated with irreversible damage or death of hair cells in the inner ear (cochlea) or damage to the auditory nerve. Causes include genetic syndromes, severe infections (meningitis), exposure to ototoxic drugs, or extremely loud noise.
• Conductive deafness. It occurs when there is a severe disruption of sound conduction in the outer or middle ear, for example, in cases of auditory canal atresia or complete destruction of the ossicular chain. This form is less common.

Clinical Significance

Deafness is diagnosed using a comprehensive audiological examination, the main component of which is pure-tone threshold audiometry. An audiogram for deafness demonstrates an absence or a sharp decrease in response to high-intensity sounds across the entire frequency range.

Rehabilitation approaches depend on the type of deafness. In cases of sensorineural hearing loss, conventional hearing aids are generally ineffective. The “gold standard” treatment is cochlear implantation, a surgical procedure in which an electrode system is implanted in the cochlea, directly stimulating the auditory nerve and restoring the ability to perceive sounds. For some forms of conductive deafness, surgical treatment aimed at restoring the sound-conducting apparatus is possible.