Benign Paroxysmal Positional Vertigo (BPPV) is caused by displacement of small crystals in the semicircular canals.

• A. A shift in the location of small crystals in the semicircular canals
• B. Inflammation of the vestibular nerve
• C. Progressive degeneration of the cochlea
• D. Abnormal endolymphatic fluid production

Answer: (A)

Displacement of otoconia into the semicircular canals causes BPPV, leading to brief vertigo triggered by head position changes. Free-floating crystals in the canal shift with movement, deflect the cupula, and produce transient spinning sensations and nystagmus. That exact description—small crystals shifting location within the semicircular canals—fits the mechanism of BPPV. Inflammation of the vestibular nerve would cause ongoing vertigo without a clear positional pattern, cochlear degeneration affects hearing, and abnormal endolymph production points to Meniere disease with hearing loss and tinnitus.