Vestibulo-Ocular Reflex Abnormalities in Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo: A Pilot Study

Abstract

Introduction: Benign paroxysmal positional vertigo (BPPV), involving the semicircular canals, is one of the most common diseases of the inner ear. The video head impulse test (vHIT) is a new test that examines the function of the canals. This study aimed to investigate the vestibulo-ocular reflex (VOR) gain, gain asymmetry and saccades after stimulating all six canals in patients definitively diagnosed with posterior semicircular canal BPPV (PSC-BPPV).

Materials and methods: Twenty-nine unilateral PSC-BPPV patients with normal oculographic and caloric results were enrolled in this study. vHIT was performed on six canals, and VOR gain, gain asymmetry and saccades were measured.

Results: Sixteen (55.17%) patients had abnormal posterior canal VOR gains in the ipsilesional ear. VOR gains in both horizontal canals were within normal limits. Superior canal VOR gains were mostly lower than normal and were not correlated to PSC abnormalities (P>0.05). No corrective saccades could be observed.

Conclusion: VOR gain in the direction of the posterior semicircular canal may be reduced in PSC-BPPV patients. Evaluation of PSC-VOR parameters could be beneficial, although superior canal measurements should be interpreted with caution.

Keywords: Benign paroxysmal positional vertigo; Head impulse test; Semicircular canals; Vestibulo-ocular reflex.

Fig1

Representation of video head impulse test (vHIT) results in the left posterior semicircular canal benign paroxysmal positional vertigo. All gain values are presented in the box over the right corner of each test. vHIT was performed in the direction of all semicircular canals. Light green lines represent the eye movement velocity