Sciatic Block in Contralateral Limb Phantom and Residual Limb Pain

Study Overview
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Brief Summary
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Participants with chronic, refractory phantom limb pain (PLP) or residual limb pain (RLP) for more than 6 months will be enrolled in this clinical trial. Aim: Define the attributable pain relief and functional improvement in participants with PLP/RLP after contralateral limb sciatic nerve block. Also, contribute to the basic science understanding of the crossed-withdraw reflex by demonstrating a known animal model phenomenon in human participants. Hypothesis: Contralateral limb sciatic nerve anesthetic block with 2% lidocaine provides immediate clinically meaningful pain reduction, defined as the proportion of patients with at least 50% improvement in NRS pain score in PLP/RLP when compared to sham.

Official Title
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Sciatic Block in Contralateral Limb for Treatment of Refractory Phantom and Residual Limb Pain; a Triple-Blind Randomized Crossover Controlled Trial

Conditions
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Pain, Amputation

Intervention / Treatment
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* Drug: 10 mL 2% lidocaine
* Drug: 10 mL preservative free saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 1. Age greater than 18 years of age at day of enrollment 2. Lower extremity amputation performed more than 12 months before study enrollment 3. PLP/RLP in affected amputated limb > 4 on NRS26 4. Pain duration of more than 6 months despite a trial of conservative therapies for at least 2 months, including oral medications, topical medicines, physical therapy, and physical modalities (i.e., heat, cold, transcutaneous electrical nerve stimulation, phonophoresis) 5. Willingness to undergo image guided diagnostic nerve block Exclusion Criteria: 1. Refusal / inability to participate or provide consent 2. Contraindications to diagnostic nerve block 3. Non-neurogenic source of PLP/RLP 4. Current opioid use > 50 morphine milligram equivalents per day 5. Any interventional pain treatment in the residual limb within the last 30 days 6. Severe uncontrolled medical condition (i.e., hypertensive crisis, decompensated hypothyroidism) 7. Use of investigational pain drug within past 30 days or other concurrent clinical trial enrollment

Ages Eligible for Study
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Minimum Age: 18 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
Interventional Model Description: Prospective Randomized Crossover Controlled Trial
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Treatment group 2% lidocaine<br>Image guided sciatic nerve anesthetic block of the contralateral limb with an injection of 10 mL 2% lidocaine. | Drug: 10 mL 2% lidocaine<br>* Image guided sciatic nerve anesthetic block of the contralateral limb with an injection of 10 mL 2% lidocaine.<br>|
| Placebo Comparator: Sham preservative free saline<br>Image guided sciatic nerve anesthetic block of the contralateral limb with an injection of 10 mL preservative free saline. | Drug: 10 mL preservative free saline<br>* Image guided sciatic nerve anesthetic block of the contralateral limb with an injection of 10 mL preservative free saline.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of the proportions of participants reporting ≥ 50% improvement in NRS pain score from baseline at 15 minutes in treatment and sham groups | Comparison of the proportions of participants reporting ≥ 50% improvement in NRS pain score on a scale of 0 (no pain) to 10 (worst pain imaginable) from baseline at 15 minutes in treatment and sham groups. | 15 minutes after treatment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean and standard deviation (SD) of change in NRS pain score at 1, 2, 3, 4, 5, 6, 24, 48, 72, 96, 120 hours post-saline and lidocaine injections | Mean and standard deviation (SD) of change in NRS pain score (0 no pain -10 worst pain imaginable) at 1, 2, 3, 4, 5, 6, 24, 48, 72, 96, 120 hours post-saline and lidocaine injections | 120 hours | 
| Mean and SD of average daily steps recorded at 24, 48, 72, 96, 120 hours post-saline and lidocaine injections (via Modus StepWatch™ or Evolution EvoWalk™) | Mean and SD of average daily steps recorded at 24, 48, 72, 96, 120 hours post-saline and lidocaine injections (via Modus StepWatch™ or Evolution EvoWalk™) | 120 hours | 
| Mean and SD of change in Orthotics and Prosthetics User's Survey (OPUS) score immediately post-injection and conclusion of washout (5 days) in saline and lidocaine groups | Mean and SD of change in Orthotics and Prosthetics User's Survey (OPUS) score ( 20 question survey scored on a 5 point range from very easy- to cannot perform this activity)immediately post-injection and conclusion of washout (5 days) in saline and lidocaine groups | 5 days | 
| Mean and SD of change in Groningen Activity Restriction Scale (GARS) score immediately post-injection and conclusion of washout (5 days) in saline and lidocaine groups | Mean and SD of change in Groningen Activity Restriction Scale (GARS) score (survey is 17 question survey scored 1= can do it fully to 4 =cannot do it all, a good score ranges from 17 to a poor score of 68 poor score) immediately post-injection and conclusion of washout (5 days) in saline and lidocaine groups | 5 days | 
| Demographic factors associated with large improvement in NRS pain score | NRS scored on a 11 point scale of 0= no pain to 10 worst pain imaginable. | 5 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Pain, Amputation, Phantom Pain