Unintentional conversion of benign paroxysmal positional vertigo caused by repositioning procedures for canalithiasis: transitional BPPV.

BPPV when diagnosed before any repositioning procedure is called primary BPPV. Primary BPPV canalithiasis treatment with repositioning procedures sometimes results in unintentional conversion of BPPV form: transitional BPPV. Objectives were to find transitional BPPV forms, how they influence relative rate of canal involvement and how to be treated. This study is a retrospective case review performed at an ambulatory, tertiary referral center. Participants were 189 consecutive BPPV patients. Main outcome measures were detection of transitional BPPV, outcome of repositioning procedures for transitional canalithiasis BPPV and spontaneous recovery for transitional cupulolithiasis BPPV. Canal distribution of primary BPPV was: posterior canal (Pc): 85.7% (162/189), horizontal canal (Hc): 11.6% (22/189), anterior canal (Ac): 2.6% (5/189); taken together with transitional BPPV it was: Pc: 71.3% (164/230), Hc: 26.5% (61/230), Ac: 2.2% (5/230). Transitional BPPV forms were: Hc canalithiasis 58% (24/41), Hc cupulolithiasis 37% (15/41) and common crux reentry 5% (2/41). Treated with barbecue maneuver transitional Hc canalithiasis cases either resolved in 58% (14/24) or transitioned further to transitional Hc cupulolithiasis in 42% (10/24). In follow-up of transitional Hc cupulolithiasis we confirmed spontaneous recovery in 14/15 cases in less than 2 days. The most frequent transitional BPPV form was Hc canalithiasis so it raises importance of barbecue maneuver treatment. Second most frequent was transitional Hc cupulolithiasis which very quickly spontaneously recovers and does not require any intervention. The rarest found transitional BPPV form was common crux reentry which is treated by Canalith repositioning procedure. Transitional BPPV taken together with primary BPPV may decrease relative rate of Pc BPPV, considerably increase relative rate of Hc BPPV and negligibly influence relative rate of Ac BPPV. Transitional BPPV forms can be produced by repositioning maneuvers (transitional Hc cupulolithiasis) or by the subsequent controlling positional test (transitional Hc canalithiasis and common crux reentry); underlying mechanisms are discussed.