RT Journal Article SR Electronic T1 Long-term efficacy of 1–1.2 kHz subthreshold spinal cord stimulation following failed traditional spinal cord stimulation: a retrospective case series JF Regional Anesthesia & Pain Medicine JO Reg Anesth Pain Med FD BMJ Publishing Group Ltd SP 903 OP 903 DO 10.1136/rapm-2019-100473 VO 44 IS 9 A1 Simon Thomson YR 2019 UL http://rapm.bmj.com/content/44/9/903.1.abstract AB