Otosclerosis is a disease of abnormal bone remodelling localized to the otic capsule of the temporal bone that produces progressive conductive hearing loss when it fixes the stapes footplate in the oval window. It affects roughly 0.3-0.5% of adults clinically, with histological evidence at autopsy in approximately 10% of Caucasian adults — most never become symptomatic.
Otosclerosis (ICD-10: H80) is a primary disease of bone unique to the otic capsule, in which normal endochondral bone is replaced first by spongy vascular bone (otospongiosis, the active phase) and later by dense sclerotic bone (otosclerosis, the inactive phase). The most common focus is the fissula ante fenestram just anterior to the oval window: as new bone deposits around the stapes footplate, the stapes becomes progressively fixed, impairing transmission of vibration from tympanic membrane to inner ear and producing a conductive hearing loss (fenestral otosclerosis, around 90% of cases). When otosclerotic foci extend into or around the cochlea (retrofenestral or cochlear otosclerosis), they cause sensorineural hearing loss either as a pure phenotype or, more commonly, as a mixed sensorineural-conductive loss superimposed on stapes fixation. Histology shows pleomorphic osteoclasts, vascular spaces, and disorganized woven bone in active foci.
The key symptoms of Otosclerosis are: Gradual, painless, progressive hearing loss usually noticed first in noisy environments and during telephone conversations, often beginning in the second to fifth decades., Bilateral but asymmetric hearing loss with the worse ear typically diagnosed first; bilateral disease eventually develops in 70-80% of patients., Paradoxically improved hearing in noisy environments (paracusis Willisii) — patients lip-read effectively despite background noise that overwhelms others., Low-pitched, persistent tinnitus in 65-75% of patients, often described as buzzing, humming, or roaring, sometimes pulsatile in the active otospongiosis phase., Mild dizziness or imbalance in roughly 25% of patients; severe vestibular symptoms are uncommon and suggest alternative diagnosis (Meniere disease, vestibular schwannoma)., Hearing loss noticeably worsening or first becoming apparent during pregnancy or after starting oral estrogen therapy in some patients., A reddish pink hue visible through an intact tympanic membrane on otoscopy — Schwartze sign — indicating vascular activity in the otospongiotic phase. Present in only 10% and not specific..
Diagnosis is made clinically by combining a typical history with otoscopy, tuning-fork tests, and pure-tone audiometry. On otoscopy the tympanic membrane is usually normal; the Schwartze sign (reddish-pink promontory visible through the membrane) is seen in only 10% of cases and reflects active otospongiosis. Weber test lateralizes to the worse-hearing ear and the Rinne test is negative (bone conduction louder than air conduction) in the affected ear. Pure-tone audiometry typically shows a conductive hearing loss greater at low frequencies, with a Carhart notch — a 5-15 dB depression of bone conduction at 2 kHz that resolves after successful stapes surgery. Bone conduction may also show high-frequency loss as cochlear involvement progresses. Tympanometry typically shows a Type As (low-compliance) curve, and acoustic stapedial reflexes are absent in advanced disease (or biphasic 'on-off' pattern in early stages). Speech discrimination is preserved out of proportion to pure-tone loss until significant cochlear involvement develops. High-resolution CT of the temporal bone is not essential for typical cases but is performed when surgery is planned to assess footplate thickness, exclude congenital anomalies (such as enlarged vestibular aqueduct or dehiscent superior semicircular canal), and identify cochlear otosclerosis. CT shows characteristic radiolucent foci anterior to the oval window in fenestral disease and 'fourth turn' or 'double ring' patterns in cochlear disease. MRI plays no role in routine diagnosis. The differential diagnosis includes superior semicircular canal dehiscence, ossicular chain discontinuity (often post-traumatic), tympanosclerosis, glomus tumor, congenital footplate fixation, Paget disease, and osteogenesis imperfecta.
Outcome is generally excellent with current treatment. Pure-tone audiometric outcomes after small-fenestra stapedotomy in experienced hands close the air-bone gap to within 10 dB in 85-95% of operated ears, with substantial subjective improvement in over 90% of patients. Serious sensorineural complications (including dead ear) occur in approximately 1-2% of operations; persistent dizziness, taste disturbance, and tinnitus are reported less commonly. The second ear may be operated after stable hearing is demonstrated in the first ear, typically 6-12 months later. Without surgery, otosclerosis progresses slowly over decades; hearing aids continue to deliver good benefit in most. Cochlear involvement progresses independently of stapes surgery and may continue after successful stapedotomy, justifying ongoing audiometric follow-up. Far-advanced disease with profound sensorineural hearing loss responds well to cochlear implantation. Pregnancy and exogenous estrogen can transiently accelerate progression but do not abrogate the benefit of subsequent surgery. Quality-of-life scores improve substantially after both hearing aid fitting and surgery; depression and social withdrawal often resolve. Recurrence (refixation of the prosthesis, erosion of the incus, or growth of new otosclerotic bone) is uncommon but possible decades later and may require revision surgery.
Diagnosis and management of otosclerosis are the province of ENT (otology). An otologist confirms the diagnosis through audiometry and imaging, offers hearing aids or surgery, and monitors progression over years. Surgery should be performed by an experienced otologist with documented outcomes in stapes microsurgery.
Find specialists →After stapedotomy: hospital discharge same day or next day. First hearing improvement noted within 1-2 weeks once tampon and packing dissolve. Audiometric assessment at 4-6 weeks and 3-6 months. Full return to noisy/active occupations within 4-6 weeks. Second-side surgery considered after 6-12 months of stable hearing in the first ear. Cochlear implant activation 2-4 weeks postoperatively with audiological tuning over the following 6-12 months.
Regular moderate aerobic exercise is encouraged for general health. After stapes surgery, avoid heavy lifting, straining, and pressure-changing sports (scuba diving, free diving, parachute jumping) for at least 4-6 weeks; gradual return to high-impact exercise from 6-8 weeks. Long-term restrictions are individualized by the operating otologist.
Choose a fellowship-trained otologist or neurotologist who performs at least 20 stapes operations per year and reports outcomes (air-bone gap closure, sensorineural loss rate, taste disturbance). Avoid surgeons who cannot share recent audiometric outcome data.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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