Analysis of Reduction Effect of the Evoked Nystagmus in the Non-Affect Side During Dix-Hallpike or Roll-test in Unilateral Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo

Objective:Comparative analysis of the reduction effect of the evoked nystagmus in the non-affect side during Dix-Hallpike（D-H） or Roll-test in unilateral posterior semicircular canal benign paroxysmal positional vertigo（PC-BPPV） and PC-BPPV without above evoked nystagmus. Method:Retrospective analysis of 210 patients diagnosed with unilateral PC-BPPV by G-Force BPPV CRP system was made. Among them, 18 patients exhibited positive nystagmus only when the non-affected side was stimulated by D-H test（Group A）, 30 was evoked only when stimulated by Roll-test（Group B）, 26 was evoked when stimulated by both Roll-test and the non-affected side D-H test（Group C）, 136 without nystagmus in the above positions（Group D）. All the patients were diagnosed by G-Force BPPV and were treated through simulative Epley or Semont CRP. Compare the reduction effect among the groups. Result:At the first time ,the reduction effect of nystagmus in Group D was superior to those in Group A and Group C（P<0.05）. There was no difference between Group D and Group B（P>0.05）. The difference between Group A and Group C was also non-significant（P>0.05）. The average CRP times of the four groups（CRP until nystagmus disappeared or no longer alleviated） were 1.44±0.63（Group A）, 1.46±0.65（Group B）, 1.52±0.87（Group C） and 1.48±0.73（Group D）respectively. There were no statistic difference between four groups（P>0.05）. The differences of final reduction effect between groups were the same as those at the first time. Conclusion:The first time reduction effect was less effective when nystagmus evoked the non-affect side during D-H test in unilateral PC-BPPV, while it might be irrelevant to the nystagmus evoked only in Roll-test. Although the times of CRP were similar among the groups, the final reduction effect of groups with nystagmus evoked the non-affect side during D-H was poorer.