Please select the eligibility criteria that correspond to the clinical trial below.
Title: Comparison of Effectiveness of Tonic, High Frequency and Burst Spinal Cord Stimulation in Chronic Pain Syndromes: a Double-blind, Randomised, Cross-over, Placebo Controlled Trial
Brief Summary: Spinal cord stimulation (SCS) is one of the most commonly undertaken neuromodulatory surgery techniques in the treatment of neuropathic pain. The indication for SCS is an ineffective conservative treatment of chronic pain syndromes. The effectiveness of SCS in the case of neuropathic pain is high. The positive result of SCS treatment is the reduction of previous painful symptoms by min. 50% and / or a reduction in the amount of taken analgesics and an improvement in the quality of life including sleep quality. Long-term studies estimate that in a properly selected group of patients more than 50% of patients achieve pain reduction by the required 50% and about 60% - 70% have an improvement in the quality of life and a reduction of pain.

The efficacy of SCS in different modes of stimulation is evaluated. Patients receive four different types of stimulation for 2-week period - not knowing what kind of stimulation it is. It is said that in one type of stimulation they would feel parestesias and in other three they would not. Patients are not informed that beside tonic, burst and high frequency stimulation, the fourth is an off stimulation to check for placebo effect. The test is double-blinded


Options:
A: Inclusion Criteria:

1. FBSS, CRPS patients with neuropathic and mixed pain in low-back and/or legs refractory to conservative therapy
2. Chronic pain as a result of FBSS that exists for at least 6 months
3. ≥ 18 years of age
4. Written consent of the patient to participate in study procedures.

Exclusion Criteria:

1. Active malignancy
2. Addiction to any of the following: drugs, alcohol and/or medication
3. Evidence of an active disruptive psychiatric disorder or other known condition significant enough to impact perception of pain, compliance to intervention and/or ability to evaluate treatment outcome as determined by investigator
4. Local infection or other skin disorder at site of surgical incision
5. Pregnancy
B: Inclusion Criteria:

1. A diagnosis of primary or idiopathic erythromelalgia
2. Patients ≥18 years who have developed chronic pain that has remained refractory to medical treatment for ≥6 months.
3. Minimum pain intensity of 5/10 on a numeric rating scale NRS at baseline.
4. Successful two-week SCS testing period with tonic stimulation (≥2 points reduction in pain NRS from baseline). This means patients will experience paresthesia during the trial period of spinal cord stimulation.

Exclusion Criteria:

1. Coexisting conditions that would increase procedural risk (e.g., sepsis, coagulopathy).
2. History of laminectomy or posterior fusion at the thoracolumbar junction, where percutaneous electrode end tips are routinely placed.
3. Abnormal pain behavior and/or unresolved psychiatric illness.
4. Unresolved issues of secondary gain or inappropriate medication use.
5. Unfit for participation for any other reason as judged by the study physician.
C: Inclusion criteria

* Subject is ≥ 18 years of age at time of informed consent;
* Subjects have been diagnosed with predominant, chronic, intractable back pain with a VAS \> 50 mm (on a 100-mm scale);
* Subjects have been diagnosed with predominant, chronic, intractable back pain for at least 6 months before study participation;
* Based on the medical opinion of the Principal Investigator, subject has a stable pain medication regiment;
* Based on the medical opinion of the Principal Investigator, there is no evidence of anatomic abnormalities that could jeopardize the placement of the device or pose a hazard to the subject;
* Subject is willing to undergo surgical implant procedure, attend visits as scheduled, and comply with the study requirements;
* Subject is willing and able to operate the patient programmer, recharging equipment and has the ability to undergo study assessments and provide accurate responses;
* Based on the opinion of the implanter, subject is a good surgical candidate for the implant procedure;
* Subject is male or non-pregnant female;
* Subject is deemed to be neuro-psycho-socially appropriate for implantation therapies based of the assessment of a clinical psychologist and principal investigator, using face-to-face encounters and the psychological testing described in the measures;
* Patient is capable of giving informed consent.

