Neural Stimulation for Hand Grasp
Condition: Quadriplegia
MeSH terms: Quadriplegia
Study type: Interventional

Summary: 
      A selective neural stimulation as the investigators propose allows to stimulate several
      muscles via a single electrode. Neural stimulation requires less energy for muscle
      activation. In our approach, 2 electrodes will be implanted above the elbow on the median and
      radial nerves. This considerably reduces the number of implanted elements and therefore i)
      the risk of infection, ii) the risk of failure, iii) the surgical risk through minimally
      invasive surgery.

      Our main hypothesis is that multipolar neural electrical stimulation of the median nerve
      (flexion) and the radial nerve (extension) allows:

        -  on the one hand, a selective, individualized motor activation (muscle by muscle)

        -  on the other hand, a synergistic motor activation (association of several muscles) for
           the purpose of production of functional movements.
    

Detailed description: 
      Electrical stimulation of the muscles has been used for decades in rehabilitation units
      specializing in the treatment of spinal cord injuries. It has been shown to be effective in
      building muscle and preventing muscle atrophy following spinal cord injury (SCI) or stroke.
      It can also be used to reduce spasticity and above all to promote functionally useful motor
      control. It is then a Functional Electric Stimulation (FES). In the quadriplegic person
      marked by a severe motor deficiency of the upper limbs, FES is today the only technique
      allowing to restore a functional gripping movements in the case where the active muscular
      resources below the elbows are missing or too weak to allow tendon transfer surgery.

      Like "Freehand", all the devices using FES directly stimulate the muscles (surface,
      intramuscular or epimysial electrodes) and therefore require a high number of internal
      components with a theoretical risk of infection and greater rejection. since each muscle must
      be activated via an electrode (up to 12 in the case of "FreeHand"). The investigators propose
      instead selective neural stimulation as it allows stimulating several muscles via a single
      electrode. Neural stimulation requires less energy for muscle activation. In our approach, 2
      electrodes will be implanted above the elbow on the median and radial nerves. This
      considerably reduces the number of implanted elements and therefore i) the risk of infection,
      ii) the risk of failure, iii) the surgical risk thanks to minimally invasive surgery. The
      procedure consisted of placing a multi-contact cuff electrode around the radial or median
      nerves and observing the effects of electrical neural stimulation in terms of muscle
      selectivity, force produced and movement induced. In a previous study, the investigators
      already proved through acute intra operative testing (under Ethics Committee approval,
      #NCT03721861) that:

        -  No failure of the electrodes or of the stimulator was noted.

        -  For all of the 8 subjects, it was possible to selectively stimulate muscle groups to
           obtain the opening of the thumb and fingers, or the flexion of the thumb, fingers and
           obtaining possibly functional grip like the forceps with opposition of the thumb or
           palmar grip.

      A second feasibility study (Ethics committee registration #2016-A00711-50) with 17
      quadriplegic patients assessed the subject's ability to use voluntary contractions of sus
      lesional muscles (EMG recordings in 8 subjects) or voluntary movements of shoulders (inertial
      recordings in 9 subjects) to control the movements of a robotic hand or the triggering of an
      electrical surface stimulation of the muscles of the forearm. All of the patients managed to
      master the proposed interface after a short familiarization period.

      On the basis of the results of these two studies, the investigator wish to take an additional
      step in the development of a gripping assistance device for patients with spinal cord injury:

      - by proposing the implantation of two cuff electrodes with percutaneous connection on the
      arm of quadriplegic people. The electrodes will be kept in place for a period of 1 month
      before being definitively explanted. An implanted cable will connect the electrodes to an
      external connector.
    

Intervention name(s): Neurostimulation
Intervention type(s): Device
Intervention description(s): Implantation of 2 multicontact cuff electrodes in the upper limb of patients with tetraplegia and control of the stimulation by contralateral shoulder movements
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Percutaneous Electrical Nerve Stimulation