[Epidural spinal cord stimulation: its efficacy and mechanisms].

Pain-alleviating effects of epidural spinal cord stimulation (ESCS) were assessed in patients with chronic intractable pain including cancer pain, and some aspects concerning its mechanisms were discussed. The temporary ESCS with percutaneously inserted electrodes was employed in 105 patients, and the implantable systems for long-term use in 19 patients. The ESCS had satisfactory effects especially in patients suffering from cancer pain, causalgia, facial and nape pain. The conditioning stimuli applied to the cervical dorsal cord exhibited interactions with the segmentally evoked spinal cord potential (SCP). The N1 wave of the SCP was inhibited up to 120 ms, while the P2 wave was facilitated for more than 100 ms, suggesting that the presynaptic inhibitory action at the dorsal horn is responsible for mechanism of the ESCS. CSF concentration of norepinephrine was significantly decreased by the ESCS therapy, indicating the existence of the relationship between norepinephrinergic descending inhibitory system and the ESCS in pain-alleviating mechanism.