Clinical study to estimate the optimal frequency for stimulation of the spinal cord to achieve relief from back pain.

This is a feasibility study to identify the optimal frequency for stimulation of the spinal cord to achieve maximum reduction in neuropathic back pain as measured by average Numerical rating Scale.

Twenty patients who suffer from back more than leg pain will be recruited into the study once they have satisfactory pain relief from both low and high frequency stimulations. Each patient will then receive stimulation at four different frequencies for 2-3 weeks in a random and blinded order. Their pain scores and function will be assessed using a variety of different tools. The data will then be used to estimate the optimal frequency.

Inclusion Criteria:

1. Complaint of persistent or recurrent low back pain, with or without equal or lesser leg pain, for at least 90 days prior to Screen.
2. Received at least 90 days of documented pain management care to address the primary pain complaint, prior to Screening (e.g. medication, physical therapy.)
3. No back surgery within 6 months prior to Screening.
4. Average low back pain intensity, during the position/activity, which routinely causes worst pain, of 5 or greater on a 0-10 numerical rating scale during Baseline period based on eDiary.
5. If taking prescription opioids for primary chronic pain complaint (low back and/or leg pain), must have been on a stable prescription (same drug(s) and dose(s)) 30 days prior to Screening to a total of less than 180 mg Oral Morphine equivalent
6. Willing and able to comply with all protocol-required procedures and assessments/evaluations (e.g. willing to comply with opioid prescription lock from the Baseline visit through End of Rate Randomization and protocol required stimulation parameter locks, complete daily eDiary).
7. 18 years of age or older when written informed consent is obtained.
8. If female of childbearing potential: not pregnant, as evidenced by a negative pregnancy test at Screening.
9. Subject signed a valid, IRB-approved informed consent form (ICF) provided in English.
10. Baseline Oswestry Disability Index score ≥ 20 and ≤ 80.
11. Received at least 30 per cent reduction in NRS of average low back pain intensity from Baseline during the end of Post Implant HF10 Sweet-Spot Search as recorded in the eDiary.

Exclusion Criteria:

1. Average worst leg pain intensity is greater than average worst low back pain intensity as reported during Baseline period based on eDiary.
2. Radiographic evidence of spinal instability requiring fusion.
3. Primary pain complaint of vascular origin (e.g. peripheral vascular disease).
4. Spinal pain secondary to neoplasm, infection, autoimmune disorder with spinal involvement, or a spinal metabolic disorder.
5. Any pain-related diagnosis or medical/psychological condition that, in the clinician's best judgment might confound reporting of study outcomes (e.g. pelvic pain, angina pain, chronic migraine.
6. Participating (or intends to participate) in another clinical study.
7. Terminal illness with anticipated survival 1 year.
8. Current condition associated with risk of immunocompromised that might increase risk of infection during study duration.
9. Currently on any anticoagulant medications that cannot be discontinued during perioperative period.
10. Are pregnant/lactating or not using adequate birth control.
11. Have untreated major psychiatric comorbidity, serious drug related behaviour issues.