The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Direct and reflex motor effects of conventional and catch-like electrical stimulation for dropped foot correction

Direct and reflex motor effects of conventional and catch-like electrical stimulation for dropped foot correction
Direct and reflex motor effects of conventional and catch-like electrical stimulation for dropped foot correction
Electrical stimulation applied to the common peroneal nerve during the swing phase of gait is an established clinical technique for the correction of dropped foot following upper motor neuron injury. The catch-like effect of skeletal muscle refers to force augmentation resulting from the inclusion of an initial high frequency burst of two or more stimuli prior to conventional low frequency electrical stimulation. There is interest in clinical utilisation of catch-like stimulation during functional applications; however the mechanism of the effect is not fully understood. The purpose of this research was to determine if the catch-like effect is a property of the muscle alone or related to spinal reflex mediated activation. In order to investigate this, direct and reflex motor effects of conventional and catch-like stimulation during dropped foot correction and other controlled conditions were assessed in unimpaired (n=12) and stroke (n=13) populations through use of electromyography. A system was developed to enable analysis of electromyography activity shortly after the application of configurable stimulation patterns. Innovative design minimised effects of stimulation artefact such that electromyography of the tibialis anterior and soleus muscles during dropped foot correction could be assessed. This system was utilised and further refined during exploratory investigations prior to structured use with study participants. Both direct and reflex motor effects of conventional stimulation were found to vary with muscle length. At typical stimulation intensities and frequencies used during dropped foot correction, direct (orthodromic) motor activation dominates voluntary or reflex mediated activation of the tibialis anterior. Enhanced contractile force when utilising catch-like stimulation with human participants, appears an effect solely inherent to muscle with no excitatory or inhibitory spinal reflex contribution. Facilitation of reflected antidromic motor activation (F-waves) with voluntary effort, observed only within the unimpaired participant group, may be an indicator of normal neuroplasticity at the spinal cord. Findings highlight the need to consider antidromic motor effects of electrical stimulation when combining its use with voluntary function during future clinical development.
Hart, Darren
de6b0ab1-b4e1-4396-bb47-f6fda0752554
Hart, Darren
de6b0ab1-b4e1-4396-bb47-f6fda0752554
Chappell, P.H.
2d2ec52b-e5d0-4c36-ac20-0a86589a880e

Hart, Darren (2013) Direct and reflex motor effects of conventional and catch-like electrical stimulation for dropped foot correction. University of Southampton, Physical Sciences and Engineering, Doctoral Thesis, 340pp.

Record type: Thesis (Doctoral)

Abstract

Electrical stimulation applied to the common peroneal nerve during the swing phase of gait is an established clinical technique for the correction of dropped foot following upper motor neuron injury. The catch-like effect of skeletal muscle refers to force augmentation resulting from the inclusion of an initial high frequency burst of two or more stimuli prior to conventional low frequency electrical stimulation. There is interest in clinical utilisation of catch-like stimulation during functional applications; however the mechanism of the effect is not fully understood. The purpose of this research was to determine if the catch-like effect is a property of the muscle alone or related to spinal reflex mediated activation. In order to investigate this, direct and reflex motor effects of conventional and catch-like stimulation during dropped foot correction and other controlled conditions were assessed in unimpaired (n=12) and stroke (n=13) populations through use of electromyography. A system was developed to enable analysis of electromyography activity shortly after the application of configurable stimulation patterns. Innovative design minimised effects of stimulation artefact such that electromyography of the tibialis anterior and soleus muscles during dropped foot correction could be assessed. This system was utilised and further refined during exploratory investigations prior to structured use with study participants. Both direct and reflex motor effects of conventional stimulation were found to vary with muscle length. At typical stimulation intensities and frequencies used during dropped foot correction, direct (orthodromic) motor activation dominates voluntary or reflex mediated activation of the tibialis anterior. Enhanced contractile force when utilising catch-like stimulation with human participants, appears an effect solely inherent to muscle with no excitatory or inhibitory spinal reflex contribution. Facilitation of reflected antidromic motor activation (F-waves) with voluntary effort, observed only within the unimpaired participant group, may be an indicator of normal neuroplasticity at the spinal cord. Findings highlight the need to consider antidromic motor effects of electrical stimulation when combining its use with voluntary function during future clinical development.

Text
Hart.pdf - Other
Download (20MB)

More information

Published date: December 2013
Organisations: University of Southampton, Electronic & Software Systems

Identifiers

Local EPrints ID: 361933
URI: http://eprints.soton.ac.uk/id/eprint/361933
PURE UUID: 6c6ab9c8-4b2a-4b13-9360-c8cd192c1142

Catalogue record

Date deposited: 10 Feb 2014 14:40
Last modified: 20 Nov 2021 16:36

Export record

Contributors

Author: Darren Hart
Thesis advisor: P.H. Chappell

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×