Brain Stimulation for Pain Control

Three areas of the brain have been used for stimulation to control chronic pain. Stimulation of the primary sensory relay nuclei of the thalamus (VPM, VPL) and internal capsule reduce pain by activating large nonpain sensory neurons which produce sensory paresthesias and inhibition of small pain fibers. The third area is the paraventricular gray matter-an area that apparently modulates pain input. Stimulation of this area reduces pain for hours with short periods of stimulation with little or no side effects. Chronic stimulation intermittently over a period of up to three years shows no tendency to tolerance, habitutation, electrode isolation, loss of effectiveness, or tissue destruction.