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Investigation of Central Pain Processing in Postoperative Shoulder Pain and Disability

Valencia, Carolina PT, PhD*; Fillingim, Roger B. PhD†,‡; Bishop, Mark PT, PhD§; Wu, Samuel S. PhD; Wright, Thomas W. MD; Moser, Michael MD; Farmer, Kevin MD; George, Steven Z. PT, PhD§

doi: 10.1097/AJP.0000000000000029
Original Articles

Background: Measures of central pain processing like conditioned pain modulation and suprathreshold heat pain response (SHPR) have been described to assess different components of central pain modulatory mechanisms. Central pain processing potentially plays a role in the development of postsurgical pain, however, the role of conditioned pain modulation and SHPR in explaining postoperative clinical pain and disability is still unclear.

Methods: Seventy-eight patients with clinical shoulder pain were included in this study. Patients were examined before shoulder surgery, at 3 months, and 6 months after surgery. The primary outcome measures were pain intensity and upper extremity disability.

Results: Analyses revealed that the change score (baseline- 3 mo) of fifth pain rating of SHPR accounted for a significant amount of variance in 6-month postsurgical clinical pain intensity and disability after age, sex, preoperative pain intensity, and relevant psychological factors were considered.

Conclusions: The present study suggests that baseline measures of central pain processing were not predictive of 6-month postoperative pain outcome. Instead, the 3-month change in SHPR might be a relevant factor in the transition to an elevated 6-month postoperative pain and disability outcomes. In patients with shoulder pain, the 3-month change in a measure of central pain processing might be a relevant factor in the transition to elevated 6-month postoperative pain and disability scores.

*Department of Applied Medicine and Rehabilitation, Sycamore Center for Wellness & Applied Medicine, Indiana State University, Terre Haute, IN

Departments of §Physical Therapy

Biostatistics

Orthopedics and Rehabilitation

College of Dentistry, University of Florida

North Florida/South Georgia Veterans Health System, Gainesville, FL

Supported by grant #AR055899 from NIAMS/NIH, Gainesville, Florida, USA. The authors declare no conflict of interest.

Reprints: Carolina Valencia, PT, PhD, Department of Applied Medicine and Rehabilitation, Sycamore Center for Wellness & Applied Medicine, Indiana State University, 567 North 5th Street, Terre Haute, IN 47809 (e-mail: carolina.valencia@indstate.edu).

Received April 1, 2013

Received in revised form December 9, 2013

Accepted September 3, 2013

© 2014 by Lippincott Williams & Wilkins