Simulation Study of Canal Switching in BPPV

The effectiveness of the modified Epley maneuver for the treatment of posterior semicircular canal benign paroxysmal positional vertigo

Objective

To compare the repositioning effect of the modified Epley maneuver and the traditional Epley maneuver for posterior semicircular canal benign paroxysmal positional vertigo (PC-BPPV).

Methods

Sixty-five patients with unilateral PC-BPPV were randomly divided into two groups. The control group received the traditional Epley maneuver, while the experimental group received the modified Epley maneuver, which prolonged the time in the healthy side lying position and the final bowing position. The number of successful repositions after one, two, and three attempts and the total number of successful repositions were recorded and compared between the two groups. A BPPV virtual simulation model was used to analyze the mechanism of the modified Epley maneuver.

Results

The first repositioning success rate of the experimental group was significantly higher than that of the control group (85% vs. 63%, p = 0.040). The experimental group achieved 100% repositioning success rate after two attempts, while the control group needed three attempts to reach 86% repositioning success rate. Four cases in the control group experienced canal switching during the repositioning process, while none in the experimental group did. The BPPV virtual simulation model showed that the modified Epley maneuver could facilitate the passage of otoliths through the posterior arm of the posterior semicircular canal, especially through the location of obstruction.

Conclusion

The modified Epley maneuver is more effective than the traditional Epley maneuver in improving the single repositioning success rate and reducing the canal switching rate for PC-BPPV. This study provides a new option for the treatment of BPPV.

Design and analysis of HSC-BPPV diagnostic maneuver based on virtual simulation

Background

The preferred supine roll test for the diagnosis of horizontal semicircular canal BPPV has several disadvantages, including difficulty in locating the affected ear, inconsistent nystagmus performance on repeated testing, and lack of a typical latency period, resulting in insensitive diagnosis.

Objectives

To investigate novel diagnostic techniques with more scientific design, more accessible application, and better diagnostic sensitivity and specificity.

Materials and methods

Based on clinical microscopic CT data, we created a virtual simulation model of BPPV using Unity software. The physical simulation of the traditional supine roll test was performed to observe and analyse the movement of the otoliths, whose initial position was the typical stable position. In addition, the normal vectors of the plane and crista ampullaris of the horizontal semicircular canal were measured using 3D Slicer software. Based on this, we analyzed the critical steps for designing diagnostic maneuvers for BPPV in the horizontal semicircular canal. For a more accurate diagnosis of horizontal semicircular canal BPPV, it is critical to rotate the horizontal semicircular canal to be parallel to gravity. It is also necessary to move the otolith by swinging the head. As a result, we developed two diagnostic maneuvers: the 60° roll test and the prone roll test. We also performed simulations to observe otolith movement and predict nystagmus performance.

Conclusions

The 60° roll test and the prone roll test can complement the supine roll test. Compared to the supine roll test, they not only effectively differentiate canalolithiasis from cupulolithiasis, but also make it easier to determine the position of the otoliths, and the characteristics of the nystagmus are more pronounced. Significant diagnostic features have significant potential benefits for home and telemedicine.