Assessment of the electric field induced in the human tissue during magnetic stimulation of the spinal cord

The purpose of this paper is to estimate the electrical field induced in the spinal cord and nearby area during lumbar magnetic stimulation.

The spinal cord is modelled as a continuous cylinder, while the vertebral column is also represented by a concentric interrupted cylinder. The coil used for magnetic stimulation is a figure of eight, whose centre is placed above T12‐L1 vertebras. The electrical field is induced and its derivative is computed using the finite difference method.

Preliminary results suggest that magnetic stimulation may be able to induce a sufficiently intense electric field inside the spinal cord, leading to the direct activation of spinal nerve roots.

If the spinal cord can be stimulated directly by magnetic stimulation, this technique can facilitate functional motor activities, including standing and stepping in paralyzed people, in a non‐invasive way.

The authors revealed the fact that functional magnetic stimulation can be applied to the spinal cord, and should be further investigated as an alternative to invasive techniques such as electrical stimulation.