New trends in neuromodulation for the management of neuropathic pain.

Since its first application in 1967, the methodology and technology of spinal cord stimulation for the management of chronic, intractable pain have evolved continuously. Despite these developments and improved knowledge of the effects of spinal anatomy and epidural contact configuration on paresthesia coverage, the clinical results of spinal cord stimulation-particularly the long-term effects-are still unsatisfactory in many patients. This dissatisfaction has come primarily from the failure of single-electrode configurations to provide consistent paresthesia coverage of the entire painful area. Therefore, new approaches were developed during the late 1990s that attempted to selectively cover one or more dermatomes with paresthesia as well as to provide sequential stimulation of different anatomic sites. These approaches have been applied both intraspinally and extraspinally by stimulating either the spinal nerves or the dorsal columns. To target parts of the latter, different methods have been developed and tested using either two-dimensional contact configurations or electronic field steering. These developments hold promise for improving long-term outcomes as well as increasing the number of pain conditions that can be treated with neuromodulation therapy. In this review, the history, theoretical basis, and evolution of these methodologies, as well as the ways in which they represent new trends in neuromodulation, are discussed.