1. 2016;19;267-280High Frequency Spinal Cord Stimulation at 10 kHz for the Treatment of Chronic Pain: 6-Month Australian Clinical Experience
   Retrospective Review
   Marc Russo, MBBS, Paul Verrills, MBBS, Bruce Mitchell, MBBS, John Salmon, MBBS, Adele Barnard, PhD, and Danielle Santarelli, PhD.

BACKGROUND: High frequency spinal cord stimulation at 10 kHz (HF10 therapy) represents a prominent advance in spinal cord stimulation (SCS) therapy, having demonstrated enhanced efficacy in patients with back and leg pain and pain relief without paresthesia that is sustained at 24 months post implant.

OBJECTIVE: To report on the effectiveness HF10 SCS therapy for a wide range of intractable pain conditions in clinical practice.

STUDY DESIGN: Retrospective investigation of 256 patients who trialed HF10 SCS for chronic intractable pain of various etiologies.

SETTING: Three Australian pain clinics.

METHODS: Two hundred fifty-six patients trialed HF10 SCS with view of a permanent implant if successful. Pain distributions included back + leg, back only, head ± neck, and neck ± arm/shoulder. About 30% of patients had previously failed traditional low-frequency paresthesia-based stimulation, while the remaining cohort were either highly refractory to treatment or not recommended by the pain physician for traditional SCS. Pain scores (numerical pain rating scale – NPRS) and functional outcome measures (Oswestry Disability Index – ODI; and activity tolerance times) were assessed at baseline, post-trial, and at 3 and 6 months post-implant as available in the medical records.

RESULTS: Of the 256 patients, 189 (73%) reported a positive trial and were implanted. Patients with back + leg pain demonstrated the highest trial success rate (81%). A mean reduction in pain, among those for whom data were available, of 50% was sustained up to 6 months post-implant across the entire patient population. Sixty-eight percent of patients who failed traditional SCS reported a positive trial and mean pain relief at 6 months was 49% (P < 0.001). An 8.6 point reduction in ODI (21%) at 6 months and improved sitting, standing, and walking tolerances were also reported.

LIMITATIONS: As data was collected retrospectively, missing data points were unavoidable; this was primarily due to inconsistent data collection and patients being lost to follow-up. Patient populations were diverse and a control group was not appropriate in this setting.

CONCLUSIONS: These retrospective results demonstrate a significant advancement for patients suffering with chronic intractable pain and are consistent with recently published clinical results for HF10 SCS. HF10 SCS appears to be a viable, paresthesia-free alternative to traditional SCS, with high trial success rates, demonstrated effectiveness in a range of pain distributions including those typically difficult to treat with traditional SCS, and the possibility to restore pain control in patients who have previously failed traditional SCS.

Key words: Spinal cord stimulation, high frequency stimulation, HF10, paresthesia-free stimulation, back pain, leg pain, cervical pain, neuromodulation