Long-term use of implanted peroneal functional electrical stimulation for stroke-affected gait: the effects on muscle and motor nerve

Frank Berenpas,Nens Van Alfen,Vivian Weerdesteyn,Alexander C Geurts

doi:10.1186/s12984-019-0556-2

Abstract

BackgroundPeripheral changes to muscle and motor nerves occur following stroke, which may further impair functional capacity. We investigated whether a year-long use of an implanted peroneal FES system reverses stroke-related changes in muscles and motor nerves in people with foot drop in the chronic phase after supratentorial stroke.MethodsThirteen persons with a chronic stroke (mean age 56.1 years, median Fugl-Meyer Assessment leg score 71%) were included and received an implanted peroneal FES system (ActiGait®). Quantitative muscle ultrasound (QMUS) images were obtained bilaterally from three leg muscles (i.e. tibialis anterior, rectus femoris, gastrocnemius). Echogenicity (muscle ultrasound gray value) and muscle thickness were assessed over a one-year follow-up and compared to age-, sex-, height- and weight-corrected reference values. Compound motor action potentials (CMAPs) and motor evoked potentials (MEPs) were obtained from the tibialis anterior muscle. Generalized estimated equation modeling was used to assess changes in QMUS, CMAPs and MEPs outcomes over the follow-up period.ResultsEchogenicity of the tibialis anterior decreased significantly during the follow-up on the paretic side. Z-scores changed from 0.88 at baseline to − 0.15 after 52 weeks. This was accompanied by a significant increase in muscle thickness on the paretic side, where z-scores changed from − 0.32 at baseline to 0.48 after 52 weeks. Echogenicity of the rectus femoris normalized on both the paretic and non-paretic side (z-scores changed from − 1.09 and − 1.51 to 0.14 and − 0.49, respectively). Amplitudes of CMAP and MEP (normalized to CMAP) were reduced during follow-up, particularly on the paretic side (ΔCMAP = 20% and ΔMEP = 14%).ConclusionsWe show that the structural changes to muscles following stroke are reversible with FES and that these changes might not be limited to electrically stimulated muscles. No evidence for improvement of the motor nerves was found.

Highlights

Stroke is typically defined as a lesion of the upper motor neuron (UMN)
These plastic changes after long-term Functional electrical stimulation (FES) use indicate central motor recovery, which raises the question whether stroke-related changes to skeletal muscles and lower motor neurons can be reversed with prolonged FES use
In this study we aimed to investigate whether a yearlong use of an implanted peroneal FES system (ActiGait®, Neurodan, Denmark, Otto Bock Group, 2006) reverses stroke-related changes in skeletal muscles and their motor innervation in people with persistent foot drop in the chronic phase after a supratentorial stroke

Summary

Introduction

Stroke is typically defined as a lesion of the upper motor neuron (UMN). it is known that secondary to this UMN lesion peripheral changes occur after a stroke [1, 2]. Increased excitability, metabolism and reorganization of the motor cortex have been reported after prolonged peroneal FES use in people with a neurological disease, including people with stroke [13,14,15,16]. These plastic changes after long-term FES use indicate central motor recovery, which raises the question whether stroke-related changes to skeletal muscles and lower motor neurons can be reversed with prolonged FES use. We investigated whether a year-long use of an implanted peroneal FES system reverses strokerelated changes in muscles and motor nerves in people with foot drop in the chronic phase after supratentorial stroke

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