Deep brain stimulation for chronic pain: Results of two multicenter trials and a structured review

Objectives. A U.S. Food and Drug Administration ruling required clinical trials to evaluate the safety and efficacy of deep brain stimulation devices, thereby limiting treatment to the investigational setting. Introduction. As an investigator in two clinical trials of deep brain stimulation, I sought to determine why pain remained an unapproved indication despite regulatory approval of the same device for tremor. Methods. The results of two multicenter trials of deep brain stimulation for pain were analyzed, and the pertinent literature was reviewed using published guidelines for the evaluation of clinical trial reports. Results. The first-generation Model 3380 lead trial enrolled 196 patients; the current Model 3387 trial enrolled 50 patients. Prospectively defined criteria for success included at least half of patients reporting greater than or equal to 50% pain relief at I year. Manufacture of the Model 3380 lead was discontinued, and the 3387 trial closed early because of slow enrollment, high attrition, and low efficacy. When results were analyzed according to the study plan, neither trial was successful. Consequently, deep brain stimulation has not been approved for pain control by the U.S. Food and Drug Administration. Conclusions. Deep brain stimulation has not been shown to produce effective long-term pain relief. Future studies of motor cortex stimulation and similar therapies will require appropriate control groups and accepted methods of data collection and analysis to support claims that predictable and reliable analgesic effects are produced in humans.