tESCS for Upper Limb Rehab in Spinal Cord Injury

Background Spinal Cord Injury affects more than 50,000 people in the UK, with an incidence of 2400 new cases every year. Muscular paralysis and sensory loss carry substantial physiological, psychological, financial, and social costs. Almost 60% of people affected by SCI sustain a high-level injury, that is, injury to spinal levels C2-T1, affecting arms and hands. Restoring hand and arm function is a top priority for people with tetraplegia, where even small improvements of motor function, combined with available assistive devices, may greatly improve independence and quality of life.

Transcutaneous spinal cord stimulation (tESCS) has emerged as a viable neuromodulation approach for facilitating the recovery of motor function in people with SCI. Studies that have applied tESCS at cervical segments combined with activity-based upper limb rehabilitation. Such active-assisted exercises such as gross and fine motor skill training, maximum voluntary contraction training, and unimanual and bimanual task performance have shown significant improvements in upper limb function.

It is believed that tESCS stimulation activates motor neuronal networks of the spinal cord, including the recruitment of afferent fibres in the posterior root, to elevate spinal network excitability. The underlying hypothesis is that after severe cervical SCI, nonfunctional sensory-motor networks within the cervical spinal cord can be transcutaneously neuromodulated to physiological states that enable and amplify voluntary control of the arm and hand.

A multicentre ONWARD Up-LIFT trial, which included 14 research sites, including QENSIU, has demonstrated functional improvements in people with incomplete chronic tetraplegia. As part of a UK Neuromodulation Network, we were awarded funding to deliver a substantial follow-up study, focusing on chronic complete tetraplegia. The results are showing some neurological recovery but modest functional improvement, indicating that some minimal level of preserved sensory or motor function is required in order to benefit from tESCS. For that reason, the investigators plan to recruit people with incomplete SCI in this study.

Rationale In the area of upper limb rehabilitation, the focus has been mainly on people with chronic SCI, likely due to the lack of alternative rehabilitation strategies and the difficulty in applying acute interventions in the clinical setting [3-8]. However, to date, there have been limited studies reporting the use of tESCS with people with subacute SCI. A randomised controlled trial with 22 complete or incomplete tetraplegic patients (3-12 months post injury, probably recruited from home) compared 8 sessions of tESCS with Armeo robot exercise to 8 sessions of Armeo alone. Both groups achieved comparable functional improvement but Armeo group had a higher change in scores. Our recent search of ClinTrials.gov (search criteria Spinal Cord Injuries, Upper extremity dysfunctions and electrical stimulation) has however, identified no current or future study which includes people with subacute SCI and randomisation.

There are multiple technologies for people with subacute tSCI, including robotics, functional electrical stimulation, or more recently Brain Computer interface. Then, why do the investigators need yet another rehabilitation technology? There are several features that stand tESCS apart from the other rehabilitation technologies, both when it comes to usability and the mechanism of action. Most notably tSCI facilitates performing functional movements, therefore it can be combined with the existing therapy sessions, rather than requiring extra sessions like e.g. robotic devices or having multiple precisely defined stimulation sites like FES. Setup time is much shorter and the price is lower than robotics. This is of critical importance for the clinical adoption of technology, where lack of time in busy therapists' and patients' schedules is often a major barrier to larger-scale trials that would provide solid scientific evidence.

An obvious advantage of using tESCS in the subacute rather than in the chronic stage is the potential to supplement natural recovery. In addition, unused muscle has inevitably deconditioned in chronic SCI, therefore weeks of training to optimise muscle health is preferred prior to chronic tESCS intervention, which itself necessitates a large number of sessions. In one research study, the investigators identified requirements for (accompanied) transport and travel time to and from the hospital as the main factors impeding recruitment and increasing dropout rates in chronic patients. These are not issues for patients undergoing primary rehabilitation Finally, while months of tESCS training are required to achieve improvement in people with chronic SCI, it is not known whether this time would be substantially shorter in people undergoing primary rehabilitation post SCI and whether these benefits would be long-lasting.

Answering these questions and demonstrating the feasibility of delivering tESCS integrated with standard upper limb therapy would be major steps toward adopting this technology into clinical practice.

The investigators aim to test the feasibility of delivering tESCS to hospitalised (undergoing primary rehabilitation) tetraplegic patients by combining it with standard upper limb therapy. The investigators hypothesise that tESCS will be straightforward to implement and that it will not significantly burden staff or interrupt the existing patient schedule. The investigators also hypothesise that combining tESCS with conventional upper limb therapy will result in larger functional and neurological improvements than therapy alone.

Over 60% of people sustaining spinal cord injury have tetraplegia, resulting in a high level of disability. tESCS has shown very promising results in people with chronic injuries. Based on results from these studies, the investigators believe that tESCS has the potential to result.in substantial improvement in neurological recovery if delivered in parallel with primary rehabilitation.

This study will provide the first high quality evidence of the feasibility of incorporating tESCS into clinical practice in the acute care setting. Physical therapy/activity is an essential co-therapy of tESCS By combining tESCS with standard therapy, the additional burden on therapists will be minimised, increasing the chances of successful clinical translation of the technology.

the investigators hypothesise that the positive effect of tESCS will be greater in the acute/subacute than in the chronic phase and that therefore it would be possible to see significant improvement after only a few weeks of intervention. Improved neurological function should lead to a reduced length of stay and healthcare costs. The results of this study will be the first step towards a larger multicentre trial evaluating the early use of tESCS, a vital step towards wider adoption of tESCS in clinical settings. Such clinical adoption would have the potential to benefit all people with acute tetraplegia.

The efficient delivery of tESCS and the relative affordability of the device (costing under £10K they are much cheaper than robotic devices) greatly enhance the generalisability of the results for any future clinical trial.

Theoretical Framework It is believed that tESCS stimulation activates motor neuronal networks of the spinal cord, including the recruitment of afferent fibres in the posterior root, to elevate spinal network excitability. The underlying hypothesis is that after severe cervical SCI, nonfunctional sensory-motor networks within the cervical spinal cord can be transcutaneously neuromodulated to physiological states that enable and amplify voluntary control of the arm and hand