Otosclerosis

Abnormal growth of BONE tissue around the auditory ossicles in the middle EAR, causing one or more of the ossicles to become locked into place or fused against the other ossicles. Most commonly affected is the stapes (stirrup), the final of the three auditory ossicles in the sequence of sound wave amplification and transmittal. Conductive HEARING LOSS, which is the primary symptom of otosclerosis, occurs as movement of the auditory ossicles becomes increasingly limited. Occasionally otosclerosis involves the COCHLEA, causing sensorineural hearing loss and sometimes vestibular dysfunction such as balance disturbances and VERTIGO.

An AUDIOLOGIC ASSESSMENT identifies the hearing loss. The otolaryngologist may request a COMPUTED TOMOGRAPHY (CT) SCAN or MAGNETIC RESONANCE IMAGING (MRI) to visualize the structures of the inner ear and to confirm the diagnosis. Surgical treatments often can restore conductive hearing loss to near normal hearing. An OPERATION to remove the immobilized ossicle and replace it with a prosthetic ossicle can permanently restore hearing in most people. Surgery is less successful in restoring hearing loss due to cochlear otosclerosis, though a HEARING AID often can improve hearing.