Following Spinal Cord Injury (SCI), 53% of people develop neuropathic pain (NP) rated as severe [Burke et al 2017, Finnerup 2014]. National SCI data identifies high pain intensity and pain interference levels with NP and significantly poorer quality of life (QoL) than other pain phenotypes [Burke et al 2018; 2019]. Individuals describe NP as more debilitating than the SCI itself [Hearne 2015], as their most persistent health issue and adequate pain relief as an unmet need [Kennedy et al 2006].
Neuronal hyperexcitability and maladaptive neuroplasticity in the corticothalamic loop are mechanisms proposed for NP after SCI [Finnerup et al 2009]. Pharmacotherapy (pregablin/gabapentin, amitriptyline and/or opioids) are the first and second line treatments recommended for NP management in SCI, although severe pain remains refractory to these treatments in 2/3 sufferers [Guy et al 2016]. Survey data report high use of non-steroidal anti-inflammatories and paracetamol [Burke et al 2019, Jensen 2005, Cardenas 2006]. Poor medication adherence exists, stemming from unacceptable side-effects and/or fear of medication dependency [Widerstrom-Noga 2020; Lofgren et al 2012], thus non-pharmacological treatment options are requested (Buscemi et al 2018; Lofgren et al 2012]
Virtual reality (immersive virtual walking, virtual illusion/imagined walking) shows promise by systematic review for reducing neuropathic pain intensity after spinal injury [Chi et al 2019]. Despite multiple studies examining virtual stimulation, sensorimotor stimulation using active walking (with robotic assistance) has not been well studied in NP after SCI despite convincing locomotor-based pre-clinical studies identifying both prevention and reversal of neuropathic pain [Duggan et al 2015 &2021, Hutchinson et al 2004].
A registered systematic review current to March 2022, identifies 1 case-series and 1 cohort study [Kressler 2014; Sawada 2021] reporting NP outcomes following robotic gait training in SCI. Issues with correctly labelling pain phenotype on study entry, other methodological concerns and inconclusive findings were highlighted. This feasibility study tests exoskeleton-based walking 3 times per week, as a mechanistic-based intervention for NP after SCI. It asks: Is it practicable and cost efficient to deliver? Does it show positive signals in reduction of pain intensity and interference levels and will scaling up to a definitive trial be warranted?
