Do patients with chronic unilateral orofacial pain due to a temporomandibular disorder show increased attending to somatosensory input at the painful side of the jaw?

Stefaan Van Damme; Charlotte Vanden Bulcke; Linda Van Den Berghe; Louise Poppe; Geert Crombez

doi:10.7717/peerj.4310

Do patients with chronic unilateral orofacial pain due to a temporomandibular disorder show increased attending to somatosensory input at the painful side of the jaw?

PeerJ. 2018 Jan 24:6:e4310. doi: 10.7717/peerj.4310. eCollection 2018.

Authors

Stefaan Van Damme¹, Charlotte Vanden Bulcke¹, Linda Van Den Berghe², Louise Poppe^{1

3}, Geert Crombez^{1

4}

Affiliations

¹ Department of Experimental-Clinical and Health Psychology, Ghent University, Ghent, Belgium.
² Department of Dentistry, Ghent University Hospital, Ghent, Belgium.
³ Department of Movement and Sport Sciences, Ghent University, Ghent, Belgium.
⁴ Center for Pain Research, University of Bath, Bath, United Kingdom.

Abstract

Background: Patients with chronic orofacial pain due to temporomandibular disorders (TMD) display alterations in somatosensory processing at the jaw, such as amplified perception of tactile stimuli, but the underlying mechanisms remain unclear. This study investigated one possible explanation, namely hypervigilance, and tested if TMD patients with unilateral pain showed increased attending to somatosensory input at the painful side of the jaw.

Methods: TMD patients with chronic unilateral orofacial pain (n = 20) and matched healthy volunteers (n = 20) performed a temporal order judgment (TOJ) task indicated which one of two tactile stimuli, presented on each side of the jaw, they had perceived first. TOJ methodology allows examining spatial bias in somatosensory processing speed. Furthermore, after each block of trials, the participants rated the perceived intensity of tactile stimuli separately for both sides of the jaw. Finally, questionnaires assessing pain catastrophizing, fear-avoidance beliefs, and pain vigilance, were completed.

Results: TMD patients tended to perceive tactile stimuli at the painful jaw side as occurring earlier in time than stimuli at the non-painful side but this effect did not reach conventional levels of significance (p = .07). In the control group, tactile stimuli were perceived as occurring simultaneously. Secondary analyses indicated that the magnitude of spatial bias in the TMD group is positively associated with the extent of fear-avoidance beliefs. Overall, intensity ratings of tactile stimuli were significantly higher in the TMD group than in the control group, but there was no significant difference between the painful and non-painful jaw side in the TMD patients.

Discussion: The hypothesis that TMD patients with chronic unilateral orofacial pain preferentially attend to somatosensory information at the painful side of the jaw was not statistically supported, although lack of power could not be ruled out as a reason for this. The findings are discussed within recent theories of pain-related attention.

Keywords: Attentional bias; Chronic pain; Hypervigilance; Orofacial pain; Somatosensory processing; Spatial attention; TMD; Temporal order judgement.

Grants and funding

This work was supported by the Research Foundation Flanders (FWO), under grant number 3G005611. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.