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Characterization of Rebound Pain Following Peripheral Nerve Block and Its Association With Gut Microbiome Diversity

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02998177
Recruitment Status : Completed
First Posted : December 20, 2016
Last Update Posted : August 22, 2017
Information provided by (Responsible Party):
Dr. David Brenner, Cork University Hospital

Brief Summary:
The objective of this study is to determine the association between gut microbiome diversity and the characteristics of rebound pain at offset of peripheral nerve block in patients who have undergone upper limb surgery. Other purposes of this study are to determine associations between gut microbiome constitution and persistent post-surgical pain; and describing rebound pain by quantifying its clinical, psychological and neurophysiological characteristics in this patient cohort.

Condition or disease
Pain, Postoperative Gastrointestinal Microbiome

Detailed Description:

Based on an emerging understanding of the importance of the gut microbiome in the human and animal responses to stress, it is clear that gut microbiota influence bidirectional signaling between the central nervous system (CNS) and gut (microbiota-gut-brain axis). One element of this influence is the role of gut microbiota in visceral hypersensitivity and pain. Important clinical implications of this understanding have begun to emerge: for instance irritable bowel syndrome (IBS) patient cohorts demonstrate distinct gut microbiome characteristics and, in pre-clinical models, manipulation of the gut microbiome lessens visceral hypersensitivity. To date, attempts to improve pain symptoms in IBS using probiotics have been modestly and variably successful.

One research area which offers potential to the discovery of novel analgesic therapies is the activation of endogenous opiate pain processing including augmentation of descending inhibition. (Broadly, identification of new targets/alkaloid modification/ proteomics efforts have been unsuccessful). Manipulation of microbiota-gut-brain axis by administering probiotics offers one potential route for such activation. There are many of examples of such manipulation altering animal behavior and physiology. In theory, opportunities for such manipulation might exist during or close to early life stress or before noxious stimuli such as elective surgery.

The relationship between the gut microbiome and somatic or neuropathic pain has not been studied. Certain of the pathways and regulators of visceral pain and hypersensitivity are also critical in somatic pain handling. These include peripheral sensitization of primary sensory afferents, central sensitization in particular of spinal ascending neurons and alteration of descending inhibitory pathways. These neuroplastic changes have been well documented in the surgical setting in the examination of persistent post-surgical pain.

"Rebound pain" is a quantifiable difference in pain scores when the block is working, versus the increase in acute pain that is encountered during the first few hours after the effects of perineural single-injection or continuous infusion local anesthetics resolve. Rebound pain may represent a manifestation of hypersensitivity and offer an accessible clinical model suitable for examining the association between gut microbiome diversity and perioperative neuroplastic changes.

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Study Type : Observational
Actual Enrollment : 20 participants
Observational Model: Case-Only
Time Perspective: Prospective
Official Title: Characterization of Rebound Pain Following Peripheral Nerve Block and Its Association With Gut Microbiome Diversity
Study Start Date : November 2016
Actual Primary Completion Date : June 16, 2017
Actual Study Completion Date : June 16, 2017

Primary Outcome Measures :
  1. Association between gut microbiome α diversity and the magnitude of rebound pain (Numerical Rating Scale) [ Time Frame: Perioperative period ]

Secondary Outcome Measures :
  1. Association between gut microbiome α diversity and magnitude of postoperative pain (Numerical Rating Scale). [ Time Frame: Perioperative period ]
  2. Association between gut microbiome α diversity and analgesic consumption (mg/24 hours). [ Time Frame: Perioperative period ]
  3. Association between gut microbiome α diversity and salivary cortisol concentration (ng/ml). [ Time Frame: Perioperative period ]
  4. Association between gut microbiome α diversity and Pain Perception Threshold (PPT, mAmp). [ Time Frame: Perioperative period ]
  5. Association between gut microbiome constitution (α diversity) and incidence of persistent post-surgical pain. [ Time Frame: Up to 4 weeks postoperatively ]
  6. Pearson's correlation coefficient for i. Maximum Numerical Rating Scale (NRS) score for rebound pain vs. ii. Pain Perception Threshold (PPT, mAmp) and Pain Tolerance Threshold (PTT, mAmp) based on Quantitative Sensory Testing. [ Time Frame: Up to 48 hours postoperatively ]

Biospecimen Retention:   Samples Without DNA
Pre- and postoperative faecal samples and preoperative salivary samples are going to be taken.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
ASA I-II patients scheduled to undergo upper limb surgery under brachial plexus block will be recruited.

Inclusion Criteria:

  • Age 18-80 years
  • Patients undergoing hand surgery for Dupuytren's contracture correction or open reduction and internal fixation of distal radius fracture under axillary brachial plexus block

Exclusion Criteria:

  • Contraindication of regional anaesthesia, patient is allergic to local anesthetics
  • Chronic pain syndrome
  • History of peripheral neuropathy
  • Preexisting nerve damage in the operated arm (sensory or motor deficit)
  • Axillary surgery in the past
  • Uncontrolled pain (Verbal Rating Score ≥5 out of 10 at rest despite adequate analgesic measures)
  • Clinically significant cognitive impairment (Minimental state score < 24)
  • Language barrier
  • Depression
  • Diabetes
  • Obesity (BMI>35)
  • Antibiotic therapy in the preceding 30 days
  • Probiotics

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02998177

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Department of Anaesthesiology, South Infirmary-Victoria University Hospital
Cork, Co. Cork, Ireland
Division of Anaesthesia and Intensive Care, Cork University Hospital
Cork, Co. Cork, Ireland
Sponsors and Collaborators
Cork University Hospital
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Study Chair: George Shorten, Professor Professor of Anaesthesia and Intensive Care Medicine, Consultant Anaesthetist, University College Cork / Cork University Hospital

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Responsible Party: Dr. David Brenner, Peripheral Nerve Block Fellow, Cork University Hospital Identifier: NCT02998177    
Other Study ID Numbers: GMB-RP
First Posted: December 20, 2016    Key Record Dates
Last Update Posted: August 22, 2017
Last Verified: August 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by Dr. David Brenner, Cork University Hospital:
Postoperative pain
Rebound pain
Gut microbiome
Gut microbiota
Peripheral nerve block
Axillary brachial plexus block
Additional relevant MeSH terms:
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Pain, Postoperative
Postoperative Complications
Pathologic Processes
Neurologic Manifestations