Application: pedicular screw placement during lumbar arthrodesis. Lumbar arthrodesis allows for the fixation of vertebras through a pedicular screw. There is an important risk involved with breaching the vertebral wall following the contact between the screw and the adjacent nerve root. This is responsible for irritations, pain and permanent injuries. Monopolar electrical stimulation during pedicular screw placement surgery allows one to breach the vertebral wall. Contact between a screw and a nerve root will generate a muscular response from the respective muscle.