Differing postural control patterns in individuals with bilateral and unilateral hearing loss

Abstract

Objectives: Hearing loss (HL) is associated with imbalance and increased fall risk. The mechanism underlying this relationship and differences across types of hearing loss remains unclear. Head mounted displays (HMD) can shed light on postural control mechanisms via an analysis of head sway.

Purpose: The purpose of this study was to evaluate head sway in response to sensory perturbations in individuals with bilateral (BHL) or unilateral hearing loss (UHL) and compare them to controls.

Materials and methods: We recruited 36 controls, 23 individuals with UHL and 14 with BHL. An HMD (HTC Vive) measured head sway while participants stood on the floor, hips-width apart. Stimuli included two levels of visuals and sound. Root Mean Square Velocity (RMSV) and Power Spectral Density (PSD) were used to quantify head sway.

Results: Adjusting for age, individuals with BHL had significantly higher anterior-posterior and medio-lateral RMSV than controls and individuals with UHL. Individuals with UHL demonstrated significantly lower response to visual perturbations in RMSV AP and in all 3 frequency segments of PSD compared to controls. Individuals with UHL showed significantly lower movements at high frequencies compared to controls. Sounds or severity of HL did not impact head sway.

Conclusions: Individuals with BHL demonstrated increased sway with visual perturbations and should be clinically assessed for balance performance and fall risk. Individuals with UHL exhibited reduced responses to visual stimuli compared with controls, which may reflect conscious movement processing. Additional studies are needed to further understand the mechanistic relationship between hearing loss and imbalance.

Keywords: Head kinematics; Head sway; Head-mounted display; Sensory integration for balance; Virtual reality.

Figure 1.

The experimental setup

Figure 2.

Head Root Mean Square Velocity (cm/s) in the medio-lateral direction (ML, left -side) and anterior-posterior direction (AP, right-hand side) for the 3 groups (control, bilateral hearing loss [BHL], unilateral hearing loss [UHL] across 2 levels of visual load (static, dynamic). The BHL group showed significantly higher velocity than controls or UHL on the static scene. Both BHL and UHL groups did not increase velocity AP with the dynamic visuals as much as controls did.

Figure 3.

Head Power Spectral Density (PSD, cm²) in the anterior-posterior direction (AP) for the 3 groups (control, bilateral hearing loss [BHL], unilateral hearing loss [UHL] across 2 levels of visual load (static, dynamic). From left to right: PSD 1 [power at 0, 0.25 Hz]; PSD 2 [power at 0.25, 0.5 Hz]; and PSD 3 [power at 0.5, 1 Hz].