Deep brain stimulation for control of intractable pain in humans, present and future: a ten-year follow-up.

Deep brain stimulation with chronically implanted electrodes has provided satisfactory control of pain in patients with intractable chronic pain syndromes, which have been refractory to medication and other conventional modalities of management. In this series the authors present their experience with 48 patients who have been followed for periods ranging from 6 months to 10 years. Long-term pain control was achieved in 30 patients (63%). Both the periventricular gray and specific sensory thalamic nuclei have been used as targets. Our results indicate that there is an initial 2-year fall-off of pain control caused by idiopathic tolerance, with stable results thereafter, regardless of site of the implant. This is suggestive of some biochemical modification of tissues around the electrode. Patients with failed-back syndrome secondary to multiple disc operations fared well; those with pain secondary to progressive neurological disorders or cancer had only short-term pain relief, and those with thalamic pain, cauda equina injury, or phantom limb pain usually had a poor result. Deep brain stimulation, in selected patients, appears to provide long-term pain control safely with few side effects or complications.