PNS Motor stim study
Research type
Research Study
Full title
Determination of efficacy of sustained motor contraction generated using StimWave Peripheral nerve stimulator
IRAS ID
310915
Contact name
Deepti Bhargava
Contact email
Sponsor organisation
Walton Centre NHS Foundation Trust
Duration of Study in the UK
0 years, 3 months, 18 days
Research summary
Paralysis is one of the most disabling features of Spinal cord injury and stroke. In select cases, where the lower motor neuron is intact, stimulation of the distal neuromuscular unit can achieve meaningful muscle contraction eg. to restore grip and release function in patients with quadriplegia, which can significantly impact upon independence and care needs. 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. This concept of functional electrical stimulation has also been utilised with external orthoses, however the applicability has been limited both due to the precision required in applying the external device each time and the need of someone else to put this on, defeating the purpose.
If a minimally invasive simple system could replicate the same function, it would be useful. StimWave PNS is one such system that is already CE marked and FDA approved for stimulation of peripheral nerves. It is currently used for stimulation of peripheral nerves for pain relief.
During programming for the same, to check for adequate placement, motor stimulation is routinely performed which elicits corresponding muscle twitch. Even though the parameters are approved for safety, it has not been used to generate a clinically meaningful sustained muscle contraction.
We hypothesise that such use is possible and this work aims to gather proof of concept for the same. For this purpose, after appropriate consent, patients who have PNS StimWave device already implanted for pain relief will be assessed. During routine programming session, their surface EMG’s (non invasive) shall be obtained to attain baseline information and check intact neuromuscular unit. They will then be asked to move the muscle to obtain EMG parameters for active contraction. Once EMG returns to baseline, stimulation parameters on the device shall be changed to trigger motor stimulation. These will be adjusted to achieve MRC grade 3 or above strength of contraction. EMG shall be recorded continuously, MRC strength will be checked and video recording (ensuring patient confidentiality) shall be done. The EMG data for triggered stimulation will be compared to active stimulation parameters. This will be end of study. The stimulation settings shall then be reverted to their original settings- the whole process being non- invasive.
As a preliminary test for how a coordinated grip can be activated, if a sustained muscle contraction can be achieved using StimWave, the principal investigator had external EMG electrodes placed on herself at the points where electrodes are usually implanted in these patients and coordinated stimulation at previously established parameters achieved required results. The video of this is attached in the addendum.
If proven to be successful, the StimWave system has the potential capability for generating voice controlled coordinated contraction of 2-3 electrodes, all of which can be placed under local anaesthetic as day case. A system has also been developed in parallel to provide sensory feedback which will automatically adjust the strength of contraction so that the grip is adequate.
Final goal therefore will be development of a product such that when a patient with residual shoulder function (C5-6 or C6-7 quadriplegic- 2 most common levels of injury), takes their hand next to a cup, and says “hold” the system will activate to obtain adequate grip, enough so they can feed themselves and when they say “release” the hand will relax.REC name
North West - Haydock Research Ethics Committee
REC reference
22/NW/0039
Date of REC Opinion
16 Feb 2022
REC opinion
Favourable Opinion