In BPPV, canalolithiasis refers to what?

• A. Otoconia inside the utricle
• B. Free-floating debris within the canal
• C. Otoconia attached to the cupula
• D. Debris in the cochlea

Answer: (B)

Canalo lithiasis means free-floating otoconia inside a semicircular canal. In this BPPV form, calcium carbonate crystals that normally sit in the utricle drift into a canal (most often the posterior canal). When you move your head, gravity moves these particles, tugging on the endolymph and deflecting the hair cells in the canal’s crista. That brief deflection triggers vertigo and a transient nystagmus that lasts seconds to under a minute. This is what sets canalolithiasis apart from cupulolithiasis, where the crystals cling to the cupula and cause longer-lasting vertigo with certain positions. Otoconia in the utricle are just normal parts of the inner ear, not the mechanism of canalithiasis, and debris in the cochlea would point to a different, primarily cochlear, problem rather than canal-based vertigo.