In benign paroxysmal positional vertigo (BPPV), the most common subtype involves the posterior semicircular canal. The pathophysiology is canalithiasis — free-floating otoliths in the endolymph. The Dix-Hallpike test provokes geotropic torsional nystagmus. The Epley canalith repositioning maneuver moves debris toward which structure for reabsorption?

• A From the posterior canal, through the common crus, into the utricle ✓
• B Through the posterior canal ampulla into the utricle
• C Into the horizontal canal, from where it exits via the ampulla
• D Directly through the round window membrane into the perilymph

Explanation

In the Epley canalith repositioning procedure for posterior canal BPPV (canalithiasis), the series of head rotations move the free otoconia sequentially: from the posterior semicircular canal arm, through the non-ampullated end, through the common crus (which posterior and anterior canals share), and into the utricle where they can be reabsorbed. The four position steps of Epley (head 45° toward affected side, Dix-Hallpike, head rotated 90° to opposite side, body rolled to lateral decubitus, then upright) trace this path. Once in the utricle, the otoconia disperse among the utricular macula. The Semont liberatory maneuver works on the same principle but with different mechanics.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.