Objective assessment of gaze stabilization exercises in people with multiple sclerosis

Dizziness and instability in gaze and posture are common symptoms in people with multiple sclerosis (PwMS). The vestibular ocular reflex (VOR) is one of the main functions of the vestibular system that may lead to gaze and postural instability if impaired. Therefore, it is important to understand if gaze stabilization is impaired in PwMS and recommend the appropriate management plan.

To objectively compare the Vestibular Ocular Reflex exercise (VORx1) metrics including eye gaze compliance, head speed compliance, symptoms and tasks perceived difficulty rating scores between PwMS (with and without dizziness) and matched healthy controls using the VestAid software.

Forty-three PwMS (21 with dizziness and 22 without dizziness) and 40 healthy controls participated in this study. A tablet app (VestAid) investigational software device was utilized to record the VORx1 metrics in horizontal trials. The VORx1 exercise is best described as the subject moving the head in the horizontal plane approximately 30° to the right and left from a target 90 cm in front of the persons face at the prescribed frequency (80 beats per minute) while keeping the non-moving target in focus. Subjects were exposed to 12 randomized visual scenes with static and optokinetic backgrounds. Gaze compliance, head speed compliance, symptoms rating, and the perceived difficulty were assessed after each visual scene. Results were analyzed using ANOVA, controlling for age, sex, and education level.

Significant group effects were observed for the eye gaze compliance, head speed compliance, perceived difficulty scores, and symptoms rating. For the eye gaze compliance and head speed compliance, healthy controls performed better than PwMS. For perceived difficulty, healthy controls rated the tasks easier than dizzy PwMS. For symptom's rating, dizzy PwMS had more reports of headache, fogginess, and nausea than healthy controls. Considering all subjects together, we observed no significant effect of exercise condition on head compliance (p = 0.21). However, significant effect of exercise condition was found on task difficulty ratings (p < 0.001).

Preliminary analyses suggest that PwMS with dizziness performed the worst with eye gaze compliance, head speed compliance, perceived task difficulty, and consistently experienced the most severe symptom scores. Additional studies are required to determine if the subjects optimized their gaze stability by slowing their speed of head turning while performing VOR exercises.