A 32-year-old woman presents with progressive bilateral hearing loss over the past 18 months. She reports tinnitus and occasional vertigo. On examination, Weber test shows lateralization to the right ear, and Rinne test shows bone conduction better than air conduction bilaterally. Otoscopy is normal. She has a family history of hearing loss in her mother. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis of Otosclerosis **Key Point:** Otosclerosis is a primary disorder of the otic capsule characterized by abnormal bone remodeling at the stapes footplate, leading to progressive conductive or mixed hearing loss. ### Clinical Presentation **High-Yield:** The classic triad of otosclerosis includes: 1. Progressive conductive or mixed hearing loss (usually bilateral) 2. Tinnitus 3. Vertigo (less common, occurs in ~25% of cases) ### Audiometric Findings **Clinical Pearl:** The Carhart notch (bone conduction dip at 2 kHz) is pathognomonic but not always present. In this case, the **bone conduction > air conduction pattern** (conductive hearing loss) on Rinne testing is the key finding. | Finding | Otosclerosis | CSOM | SSNHL | |---------|--------------|------|-------| | Onset | Gradual, progressive | Acute/chronic drainage | Sudden (hours–days) | | Otoscopy | Normal | Perforation/discharge | Normal | | Bone–air gap | Present (conductive) | Present (conductive) | Absent (sensorineural) | | Bilateral | Often | Usually unilateral | Variable | | Family history | Yes (60%) | No | No | | Tinnitus | Common | Variable | Common | ### Why This Patient Has Otosclerosis 1. **Progressive bilateral conductive hearing loss** — hallmark of otosclerosis 2. **Normal otoscopy** — stapes fixation is not visible on external exam 3. **Bone > air conduction** — confirms conductive component 4. **Family history** — otosclerosis has autosomal dominant inheritance with incomplete penetrance (60% familial) 5. **Age and sex** — typically presents in women aged 20–40 years 6. **Tinnitus and vertigo** — common associated symptoms ### Pathophysiology Otosclerosis involves abnormal osteoclastic and osteoblastic activity in the otic capsule, most commonly at the **oval window (stapes footplate)**. This leads to stapes fixation and progressive conductive hearing loss. Mixed hearing loss can develop if cochlear involvement occurs (cochlear otosclerosis). ### Diagnostic Confirmation **High-Yield:** High-resolution CT temporal bone shows: - Lucent (lytic) foci around the oval window - Demineralization of the otic capsule - Stapes fixation (may not be visible on CT but inferred from clinical findings) [cite:Dhingra 8e Ch 12]