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 e100473 DO 10.1136/rapm-2019-100473 A1 Thomson, Simon YR 2019 UL http://rapm.bmj.com/content/early/2019/05/21/rapm-2019-100473.abstract AB