Continuous Head Motion is a Greater Motor Control Challenge than Transient Head Motion in Patients with Loss of Vestibular Function

Abstract

Background. The vestibular system is vital for gaze stability via the vestibulo-ocular reflex, which generates compensatory eye motion in the direction opposite to head motion. Consequently, individuals with peripheral vestibular loss demonstrate impaired gaze stability that reduces functional capacity and quality of life. To facilitate patients’ compensatory strategies, two classes of gaze stabilization exercises are often prescribed: (i) transient (eg, ballistic) and (ii) continuous. However, the relative benefits of these two classes of exercises are not well understood. Objective. To quantify head motion kinematics in patients with vestibular loss while they performed both classes of exercises. Methods. Using inertial measurement units, head movements of 18 vestibular schwannoma patients were measured before and after surgical deafferentation and compared with age-matched controls. Results. We found that the head movement during both classes of exercises paralleled those of natural head movement recorded during daily activities. However, head movement patterns were more informative for continuous than transient exercises in distinguishing patients from healthy controls. Specifically, we observed coupling between kinematic measures in control subjects that was absent in patients for continuous but not transient head motion exercises. In addition, kinematic measures (eg, cycle duration) were predictive of standard clinical measures for continuous but not transient head motion exercises. Conclusions. Our data suggest that performing continuous head motion is a greater motor control challenge than transient head motion in patients with less reliable vestibular feedback during the sub-acute stage of recovery, which may also prove to be a reliable measure of progression in vestibular rehabilitation protocols.

Head movement kinematics are differentially altered for extended versus short duration gait exercises in individuals with vestibular loss

“…Finally, here we have further shown that head kinematics and step cycle duration—both during short duration FGA and extended duration gait rehabilitation exercises—are predictive of several clinical measures, but not of subjective quality of life assessments. In this context, our findings add to a growing body of work demonstrating comparable conclusions based on head movements during other classes of vestibular exercises (i.e., gaze 55 , 56 and balance 49 ). Moreover, we found that kinematic measures from both short and extended duration conditions better predicted physiological (i.e., vHIT) measures preoperatively than postoperatively.…”

Head movement kinematics are altered during balance stability exercises in individuals with vestibular schwannoma

“…Comparisons were also made between the head movement kinematics of preoperative versus postoperative VS subjects. Additionally, we correlated these kinematic data with standard clinical outcome measures [16][17][18][19] to determine whether postoperative head kinematics during balance exercises correlate with preoperative clinical measures. Finally, we addressed whether it was possible to compute a robust "kinematic score" based on head kinematic data obtained from a subset of exercises.…”

Regional differences in patient-reported outcomes as a proxy of healthcare practices for Americans living with vestibular symptoms

“…The vestibular system is highly adaptable [12] with compensation for eighth cranial nerve section typically occurring within seven days [27]. Furthermore, individuals may learn how to cope with their symptoms by deploying strategies that allow them to remain functional despite their vestibular impairment [49]. This behavior, largely based on the apparent improvement of symptoms, is explicitly seen with vestibular schwannoma, in which patients demonstrate better postural control at intermediate stages of tumor development, only to observe further balance declines at later stages when the tumor is significantly larger and compensatory strategies are no longer effective [35].…”