title: Clinical Outcomes of 1 kHz Subperception Spinal Cord Stimulation in Implanted Patients With Failed Paresthesia-Based Stimulation: Results of a Prospective Randomized Controlled Trial.
abstract: BACKGROUND
  Pain relief via spinal cord stimulation (SCS) has historically revolved around producing paresthesia to replace pain, with success measured by the extent of paresthesia-pain overlap. In a recent murine study, by Shechter et al., showed the superior efficacy of high frequency SCS (1 kHz and 10 kHz) at inhibiting the effects of mechanical hypersensitivity compared to sham or 50 Hz stimulation. In the same study, authors report there were no differences in efficacy between 1 kHz and 10 kHz delivered at subperception stimulation strength (80% of motor threshold). Therefore, we designed a randomized, 2 × 2 crossover study of low frequency supra-perception SCS vs. subperception SCS at 1 kHz frequency in order to test whether subperception stimulation at 1 kHz was sufficient to provide effective pain relief in human subjects.
  
  
  METHODS
  Twenty-two subjects with SCS, and inadequate pain relief based on numeric pain rating scale (NPRS) scores (>5) were enrolled, and observed for total of seven weeks (three weeks of treatment, one week wash off, and another three weeks of treatment). Subjects were asked to rate their pain on NPRS as a primary efficacy variable, and complete the Oswestry Disability Index (ODI) and Patient's Global Impression of Change (PGIC) as secondary outcome measures.
  
  
  RESULTS
  Out of 22 subjects that completed the study, 21 subjects (95%) reported improvements in average, best, and worst pain NPRS scores. All NPRS scores were significantly lower with subperception stimulation compared to paresthesia-based stimulation (p < 0.01, p < 0.05, and p < 0.05, respectively). As with NPRS scores, the treatment effect of subperception stimulation was significantly greater than that of paresthesia based stimulation on ODI scores (p = 3.9737 × 10-5) and PGIC scores (p = 3.0396 × 10-5).
authors.affiliation: The Center for Clinical Research, Carolinas Pain Institute, Winston-Salem, NC, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: North
authors.affiliation: The Center for Clinical Research, Carolinas Pain Institute, Winston-Salem, NC, USA. jhong@ccrpain.com.
authors.forename: Kyung-Soo Jason
authors.initials: KJ
authors.lastname: Hong
authors.affiliation: Mathematical Sciences, United States Air Force Academy, Colorado Springs, CO, USA.
authors.forename: Philip Young
authors.initials: PY
authors.lastname: Cho
mesh_terms: D000293:Adolescent; D000368:Aged; D055592:Biophysical Phenomena; D059350:Chronic Pain / Q000209:etiology / Q000628:therapy*; D018592:Cross-Over Studies; D055111:Failed Back Surgery Syndrome / Q000150:complications / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010292:Paresthesia / Q000150:complications; D011446:Prospective Studies; D062187:Spinal Cord Stimulation / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
keywords: Axial pain; Oswestry disability index; chronic pain; high frequency spinal cord stimulation; numeric pain rating scale; paresthesia; patient global impression of change; spinal cord stimulation; subperception stimulation