Improving impaired balance function: Real-time versus carry-over effects of prosthetic feedback

Abstract

This study investigated whether training with realtime prosthetic biofeedback (BF) of trunk sway induces a carry-over improvement in balance control once BF is removed. 12 healthy older adults and 7 uncompensated unilateral vestibular loss patients were tested. All participants performed a battery of 14 balance and gait tasks (pre-test) upon their initial lab visit during which trunk angular sway was measured at L1-3. They then received balance BF training on a subset of 7 tasks, three times per week, for two consecutive weeks. BF was provided using a multi-modal biofeedback system with graded vibrotactile, auditory, and visual cues in relation to subject-specific angular displacement thresholds. Performance on the battery of the 14 balance and gait tasks (without BF) was re-assessed immediately after the 2 week training period, as well as 1 week later to examine BF carry-over effects. Significant reductions in trunk angular displacement were observed with the real-time BF, compared to the pre-test trials. The effects of BF persisted when BF was removed immediately after the final training session. BF carry-over effects were less evident at one week post-training. This evidence supports the potential short-term effects of BF training in a limited number of tasks after the BF is removed in healthy elderly subjects and those with vestibular loss. However, the prospect for longer term (>1 week) effects of prosthetic training on balance control remains currently unknown.

Short-term retention effect of rehabilitation using head position-based electrotactile feedback to the tongue: Influence of vestibular loss and old-age

“…Our data has shown that the amount of the post-therapeutic changes is proportional to the degree of vestibular loss, patients with profound deficits benefiting more from this therapy than those with unilateral losses. This is in line with previously reported findings showing that body swaybased auditory [18,19] and multi-modal [20] biofeedback have a greater stabilizing effect in vestibular patients than in healthy subjects.…”

“…In the present study, analysis of the therapy effect in posturographic scores revealed similarities with those observed in patients wearing auditory [2,3,18,19,24,25], vibrotactile [6,21,25,26] or multi-modal [20,22] biofeedback devices providing a real-time postural signal. Our patients, however, were tested without feedback, 4 h after the last use of the BrainPort balance device.…”

The effect of prosthetic feedback on the strategies and synergies used by vestibular loss subjects to control stance

“…We assume that long-term training would have reduced the feedback thresholds to values of HCs as BVL values would be individually reset to lower values following reassessment with no feedback. Lower no feedback values would be achieved via a carry-over effect of the feedback to the no feedback condition [3]. …”

“…For these reasons, a number of investigators have developed balance prostheses to provide persons with balance problems a replacement for vestibular sensory information on body sway. Such prosthetic systems generally rely on vibrotactile or auditory feedback or both modes, appropriately coded with body sway information [3-9]. There are variations concerning where the sway measures are taken, and how the sway signals are processed, and at which body location the feedback is provided.…”

“…There are variations concerning where the sway measures are taken, and how the sway signals are processed, and at which body location the feedback is provided. However, the general conclusion is that such feedback helps UVL and BVL patients improve their balance during stance and gait [3,7,9]. …”