Electrical stimulation of the nervous system.

Twenty-seven patients with chronic pain had dorsal column stimulators implanted for pain control over a period of three years. Technical factors of electrode placement and type of unit were not found to correlate with the degree of pain relief. The preoperative psychological attitude of the patient correlated highly with the degree of pain relief and was the single most important factor in patient selection and evaluation. Theoretical concepts of pain psychophysiology in relation to the gate theory and areas for more extensive investigation of pain are discussed.