Direct Comparison of Spinal Cord Stimulator Parameter Settings

Study Overview
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Brief Summary
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(Primary) To compare the clinical effects and side effects of two different stimulation strategies that do not produce any sensory percept (1000 Hz and placebo) on clinical benefit for electrodes implanted for chronic pain as measured by the Visual Analog Pain Scale for back and leg pain, the Brief Pain Inventory, the SF-36, and the Pain Vigilance and Awareness Questionnaire. (Secondary) To compare the clinical effects of the subthreshold (paresthesia-free) stimulation patterns with conventional (paresthesia-producing) stimulation patterns to evaluate the necessity of paresthesias and current amplitudes on clinical benefit for pain. To identify the ability of subthreshold high-frequency to improve axial pain or the affective component of pain.

Detailed Description
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This is a prospective, randomized, double-blind study of different stimulation patterns in patients undergoing implantation of neurostimulator systems for chronic medically intractable neuropathic pain. Research participants will be individuals who have undergone implantation of neurostimulator electrodes into the spinal column or peripheral nervous system for clinical treatment of neuropathic pain. All patients will already have undergone empiric programming of the stimulator using conventional settings (typically 40-60 Hz, 350-450 usec pulse width). However, other stimulation parameters, including high-frequency stimulation, are also feasible and FDA-approved using the implanted device, and it is possible to do this without producing a sensory percept, which makes it possible to test efficacy in a double blind manner. For this study, two different stimulation parameters will be tested during four two-week periods: 1000 Hz and placebo. Clinical response and side effect profile for each setting will be measured.

Official Title
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Direct Comparison of Spinal Cord Stimulator Parameter Settings

Conditions
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Spinal Cord Stimulation, High-frequency Stimulation, High-density Stimulation

Intervention / Treatment
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* Device: High-frequency stimulation
* Device: Sham Stimulation
* Device: Conventional spinal cord stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-75 years Diagnosis of chronic neuropathic pain for which placement of electrodes into the spinal column is planned for clinical indications (failed back surgery syndrome, peripheral neuropathy or complex regional pain syndrome) History of implantation of spinal cord stimulation system with rechargeable implanted neurostimulator Exclusion Criteria: Significant dementia or other condition preventing informed consent by the patient. Current drug or alcohol abuse or dependence. Uncontrolled depression or anxiety or failure to pass psychological screening for spinal cord stimulation. Inability or unwillingness to cooperate with clinical testing.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: high-frequency stimulation<br>Patients will randomly be assigned to receive sub-threshold high-frequency spinal cord stimulation for 2 weeks. | Device: High-frequency stimulation<br>* Patients in this group will receive sub-threshold high-frequency (aka 1200Hz) spinal cord stimulation for 2 weeks.<br>|
| Sham Comparator: placebo stimulation<br>Patients will randomly be assigned to receive sham spinal cord stimulation for 2 weeks. | Device: Sham Stimulation<br>* Patients in this group will receive receive sham spinal cord stimulation (aka no stimulation) for 2 weeks.<br>|
| Active Comparator: conventional spinal cord stimulation<br>Patients will receive conventional spinal cord stimulation for 2 weeks prior to both the high-frequency or sham stimulation. | Device: Conventional spinal cord stimulation<br>* Patients will receive conventional spinal cord stimulation (aka 60Hz, aka tonic stimulation, aka paresthesia-based stimulation) for 2 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual Analog Pain Scale | Assessment of overall degree of back and leg pain during each arm of spinal cord stimulation. Scores range from 0 - 100, with a higher score indicating more pain | 8 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Brief Pain Inventory (BPI) | The BPI assesses pain at its worst, least, average, and now (current pain). Each item is rated on a scale of 0 - 10 with 10 indicating higher levels of pain | 8 weeks | 
| SF-36 | The SF-36 is a measure of quality of life, with scores ranging from 0 - 100, with higher scores indicating a higher quality of life. | 8 weeks | 
| Pain Vigilance and Awareness Questionnaire (PVAQ) | The PVAG is a measure of vigilance and attention to pain. Total scores can range from 0 to 90, with higher scores indicating more pain vigilance. | 8 weeks | 
| Number of Patients with Side Effects of Stimulation | Incidence of side effects of stimulation | 8 weeks |