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Otosclerosis
Otosclerosis is abnormal bone remodelling in the otic capsule that fixes the stapes footplate in the oval window; the typical patient is a young woman with progressive conductive hearing loss and a normal eardrum, and the solution is a hearing aid or stapedotomy.
Why it matters in the exam
The exam shows a woman in her 20s to 40s with progressive conductive hearing loss, sometimes bilateral, that worsened in pregnancy, and with a family history (autosomal dominant inheritance with incomplete penetrance). The eardrum is normal; sometimes a reddish hue (Schwartze sign) indicates active disease. The common site is the fissula ante fenestram, in front of the oval window. On the audiogram: an air-bone gap with a "Carhart notch" — an apparent fall in bone conduction around 2000 Hz that disappears after successful surgery.
On tympanometry the tympanogram is usually type As (low compliance), and the stapedial reflex is absent; early on an inverted response appears (on-off effect). Paracusis Willisii — better hearing of speech in noise. A negative Rinne test with a 512 Hz fork indicates a gap of at least about 20 dB. Before surgery, superior semicircular canal dehiscence must be excluded; it also has an air-bone gap, but the stapedial reflexes are preserved.
Stapedotomy — a small opening in the stapes footplate and insertion of a prosthesis (piston) attached to the incus — suits a significant air-bone gap when a hearing aid is not satisfactory. The worse-hearing ear is operated on first, and surgery is not done on an only hearing ear, an ear with a perforation or active infection, or an ear with active Ménière disease. Complications: total sensorineural loss ("dead ear") in about 1%, vertigo, altered taste from chorda tympani injury and facial nerve injury. A perilymph gusher is expected in inner ear malformation (such as the X-linked syndrome with a widened internal auditory canal), so CT is performed before surgery in an adolescent or when a malformation is suspected.
Key points
- Stapes fixation, fissula ante fenestram.
- Young woman, worse in pregnancy.
- Carhart notch around 2000 Hz.
- Absent reflex, As tympanogram.
- Stapedotomy or a hearing aid.
Summary table
| Aspect | Finding | Meaning |
|---|---|---|
| Who | Young woman, family history, worse in pregnancy | High suspicion |
| Otoscopy | Normal eardrum, sometimes Schwartze | Active disease |
| Audiogram | Air-bone gap, Carhart notch around 2000 Hz | Disappears after surgery |
| Tympanometry | As, absent stapedial reflex | Stapes fixation |
| Treatment | Hearing aid or stapedotomy | Surgery on the worse-hearing ear |
| Differential diagnosis | Superior canal dehiscence | Reflexes preserved |
A free exam question
מה מהבאים נכון בהתייחס לבדיקת Acoustic Reflex Threshold? (the question as examined, in Hebrew)
- א. הרפלקס מופעל רק בצד שבו אירע הגירוי
- ב. הרפלקס מופעל בדרך כלל בעוצמות צליל של 40-60 ד"ב
- ג. בדיקת הרפלקס עשויה לסייע להבחין בין פתולוגיה קוכליארית לפתולוגיה רטרו-קוכליארית
- ד. הרפלקס לא מופק במצב של Superior Semi-Circular Canal Dehiscence
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Sources
- Cummings Otolaryngology: Head and Neck Surgery, 7th edition (2021) — Otosclerosis and stapes surgery
- Glasscock-Shambaugh Surgery of the Ear, 7th edition (2022) — Otosclerosis: diagnosis and stapedotomy
- AAO-HNS Committee on Hearing and Equilibrium guidelines for reporting conductive hearing loss, 1995 — Air-bone gap reporting
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.