**Question:** Feature in otosclerosis include -

A. Stapes ankylosis
B. Tympanic membrane retraction
C. Inner ear malformations
D. Vestibular dysfunction

**Correct Answer:** A. Stapes ankylosis

**Core Concept:** Otosclerosis is a genetic disorder characterized by the abnormal bone formation in the region of the cochlea. It primarily affects the footplate of the stapes bone, which is a component of the ossicles in the middle ear. Ankylosis is the fusion of bones, which in this case leads to fixation of the stapes bone to the oval window, impairing the transmission of sound vibrations to the inner ear and affecting hearing.

**Why the Correct Answer is Right:** Ankylosis of the stapes bone is the key feature of otosclerosis. This occurs due to the abnormal bone formation within the footplate of the stapes bone, causing its fusion with the oval window. As a result, the transmission of sound vibrations to the inner ear is compromised, leading to a decrease in hearing sensitivity.

**Why Each Wrong Option is Incorrect:**

B. Tympanic membrane retraction: This is a condition affecting the eardrum (tympanic membrane), causing it to thin, shrink, and retract. While it can occur in patients with otosclerosis, it is not the primary feature of this disorder.

C. Inner ear malformations: Otosclerosis primarily affects the middle ear structures, specifically the stapes bone and oval window, rather than the inner ear structures.

D. Vestibular dysfunction: Although otosclerosis can lead to vestibular symptoms due to the impaired hearing, the primary feature is the ankylosis of the stapes bone, not vestibular dysfunction.

**Clinical Pearl:** Otosclerosis is a common cause of conductive hearing loss, primarily affecting individuals between the ages of 20 and 40. Early diagnosis and treatment can prevent further hearing loss or even restore some hearing, emphasizing the importance of routine audiologic evaluations and appropriate management of suspected cases.