Selectivity of transcutaneous stimulation of lumbar posterior roots at different spinal levels in humans.
Krenn M, Toth A, Danner SM, Hofstoetter US, Minassian K, Mayr W.
Posterior root-muscle (PRM) reflexes can be elicited by epidural as well as recently also transcutaneous electrical stimulation of the lumbar spinal cord. We tested the selectivity of transcutaneous spinal cord stimulation by eliciting PRM reflexes and recording the compound muscle action potentials of the thigh and shank. The stimulation set-up consisted of an electrode array with 7 levels centered at the spinal level of T12. With the variation of the stimulation level a definite change in the recruitment of PRM reflexes was observed. Even though the distribution of the generated electrical field with transcutaneous electrodes is unfocused in relation to the target structures, a selective stimulation is possible.