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Less Efficacious Conditioned Pain Modulation and Sensory Hypersensitivity in Chronic Whiplash-associated Disorders in Singapore

Ng, Tze Siong PhD-C*,†,‡; Pedler, Ashley PhD; Vicenzino, Bill PhD*,§; Sterling, Michele PhD

The Clinical Journal of Pain: May 2014 - Volume 30 - Issue 5 - p 436–442
doi: 10.1097/AJP.0b013e3182a03940
Original Articles

Objectives: Cultural differences in pain perception exist. Although chronic whiplash-associated disorder (WAD) is well investigated in western countries, little is known about its presentation in Singapore. We studied the neck motion and pain sensitivity in people with chronic WAD in Singapore.

Materials and Methods: Thirty chronic WAD participants (>3 mo, Neck Disability Index: 40% [SD 17%]) were age, sex, and ethnicity matched with 30 pain-free controls. All 60 participants underwent the following tests: active neck motion, pain thresholds (pressure, brachial plexus provocation test [BPPT], cold), cold pain tolerance, and conditioned pain modulation (CPM). The test stimulus of contact heat and conditioning stimulus of cold water immersion was used to assess CPM. Data were evaluated to determine differences between WAD and control groups.

Results: Active neck motion (F 1,29=80.02), pain thresholds of blunt pressure (F 1,29=20.84), BPPT (F 1,29=54.56), and cold (Z=−4.31) were significantly lower in participants with WAD (P<0.0001). Cold pressor pain tolerance was significantly lower in participants with WAD (Z=−2.89, P=0.02). A less efficacious CPM was also demonstrated in participants with WAD (F 1,29=9.20, P=0.03). A combination of BPPT and cold hyperalgesia best predicted the WAD group (sensitivity=96.7%, specificity=96.7%).

Discussion: These findings of sensory hypersensitivity and decreased neck motion in Singaporeans with chronic WAD are consistent with physical impairments reported in western populations.

Physiotherapy Section, Department of Rehabilitation, National University Hospital, Singapore, Singapore

*Division of Physiotherapy, School of Health and Rehabilitation Sciences

§Centre for Clinical Excellence in Spinal Pain, Injury and Health, Division of Physiotherapy, The University of Queensland, St Lucia

Centre of National Research on Disability and Rehabilitation Medicine (CONROD), The University of Queensland, Herston, QLD, Australia

T.S.N.’s doctoral studies are supported by Ministry of Health and National University Hospital, Singapore. M.S. receives a fellowship from the National Health and Medical Research Council of Australia. The remaining authors declare no conflict of interest. Funding of the project was provided by School of Health and Rehabilitation Sciences, The University of Queensland.

Reprints: Michele Sterling, PhD, Centre of National Research on Disability and Rehabilitation Medicine (CONROD), Edith Cavell Building, University of Queensland, Herston, QLD 4029, Australia (e-mail:

Received March 3, 2013

Accepted June 8, 2013

© 2014 by Lippincott Williams & Wilkins