Features of superior canal dehiscence are -a) Positive Romberg’s signb) Positive Tullio’s phenomenonc) Positive Hennebert’s signd) Oscillopsiae) Positive Dix-Hallpike maneuver

**Core Concept**
Superior canal dehiscence (SCD) is a condition characterized by a thinning or absence of the bone overlying the superior canal of the vestibular system, leading to abnormal sound-induced eye movements and other vestibular symptoms.

**Why the Correct Answer is Right**
Tullio's phenomenon is a characteristic feature of SCD, where loud sounds induce a feeling of vertigo or nystagmus. This occurs due to the abnormal transmission of sound-induced pressure changes to the endolymph in the superior canal, which activates the vestibular nerve and causes eye movements. The Dix-Hallpike maneuver is typically used to diagnose benign paroxysmal positional vertigo (BPPV), not SCD. Romberg's sign is indicative of proprioceptive loss, and Hennebert's sign is associated with middle ear problems. Oscillopsia is a symptom of peripheral vestibular disorders, but it is not a specific feature of SCD.

**Why Each Wrong Option is Incorrect**
**Option A:** Romberg's sign is a test of proprioception, not a feature of SCD.
**Option C:** Hennebert's sign is associated with middle ear problems, not SCD.
**Option D:** Oscillopsia is a symptom of peripheral vestibular disorders, not specific to SCD.
**Option E:** The Dix-Hallpike maneuver is used to diagnose BPPV, not SCD.

**Clinical Pearl / High-Yield Fact**
Tullio's phenomenon is a key feature of SCD, and it can be elicited by having the patient wear headphones and play loud music while observing for eye movements.

**Correct Answer: B. Tullio's phenomenon**