Abstract
HYPOTHESIS: We aimed to investigate the effect of the head excursion angle on the success of the Sémont Maneuver (SM). BACKGROUND: SM is performed with the head turned by 45 degrees toward the unaffected ear. In clinical routine, it is unlikely that physicians can turn the head to a position of exactly 45 degrees. Moreover, it is unclear how possible deviations from 45 degrees would affect the outcome with SM. METHODS: We used an in vitro model (upscaled by ×5) of a posterior semicircular canal with canalithiasis to study head excursion angles (0-75 degrees) and minimum waiting times in SM. Additionally, we measured actual head excursion angles performed by trained physicians during SM on a healthy subject. RESULTS: Successful canalith repositioning to the utricle was possible at head excursion angles between 21 and 67 degrees. Waiting time increased from 16 to 30 seconds with increasing deviation from 45 degrees. Angles larger than 67 degrees or smaller than 21 degrees did not lead to successful repositioning even after a waiting period of 5 minutes. Physicians set head excursion angles of 50 degrees ±SD 4.8 degrees while performing the SM. CONCLUSION: Angular deviations up to ±20 degrees from the ideal SCC plane (45 degrees) still allows for successful SM. Although the tested physicians tended to underestimate the actual head excursion angle by 5 degrees (and more), the success of SM will not be affected provided that the waiting time is sufficiently long. Further, the results suggest that the Brandt-Daroff maneuver is a form of habituation training rather than a liberatory maneuver.