This study shows that treatment of PC‐BPPV with Epley's manoeuvre is more effective than a sham procedure at short‐term follow up. After 24 h, PC‐BPPV had resolved in 80% of patients treated with Epley's manoeuvre compared with only 10% of those treated with the sham procedure. The study design comprises a short interval between treatment and evaluation, whereas previous studies assessed treatment outcome after 1–5 weeks.3,4,5
Long follow‐up periods, however, tend to confound the results because of either spontaneous particle migration out of the canal by natural head movements or reaccumulation of particles in the canal despite successful initial treatment. The first argument appears to be more relevant, as a considerable proportion of patients experience spontaneous remission within 1 week. Published figures vary widely, reaching 51% in one study.7
On the other hand, the recurrence rate after successful treatment has been estimated at only 15% a year8
and 26% within 60 months.9
Thus, the design of our study with an early outcome assessment relates the recovery rate directly to the intervention and minimises the effect of spontaneous remission. The effect of Epley's manoeuvre is also long lasting as, 4 weeks after treatment, 85% of patients who underwent Epley's manoeuvre were still asymptomatic. Early relapses within the first week after successful treatment were noted in only 1 of 28 patients, indicating that post‐treatment restrictions are usually not required.
All previous trials on the efficacy of Epley's manoeuvre in PC‐BPPV showed a positive effect compared with no treatment or sham procedures,2
except for one study that did not perform Epley's manoeuvre properly by applying insufficient head rotation.6
Similar to our study, previous double‐blind controlled studies on the efficacy of Epley's manoeuvre found that positional vertigo was abolished in 76% of patients after 1 week,5
in 67% after 1–2 weeks4
and in 89% after 1 month.3
The remission rate in the control group, however, ranged from 27% to 48%, which is considerably higher than that in the present study, where only 10% were asymptomatic on follow‐up.3,4,5
We speculate that the difference between the Epley's manoeuvre group and the control group was more pronounced in our study than that in previous studies, as previous studies may have included a larger proportion of spontaneous remissions in their controls due to longer follow‐up intervals.
Clinical experience suggests that repeating Epley's manoeuvre during one session increases its effectiveness. Accordingly, 57% of patients required more than one Epley's manoeuvre to convert the Dix–Hallpike test to negative at the initial treatment session. Most previous studies also repeated Epley's manoeuvre during the treatment session when necessary, as originally advised by Epley.1,3,4,5
A recent study, however, that aimed to examine the benefit of repeated against single Epley's manoeuvres during one treatment session showed only a trend for multiple manoeuvres that was not statistically significant.10
Thus, the important question of whether repeated Epley's manoeuvres during one session are more effective than just one remains to be examined systematically.