Al-Kaisy A, et al. - In view of the increasing use of high frequency paresthesia-free spinal cord stimulation related to improved outcomes in the therapy of neuropathic pain, authors sought to assess the effect of varying frequency on pain relief and the placebo effect. Significant pain relief for axial low back pain could be provided with 5,882 Hz stimulation vs lower frequencies and sham stimulation. Similar analgesic effects to 1,200 Hz and 3,030 Hz were produced with sham stimulation, and this effect could influence future neuromodulation clinical trial designs.