Trigger-point Blockade in Persistent Pain After Open Groin Hernia Repair

Study Overview
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Brief Summary
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Groin hernia repair is a common procedure performed in approximately 2,000 patients per one million inhabitants. Severe chronic pain following groin hernia repair is seen in 2-5% of the patients indicating that a large number of patients each year suffer from debilitating reduction in health-related quality of life. This study examines the effect of ultra-sound guided blocks with local anesthesia in the groin in regard to pain relief and sleep quality. The hypothesis of the study is that a block will confer significant pain relief to patients with severe chronic pain following open groin hernia repair.

Detailed Description
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This placebo-controlled, randomized, double-blind, cross-over study in subjects with severe pain after open groin hernia, examines the effect of an ultra-sound guided local anesthetic block of a trigger-point, situated near the spermatic cord at the superficial inguinal ring. In order to compare effects and distribution of the blocks in patients vs. healthy subjects, the block is tested and examined in volunteers using a similar methodology.

Official Title
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Trigger-point Blockade in Persistent Pain After Open Groin Hernia Repair

Conditions
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Inguinal Hernia, Chronic Pain

Intervention / Treatment
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* Drug: Bupivacaine
* Drug: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with persistent pain (< 6 mo) after open groin hernia repair Patients with maximal pain area 3 cm or less from the superficial inguinal ring Patients living in the Capital Region of Denmark (Region Hovedstaden) or the Region of Zealand (Region Sjælland) Exclusion Criteria: Known allergy to bupivacaine or other local anesthetics of amide-type Declared incapable of making his/hers own affairs Does not comprehend Danish in the written or spoken language Cognitive impairment to a degree influencing the testing reliability Known recurrence of the inguinal hernia Other surgical procedures performed in the groin or on the external genitals Neuropathy affecting the groin region caused by other conditions, e.g. post-stroke, multiple sclerosis, herniated intervertebral disc Abuse of alcohol or drugs Unable to cooperate with the sensory examinations

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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Accepts Healthy Volunteers

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
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bupivacaine<br>injection, 25 mg, once, 5 min | Drug: Bupivacaine<br>* 10 ml of bupivacaine 2.5 mg/ml deposited by ultra-sound guidance around the spermatic cord<br>* Other names: Bupivacain SAD;|
| Placebo Comparator: Placebo<br>injection, 10 ml 0.9% sodium chloride, once, 5 min | Drug: Placebo<br>* 10 ml 0.9% physiological saline deposited by ultra-sound guidance around the spermatic cord<br>* Other names: Normal saline;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Normalized summed pain intensity difference (SPID) | The number of patients with normalized summed pain intensity differences (SPID) of more or equal to 50% after bupivacaine AND SPID less or equal to 25% after placebo. | 20 min | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Thermal thresholds | Quantitative changes in thermal thresholds (warmth detection threshold, cool detection thresholds, heat pain threshold) after bupivacaine compared to placebo | 20 min | 
| Suprathreshold heat stimulation | Quantitative changes in pain ratings to suprathreshold heat stimulation after bupivacaine compared to placebo | 20 min | 
| Pressure pain thresholds | Quantitative changes in pain rating to pressure algometry stimulation after bupivacaine compared to placebo | 20 min | 
| Sensory mapping | Quantitative changes in area of cool hypoesthesia assessed by a thermal roller after bupivacaine compared to placebo | 20 min | 
| Pain questionnaire | Quantitative changes in summed pain intensity differences (SPIDs) during rest, movement and during auto-palpation, assessed morning and evening after bupivacaine compared to placebo | 7 days | 
| Sleep quality | Quantitative changes in sleep quality assessed each morning, after bupivacaine compared to placebo | 7 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Chronic Pain, Inguinal Hernia, Outcome, Surgical Procedure, Operative