A Study of Contralateral Limb Block

Study Overview
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Brief Summary
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This research is being done to determine if an anesthetic like Lidocaine, may be effective when injected around the sciatic nerve of the intact limb in patients with limb loss pain on the contralateral side.

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

Conditions
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Limb Pain, Phantom

Intervention / Treatment
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* Drug: Lidocaine
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Lower extremity amputation performed more than 12 months before study enrollment PLP/RLP in affected amputated limb > 4 on NRS26 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) Willingness to undergo image guided diagnostic nerve block Exclusion Criteria: Refusal / inability to participate or provide consent Contraindications to diagnostic nerve block Non-neurogenic source of PLP/RLP Current opioid use > 50 morphine milligram equivalents per day Any interventional pain treatment in the residual limb within the last 30 days Severe uncontrolled medical condition (i.e., hypertensive crisis, decompensated hypothyroidism) 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: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Lidocaine Group<br>Subjects will receive a lidocaine injection in the back of their residual limb. | Drug: Lidocaine<br>* 2 teaspoons of 2% lidocaine injection<br>|
| Placebo Comparator: Sham Group<br>Subjects will receive a placebo injection in the back of their residual limb. | Drug: Placebo<br>* Saline injection<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in pain | Measured using self-reported Numerical Rating Scale (NRS) where 0=no pain and 10=worst pain. | Baseline, 60 minutes post injection | 
| Change in Functional Improvement | Measured using self-reported 20-item Orthotic and Prosthetics User's Survey (OPUS) Lower Extremity Functional Status Measurement survey. Total scores range from 0-100 scale with higher scores indicating a better outcome. | Baseline, 5 days post-injection | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in disability | Measured using self-reported 18-item The Groningen Activity Restriction Scale (GARS) that is a general disease independent instrument for measuring disability. Total scores range from 18-72. The higher the score the greater the disability. | Baseline, 5 days post-injection | 
| Change in Pressure-Pain Algometry | Qualified study personnel will measure pain pressure threshold three times at each visit with an algometer on the participant's residual limb at the point of a maximal pain as indicated by the participant during pre-block physical examination, reported in kilopascal (kPa). | Baseline, 5 days post-injection | 
| Step Count | Number of daily steps recorded by Modus StepWatch™ or Evolution EvoWalk™ fitted to the participant's prostheses | 5 days post-injection |