Lateralization of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) with the latency test: a pilot study

Background: The treatments of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) have low remission rates ranging between 60% and 90%, connected to the difficulty in correctly identifying the affected side of HSC-BPPV. Objective: To propose and compare the efficacy of the latency test (LT) in identifying the affected ear in patients with HSC-BPPV. Materials and methods: Twenty-one subjects diagnosed with HSC-BPPV, as ascertained by head rolling test (HRT), were prospectively identified. Lateralization was assessed with pseudo-spontaneous nystagmus, lying-down nystagmus, bow and lean (BLT), HRT and LT tests. LT is a novel technique involving a 180° movement of the head and the analysis of the time required to reverse the nystagmus. Results: About 57% of patients were diagnosed with geotropic, and 43% with apogeotropic type HSC-BPPV. LT achieved a correct side diagnosis in 86%. Efficacy analysis of the tests compared to HRT revealed a substantial fair level of agreement for lying-down test (κ = 0.32, p <.05), a slight level of agreement for BLT (κ = 0.19, p <.05) and a substantial level of agreement for LT (κ = 0.071, p <.001). Conclusions and significance: LT was proven to show a substantial level of agreement compared to HRT in identifying the affected ear in patients with HSC-BPPV in this pilot study.