Stimulation of the spinal neuraxis by biocompatible electrical current in the human.

A 5-year retrospective study shows that stimulation of the neuraxis by biocompatible on-demand electrical energy systems is an effective alternative in the management of chronic organic regional pain syndromes. The clinical criteria of improved sense of well-being - reduction of drug intake and increase in activities of daily living - were employed to show that 50% of selected patients reported improvement in 60% of the cases in which stimulation-induced hypalgesia (SIH) was present. There is no apparent significant difference between mono- and bipolar electrical systems. There was no surgical mortality in the series. Complications of electrode migration (6%), rejection syndrome (14%), infection (6%) and unknown causes (8%) did present technical problems that are being resolved. Granulation tissue, apparently stimulated by electrical energy, suggests application in the healing processes. The existence of a variable response neuronal adaptation system is suggested in some patients by the drop in stimulation efficacy after long-term stimulation of fully implanted systems. Challenge of SIH by antagonist naloxone produced variable responses in cooperative patients. The soporific effect seen with transcutaneous electrical nerve stimulation reported in 40% of cases is not seen with the fully implanted epidural systems, despite the use of similar on-demand pulse generators. Biocompatible electrical stimulation of the spinal neuroaxis holds promise as a management modality for highly selected human patients with chronic pain syndromes.