[Efficacy analysis of Epley procedure and Semont procedure with different lateral lying angles of the head in posterior semicircular canal BPPV].

To investigate the effects of the Epley and Semont procedures with varying lateral angles of the head on posterior semicircular canal benign paroxysmal positional vertigo （PC-BPPV）. A total of 115 patients with unilateral PC-BPPV were randomly divided into five groups: Epley group, Semont group, Semont+10° group, Semont+20° group, and Semont+30° group, with 23 patients in each group. Corresponding reduction treatments were performed. The total effective rates for the Epley group, Semont group, Semont+10° group, Semont+20° group, and Semont+30° group were 95.7% （22/23）, 4.3% （1/23）, 30.4% （7/23）, 52.2% （12/23）, and 87.0% （20/23） respectively. The inefficiencies were 4.3% （1/23）, 95.7% （22/23）, 69.6% （16/23）, 47.8% （11/23）, and 13.0% （3/23）. Statistically significant differences were observed in the total effective rates among the five groups （χ²=54.11, <0.01）. The total effective rates in the Semont group, Semont+10° group, and Semont+20° group were significantly different from that of the Epley group （<0.01）, while no statistically significant difference was found between the Semont+30° group and the Epley group （= 0.608>0.012 5）. Among the four Semont methods with different lateral lying angles, the total effective rate of reduction treatment increased with the elevation of the lateral lying angle on the affected side. The efficacy of the Semont+30° group in treating PC-BPPV was not significantly different from the Epley group's reduction effect, which was markedly superior to that of the other four Semont methods at different angles. Therefore, the Semont+30° reduction technique is recommended for the treatment of PC-BPPV.