Neurophysiological and clinical outcome measures of the impact of electrical stimulation on spasticity in spinal cord injury: Systematic review and meta-analysis

This systematic review and meta-analysis aims to determine whether non-invasive electrical stimulation (ES) is effective at reducing spasticity in people living with spinal cord injury (SCI). PubMed, Web of Science, Scopus and Cochrane Central Register of Controlled Trials databases were searched in April 2022. Primary outcome measures were the Ashworth scale (AS), Modified Ashworth scale (MAS), Pendulum test and the Penn spasm frequency scale (PSFS). Secondary outcomes were the Hoffman (H)- reflex, motor-evoked potentials (MEPs) and posterior-root reflexes (PRRs). A random-effects model, using two correlation coefficients, (Corr=0.1, Corr=0.2) determined the difference between baseline and post-intervention measures for RCTs. A quantitative synthesis amalgamated data from studies with no control group (non-RCTs). Twenty-nine studies were included: five in the meta-analysis and 17 in the amalgamation of non-RCT studies. Twenty studies measured MAS or AS scores, 14 used the Pendulum test and one used the PSFS. Four measured the H-reflex and no studies used MEPs or PRRs. Types of ES used were: transcutaneous electrical nerve stimulation (TENS), transcutaneous spinal cord stimulation (TSCS), functional electrical stimulation (FES) cycling and FES gait. Meta-analyses of 3 studies using the MAS and 2 using the Pendulum test were carried out. For MAS scores, non-invasive ES was effective at reducing spasticity compared to a control group (p = 0.01, Corr=0.1; p = 0.002, Corr=0.2). For Pendulum test outcomes, there was no statistically significant difference between intervention and control groups. Quantitative synthesis of non-RCT studies revealed that 22 of the 29 studies reported improvement in at least one measure of spasticity following non-invasive ES, 13 of which were statistically significant (p < 0.05). Activation of the muscle was not necessary to reduce spasticity. Non-invasive ES can reduce spasticity in people with SCI, according to MAS scores, for both RCT and non-RCT studies, and Pendulum test values in non-RCT studies. This review could not correlate between clinical and neurophysiological outcomes; we recommend the additional use of neurophysiological outcomes for future studies. The use of TSCS and TENS, which did not induce a muscle contraction, indicate that activation of afferent fibres is at least required for non-invasive ES to reduce spasticity

The Immediate and Short-Term Effects of Transcutaneous Spinal Cord Stimulation and Peripheral Nerve Stimulation on Corticospinal Excitability

Rehabilitative interventions involving electrical stimulation show promise for neuroplastic recovery in people living with Spinal Cord Injury (SCI). However, the understanding of how stimulation interacts with descending and spinal excitability remain unclear. In this study we compared the immediate and short-term (within a few minutes) effects of pairing Transcranial Magnetic Stimulation (TMS) with transcutaneous Spinal Cord stimulation (tSCS) and Peripheral Nerve Stimulation (PNS) on Corticospinal excitability in healthy subjects. Three separate experimental conditions were assessed. In Experiment I, paired associative stimulation (PAS) was applied, involving repeated pairing of single pulses of TMS and tSCS, either arriving simultaneously at the spinal motoneurones (PAS0ms) or slightly delayed (PAS5ms). Corticospinal and spinal excitability, and motor performance, were assessed before and after the PAS interventions in 24 subjects. Experiment II compared the immediate effects of tSCS and PNS on corticospinal excitability in 20 subjects. Experiment III compared the immediate effects of tSCS with tSCS delivered at the same stimulation amplitude but modulated with a carrier frequency (in the kHz range) on corticospinal excitability in 10 subjects. Electromyography (EMG) electrodes were placed over the Tibialis Anterior (TA) soleus (SOL) and vastus medialis (VM) muscles and stimulation electrodes (cathodes) were placed on the lumbar spine (tSCS) and lateral to the popliteal fossa (PNS). TMS over the primary motor cortex (M1) was paired with tSCS or PNS to produce Motor Evoked Potentials (MEPs) in the TA and SOL muscles. Simultaneous delivery of repetitive PAS (PAS0ms) increased corticospinal excitability and H-reflex amplitude at least 5 min after the intervention, and dorsiflexion force was increased in a force-matching task. When comparing effects on descending excitability between tSCS and PNS, a subsequent facilitation in MEPs was observed following tSCS at 30-50 ms which was not present following PNS. To a lesser extent this facilitatory effect was also observed with HF- tSCS at subthreshold currents. Here we have shown that repeated pairing of TMS and tSCS can increase corticospinal excitability when timed to arrive simultaneously at the alpha-motoneurone and can influence functional motor output. These results may be useful in optimizing stimulation parameters for neuroplasticity in people living with SCI

