PNS Motor Stimulation Study

Paralysis is one of the most disabling features of Spinal cord injury and stroke. In select cases, where the nerve is intact, stimulation can achieve meaningful muscle contraction e.g. to restore grip and release function. Previously, products to serve this purpose had been developed and successfully implanted (Freehand device). However, they had technical and cost limitations and have gone out of production. The investigators aim to investigate if a simple implantable and commercially available system could replicate the same function. Patients implanted with a wireless peripheral nerve stimulation (PNS) system for chronic pain in the upper limb shall be identified and approached for consent. Surface electromyography (EMG, baseline and with active contraction) shall be performed to confirm intact motor nerves. Baseline MRC (Medical Research Council Scale for Muscle Strength) grade shall be assessed. PNS shall be programmed to produce muscle contraction (within FDA approved safe limits for the device) with the EMG monitoring. The muscle contraction shall be recorded on video for further evaluation. Strength of contraction shall be assessed on the MRC scale. Stimulation parameters shall be then re-adjusted to pain-relief setting. Neurological examination shall be performed and return to baseline EMG ascertained. Data shall be analysed and the Study shall end when the data for the last participant is gathered.

Inclusion Criteria: * Male or Female, aged 18 years or above with implanted Curonix (formerly: Stimwave) PNS for radial, ulnar or median nerve; * Functioning lower motor neuron (LMN) pathway determined by baseline EMG. Exclusion Criteria: * Age \