Title

The effect of paired corticospinal-motoneuronal stimulation on maximal voluntary elbow flexion in cervical spinal cord injury: An experimental study

Document Type

Journal Article

Publication Title

Spinal Cord

ISSN

1476-5624

Volume

57

Issue

9

First Page

796

Last Page

804

PubMed ID

31086274

Publisher

Springer

School

School of Medical and Health Sciences

Funders

National Health and Medical Research Council

Grant Number

NHMRC Number : 1055084

Comments

Originally published as: Dongés, S. C., Boswell-Ruys, C. L., Butler, J. E., & Taylor, J. L. (2019). The effect of paired corticospinal-motoneuronal stimulation on maximal voluntary elbow flexion in cervical spinal cord injury: An experimental study. Spinal Cord, 57, 796-804 . Original publication available here

Abstract

STUDY DESIGN: Randomised, controlled, crossover study.

OBJECTIVES: Paired corticospinal-motoneuronal stimulation (PCMS) involves repeatedly pairing stimuli to corticospinal neurones and motoneurones to induce changes in corticospinal transmission. Here, we examined whether PCMS could enhance maximal voluntary elbow flexion in people with cervical spinal cord injury.

SETTING: Neuroscience Research Australia, Sydney, Australia.

METHODS: PCMS comprised 100 pairs of transcranial magnetic and electrical peripheral nerve stimulation (0.1 Hz), timed so corticospinal potentials arrived at corticospinal-motoneuronal synapses 1.5 ms before antidromic motoneuronal potentials. On two separate days, sets of five maximal elbow flexions were performed by 11 individuals with weak elbow flexors post C4 or C5 spinal cord injury before and after PCMS or control (100 peripheral nerve stimuli) conditioning. During contractions, supramaximal biceps brachii stimulation elicited superimposed twitches, which were expressed as a proportion of resting twitches to give maximal voluntary activation. Maximal torque and electromyographic activity were also assessed.

RESULTS: Baseline median (range) maximal torque was 11 Nm (6-41 Nm) and voluntary activation was 92% (62-99%). Linear mixed modelling revealed no significant differences between PCMS and control protocols after conditioning (maximal torque: p = 0.87, superimposed twitch: p = 0.87, resting twitch: p = 0.44, voluntary activation: p = 0.36, biceps EMG: p = 0.25, brachioradialis EMG: 0.67).

CONCLUSIONS: Possible explanations for the lack of effect include a potential ceiling effect for voluntary activation, or that PCMS may be less effective for elbow flexors than distal muscles. Despite results, previous studies suggest that PCMS is worthy of further investigation.

DOI

10.1038/s41393-019-0291-3

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