A Quantitative Sensory Testing Paradigm to Obtain Measures of Pain Processing in Patients Undergoing Breast Cancer Surgery

Summary

Persistent postsurgical pain may be related to changes in pain processing. By assessing pain in response to standardized stimuli, changes in pain processing can be elucidated. We present methods to obtain pain thresholds to different stimuli and a measure of endogenous analgesia in patients undergoing breast cancer surgery.

Abstract

Chronic pain following surgery, persistent postsurgical pain, is an important highly prevalent condition contributing to significant symptom burden and lower quality of life. Persistent postsurgical pain is relatively refractory to treatment hence generating a high need for preventive strategies and treatments. Therefore, the identification of patients at risk of developing persistent pain is an area of active ongoing research. Recently it was demonstrated that peri-operative disruptions in central pain processing may be able to predict persistent postsurgical pain at long term follow-up in breast cancer patients. The aim of the current report is to present a short protocol to obtain pain thresholds to different stimuli at multiple sites and a measure of endogenous analgesia in breast cancer patients. We have used this method successfully in a clinical context and detail some representative results from a clinical study.

Introduction

Chronic pain following surgery, persistent postsurgical pain, is an important condition contributing to significant symptom burden and lower quality of life¹. Persistent post-surgical pain remains poorly understood, but is broadly recognized as pain lasting more than 3 months after surgery². The condition is common, with estimates of its prevalence ranging from 10% to 50% of all postsurgical patients³. High-risk procedures include breast surgery⁴, thoracotomy⁵, limb amputation⁶, and hernia repair⁷. Pers....

Protocol

This protocol has been approved in the context of a previous randomized controlled trial⁸ by the human research ethics committee region Arnhem-Nijmegen, the Netherlands (nr. 2004/239).

1. Preparation for Testing

1. Informed consent:
   1. Review the informed consent form together with the patient.
   2. Answer any questions that patient may have regarding the study.
   3. Obtain written informed consent by having the patient sign the informed consent form and signing it yourself.
2. Testing environment:
   1. Perform all the measure....

Results

In a previously published clinical trial in women (N = 94) undergoing surgery for breast cancer, we measured electrical and pressure pain thresholds as well as CPM using the protocol described in this report⁸. We performed the testing paradigm pre-operatively and at various time points throughout the year following surgery. We found that women who developed persistent postsurgical pain 12 months after breast cancer surgery, defined as a VAS of >30 mm, e.......

Discussion

Our method of quantifying pressure pain thresholds, electrical pain thresholds, and CPM can be successfully applied in a clinical context given its short duration (~20 minutes). We have previously shown that pressure pain values obtained early after surgery may be of value in predicting persistent pain at long term follow-up in the context of breast cancer surgery⁸. While electrical pain thresholds CPM were not predictive of persistent pain in our study, others have shown that these measures may b.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Bed	N/A	N/A	Any type of hospital bed or medical exam table
Desk	N/A	N/A	Any type of commercially available desk
Office chair	N/A	N/A	Any type of commercially available office chair
Force FPX 50 Pressure algometer	Wagner Instruments, Greenwich, CT, USA	N/A	Pressure algometer with a 1.0 cm2 circular tip to deliver pressure to perform pressure pain threshold measurements
Desktop computer	N/A	N/A	Any type of commercially available Windows computer to run QST-IV Stimulus Manager software on to control the QST-IV stimulator
QST-IV Stimulus Manager	Embedded Control BV, Ruurlo, the Netherlands	N/A	Software to control the settings of QST-IV electrical stimulator
QST-IV Electrical Stimulator	Embedded Control BV, Ruurlo, the Netherlands	N/A	Electrical quantitative sensory testing device with a patient operated switch. Device used to deliver electrical current to perform the electrical threshold measurements
VAS Slider	Embedded Control BV, Ruurlo, the Netherlands	N/A	The VAS slider consists of a box with a mobile lever on a horizontal bar that represents the VAS and is connected to the QST-IV.
Kendall H34SG 50 x 45 mm	Covidien, Mansfield, USA	N/A	Self-adhesive skin electrodes to apply to the measurement points on the skin to deliver electrical stimualtion
Crushed Ice	N/A	N/A	Ice generated by ice machine to cool water sufficiently for the cold pressor test
Bucket	N/A	N/A	Any type of commercially available 10 L bucket
Surgical skin marker	Covidien, Mansfield, USA	N/A	Any type of commercially available surgical skin marker
Stopwatch	N/A	N/A	Any type of commercially available stopwatch
Measurement form	N/A	N/A	Score form provided in the manuscript
Pencil	N/A	N/A	Any type of commercially available pencil
Thermometer	N/A	N/A	Thermometer to measure water temperature of ice water
Ruler	N/A	N/A	Any type of commercially available ruler