Postural Control in Patients with Unilateral Vestibular Lesions Is More Impaired in the Roll than in the Pitch Plane: A Static and Dynamic Posturography Study

Abstract

The postural instability of patients with vestibular loss (11 with bilateral and 101 with unilateral vestibular loss) at different times following the lesion was investigated by means of posturography and compared to healthy subjects. In addition, subjects submitted to galvanic vestibular stimulation were also studied to compare their postural performances with those of patients with complete unilateral vestibular lesion. The platform consisted of a static computerized force platform, on which a seesaw platform could be placed to test the subjects in dynamic conditions. The displacement of the center of foot pressure was measured under different conditions: subjects standing on the fixed platform, eyes open and eyes closed and subjects standing on the seesaw platform, eyes open and eyes closed. In the last condition, balance was tested in the subject’s pitch plane by allowing the platform to rotate forwards and backwards only and in the patient’s roll plane by allowing the platform to rotate to the left and to the right. The results showed that in static conditions, only bilateral vestibular loss patients had abnormal values compared to controls. In contrast, in dynamic eyes-closed conditions, both bilateral and unilateral patients could be differentiated from controls. Bilateral patients were unable to stand up without falling in both pitch and roll planes. Unilateral patients fell in the first week following the lesion and exhibited increased postural oscillations in both planes from the 2-week up to the 1-year postlesion stage. In addition and more importantly, they fell more often or had higher sway in the roll than in the pitch plane. Therefore, this study suggests that dynamic posturography on a seesaw platform could be a valuable tool for clinical diagnosis and quantitative analysis of imbalance in patients suffering from a unilateral vestibular loss up to 1 year after the lesion.

Recovery after Vestibular Lesions: From Animal Models to Patients

“…results]. A somewhat similar result was also obtained in humans by comparing the effects of a galvanic stimulation of the labyrinths in healthy subjects with those of an unilateral vestibular lesion in patients [108] . Hence, we concluded that the selective lesions of each end organ or the corresponding subdivision of the vestibular nerve could give at least an approximate idea of the effects of a selective stimulation of that end organ.…”

“…In order to test these two hypotheses, the postural instability of 11 patients with bilateral and 88 with unilateral vestibular loss (vestibular neurotomy, acoustic neurinoma resection, chemical labyrinthectomy and vestibular neuritis) was investigated using static and dynamic posturography at various times following the lesion [108] . Caloric and head impulse tests, vestibular evoked myogenic potentials evoked by short tone burst and short duration galvanic currents were used to select the patients.…”

Effects of Acetyl-<i>DL</i>-Leucine in Vestibular Patients: A Clinical Study following Neurotomy and Labyrinthectomy

“…It is also interesting that all statistically significant differences identified on the force platform between the acetyl-DL -leucine and placebo groups, in any experimental conditions, involved the movement of the center of mass in the frontal plane, and never in the sagittal plane. Indeed, we have recently found that following unilateral labyrinthectomy patients tested blindfolded and with a seesaw platform (which decreases proprioceptive afferences more than underfoot foam rubber) had much higher sway in the mediolateral than in the anteroposterior plane [Mbongo et al, 2005].…”

Role of Vestibular Input in Triggering and Modulating Postural Responses in Unilateral and Bilateral Vestibular Loss Patients

“…The Satel platform is a square static force platform, described previously [Mbongo et al, 2005], on which we placed two different elements: -A seesaw platform, consisting of a rigid plexiglas plate supported on two arcs with a 55 cm radius of curvature and a maximum height of 6 cm [Mbongo et al, 2005]. The task involving this platform is a self-regulated balance task, involving only one degree of freedom of movement, either in the AP or ML direction.…”

“…We recently showed [Mbongo et al, 2005] that investigating dynamic balance using a nonmotorized seesaw platform is a useful and robust test for evaluating the effects on balance of a unilateral vestibular deficit up to 2 years after the lesion. On this platform, the movement of the support is rolling (25° = maximum angle of rotation) in response of the postural reactions of the subject (like a rocking platform).…”