Title: A Sensory Training System (STS) for use at home by people with persistent limb pain
Funder: Versus Arthritis

Abstract: Chronic pain affects around half of the UK population. Of these, 5.5 million people experience neuropathic pain such as Complex Regional Pain Syndrome (CRPS), a chronic pain condition of the limbs that is commonly triggered by trauma. These populations experience poor response to current treatments, are very disabled, and their care is primarily focused on self-management of persistent pain. Our ultimate goal is to develop a commercially available Sensory Training System (STS) for independent home use by people who have persistent limb pain, so they can re-gain normal limb sensation. This proposal describes device modifications and clinical testing of our current STS to help work towards this goal. When a person with chronic neuropathic pain receives contact to their painful body part, their ability to determine the nature and location of that stimulus on their painful skin is commonly lost. Furthermore, non-painful stimuli, such as light touch, are perceived as painful. The negative impacts of these altered perceptions can be highly disabling. Clinically, the ability to discriminate sensations is assessed via two-point discrimination tests. Two probes are simultaneously applied to the person’s skin and they have to try to distinguish one or two contact points. The shorter the recorded two-probe distance, the better the sensory discrimination performance. Poor two-point discrimination is associated with higher pain intensity and altered brain representation of the affected body part. Published studies describe interventions that improve two-point discrimination ability, reduce pain, and normalise the brain’s representation of the painful area. However, no commercially available device, or one in development, enables independent sensory discrimination training by patients at home or in a hospital environment. Current sensory discrimination training in clinical practice is labour intensive with poor adherence. Working with people with CRPS, we have co-designed a home-use STS which improves two-point discrimination. Our STS comprises a pattern of electrodes (an array), held in place close to the painful area on the patient’s limb. Individual electrodes deliver a pleasant sensation in a random order. The patient decides which electrode(s) was stimulated and records this electronically. Software progressively increases the task difficulty. However, in our recent home-study, no patient used the device for 30 minutes/day for 30 days, which published literature indicates is the ‘therapeutic dose’ likely to change pain. Patients tells us the application and removal of the electrode array needs to be substantially improved, and the task made more challenging and engaging. Working with patients and public, and carefully selected collaborators, we will conduct laboratory and clinical investigations, across four interlinked work packages (WPs) to: Co-design a customised wearable electrode array and game-based training environment, that provides an easy to use and engaging electrical STS (WPs 1 and 2). Collect pilot clinical data on a sample of CRPS patients to determine STS use, and its relationship with two-point discrimination and pain intensity (WP3). Use our findings to establish the specification for a commercial device that will meet regulatory requirements and is suitable for future development and testing (WP4).


Research activity codes: 6.3 MEDICAL DEVICES
Health categories: MUSCULOSKELETAL;NEUROLOGICAL