Otosclerosis is defined as an abnormal bone growth in the ear, affecting the stapes bone, which eventually results in a hearing loss. This hardening of bone can occur in the middle ear, the inner ear, or both parts of the ear. Otosclerosis can cause different types of hearing loss, depending on which structure within the ear is affected. When this bone growth involves only the stapes (middle ear bone) it is called stapedial otosclerosis and causes only a conductive hearing loss, which is most common. When the bone growth spreads to the inner ear (cochlea) it is referred to as cochlear otosclerosis and results in a sensorineural hearing loss. When both portions of the ear are involved, a mixed hearing loss (conductive and sensorineural) occurs. The amount of hearing loss present due to involvement of the stapes (stapedial otosclerosis) and the degree of hair cell loss (cochlear otosclerosis) can be determined only by a careful hearing test
Treatment of otosclerosis relies on two primary options: hearing aids and a surgery called a stapedectomy. Hearing aids are usually very effective early in the course of the disease, but eventually a stapedectomy may be required for definitive treatment. A stapedectomy consists of removing a portion of the sclerotic stapes footplate and replacing it with an implant that is secured to the incus. This procedure restores continuity of ossicular movement and allows transmission of sound waves from the eardrum to the inner ear. A modern variant of this surgery called a stapedotomy, is performed by drilling a small hole in the stapes footplate with a micro-drill or a laser, and the insertion of a piston-like prosthesis.
Medications can be prescribed for this condition, particularly for cochlear otosclerosis. This treatment cannot reverse hearing loss, but may slow the progression of both the conductive and sensorineural components of the disease process. Rarely, the progression of cochlear otosclerosis can lead to severe hearing loss. In these cases a cochlear implant can be used to treat the hearing loss.