Selectivity of transcutaneous stimulation of lumbar posterior roots at different spinal levels in humans

Abstract

Posterior root-muscle (PRM) reflexes can be elic- ited by epidural as well as recently also transcutaneous elec- trical stimulation of the lumbar spinal cord. We tested the se- lectivity of transcutaneous spinal cord stimulation by eliciting PRM reflexes and recording the compound muscle action po- tentials of the thigh and shank. The stimulation set-up con- sisted of an electrode array with 7 levels centered at the spinal level of T12. With the variation of the stimulation level a defi- nite 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.