1. 2020;23;E369-E37610 kHz High-Frequency Spinal Cord Stimulation for Chronic Thoracic Pain: A Multicenter Case Series and a Guide for Optimal Anatomic Lead Placement
   Retrospective Study
   Ali Nairizi, MD, Shawn Sills, MD, Jeffrey Foster, DO, Dawood Sayed, MD, and Andrew Miller, BS.

BACKGROUND: Surgical options for thoracic pain are limited and carry significant risk and morbidity. Spinal cord stimulation has the potential to be used for treatment of thoracic pain, as it has been useful for treating multiple types of chronic pain. Conventional tonic stimulation is limited in the treatment of thoracic pain, as it can produce paresthesia that is difficult to localize. Conversely, high-frequency spinal cord stimulation (HF-SCS) does not activate dorsal column A Beta fibers and does not produce paresthesia, and thus may be more beneficial in treating thoracic back pain not manageable with tonic stimulation.

OBJECTIVES: To evaluate (1) the efficacy of 10 kHz HF-SCS for patients with chronic thoracic pain; and (2) appropriate paresthesia-free lead placement and programming targets for 10 kHz HF-SCS for patients with chronic thoracic pain.

STUDY DESIGN: Retrospective case series.

SETTING: Multisite academic medical center or pain clinic.

METHODS: A retrospective chart review was performed on 19 patients with thoracic back pain who underwent HF-SCS implantation. These patients had lead placement and stimulation between the T1-T6 vertebral levels. Outcome measures collected include location of device implant, stimulation settings, and pain scores at baseline, end of trial, and 1, 6, and 12 months postimplant. Follow-up phone calls collected information on if the patient reported functional improvement, improved sleep, or decreased pain medication usage. A Wilcoxon signed-rank test compared differences in mean pain scores across time points.

RESULTS: Significantly decreased Visual Analog Scale scores were observed with 17/19 (89.5%) patients demonstrating response to therapy (> 50% reduction in pain scores). These results were sustained relative to baseline at 1, 6, and 12 months postimplant, depending on length of follow-up. Many patients also reported functional improvement (17/19), improved sleep (14/19), and reduction in use of pain medications after implantation (9/19). A total of 15/19 patients reported best relief when contacts over T1 or T2 vertebrae were used for stimulation.

LIMITATIONS: This study is limited by its retrospective design. Additionally, including documentation from multiple sites may be prone to selection and abstraction bias. Data were also not available for all patients at all time points.

CONCLUSIONS: HF-SCS may be a viable option for significant, long-lasting pain relief for thoracic back pain. There may also be evidence for anatomically based lead placement and programming for thoracic back pain. Randomized, controlled trials with extended follow-up are needed to further evaluate this therapy.

KEY WORDS: Thoracic pain, back pain, spinal cord stimulation, high frequency, 10 kHz