Abstract
A complete lack of bilateral activation of tibialis anterior (TA) during gait initiation (GI), along with bradykinetic anticipatory postural adjustments (APAs), often occurs in patients with Parkinson’s disease (PD) in their OFF-medication state. Functional electrical stimulation (FES) is a non-pharmacological method frequently used in neurorehabilitation to optimize the effect of L-DOPA on locomotor function in this population. The present study tested the potential of bilateral application of FES on TA to improve GI in PD patients. Fourteen PD patients (OFF-medication state, Hoehn and Yahr state 2-3) participated in this study. They performed series of 10 GI trials on a force-plate under the following experimental conditions: (1) GI without FES (control group), (2) GI with 2Hz-FES (considered as a very low FES frequency condition without biomechanical effect; placebo group) and (3) GI with 40Hz-FES (test group). In (2) and (3), FES was applied bilaterally to the TA during APAs (300 mA intensity/300 μs pulse width). Main results showed that the peak of anticipatory backward center of pressure shift, the forward center of mass (COM) velocity and shift at foot off were significantly larger in the 40 Hz FES condition than in the control condition, while the duration of step execution was significantly shorter. In contrast, the capacity of participants to brake the fall of their COM remained unchanged across conditions. Globally taken, these results suggest that acute application of 40-Hz FES to the TA may improve the capacity of PD patients to generate APAs during GI, without altering their balance capacity. Future studies are required before considering that TA FES application might be a valuable tool to improve GI in PD patients and be relevant to optimize the effects of L-DOPA medication on locomotor function.
Highlights
METHODSGait initiation (GI), the transient period between steady-standing posture and steady-state walking, is a functional task known to be altered in patients with Parkinson’s Disease (PD) (Halliday et al, 1998)
The present study tested the potential of bilateral application of Functional electrical stimulation (FES) on tibialis anterior (TA) to improve gait initiation (GI) in Parkinson’s disease (PD) patients
Post hoc test showed that xPMAX (p < 0.001; d = 0.38), x’MTO (p < 0.05; d = 0.58) and xMTO (p < 0.001; d = 0.17) were significantly larger in the 40 Hz FES condition than in the control condition, while EXE was significantly shorter (p < 0.05, d = 0.62, Figure 2)
Summary
Gait initiation (GI), the transient period between steady-standing posture and steady-state walking, is a functional task known to be altered in patients with Parkinson’s Disease (PD) (Halliday et al, 1998). During APAs, the tibialis anterior (TA) are activated bilaterally, which is responsible of backward center-of-pressure (COP) shift This COP shift is necessary to generate the initial forces to propel the center-ofmass (COM) forward during the execution phase, and reach the desired step length and velocity (Lepers and Brenicre, 1995). PD patients in their OFF-medication state (i.e., after 12-h withdrawal from their antiparkinsonian’s L-DOPA medications) were included because this is the condition where alterations in APAs development and associated TA activity mainly occur. Repeated-measures ANOVAs were used to test the effect of the condition (control, 2 Hz FES, 40 Hz FES) on TABLE 1 | Demographic characteristics and clinical parameters of PD patients. MDS-UPDRS, Movement disorders society-Unified Parkinson’s Disease Rating Scale; STS, Sit-to-Stand Task, STS score corresponds to the number of rising from a chair performed during 15 s; MMSE, Mini Mental State Exam. Effect sizes were classified as trivial (
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