The Effect of Unilateral Vestibular Loss on Standing Balance During Postural Threat

Abstract

Objective: Vestibular deficit patients have an increased fall risk and fear of falling. Postural threat, known to increase balance-related fear and anxiety, influences vestibular gains during quiet standing in young healthy adults. The current study examined whether there is a similar relationship for peripheral unilateral vestibular loss (UVL) patients in comparison to age-matched healthy controls (HC). Setting: University laboratory. Study Design: Prospective laboratory study. Patients and Controls: Eleven UVL patients, nine with vestibular neurectomy. Eleven aged-matched HCs. Main Outcome Measures: Subjects stood on a hydraulic lift placed at two heights: low (0.8 m, away from the edge) and high (3.2 m, at the edge). Amplitude (root mean square), mean power frequency (MPF), and mean position were analyzed for center of foot pressure (COP) and 90% ranges for angle amplitude and velocity for trunk sway. Results: Group interactions were strongest for anterior-posterior (AP) COP and trunk pitch angle. AP lean away from the edge was greater in HCs than UVLs. HCs, but not UVLs had a decrease in root mean square AP COP with height. Trunk pitch sway was changed similarly. Both groups had increased trunk pitch velocity at height. Changes with height were less for roll: MPF of lateral COP increased with height for UVLs with no changes for HCs, and trunk roll amplitude decreased for both groups. Conclusions: This report provides evidence for a differential effect of height induced postural threat on balance control between UVLs and HCs presumably due to the reduced vestibular-spinal gain in UVL subjects.

Characterization of Postural Sway in Patients With Persistent Postural-Perceptual Dizziness (PPPD) Using Wearable Motion Sensors

“…Compared to (Normal), patients adopted postural control strategies that reduced body sway [CSD (1)] or generated increased back-andforth sway [CSD (2)]. CSD(1) resulted from bottom-totop stiffening (B) seen in normal humans and patients with unilateral vestibular loss under conditions of postural threat (21). CSD(2) involved either a stiffened ankle strategy with superimposed upper body sway (C) or a hip strategy (D), both of which can be observed clinically in patients with PPPD and are capable of being normalized transiently with distraction (30).…”

“…The primary aims of this study were to further elucidate altered postural control in patients with PPPD and assess the feasibility of using a wearable device to detect sway patterns that might aid clinical diagnosis. Previous studies found differences in anterior-posterior (AP) and medial-lateral (ML) sway in response to visual inputs and postural threats in healthy individuals (21). Thus, AP and ML sway displacements were measured with accelerometers worn about the waist during the SOT.…”