The effects of vibrotactile biofeedback training on trunk sway in Parkinson's disease patients

Background: Postural instability in Parkinson's disease (PD) can lead to falls, injuries and reduced quality of life. We investigated whether balance in PD can improve by offering patients feedback about their own trunk sway as a supplement to natural sensory inputs. Specifically, we investigated the effect of artificial vibrotactile biofeedback on trunk sway in PD. Methods: Twenty PD patients were assigned to a control group (n = 10) or biofeedback group (n = 10). First, all patients performed two sets of six gait tasks and six stance tasks (pre-training assessment). Subsequently, all subjects trained six selected tasks five times (balance training). During this training, the feedback group received vibrotactile feedback of trunk sway, via vibrations delivered at the head. After training, both groups repeated all twelve tasks (post-training assessment). During all tasks, trunk pitch and roll movements were measured with angular velocity sensors attached to the lower trunk. Outcomes included sway angle and sway angular velocity in the roll and pitch plane, and task duration. Results: Overall, patients in the feedback group had a significantly greater reduction in roll (P = 0.005) and pitch (P < 0.001) sway angular velocity. Moreover, roll sway angle increased more in controls after training, suggesting better training effects in the feedback group (P < 0.001). Conclusions: One session of balance training in PD using a biofeedback system showed beneficial effects on trunk stability. Additional research should examine if these effects increase further after more intensive training, how long these persist after training has stopped, and if the observed effects carry over to non-trained tasks. (C) 2012 Elsevier Ltd. All rights reserved.