Interlimb conditioning of lumbosacral spinally evoked motor responses after spinal cord injury

Atkinson, Darryn A.; Sayenko, Dimitry G.; D’Amico, Jessica M.; Mink, Amber M.; Lorenz, D.; Gerasimenko, Yury; Harkema, Susan J.

doi:10.1016/j.clinph.2020.03.021

Cited by 15 publications

(24 citation statements)

References 65 publications

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“…The results imply that the effect of tSCS varies between cortical and spinal networks, inhibiting the former and facilitating the latter. Moreover, ulnar nerve stimulation has been shown to potentiate spinally evoked motor responses (M-wave) (evoked by single pulse tSCS at a level between the lower thoracic and upper lumbar) across multiple muscles of the lower limb in both neurologically intact and spinal cord injured individuals (both complete and incomplete) (Atkinson et al, 2020). This signifies that conditioning of descending interlimb projections to lumbosacral motor pools occurs at least in part by similar networks that are activated with tSCS.…”

Section: Introductionmentioning

confidence: 98%

Simultaneous Cervical and Lumbar Spinal Cord Stimulation Induces Facilitation of Both Spinal and Corticospinal Circuitry in Humans

2021

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Coupling between cervical and lumbar spinal networks (cervico-lumbar coupling) is vital during human locomotion. Impaired cervico-lumbar coupling after neural injuries or diseases can be reengaged via simultaneous arm and leg cycling training. Sensorimotor circuitry including cervico-lumbar coupling may further be enhanced by non-invasive modulation of spinal circuity using transcutaneous spinal cord stimulation (tSCS). This project aimed to determine the effect of cervical, lumbar, or combined tSCS on spinal reflex (Hoffmann [H-]) and corticospinal (motor evoked potential [MEP]) excitability during a static or cycling cervico-lumbar coupling task. Fourteen neurologically intact study participants were seated in a recumbent leg cycling system. H-reflex and MEP amplitudes were assessed in the left flexor carpi radialis (FCR) muscle during two tasks (Static and Cycling) and four conditions: (1) No tSCS, (2) tSCS applied to the cervical enlargement (Cervical); (3) tSCS applied to the lumbar enlargement (Lumbar); (4) simultaneous cervical and lumbar tSCS (Combined). While cervical tSCS did not alter FCR H-reflex amplitude relative to No tSCS, lumbar tSCS significantly facilitated H-reflex amplitude by 11.1%, and combined cervical and lumbar tSCS significantly enhanced the facilitation to 19.6%. Neither cervical nor lumbar tSCS altered MEP amplitude alone (+4.9 and 1.8% relative to legs static, No tSCS); however, combined tSCS significantly increased MEP amplitude by 19.7% compared to No tSCS. Leg cycling alone significantly suppressed the FCR H-reflex relative to static, No tSCS by 13.6%, while facilitating MEP amplitude by 18.6%. When combined with leg cycling, tSCS was unable to alter excitability for any condition. This indicates that in neurologically intact individuals where interlimb coordination and corticospinal tract are intact, the effect of leg cycling on cervico-lumbar coupling and corticospinal drive was not impacted significantly with the tSCS intensity used. This study demonstrates, for the first time, that tonic activation of spinal cord networks through multiple sites of tSCS provides a facilitation of both spinal reflex and corticospinal pathways. It remains vital to determine if combined tSCS can influence interlimb coupling after neural injury or disease when cervico-lumbar connectivity is impaired.

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Section: Introductionmentioning

confidence: 98%

Simultaneous Cervical and Lumbar Spinal Cord Stimulation Induces Facilitation of Both Spinal and Corticospinal Circuitry in Humans

2021

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“…The cathode was positioned dorsally over the vertebral column in the majority of studies, otherwise electrodes were used that alternated polarity within a biphasic pulse [ 16 – 18 , 23 , 40 , 69 , 70 ]. Some studies specified a paravertebral dorsal electrode orientation [ 16 – 19 , 68 ], whereas most others placed the electrode in the midline over the vertebral column [ 14 , 20 , 23 , 25 , 26 , 36 , 37 , 40 – 44 , 67 , 69 – 72 ]. Many studies targeted a single site, however, 8 out of 14 therapeutic investigations favoured the stimulation of multiple sites simultaneously [ 36 , 37 , 40 – 43 , 67 , 71 ].…”

