A wearable proprioceptive stabilizer (Equistasi®) for rehabilitation of postural instability in Parkinson's disease: a phase II randomized double-blind, double-dummy, controlled study

Abstract

Background: Muscle spindles endings are extremely sensitive to externally applied vibrations, and under such circumstances they convey proprioceptive inflows to the central nervous system that modulate the spinal reflexes excitability or the muscle responses elicited by postural perturbations. The aim of this pilot study is to test the feasibility and effectiveness of a balance training program in association with a wearable proprioceptive stabilizer (Equistasi) that emits focal mechanical vibrations in patients with PD.

Methods: Forty patients with PD were randomly divided in two groups wearing an active or inactive device. All the patients received a 2-month intensive program of balance training. Assessments were performed at baseline, after the rehabilitation period (T1), and two more months after (T2). Posturographic measures were used as primary endpoint; secondary measures of outcome included the number of falls and several clinical scales for balance and quality of life.

Results: Both groups improved at the end of the rehabilitation period and we did not find significant between-group differences in any of the principal posturographic measures with the exception of higher sway area and limit of stability on the instrumental functional reach test during visual deprivation at T1 in the Equistasi group. As for the secondary outcome, we found an overall better outcome in patients enrolled in the Equistasi group: 1) significant improvement at T1 on Berg Balance Scale (+45.0%, p = .026), Activities-specific Balance Confidence (+83.7, p = .004), Falls Efficacy Scale (-33.3%, p = .026) and PDQ-39 (-48.8%, p = .004); 2) sustained improvement at T2 in terms of UPDRS-III, Berg Balance Scales, Time Up and Go and PDQ-39; 3) significant and sustained reduction of the falls rate.

Conclusions: This pilot trial shows that a physiotherapy program for training balance in association with focal mechanical vibration exerted by a wearable proprioceptive stabilizer might be superior than rehabilitation alone in improving patients' balance.

Trial registration: EudraCT 2013-003020-36 and ClinicalTrials.gov (number not assigned).

Figure 1. The wearable postural stabilizer (Equistasi) employed in the present study.

Figure 2. The CONSORT flow diagram for this study.

Figure 3. The sway area and the displacement along the AP axis (expressed as value normalized to the baseline) at the instrumental FRT during EO (left panels) and EC (right panels) conditions.

Data are presented as mean ± standard deviation. Abbreviations: AP: antero-posterior; EC: eyes closed; EO: eyes open; *: p = .006; **: p = .02; ***: p = .01 (Wilcoxon signed-rank test).

Figure 4. The Falls rate over the 2-month observation period.

Data are presented as mean ± standard deviation (A) and individual trends excluding patients with no baseline history of falls (B). Abbreviations: *: p = .03; **: p = .0001; ***: p = .003 (Wilcoxon signed-rank test); #: p = .03 (Mann-Whitney U test).