BPPV and Canalith Repositioning: Mechanism, Testing, and Maneuvers
Mechanism and presentation
BPPV occurs when otoconia dislodge into a canal, most often the posterior canal. Canalithiasis causes free-floating debris with latency and fatigability; cupulolithiasis causes immediate, persistent nystagmus. Posterior canal BPPV produces upbeat-torsional nystagmus on Dix-Hallpike. Horizontal canal BPPV produces horizontal nystagmus on supine roll, geotropic in canalithiasis and apogeotropic in cupulolithiasis or short-arm variants.
Repositioning maneuvers
For posterior canal BPPV, the Epley maneuver sequentially rotates the head and body to move debris from the posterior canal into the utricle; the Semont maneuver is a rapid liberatory swing. For horizontal canal canalithiasis, the Lempert (barbecue) roll or Gufoni maneuver is used. For apogeotropic horizontal canal, the Gufoni or forced prolonged positioning may be used. After repositioning, advise against abrupt head movements briefly, though evidence for strict restrictions is limited.
Assessment of success
The goal is resolution of positional nystagmus and symptoms. Re-test after a maneuver. Persistent symptoms may require repeat maneuvers or re-evaluation for another canal or central cause. Atypical nystagmus (vertical without torsion, direction-changing, non-fatigable) should prompt reconsideration.
Common traps
Treating BPPV without identifying the canal; using an Epley maneuver for horizontal canal disease; missing bilateral or multi-canal involvement; failing to recheck. Another trap is attributing persistent dizziness after successful repositioning to unresolved BPPV when residual dizziness is common.
Worked example
A patient has brief vertigo with right Dix-Hallpike and upbeat-torsional nystagmus. Perform right Epley: turn head 45 degrees right, lay supine, rotate head 90 degrees left, roll to left side, then sit up. Recheck Dix-Hallpike; if negative, the posterior canal is cleared.