Section: Resultsmentioning

confidence: 99%

“…The most common vertebral level stimulated for targeting lower limb motor activity was T11-T12 and/or L1-L2. Two studies placed electrodes within the range of T9-L2, but adjusted the exact positions based on evoked EMG motor responses [ 25 , 26 ]. An additional secondary stimulating electrode was also placed on the coccygeal bone during two experiments [ 41 , 67 ].…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the inhibition of tSCS evoked responses via tendon vibration is consistent with the stimulation of reflex responses from Ia afferents [ 5 , 22 ]. Other studies have focused on alternative methods to demonstrate spinal neuromodulation of motor responses through outcomes such as increased response latencies [ 2 , 23 ], differential muscle activation patterns [ 24 ], phase-dependent modulation of reflex responses [ 5 , 14 ] and the alteration of amplitudes subsequent to afferent input [ 25 ] or interlimb conditioning [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Transcutaneous spinal cord stimulation and motor responses in individuals with spinal cord injury: A methodological review

et al. 2021

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Background Transcutaneous spinal cord stimulation (tSCS) is a non-invasive modality in which electrodes can stimulate spinal circuitries and facilitate a motor response. This review aimed to evaluate the methodology of studies using tSCS to generate motor activity in persons with spinal cord injury (SCI) and to appraise the quality of included trials. Methods A systematic search for studies published until May 2021 was made of the following databases: EMBASE, Medline (Ovid) and Web of Science. Two reviewers independently screened the studies, extracted the data, and evaluated the quality of included trials. The electrical characteristics of stimulation were summarised to allow for comparison across studies. In addition, the surface electromyography (EMG) recording methods were evaluated. Results A total of 3753 articles were initially screened, of which 25 met the criteria for inclusion. Studies were divided into those using tSCS for neurophysiological investigations of reflex responses (n = 9) and therapeutic investigations of motor recovery (n = 16). The overall quality of evidence was deemed to be poor-to-fair (10.5 ± 4.9) based on the Downs and Black Quality Checklist criteria. The electrical characteristics were collated to establish the dosage range across stimulation trials. The methods employed by included studies relating to stimulation parameters and outcome measurement varied extensively, although some trends are beginning to appear in relation to electrode configuration and EMG outcomes. Conclusion This review outlines the parameters currently employed for tSCS of the cervicothoracic and thoracolumbar regions to produce motor responses. However, to establish standardised procedures for neurophysiological assessments and therapeutic investigations of tSCS, further high-quality investigations are required, ideally utilizing consistent electrophysiological recording methods, and reporting common characteristics of the electrical stimulation administered.

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“…Restoration of volitional movement with epidural spinal cord stimulation in patients who were previously thought to have "complete" SCI has resulted in an evolving understanding of what constitutes an irreversible injury. [43][44][45][46][47] As biomarkers are identified elucidating the pathophysiology of SCI enabling differentiation between patients with capacity for recovery and those who are less likely to improve, there will be increased need for infrastructure to support early intervention.…”

Section: Evolving Understanding Of Scimentioning

confidence: 99%

Litigation risks despite guideline adherence for acute spinal cord injury: time is spine

Rafter

Vasdev

Hurrelbrink

et al. 2020

Neurosurgical Focus

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OBJECTIVECurrent guidelines do not specify timing for management of acute spinal cord injury (aSCI) due to lack of high-quality evidence supporting specific intervals for intervention. Randomized prospective trials may be unethical. Nonetheless, physicians have been sued for delays in diagnosis and intervention.METHODSThe authors reviewed both the medical literature supporting the guidelines and the legal cases reported in the Westlaw and Lexis Advance databases from 1972 to 2018 resulting in awards or settlements, to identify whether surgeons are vulnerable to litigation despite the existence of guidelines not mandating specific timing of care.RESULTSTiming of intervention was related to claims in 59 (36%) of 163 cases involving SCI. All 22 trauma cases identified cited timing of intervention, sometimes related to delayed diagnosis, as a reason for the lawsuit. The mean award of 10 cases in which the plaintiffs’ awards were disclosed was $4,294,384. In the majority of cases, award amounts were not disclosed.CONCLUSIONSBecause conduct of a prospective, randomized trial to investigate surgical timing of intervention for aSCI may not be achievable, evidence-based guidelines will be unlikely to mandate specific timing. Nonetheless, surgeons who unreasonably delay intervention for aSCI may be at risk for litigation due to treatment delay. This is increasingly likely in an environment where “complete” SCI is difficult to verify. SCI may at some point be recognized as a surgical emergency, as brain injury generally is, despite a lack of prospective randomized trials supporting this implementation, challenging the feasibility of the US trauma infrastructure to provide care for these patients.

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Interlimb conditioning of lumbosacral spinally evoked motor responses after spinal cord injury

Cited by 15 publications

References 65 publications

Simultaneous Cervical and Lumbar Spinal Cord Stimulation Induces Facilitation of Both Spinal and Corticospinal Circuitry in Humans

Simultaneous Cervical and Lumbar Spinal Cord Stimulation Induces Facilitation of Both Spinal and Corticospinal Circuitry in Humans

Transcutaneous spinal cord stimulation and motor responses in individuals with spinal cord injury: A methodological review

Litigation risks despite guideline adherence for acute spinal cord injury: time is spine

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