[Clinical analysis for 16 cases with atypical nystagmus of posterior semicircular canal benign paroxysmal positional vertigo].

To study clinical features and evaluate the efficacy of manual reduction in treatment of atypical nystagmus in patients with posterior semicircular canal benign paroxysmal positional vertigo(PSC-BPPV). Sixteen cases of atypical nystagmus in patients with PSC-BPPV were retrospectively analyzed. The results were compared with 28 patients of typical nystagmus with PSC-BPPV.All the patients were followed up for 3 months. Statistical data analysis was carried out with SPSS 20.0. Sixteen cases of atypical nystagmus patients with PSC-BPPV included 5 cases of left 31.25%(5/16) and 11 cases of right 68.75%(11/16), 5 patients showed typical nystagmus in the straight-head hanging position and without vertical down-beating in returning to the sitting positions with torsional component pointed to intact side,4 patients showed same nystagmus in hanging position and vertical down-beating in returning to the sitting positions without torsional component, one patient showed nystagmus of vertical up-beating and vertical down-beating in Dix-Hallpike test without torsional component,2 patients showed unobservable nystagmus in Dix-Hallpike test but showed nystagmus of vertical up-beating with torsional component pointed to affected side in the roll test position,4 patients showed nystagmus of vertical down-beating in the straight-head hanging position with torsional component pointed to intact side and reversible direction nystagmus in returning to the sitting positions.One patient's nystagmus time of duration was longer than 1 min,while 15 patients' nystagmus duration were shorter than 1 min.Twenty-eight patients with typical nystagmus in PSC-BPPV nystagmus duration were shorter than 1 min.No patient had been affected bilateral in two groups. All patients received manual reduction treatment according to the nystagmus direction and time of duration. The effective rate after the first day was 62.50%(10/16) in atypical nystagmus patients with PSC-BPPV group and 92.86%(26/28) in typical nystagmus with PSC-BPPV group, the difference was significant(χ²=5.134,=0.015). The total effective rate was 93.75%(15/16)after more than once in atypical group and 100.00%(28/28) in typical group, the difference was not significant(χ²=2.780,=0.095).The numbers of circulation of first success in manual reduction management were(2.76±1.13)times in atypical group and (1.68±0.61)times in typical group.The difference was significant(=4.293,=0.000). The recurrence rate was 18.75% in atypical group and 14.28% in typical group after during follow-up for 6 months, the difference was not significant(χ²=1.681,=0.509). It showed that clinical manifestation with atypical nystagmus in patients with PSC-BPPV was complicated. Some patients' nystagmus could change to typical after treatment.The manual reduction was an effective treatment.The effective rate after first manual reduction was lower than typical group, it's needed more circulation of first success in manual reduction management. The recurrence rate was not significant in two groups.