Rebalancing the Vestibular System by Unidirectional Rotations in Patients With Chronic Vestibular Dysfunction

Abstract

Introduction: Vestibular dysfunction is a common disorder that results in debilitating symptoms. Even after full compensation, the vestibulo-ocular reflex (VOR) could be further improved by using rehabilitation exercises and visual-vestibular adaptation. We hypothesized that in patients with asymmetric vestibular function, the system could be rebalanced by unidirectional rotations toward the weaker side (i.e., a pure vestibular stimulation).Methods: Sixteen subjects (5 female and 11 male, 43.2 ± 17.0 years old) with chronic vestibular dysfunction that was non-responsive to other types of medical treatment were recruited for the study (ClinicalTrials.gov Identifier: NCT01080430). Subjects had VOR asymmetry quantified by an abnormal directional preponderance (DP) with rotation test and no previous history of central vestibular problems or fluctuating peripheral vestibular disorders. They participated either in the short-term study (one session) or the long-term study (7 visits over 5 weeks). Rehabilitation consisted of five trapezoid unidirectional rotations (peak velocity of 320°/s) toward the weaker side. Care was taken to slowly stop the rotation in order to avoid stimulation in the opposite direction during deceleration. To study the short-term effect, VOR responses were measured before and 10, 40, and 70 min after a single unidirectional rotational rehabilitation session. For long-term effects, the VOR gain was measured before and 70min after rehabilitation in each session.Results: We observed a significant decrease in VOR asymmetry even 10 min after one rehabilitation session (short-term study). With consecutive rehabilitation sessions in the long-term study, DP further decreased to reach normal values during the first 2 sessions and only one subjects required further rehabilitation after week 4. This change in DP was due to an increase in responses during rotations toward the weaker side and a decrease in VOR responses during rotations in the other direction.Conclusion: Our results show that unidirectional rotation can reduce the VOR imbalance and asymmetry in patients with previously compensated vestibular dysfunction and could be used as an effective supervised method for vestibular rehabilitation even in patients with longstanding vestibular dysfunction.

Posture Deficits and Recovery After Unilateral Vestibular Loss: Early Rehabilitation and Degree of Hypofunction Matter

“…The frequency of chair rotation was around 0.005 Hz, including a resting period of 120-150 s between each chair rotation. This VR paradigm was found to reduce the contralateral intact horizontal VOR response in animal models of unilateral vestibular loss (Ushio et al, 2011), and to increase the VOR gain on the hypofunction side in unilateral vestibular patients (Sadeghi et al, 2018). The four subgroups of patients with UVH in the present study were subjected to the same training protocol, including an equal number of training sessions.…”

Improvement After Vestibular Rehabilitation Not Explained by Improved Passive VOR Gain

“…Additionally, those patients reported reduced dizziness compared to control subjects. More recently, Sadeghi et al have used passive ipsilesional whole-body rotation to reduce VOR asymmetry (12). There is some evidence the VOR gain can improve to faster, active (self-generated) head velocity rotation as well.…”

Reporting of exercise dose and dosage and outcome measures for gaze stabilisation in the literature: a scoping review

“…Although outside the initial purpose of this scoping review, we did find that only 25 studies focused solely on gaze stabilisation as an intervention 19–22 25 28 30 32 33 38–53. Most studies included a combination of gaze stabilisation with other interventions such as balance and gait training.…”

“…When dose speed and excursion were reported, values varied widely. Exercise velocities and frequencies ranged from 20°/s22 26 to 320°/s30 and from 0.04 to 10 Hz, respectively. In a number of studies, the speed was often up to patient’s discretion or comfort.…”