Adverse effects of semicircular circle angles variation on Epley repositioning procedure: a study on reconstruction...

Background: For patients with posterior semicircular canal (PSC) BPPV, Epley re-position maneuver and some improvement methods are the most efficient treatment methods. But there were still 9.43% patients who were not benefit from Epley re-position maneuver.Objective: To measure the angles of semicircular canals and evaluate its effect on Epley maneuver.Methods: Fifteen skull specimens, containing 30 temporal bone specimens were included. After Micro-CT scanning, 3D reconstruction was loaded with the CT image. The angles between each semicircular canal and each standard skull plane were measured. Furthermore, the angles' effect on Epley maneuver was evaluated according to the three-dimension (3D) model.Results: Angles of PSC plane: Frankfurt plane was 71.54 ± 6.51, sagittal plane was 53.77 ± 5.36°, and the coronal plane was 43.33 ± 3.56°. Angles between PSC and the sagittal plane of skulls had an adverse effect on Epley maneuver, when it was less than 45°.Conclusion: 1. Variation could be found in angles between the semicircular canals and the standard planes of skulls, which meant variation of semicircular canals' location existing in skulls. 2. The variation of angles between PSC and sagittal plane could have an adverse effect on the Epley maneuver when the angle was less than 45°, which may cause the Epley maneuver to be invalid.