ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 447

Discriminating between Central & Peripheral Pain Sensitization Using a Slowly Repeated Evoked Pain Protocol

Manuel Romero1, Stephen Bruehl2, Gustavo A Reyes del Paso3 and Pablo De la Coba3, 1University Hospital of Jaén, Jaén, Spain, 2Department of Anesthesiology, Vanderbilt University, Nashville, TN, 3Department of Psychology, University of Jaén, Jaén, Spain

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: , , ,

Session Information

Date: Sunday, October 21, 2018

Session Title: Pain Mechanisms – Basic and Clinical Science Poster

Session Type: ACR Poster Session A

Session Time: 9:00AM-11:00AM

Background/Purpose:

  • In a prior study, the response of pain sensitization by fibromyalgia (FM) patients to a protocol of Slowly Repeated Evoked Pain (SREP)* was strongly associated with clinical pain. However, this protocol needs further investigation regarding its underlying mechanisms and clinical usefulness.

* SREP differs from Temporal Summation of Pain (TSP) in which the frequency of painful stimuli is usually around 0.33 Hz in TSP, whereas it is 10 times slower (0.03 Hz) in SREP.

  • This study explored the central vs. peripheral origin of the pain sensitivity observed in response to SREP protocol when this was applied to patients with chronic pain characterized by central sensitization (FM) vs. characterized by peripheral sensitization (rheumatoid arthritis, RA) vs. healthy controls (HC).

Methods:

  • Fifty-nine patients with FM, 30 with RA, and 50 HC matched in socio-demographic variables participated in this study.
  • Potential group differences of psychological factors were controlled: Clinical Pain (McGill Questionnaire), Anxiety and Depression (HADS), and Catastrophization (CSQ).
  • Participants were instructed in the use of a Visual Analogue Scale (VAS) to assess the pain caused by a pressure algometer on the nail of the third finger.
  • Threshold and tolerance were obtained to calculate the intensity of the pain stimulus individually for each participant. Then, a series of 9 pain stimuli of 5s duration and low-moderate intensity was applied at a 30s interval.
  • SREP sensitization index was quantified as the difference in pain scores between the 9th and 1st painful stimuli.

Results:

  • The repeated measures ANOVA showed a significant increase in subjective pain ratings of the SREP series exclusively for the FM group (see Figure).
  • Logistic regressions revealed an acceptable diagnostic accuracy of SREP index to discriminate between FM & AR and FM & HC, but not between AR & HC (see Table).

Conclusion:

  • SREP seems to be based on central processes rather than to be related to peripheral sensitization.
  • SREP could be presented as a simple tool that would allow in a complementary way to explore the level of central pain sensitization in patients with chronic pain.
  • Potential clinical utility of SREP warrants further investigation.

Disclosure: M. Romero, None; S. Bruehl, None; G. A. Reyes del Paso, None; P. De la Coba, None.

To cite this abstract in AMA style:

Romero M, Bruehl S, Reyes del Paso GA, De la Coba P. Discriminating between Central & Peripheral Pain Sensitization Using a Slowly Repeated Evoked Pain Protocol [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/discriminating-between-central-peripheral-pain-sensitization-using-a-slowly-repeated-evoked-pain-protocol/. Accessed January 20, 2021.

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