An investigation of functional electrical stimulation cycling for people with spinal cord injury

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Neurophysiological and clinical outcome measures of the impact of electrical stimulation on spasticity in spinal cord injury:Systematic review and meta-analysis

This systematic review and meta-analysis aims to determine whether non-invasive electrical stimulation (ES) is effective at reducing spasticity in people living with spinal cord injury (SCI). PubMed, Web of Science, Scopus and Cochrane Central Register of Controlled Trials databases were searched in April 2022. Primary outcome measures were the Ashworth scale (AS), Modified Ashworth scale (MAS), Pendulum test and the Penn spasm frequency scale (PSFS). Secondary outcomes were the Hoffman (H)- reflex, motor-evoked potentials (MEPs) and posterior-root reflexes (PRRs). A random-effects model, using two correlation coefficients, ([Formula: see text] , [Formula: see text]) determined the difference between baseline and post-intervention measures for RCTs. A quantitative synthesis amalgamated data from studies with no control group (non-RCTs). Twenty-nine studies were included: five in the meta-analysis and 17 in the amalgamation of non-RCT studies. Twenty studies measured MAS or AS scores, 14 used the Pendulum test and one used the PSFS. Four measured the H-reflex and no studies used MEPs or PRRs. Types of ES used were: transcutaneous electrical nerve stimulation (TENS), transcutaneous spinal cord stimulation (TSCS), functional electrical stimulation (FES) cycling and FES gait. Meta-analyses of 3 studies using the MAS and 2 using the Pendulum test were carried out. For MAS scores, non-invasive ES was effective at reducing spasticity compared to a control group (p = 0.01, [Formula: see text]; p = 0.002, [Formula: see text]). For Pendulum test outcomes, there was no statistically significant difference between intervention and control groups. Quantitative synthesis of non-RCT studies revealed that 22 of the 29 studies reported improvement in at least one measure of spasticity following non-invasive ES, 13 of which were statistically significant (p < 0.05). Activation of the muscle was not necessary to reduce spasticity. Non-invasive ES can reduce spasticity in people with SCI, according to MAS scores, for both RCT and non-RCT studies, and Pendulum test values in non-RCT studies. This review could not correlate between clinical and neurophysiological outcomes; we recommend the additional use of neurophysiological outcomes for future studies. The use of TSCS and TENS, which did not induce a muscle contraction, indicate that activation of afferent fibres is at least required for non-invasive ES to reduce spasticity

The effects of FES cycling combined with virtual reality racing biofeedback on voluntary function after incomplete SCI: A pilot study

Background Functional Electrical Stimulation (FES) cycling can benefit health and may lead to neuroplastic changes following incomplete spinal cord injury (SCI). Our theory is that greater neurological recovery occurs when electrical stimulation of peripheral nerves is combined with voluntary effort. In this pilot study, we investigated the effects of a one-month training programme using a novel device, the iCycle, in which voluntary effort is encouraged by virtual reality biofeedback during FES cycling. Methods Eleven participants (C1-T12) with incomplete SCI (5 sub-acute; 6 chronic) were recruited and completed 12-sessions of iCycle training. Function was assessed before and after training using the bilateral International Standards for Neurological Classification of SCI (ISNC-SCI) motor score, Oxford power grading, Modified Ashworth Score, Spinal Cord Independence Measure, the Walking Index for Spinal Cord Injury and 10 m-walk test. Power output (PO) was measured during all training sessions. Results Two of the 6 participants with chronic injuries, and 4 of the 5 participants with sub-acute injuries, showed improvements in ISNC-SCI motor score &gt; 8 points. Median (IQR) improvements were 3.5 (6.8) points for participants with a chronic SCI, and 8.0 (6.0) points for those with sub-acute SCI. Improvements were unrelated to other measured variables (age, time since injury, baseline ISNC-SCI motor score, baseline voluntary PO, time spent training and stimulation amplitude; p &gt; 0.05 for all variables). Five out of 11 participants showed moderate improvements in voluntary cycling PO, which did not correlate with changes in ISNC-SCI motor score. Improvement in PO during cycling was positively correlated with baseline voluntary PO (R2 = 0.50; p &lt; 0.05), but was unrelated to all other variables (p &gt; 0.05). The iCycle was not suitable for participants who were too weak to generate a detectable voluntary torque or whose effort resulted in a negative torque. Conclusions Improved ISNC-SCI motor scores in chronic participants may be attributable to the iCycle training. In sub-acute participants, early spontaneous recovery and changes due to iCycle training could not be distinguished. The iCycle is an innovative progression from existing FES cycling systems, and positive results should be verified in an adequately powered controlled trial