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Clinical characteristics and associated factors of canal switch in benign paroxysmal positional vertigo.

BACKGROUND
Canal switch benign paroxysmal positional vertigo (CS-BPPV) is a transition of BPPV involving one canal to another canal during or after canalith repositioning procedures (CRP).


OBJECTIVE
To investigate the clinical characteristics of CS-BPPV and its associated factors.


METHODS
The data of 2,303 patients with BPPV involving the lateral canal (LC) or posterior canal (PC) were retrospectively analyzed. Demographics, etiologies, and various clinical parameters related to CRP were compared between patients with and without CS-BPPV.


RESULTS
Sixty-eight (2.95%) patients exhibited CS-BPPV. For patients with CS-BPPV from the PC to the LC, as well as those with CS-BPPV from the LC to the PC, the CRP number for the original canal in CS-BPPV was significantly greater than in non-CS-BPPV (P = 0.002). More CRP cycles were required to treat CS-BPPV than non-CS-BPPV involving the same canal. Multivariate analysis showed that CS-BPPV from the LC to the PC was significantly associated with multiple CRP cycles and use of the Gufoni maneuver (P = 0.038 and P < 0.001, respectively).


CONCLUSIONS
The use of multiple cycles of CRP and the Gufoni maneuver were significantly associated with the onset of CS-BPPV. Furthermore, more CRP cycles were needed for the treatment of CS-BPPV than for non-CS-BPPV involving the same canal.