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Nerve deafness, also known as sensorineural hearing loss, is an ear condition whose symptoms include decreased hearing abilities or total deafness because of inner ear damage. It affects millions of people at varying degrees of severity. The condition can result from defects present at birth, referred to as congenital defects, or symptoms acquired later in life. Most occurrences of nerve deafness are attributed to abnormalities of hair cells located in the inner ear.
Irreversible damage to parts of the the inner ear, specifically the hair cells found in the cochlea, distinguishes nerve deafness from other hearing loss conditions, although very rare instances of impairments to the auditory centers of the brain and the cranial nerve have been discovered. Damage to the brain's auditory processors leads to a more serious sensorineural deafness called central hearing loss, marked by an inability to interpret sounds so that speech is rendered incomprehensible. Most cases of nerve deafness occur from damage to hair cells, preventing auditory information from being relayed to the acoustical nerve and causing some degree of deafness. The number of abnormal hair cells determines how severe the hearing loss will be.
Injury to or destruction of the hair cells in the inner ear might stem from congenital sources, inherited dominant or recessive genes associated with hearing loss, or from acquired external influences, such as an infection, disease or trauma. Acquired nerve deafness has been connected to abnormalities and diseases of nearly every organ system, side effects of some medications and physical injuries. Lifestyles that incorporate constant exposure to loud noises, such as daily headphone use at full volume, also can lead to such trauma. Some acquired causes can trigger rapid hearing loss called sudden sensorineural hearing loss which usually resolves itself within a couple of weeks.
Nerve deafness that develops from inherited dominant or recessive genes can be syndromic, which refers to hearing loss that appears along with abnormal symptoms in other parts of the body, or non-syndromic. The presence of a dominant deafness gene in a family requires only one parent to carry and pass on the gene to the children for it to manifest. This usually produces hearing loss that continues in family members from one generation to the next.
Accurate diagnosis of nerve deafness involves quick screening tests for hearing and audiometry. If nerve deafness is discovered, electroacoustic hearing aids that are placed in or behind the ear can be utilized for mild to moderate cases. Profound hearing loss might necessitate the use of a cochlear implant, requiring a surgical procedure to embed the internal component of the device.