The fluid waves stimulate delicate nerve endings in the hearing canals. Electrical impulses are transmitted on the nerve to the brain where they are interpreted as understandable sound. If there is some difficulty in the external or middle ear, a conductive hearing impairment occurs. If the trouble lies in the inner ear, a sensorineural or nerve hearing impairment is the result. When there is difficulty in both the middle and the inner ear a mixed or combined impairment exists.
Mixed impairments are common in otosclerosis.
Had we been able to examine your middle ear under the microscope before a hearing impairment developed, we could have seen minute areas of both softening and hardening of the bone. This process may spread to the stapes, the inner ear, or to both sides. When otosclerosis spreads to the inner ear a sensorineural hearing impairment may result due to interference with the nerve function. This nerve impairment is called cochlear otosclerosis and once it develops it may be permanent. In selected cases medication may be prescribed in an attempt to prevent further nerve impairment.