Hearing loss that originates in the inner ear is referred to as sensorineural hearing loss or “nerve loss”. About 90% of hearing losses are sensorineural, most commonly caused by damage to the inner hair cells. A picture of a cochlea with damaged hair cells appears to the right. Once damaged, hair cells can’t be repaired or restored. Sensorineural hearing loss most often occurs from genetic factors such as family inheritance, excessive noise exposure, or changes in the inner ear due to the natural aging process. Other causes of sensorineural hearing loss can include medications, tumors, infections, diabetes or other kidney disease, or cardiovascular disease. In many cases the cause is unknown. A sensorineural heairng loss can be of any degree, from very mild to profound.
Sound can be blocked in multiple places along the path to the brain. When a hearing loss occurs from conditions in the inner ear as well as the outer or middle ear, it is called a mixed hearing loss because it is a combination of conductive and sensorineural components. An example of a mixed hearing loss may be someone with inner ear hair cell damage due to noise damage who at the same time has an ear infection which is stopping the eardrum from vibrating normally. The conductive portion of a mixed hearing loss can often be medically treated, but even after successful treatment there will still be an underlying sensorineural hearing loss which is permanent and may warrant a hearing aid depending on the level of severity.