This is a prospective, randomized, double-blind study of different stimulation patterns in patients undergoing implantation of neurostimulator systems for chronic medically intractable neuropathic pain. Research participants will be individuals who have undergone implantation of neurostimulator electrodes into the spinal column or peripheral nervous system for clinical treatment of neuropathic pain. All patients will already have undergone empiric programming of the stimulator using conventional settings (typically 40-60 Hz, 350-450 usec pulse width). However, other stimulation parameters, including high-frequency stimulation, are also feasible and FDA-approved using the implanted device, and it is possible to do this without producing a sensory percept, which makes it possible to test efficacy in a double blind manner. For this study, two different stimulation parameters will be tested during four two-week periods: 1000 Hz and placebo. Clinical response and side effect profile for each setting will be measured.