Objective We aimed to investigate the effect of adding "rapid decelerations" and "vibrations" during a SemontPLUS maneuver on the dynamics of the inner ear and the success rate of canalolithiasis repositioning. Methods We used a previously described upscaled (5×) in vitro model of the posterior semicircular canal of the inner ear to analyze the trajectory of a single and clumped surrogate otolith particle (metallic sphere) during a SemontPLUS maneuver (-60 degrees below earth horizontal) on a repositioning chair (TRV). We compared the angular displacement of these particles with and without the application of "vibrations" or "rapid decelerations" using TRV. We recorded the success rates of the SemontPLUS maneuver for each condition. Results After the first step of the SemontPLUS, the application of "vibrations" increased the angular displacement of single particles from 119.9 to 125.9 degrees and clumps from 106.7 to 122.8 degrees. Clumps traveled shorter distances than single particles. "Rapid decelerations" also increased the angular displacement from 119.9 to 123.4 degrees and from 106.7 to 111.7 degrees for singles and clumps, respectively. "Vibrations" and "rapid decelerations" applied on the in vitro model resulted in enhanced repositioning success rates to 60 and 73%, respectively. Conclusions Adding "rapid decelerations" or "vibrations" to the SemontPLUS maneuver increased otolith particle displacement and improved the repositioning success rates in an in vitro model. However, the effect size of these additional modalities on angular displacement is small, and their use in clinics to improve repositioning in the SemontPLUS would have to be supported by further clinical trials.
