Endogenous Pain Facilitation and Inhibition in Postpartum Women

December 15, 2017 updated by: Wake Forest University
This study seeks to further understand these three observations - (1) that the time period surrounding childbirth accelerates recovery from pain after injury (2) that this likely reflects dampened facilitating mechanisms and exaggerated inhibitory mechanisms, and (3) that stress may interfere with this protection. In this study the investigators will compare women within 2 weeks of delivery to age matched controls and anticipate that pain inhibition is increased after delivery, pain facilitation is decreased, and that there is a relationship between these pain responses and the degree of pre-existing stress.

Study Overview

Detailed Description

Nearly half of the world's population experiences labor and delivery processes which are associated with microscopic or gross tissue injury to the mother. Since this experience is widespread and occurs relatively early in life, the psychosocial, medical, and financial consequences of chronic pain following childbirth could be enormous. Surprisingly, previous studies with long term follow up of new mothers have included pain as a secondary measure and / or have focused on prevalence of pain without determining whether pain predated delivery or even pregnancy itself. The investigators recently performed a long term follow up study of over 1,200 women, and noted that pain which began during the childbirth itself was surprisingly rare in comparison to other physical injuries. Additionally, two central factors hypothesized to confer risk of chronic pain after other injuries including surgery, pre-dating chronic pain and degree of tissue and nerve injury, contributed minimally to the acute and sub-acute pain after childbirth. These two observations, low incidence of chronic pain and minimal effect of degree of tissue injury and history of chronic pain on sub-acute pain, point towards a potential protective effect of pregnancy or delivery on the response to physical injury.

Study Type

Observational

Enrollment (Actual)

80

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • North Carolina
      • Winston-Salem, North Carolina, United States, 27157
        • Wake Forest Baptist Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Female

Sampling Method

Probability Sample

Study Population

Healthy women 10-14 days postpartum following term vaginal delivery, who are breast feeding and age- and race- matched healthy, nonpregnant women, either nulliparous or at least 1 year beyond delivery.

Description

Inclusion Criteria:

  • female
  • 10-14 days postpartum, term vaginal delivery
  • breastfeeding (postpartum women)
  • health non-pregnant female (nulliparous or at least 1 year beyond delivery)

Exclusion Criteria:

  • Allergy to chili peppers
  • pregnant
  • pain medication (narcotic or non-narcotic) within 4 hours of study visit Average pain in the 24 hours preceding the study visit >3. Postpartum women that score >13 on the Edinburgh Postnatal Depression Scale

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort
endogenous pain facilitation
Pain facilitation is studied by a simple test of applying over the counter capsaicin cream to the skin for only 30 min, then removing it and heating the skin to a non-noxious temperature.
endogenous pain inhibition
Pain inhibition is studied by a simple test of mild pain on one area of the body reducing response to a pain stimulus in another area.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Area of hyperalgesia will be the primary outcome measure
Time Frame: 40 minutes post capsaicin application
Hyperalgesia and allodynia on the skin of the forearm will be established by heating the forearm with a 4 cm2 Peltier controlled thermode (TSA®) to 45 degrees Celsius for 5 minutes. The investigators will then apply topical capsaicin (0.075% cream, Bioglan Pharmaceuticals) under an occlusive dressing at the same site as the thermal probe for 30 minutes. 40 minutes after removal of the capsaicin cream the site will be heated to 40 degrees Celsius for 5 minutes (rekindling) following the end of capsaicin application. The investigators will test skin sensations with the filament and cotton wisp after this heating.
40 minutes post capsaicin application
Percent reduction in degree of pain to the 49 degrees Celsius stimulus during the time the foot is immersed in the cold water
Time Frame: 15 minutes
Conditioned pain modulation will be induced by placing a foot in a container of circulating water maintained at 10 degrees Celsius for 90 seconds. Thirty seconds after the foot is placed into container of circulating water, the stimulus response to heat on the contralateral forearm will be measured using a 49 degrees Celsius stimulus for 5 seconds. The foot will then be withdrawn and warmed with warm blankets. The stimulus response to heat stimuli on the arm will be measured 5 and 15 min thereafter.
15 minutes

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: James C. Eisenach, MD, Wake Forest University Health Sciences

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2013

Primary Completion (Actual)

December 5, 2017

Study Completion (Actual)

December 5, 2017

Study Registration Dates

First Submitted

April 25, 2013

First Submitted That Met QC Criteria

April 25, 2013

First Posted (Estimate)

April 30, 2013

Study Record Updates

Last Update Posted (Actual)

December 19, 2017

Last Update Submitted That Met QC Criteria

December 15, 2017

Last Verified

December 1, 2017

More Information

Terms related to this study

Other Study ID Numbers

  • IRB00022603

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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