What is the usage of a spinal cord stimulator (SCS) for chronic pain management in patients who have not responded to other treatments?

Spinal Cord Stimulation Usage for Chronic Pain Management

Spinal cord stimulation should be used as part of a multimodal treatment strategy for patients with persistent radicular pain, Complex Regional Pain Syndrome (CRPS), peripheral neuropathic pain, peripheral vascular disease, and postherpetic neuralgia who have failed conservative therapies, but only after completing a successful trial period and obtaining psychological clearance. 1

Primary Indications

First-Line Indication

• Persistent radicular pain in patients who have not responded to other therapies is the primary indication for SCS 1
• Failed Back Surgery Syndrome represents a well-established indication with demonstrated efficacy 2

Additional Approved Indications

• Complex Regional Pain Syndrome Type I (reflex sympathetic dystrophy) has limited but favorable evidence supporting SCS use 1, 2
• Peripheral neuropathic pain including diabetic neuropathy and causalgic pain respond relatively well to long-term SCS 1, 3
• Peripheral vascular disease benefits from the sympatholytic effects of SCS 1, 4
• Postherpetic neuralgia may be considered, though it responds less favorably than other neuropathic conditions 1, 3

Mandatory Prerequisites Before SCS Consideration

Conservative Treatment Requirements

• Minimum 3 months of conservative management including trials of simple analgesics and NSAIDs 5
• Documented trials of first-line neuropathic pain medications: gabapentinoids (gabapentin, pregabalin), tricyclic antidepressants, or SNRIs 5
• Structured physical therapy program completion 5
• Image-guided epidural steroid injections using fluoroscopic guidance should be attempted before SCS 5

Psychological and Safety Clearance

• Favorable psychological evaluation is explicitly required before SCS trial 5
• Absence of untreated psychiatric comorbidity or current enrollment in multidisciplinary pain management program 5
• No evidence of drug addiction 6
• Documentation excluding coagulopathy, anticoagulant/antiplatelet therapy, or thrombocytopenia 5
• Patient must be capable of operating the stimulating device 5

Diagnostic Requirements

• Imaging findings must correlate with documented neural compression and clinical presentation 5
• Baseline validated outcome measures (VAS or ODI) must be documented to objectively measure trial success 5

Critical Procedural Requirements

Trial Period

• A spinal cord stimulation trial must be performed before considering permanent implantation 1, 6
• This trial period determines whether the patient will benefit from permanent implantation 1

Shared Decision-Making

• Specific discussion of potential complications associated with SCS placement is mandatory 1
• Hardware-related complications including lead migration and connection issues occur in 10-29% of cases 5, 7
• Infection risk must be carefully discussed, with reported rates of 10-29% 5
• Potential need for revision surgery should be addressed 7

Mechanism of Action

• SCS relieves chronic intractable pain by stimulating nerve fibers in the spinal cord, which inhibits pain signal conduction to the brain according to the gate control theory 4, 8
• The sympatholytic effect of SCS is responsible for effectiveness in peripheral ischemia and CRPS 4
• Conventional SCS activates dorsal column Aβ fibers, resulting in alterations in sensory thresholds and cortical processing 8

Conditions Where SCS Is NOT Recommended

• Tethered cord syndrome - ASA does not specifically recommend SCS due to limited evidence 7
• Adhesive arachnoiditis - evidence does not strongly support SCS use 7
• Osteomyelitis-related pain - no specific evidence supporting SCS 5
• For these conditions, spinal neurolytic blocks may be more appropriate for focal pain in limited dermatomes 5, 7

Treatment Algorithm Position

SCS should only be considered when:

1. Pain is predominantly neuropathic in nature 7
2. All conservative treatments have failed 7
3. Psychological contraindications have been ruled out 7
4. Patient meets all mandatory prerequisites listed above 5

Common Pitfalls to Avoid

• Never proceed without psychological clearance - this is an explicit requirement that cannot be bypassed 5
• Never skip the trial period - permanent implantation without successful trial is contraindicated 1
• Never use SCS as first-line therapy - it is part of an overall treatment strategy used only after conservative treatments have failed 1, 4
• Do not proceed if imaging does not correlate with clinical presentation - neural compression must be documented 5
• Avoid in patients on anticoagulation without proper clearance and coagulation studies 5

Long-Term Considerations

• SCS may reduce pain but will not eliminate it completely 4
• Long-term success rates vary by condition: causalgic and diabetic neuropathic pain respond relatively well (47% long-term success), while postherpetic pain and intercostal neuralgia respond less favorably 3
• Cost-benefit analysis shows significant support for SCS as an effective alternative treatment 4
• Follow-up evaluations should be part of the long-term treatment strategy 1