Exclusion criteria

* Obvious mechanical instability related to pain (diagnosed by imaging taken within the past 6 months);
* Unresolved malignancies in the last six months;
* Subject has post-herpetic neuralgia (shingles);
* Subject has an active systemic infection or is immune-compromised;
* Based on the medical opinion of the Principal Investigator the subject has other psychological conditions (e.g., psychosis, suicidal ideation, borderline personality disorder, somatization, narcissism), other health conditions (e.g., substance abuse, another chronic condition requiring the regular use of opioid medication), or other legal concerns that would preclude his/her enrollment in the study or potentially confound the results of the study;
* Subject is currently enrolled in or plans to enroll in any concurrent drug and/or device study while participating in this study;
* Insulin-dependent diabetic who is not controlled through diet and/or medication (determined by the physician) or non-insulin dependent diabetic who is not well controlled through diet and/or medication;
* Bleeding complications or coagulopathy issues;
* Pregnant/lactating or not using adequate birth control;
* A life expectancy of less than one year;
* Any active implanted device whether turned off or on;
* A previous SCS experience;
* Conditions requiring Magnetic Resonance Imaging (MRI) evaluation or diathermy procedures.
D: Inclusion Criteria:

1. Patient must be willing and able to provide written informed consent prior to any clinical investigation-related procedure.
2. Age ≥ 18 years
3. Patient has chronic (at least 6 months), refractory axial low back pain with a neuropathic component and is not a candidate for spine surgery
4. Patient has back pain for ≥ 6 months inadequately responsive to supervised conservative care
5. Patient has not had spine surgery for back or leg pain
6. Patient is a candidate for spinal cord stimulation
7. Low back pain ≥ 6 on Numerical Rating Scale
8. Oswestry Disability Index score of ≥ 30%
9. Willing and able to comply with the instructions for use, operate the study device, and comply with this Clinical Investigation Plan

Exclusion Criteria:

1. Pathology seen on imaging tests obtained within the past 12 months that is clearly identified and is likely the cause of the CLBP, that can be addressed with surgery.
2. Primary complaint of leg pain, or leg pain is greater than back pain
3. Back pain is due to any of the following:

   * spinal instability defined as \> 2 mm translation on radiographic imaging
   * visceral causes (e.g., endometriosis or fibroids)
   * vascular causes (e.g., aortic aneurysm)
   * spinal infection (e.g., osteomyelitis)
   * inflammation or damage to the spinal cord (e.g. arachnoiditis or syringomyelia)
   * tumor or spinal metastases
4. Has widespread pain (e.g. fibromyalgia) or pain in other area(s), not intended to be treated in this study (e.g. neck pain, shoulder pain)
5. Patient has seronegative spondyloarthropathy (e.g. rheumatoid, lupus, psoriatic)
6. Neurological deficit (e.g. foot drop)
7. Prior lumbar spine surgery or sacroiliac joint fusion
8. Patient has used a morphine equivalent daily dose of more than 50 MME in the last 30 days
9. Patient is bed bound
10. Patients with regular intake of systemic steroids (except inhaled steroids used to treat asthma)
11. Imaging (MRI, CT, X-ray) findings within the last 12 months that contraindicates lead placement
12. Known allergic reaction to implanted materials
13. Severe scoliotic deformity (\>11 degrees in thoracic or lumbar spine)
14. Patient has a history of, or existing intrathecal drug pump
15. Patient has previous experience with neuromodulation devices, including a failed trial
16. BMI \> 40
17. Patient is enrolled, or intends to participate, in another clinical drug and/or device study or registry that may interfere with the results of this study, as determined by Abbott personnel
18. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with follow-up requirements of the clinical investigation results.
19. Failed psychological evaluation
20. Suspicion or evidence of untreated mental illness, or substance abuse
21. Patient demonstrated 2 or more Waddell's signs of nonorganic behavior
22. Patient is in current litigation for back pain/injury, or is currently receiving worker's compensation
23. Pregnant or nursing subjects and those who plan pregnancy during the clinical investigation follow-up period.

    * Female subjects of child-bearing potential must have a negative pregnancy test done within 7 days prior to enrollment/baseline visit per site standard test.

Answer: A