Fondation Suisse pour les Cyberthèses

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Why this approach ?

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1. A spinal cord lesion does not heal

Lesions of the central nervous system (CNS), cerebral (CVA), or medullary, are particularly dramatic due to the limited healing capacities of the CNS.  Thus, a spinal cord lesion does not heal.

In fact, basic research into the regeneration of the spinal cord has hardly progressed at all in recent years, and on ethical grounds, it would not be honest to give false hope, as this research comes up against the extreme complexity of the central nervous system (CNS). It must therefore be accepted that the tangible results are still uncertain, even in the long term.

A parallel can be drawn with nodal tissues  in the heart, responsible for  autonomous heartbeats, infinitely  less complex than the spinal cord and whose secrets have still not been revealed since the appearance some fifty years ago of the first pacemakers. These certainly still have several years in front of them!

This is why we consider that the most promising current approach is the development of machines to assist in re-education and walking, using the latest neuro technology in conjunction with robotic therapeutic devices.

2. Paraplegia: total and partial

Paraplegic patients can be separated into 2 distinct groups :
  • 20%, with a total and irreversible medullary injury, will remain paralysed;
  • 80%, with a partial medullary injury, show varying degrees of potential for recuperation through substitutive neuroplasticity.
3. Neuroplasticity of the CNS

One possible method of rehabilitation deserves further development: the central nervous system's remarkable ability of substitutive neuroplasticity. Through their reorganisation, the unaffected nerve circuits, still healthy, can substitute themselves for damaged nerve circuits, to carry out a function.

This plasticity can be stimulated by exercises, which must conform to the strict criteria outlined below, with the aim of reprogramming the motor pattern of movements.

4. Active participation  of the paralysed muscles

This rehabilitation requires the repeated execution of precise coordinated functional movements. These movements must not be made in a passive way, imposed by external means, but on the contrary carried out with the active participation of the paralysed muscles, using electrical neuromuscular stimulation.

5. Mimicry of the voluntary activity

The movements induced by neuromuscular electro stimulation must closely «mimic» the deficient natural voluntary activity; walking for example.
This mimicry requires the ability to totally control articular movements in amplitude, speed and force, to guarantee the values corresponding to the same natural voluntary movements.
The respect of these fundamental and inescapable criteria for movement control has demanded the development of an innovative device for electrical neuromuscular stimulation retro controlled in real time (CLEMS: Closed-Loop Electrical Muscle Stimulation). To ensure this closed-loop control of the stimulation, the device uses sensors of articular position and force incorporated in the orthosis.

6. Re-training following a loss of physical condition

Paralysed patients generally show considerable atrophy of the paralysed muscles, frequently accompanied by articular ankylosis, which leads to restriction of mobility in the limbs.  Consequently, their physical condition is usually insufficient, and needs re-training before any specific walk training can be effective.