Evaluating reticulospinal plasticity in neural circuits from a novel wearable treatment (‘PowerBead’) as a potential method for regaining finger extension post-stroke.

Background Improving upper limb(UL) recovery post-stroke represents a major clinical goal. Over 80% of stroke survivors fail to regain full UL function[1;2;3]and ~50% of survivors experience moderate to severe impairment[4]. ~32,000 survivors each year have little/no finger extension. Finger extension is a key factor determining the potential for recovery via the corticospinal tract(CST) and onward referral to clinics for physiotherapy. Without finger extension, patients are deemed unsuitable for support. Regaining even a flicker of finger extension could be life-changing for these individuals. Intervention Muscle spindle afferents(MSA) are a major sensory input to the motor system that can be artificially activated with a sharp mechanical 'tap'. MSA activation creates a powerful signal into the brain/spinal cord; stimulating a weak muscle or suppressing an overactive muscle. Pairing MSA activation with timed sound signals has been shown to induce long-term neuroplastic changes, improving muscle activation and function[5]. This may provide a passive method for regaining finger function, when targeting the extensor digitorum. To do so, individuals need to access treatment for a minimum of 6 hours per day for many months. Such stimuli have been successfully integrated into our patented wearable technology, TRL6(Fig.1) which comprises: 1) A "PowerBead" delivering a 'tap' in a wrist band. 2) An earpiece delivering a click . Prototypes were co-designed with stroke survivors, NHS physiotherapists and occupational therapists(OTs). Figure 1 Our device is thought to stimulate recruitment of the reticulospinal tract(RST) for stroke survivors whose CST is severely damaged. Our key innovation is the ability to meet the muscle tap force and timing to elicit a muscle response within a wearable form. This approach could provide the opportunity to regain 30-50% UL function[5]. We have data from: Study(n=16) showing PowerBead mechanical stimulation produces a stretch reflex. This indicates that it generates a MSA volley(Fig2.[a-c]). Study (Baker and team) demonstrates the significance in pairing MSA activation with an acoustic cue for improving ARAT scores and functional recovery[3] (Fig.2[d]). Study(n=3) showing PowerBead mechanical stimulation paired with click from headphones elicits RST plasticity after 5 hours of wearing the device(Fig.3). Study(UCLan physiotherapy department) 8 healthy participants tolerance of wearing the Powerbead(TRL4); participants were comfortable wearing the early prototype for 4 hours. Study(Southampton physiotherapy department) demonstrating the PowerBead(TRL4) to groups of NHS physiotherapists/ OTs, early feedback on the potential of the technology. Focus group demonstrating PowerBead(TRL4) at West Middlesex University Hospital to NHS stroke rehabilitation staff, further feedback regarding potential for adoption by the NHS. Figure 2 Figure 3 PPI We have a PPI group comprising stroke survivors, support workers and volunteers led by Dr Stockley to provide us with feedback on every aspect of the development. Dissemination We will develop an evidence generation plan for our study and publish the results. We will appoint stroke ambassadors to deliver technology demonstrations, setting up events with patient groups and therapists so they can try out the technology. We will work with the Queen Square Upper Limb Rehabilitation Clinic (Professor Ward) and our PPI group to ensure content is suitable for wider audiences.