A Safety and Effectiveness Trial of Spinal Cord Stimulation of the Dorsal Root Ganglion for Chronic Lower Limb Pain

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the safety and effectiveness of the AXIUM Neurostimulator System for the treatment of chronic lower limb pain in persons diagnosed with Complex Regional Pain Syndrome (CRPS) or Peripheral Causalgia (PC).

Detailed Description
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The ACCURATE study is a prospective, randomized, controlled, multicenter clinical trial designed to assess the safety and efficacy of the Spinal Modulation Axium Neurostimulator System as an aid in the management of chronic, intractable pain of the lower limbs, including unilateral or bilateral pain associated with one of the following conditions: Complex Regional Pain Syndrome (CRPS) or Peripheral Causalgia (also referred to as CRPS Type II). Enrolled subjects were diagnoses with CRPS or peripheral causalgia; experienced pain for at least six months; and failed to achieve adequate pain relief from at least two prior pharmacologic treatments. All subjects had a temporary trial neurostimulator (TNS). If the subject was a treatment success at the end of TNS they were scheduled for the fully implantable neurostimulator (INS) implant procedure. If not, subjects were exited from the study.

Official Title
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A Prospective, Randomized, Multi-Center, Controlled Clinical Trial to Assess the Safety and Efficacy of the Spinal Modulation™ AXIUM™ Neurostimulator System in the Treatment of Chronic Pain (ACCURATE Trial)

Conditions
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Chronic Lower Limb Pain

Intervention / Treatment
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* Device: AXIUM Neurostimulator System
* Device: Control Spinal Cord Stimulation Device


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subject is male or female between the ages of 22 and 75 years Subject is able and willing to comply with the follow-up schedule and protocol Subject has chronic, intractable pain of the lower limb(s) for at least 6 months Subjects are diagnosed with complex regional pain syndrome (CRPS) and/or peripheral causalgia Subjects have a minimum Visual Analog Scale (VAS) greater than or equal to 60 mm in the area of greatest pain in the lower limbs. Subject has failed to achieve adequate pain relief from at least 2 prior pharmacologic treatments from at least 2 different drugs classes Subject has had stable neurologic function in the past 30 days In the opinion of the Investigator, the subject is psychologically appropriate for the implantation of an active implantable medical device Subject is able to provide written informed consent Exclusion Criteria: Back pain is the greatest region of pain as measured on the baseline VAS. Female subject of childbearing potential is pregnant/nursing, plans to become pregnant or is unwilling to use approved birth control Subject has exhibited escalating or changing pain condition within the past 30 days as evidenced by Investigator examination Subject is currently involved in medically related litigation, including workers compensation Subject has had corticosteroid therapy at an intended site of stimulation within the past 30 days Subject's pain medication(s) dosage(s) are not stable for at least 30 days Subject has had radiofrequency treatment of an intended target Dorsal Root Ganglion within the past 3 months Subject has previously failed spinal cord stimulation therapy Subject currently has an active implantable device including implantable cardioverter defibrillator, pacemaker, spinal cord stimulator or intrathecal drug pump or subject requires magnetic resonance imaging (MRIs) or diathermy Subject has pain only within a cervical distribution Subject has cognitive, physical or sensory impairment that, in the opinion of the Investigator, may limit their ability to operate the device Subject currently has an indwelling device that may pose an increased risk of infection Subject currently has an active systemic infection. Subject has, in the opinion of the investigator, a medical comorbidity that contraindicates placement of an active medical device Subject has participated in another clinical investigation within 30 days Subject has a coagulation disorder or uses anticoagulants that, in the opinion of the Investigator, precludes participation Subject has been diagnosed with cancer in the past 2 years Imaging (MRI, CT, x-ray) findings within the last 12 months that, in the Investigator's opinion, contraindicates lead placement Subject is a prisoner

Ages Eligible for Study
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Minimum Age: 22 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: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: AXIUM Neurostimulator System<br>The AXIUM Neurostimulator System is an investigational spinal cord stimulation device that is designed to stimulate the dorsal root ganglion (DRG) of the spine located on the back surface of the spinal cord where nerves exit the backbone. The device has 2 parts that are placed surgically (implanted) : 1) a pulse generator which is placed under the skin in the buttocks or abdomen, and 2) up to four wires (leads) that have one end attached to the pulse generator, and the other end secured to the tissue near the target treatment area. | Device: AXIUM Neurostimulator System<br> <br> * Other names: DRG Stimulation;|
| Active Comparator: Control Spinal Cord Stimulation Device<br>The Control Spinal Cord Stimulation Device is a commercially available spinal cord stimulator indicated for the treatment of chronic lower limb pain. | Device: Control Spinal Cord Stimulation Device<br> <br> * Other names: SCS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Primary Composite Endpoint - Treatment Success | Treatment Success is defined as at least 50% lower limb pain relief (VAS score reduction) at the end of trial phase, received at least 50% lower limb pain relief at the 3-month visit post implant, and the absence of a stimulation related neurological deficit. Pain scores were measured using Visual Analog Scale (VAS). The VAS score ranges from 0-100 mm with a higher score indicating higher pain intensity ( 0 representing No Pain and 100 mm representing Worst Imaginable Pain). | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Positional Effects on Paresthesia Intensities | Positional effects on paresthesia intensities at 3 months in the Control group versus the Treatment Group. This endpoint will compare the difference in paresthesia scores upright and supine between the AXIUM and Control groups. Paresthesia intensity was rated by subjects using a paresthesia intensity rating scale. Subjects rated the intensity of their perception of paresthesia, while upright and supine, on an 11-point numeric rating scale from 0 representing No feeling to 10 Very intense. Perceived paresthesia intensity difference between supine and upright positions was calculated and averaged across each group. | 3 months |