What are the recommended nerve block treatments for a patient with a history of Spinal Cord Injury (SCI) and Complex Regional Pain Syndrome (CRPS)?

Nerve Block Treatment for Spinal Cord Injury Patients with Complex Regional Pain Syndrome

Primary Recommendation

For SCI patients with CRPS, sympathetic nerve blocks (stellate ganglion block for upper extremity or lumbar sympathetic block for lower extremity) should be used as first-line interventional treatment when integrated into a multimodal rehabilitation program, but only when there is consistent improvement and increasing duration of pain relief with successive blocks. 1, 2, 3

Treatment Algorithm

Initial Management Phase

Start with pharmacological therapy before proceeding to nerve blocks:

• Initiate gabapentinoids (gabapentin up to 2400 mg daily or pregabalin) as first-line treatment for neuropathic pain in SCI patients 1, 2
• Add tricyclic antidepressants (amitriptyline 10-25 mg/day) when gabapentinoid monotherapy is insufficient, particularly in patients over 40 years 1, 2
• Obtain baseline ECG before starting amitriptyline in patients over 40 due to cardiac risks 2
• Continue gabapentinoid treatment for more than 6 months in association with tricyclic antidepressants or serotonin reuptake inhibitors when monotherapy fails 1, 2

Interventional Nerve Block Criteria

Proceed to sympathetic blocks only when:

• Physical therapy and pharmacological management have been optimized but pain remains moderate to severe 1, 4
• Pain prevents meaningful participation in physical therapy 4
• Sympathetically maintained pain component is suspected 1, 3

Specific Nerve Block Techniques

For upper extremity CRPS in SCI patients:

• Perform stellate ganglion block at C6 or C7 vertebral level using either fluoroscopy (50% of practitioners) or ultrasound guidance (47% of practitioners) 5
• Use 5-10 mL total volume of 0.25% bupivacaine 5
• Consider continuous stellate ganglion block with 0.125% bupivacaine at 2 mL/h for one week in severe cases 6

For lower extremity CRPS in SCI patients:

• Perform lumbar sympathetic block at L2 or L3 level under fluoroscopic guidance 5
• Use 10-20 mL total volume of 0.25% bupivacaine 5
• Radiofrequency treatment is preferred over phenol neurolysis for prolonged lumbar sympathetic blockade due to comparable efficacy with lower risk of side effects 7

Critical Decision Points for Continuing Blocks

Continue the series of sympathetic blocks only if:

• Each successive block demonstrates progressively longer duration of pain relief 1, 3, 8
• Patient shows objective functional improvements including measurable gains in activities of daily living, cognitive function, and autonomic stability 3
• Relief duration extends beyond 1-7 days with each block 5

Discontinue sympathetic blocks if:

• No consistent improvement occurs after 1-3 consecutive blocks 5
• Duration of relief does not increase with successive blocks 1, 3
• Patient develops complications or contraindications 1

Alternative Nerve Block Approaches

For refractory cases not responding to sympathetic blocks:

• Consider continuous infraclavicular brachial plexus block with 0.125% bupivacaine at 5 mL/h for upper extremity CRPS, which may provide superior pain relief in the first 12 hours compared to stellate ganglion block 6
• Continuous epidural infusion analgesia coupled with exercise therapy may be attempted 7

Advanced Interventional Options

When nerve blocks fail to provide adequate relief:

• Proceed to spinal cord stimulation trial for CRPS patients who have not responded to sympathetic blocks and other therapies 1, 2, 3
• A temporary trial must demonstrate >50% pain reduction and measurable functional improvement before permanent implantation 2, 3
• Spinal cord stimulation should be integrated into multimodal treatment, not used as monotherapy 3

For severe refractory cases:

• Ketamine infusion (0.1-0.35 mg/kg/h over 6 hours daily for 5 days) can be used as second-line or rescue therapy for CRPS with central sensitization 2
• Use extreme caution in elderly patients due to significant risk of confusion and delirium 2
• Monitor respiratory parameters closely when combining with opioids or benzodiazepines 2

Critical Pitfalls to Avoid

Do not use peripheral somatic nerve blocks for long-term treatment of chronic pain in SCI patients with CRPS - these are explicitly contraindicated by ASA guidelines 1, 8

Do not perform sympathetic blocks for non-CRPS neuropathic pain - sympathetic blockade is specifically indicated for CRPS with sympathetically maintained pain, not for general neuropathic pain from SCI 1, 8

Do not continue indefinite series of blocks without documented progressive improvement - the key criterion is demonstrating increasing duration of relief with each successive block, not simply repeating blocks at fixed intervals 1, 3

Do not neglect physical therapy - nerve blocks must be integrated into a comprehensive rehabilitation program with physical therapy as the cornerstone treatment; blocks alone are insufficient 2, 3, 4

Do not perform blocks without image guidance - use fluoroscopy or ultrasound to reduce complications including pneumothorax with stellate ganglion blocks and vascular injury with lumbar sympathetic blocks 8, 9

Monitoring and Documentation Requirements

Document the following with each block:

• Duration of pain relief from previous block 3, 5
• Objective functional improvements beyond pain scores (ADL capacity, range of motion, autonomic changes) 3
• Temperature changes in affected limb indicating sympathetic response 3
• Ability to participate more effectively in physical therapy 4