A 30-year-old woman with family history of hearing loss from mother’s side developed hearing problem during pregnancy. Hearing loss is B/L, slowly progressive. Pure tone audiometry shows an apparent bone conduction hearing loss at 2000 Hz. What is the most likely diagnosis:

**Core Concept**
The underlying principle being tested involves **otosclerosis**, a condition characterized by abnormal bone growth in the middle ear, leading to **hearing loss**. This condition often presents with a familial pattern and can be exacerbated by pregnancy due to hormonal changes.

**Why the Correct Answer is Right**
Otosclerosis typically causes a conductive hearing loss due to fixation of the **stapes bone**, but in some cases, it can also affect the **cochlea**, leading to a sensorineural component. The condition often presents with a specific finding on **pure tone audiometry** known as Carhart's notch, which is a dip in bone conduction thresholds, classically at **2000 Hz**.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect as it does not specifically relate to the symptoms and audiometric findings presented.
**Option B:** Similarly, this option does not match the clinical scenario of progressive hearing loss with a specific audiometric pattern.
**Option C:** This choice is also incorrect as it does not align with the familial, pregnancy-related, and specific audiometric characteristics described.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **otosclerosis** can present with a variety of hearing loss patterns, but the presence of **Carhart's notch** on pure tone audiometry is highly suggestive of this diagnosis, especially in the context of a familial history and pregnancy-related worsening.

**Correct Answer:** D. Otosclerosis.

✓ Correct Answer: A. Otosclerosis