This study is a prospective, single-arm, open label, single center to confirm the effectiveness and safety of an ultra-high frequency (500 KHz) spinal cord stimulation in patients with chronic back pain or lower limb pain.

This study is a prospective, single-arm, open label, single center to confirm the effectiveness and safety of an ultra-high frequency (500 KHz) spinal cord stimulation in patients with chronic back pain or lower limb pain. The trial length is 14 days. Patients will be given ultrahigh frequency pulse stimulation, up to 3 times in every 24 hours, and VAS will be obtained at least once a day. Compared to previous study conducted last year, patient can now have two lead implant sites for different pain locations. The electrode implantation site will be epidural space instead of Dorsal Root Ganglion (DRG).

Inclusion Criteria:

1. Age ≧20 and ≦75
2. Have a symptom of back or lower limb pain with a diagnosis related to spinal lesion, herniated disc, nerve injury, stenosis, failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS) or ischemic lower limb pain and have pain history of >6 months.
3. Have an average pain score >5 by Visual Analogue Scale (VAS) on inclusion.
4. Has failed to achieve adequate pain relief from prior pharmacologic treatments.
5. In the judgement of the investigator, the subject is an appropriate candidate for the trial procedure.
6. The subject is willing and able to comply with the procedure and requirements of this trial.
7. The participant is able to understand and provide informed consent, and has signed their written informed consent in accordance with Institutional Review Board (IRB) requirements.

Exclusion Criteria:

1. Have evidence of a mental or psychological condition that affects pain perception and has difficulty/disability performing objective pain assessment, or have previously failed mental or psychological assessments administered by a psychiatrist that may be deemed to indicate the subject's lack of suitability for participation in this study.
2. Subject has exhibited unstable pain condition within the past 30 days as interviewed by Investigator.
3. Be on anticoagulant medication with International Normalized Ratio (INR) >1.5 or platelet count less than 100,000/μL, peripheral vascular diseases (PVDs), visceral pain or uncontrolled Diabetes mellitus (DM).
4. Has had corticosteroid therapy at an intended site of stimulation within the past 30 days.
5. Pain medication(s) dosages(s) are not stable for at least 30 days at investigator's discretion.
6. Currently has an active implantable device including International Classification of Diseases (ICD), pacemaker, spinal cord stimulator or intrathecal drug pump or subject requires magnetic resonance imaging (MRIs) or diathermy.
7. Have a current diagnosis of cancer with active symptoms.
8. Have a known terminal illness with life expectancy less than one year.
9. Have a systematic or local infection, which may increase study risk.
10. Currently has an indwelling device that may pose an increased risk of infection.
11. Be pregnant or breast feeding.
12. Have a medical history of drug or alcohol addiction within the past 2 years.
13. Participation in any investigational study in the last 30 days or current enrollment in any trial.
14. Be currently involved in an injury claim law suit or medically related litigation, including workers compensation.
15. Be a prisoner.

14 days from baseline