Blog Post Author Biography: Yuki Sugimoto is an Assistant Professor in the Department of Physical Therapy & Human Movement Science at the Feinberg School of Medicine, Northwestern University, and has a clinical background as a certified athletic trainer. One of Dr. Sugimoto’s research interests is the sensory reweighting system and changes in reliance on visual and vestibular feedback in individuals with chronic ankle instability.

Citation: Sugimoto YA, McKeon PO, Rhea CK, et al. Sensory Reweighting System Differences on Vestibular Feedback With Increased Task Constraints in Individuals With and Without Chronic Ankle Instability. J Athl Train. 2024;59(7):713-723. doi:10.4085/1062-6050-0246.22

Take-to-the-clinic message: The results highlight the importance of considering vestibular feedback reliance during postural control assessment and rehabilitation in individuals with chronic ankle instability (CAI). Combining tests such as the horizontal head impulse test with single-limb postural assessments may reveal underlying sensory reweighting dysfunction, especially under varying environmental and task conditions. Clinicians should explore multisensory feedback approaches that challenge vestibular function to improve rehabilitation outcomes in individuals with CAI.

Background: Postural stability is critical for motor behavior in dynamic environments and relies on the ability to reweight sensory feedback from somatosensory, visual, and vestibular systems as environmental and task constraints change. Individuals with CAI may have sensory reweighting deficits, leading to an over-reliance on visual feedback and difficulties maintaining postural control, especially in complex tasks like single-limb stance. However, current evidence suggests that somatosensory feedback contributions to postural control in individuals with CAI cannot be ruled out based solely on balance scores in single-limb stance with and without eyes closed. In addition, the sensory reweighting system in individuals with CAI and whether they upweight visual feedback to maintain posture in bilateral and unilateral (uninjured, injured) stances compared to healthy individuals remains unknown.

Purpose: The primary purpose of the study was to examine the sensory reweighting system changes to control posture in a simple double-limb stance and a more complex uninjured- or injured-limb stance under increased environmental constraints, manipulating somatosensory and visual information, for individuals with and without CAI. The secondary purpose of the study was to determine the effect of environmental and task constraints on postural stability.

Methods: The study included 42 physically active individuals with and without unilateral CAI. Participants completed postural control assessments using the Sensory Organization Test (SOT) on a NeuroCom dynamic posturography platform, which measures the ability to integrate somatosensory, visual, and vestibular feedback across six conditions of varying complexity. Equilibrium balance scores were calculated based on center-of-gravity sway, and sensory reweighting ratios were determined to assess the weighting of different sensory systems.

Results: The study is the first investigation of how the sensory reweighting system adapts to control posture under increased task constraints and how postural control is influenced by both environmental and task constraints in individuals with and without CAI. Notably, the CAI group did not reduce their reliance on vestibular feedback when standing on the injured limb. However, the inability to downweight vestibular feedback may represent a compensatory reliance for individuals with CAI, as they maintained postural stability on the injured limb better than healthy controls. Both groups showed different patterns of sensory feedback use depending on the task. Somatosensory input was the most emphasized during double-limb stance, whereas visual feedback was prioritized during single-limb stance in both injured and uninjured limbs. Differences in postural control between groups were shaped by task and environmental demands, although individuals with CAI demonstrated postural control similar to that of healthy participants.

Rolling the field forward: This research demonstrates that while individuals with CAI do not downweight vestibular feedback to maintain posture on their injured limb, this reliance may serve as a compensatory mechanism, allowing them to maintain better postural stability than those without CAI. In addition, postural control in both groups was influenced by the specific sensory systems engaged and the constraints imposed by the task. Clinicians should consider using a multisensory feedback approach in their interventions, challenging vestibular input, with and without visual cues, during tasks with increased demands to improve postural control for individuals with CAI.

Question for the researchers: How might clinicians implement multisensory feedback approaches in rehabilitation programs to specifically address the compensatory reliance on vestibular feedback observed in individuals with CAI?