Endogenous pain modulation assessed with offset analgesia is not impaired in chronic temporomandibular disorder pain patients

Abstract

Background: Abnormal endogenous pain modulation (EPM) was suggested as a pathophysiological characteristic of chronic pain. EPM has been investigated using psychophysical tests for pain facilitation and inhibition such as temporal summation of pain and conditioned pain modulation, respectively. Another psychophysical test for pain inhibition is offset analgesia (OA), where small variations in noxious stimulus intensity over time elicit a disproportionately large analgesic response. OA has been investigated in patients with mixed pain conditions, but not in chronic temporomandibular disorder (TMD) patients. Objective: To compare OA responses in chronic TMD female cases to age-matched, pain-free female controls. Methods: Offset analgesia was assessed by applying noxious heat over the non-dominant forearm of chronic TMD cases (n = 22) and controls (n = 17), using a previously reported paradigm with individualised test temperatures (TT): T1(5 seconds) = TT, T2(5 seconds) = TT + 1°C and T3(20 seconds) = TT. Clinical and psychosocial characteristics were measured. Main outcomes for OA were delta computerised visual analogue scale (COVAS), per cent change (T2-T3/T2-T1) and area under the curve (AUC) ratio of pain ratings controlling for TT. Results:No statistically significant between-group differences were found for delta COVAS (TMD cases mean ± SD = 53.5 ± 22.0; controls = 51.6 ± 22.9, P = 0.876) and per cent change (T2-T3/T2-T1) (cases mean = 327.2 ± 375.1; controls = 226.9 ± 553.4, P = 0.515), with both groups presenting a robust OA response. TMD cases perceived more pain during OA trials than controls, as measured by AUC ratio (mean difference [95% CI] = −15.6 [−26.9, −3.5], P = 0.017). Conclusion:Chronic TMD cases presented with similar OA response over the forearm as controls; however, they experienced greater pain during testing. Future studies including this patient population should investigate OA responses over painful body sites, for example, jaw/face. K E Y W O R D Schronic oro-facial pain, endogenous pain modulation, musculoskeletal pain, offset analgesia, psychophysics, temporomandibular disorders

The effect of acute‐experimental pain models on offset analgesia

“…Studies have shown that cold pain (Nissen et al, 2018) and isometric exercise (Harris et al, 2018) did not affect OA when measured at a remote test site. Interestingly, even in patients with chronic temporomandibular disorder, another trigeminal pathology, the OA response was normal, but again, the measurement was performed outside of the trigeminal system (Moana-Filho et al, 2019). These results can be explained by different methodological and analytical approaches.…”

Persistent dentoalveolar pain disorder: A putative intraoral chronic overlapping pain condition

“…Other study supporting central amplification of pain in PDAP patients showed greater activation in brain regions related to the sensory‐discriminative and cognitive components of pain perception in patients relative to pain‐free controls following matched dentoalveolar pressure intensity stimulation during functional magnetic resonance imaging (Moana‐Filho, Bereiter, & Nixdorf, ). Put together, these findings suggest dysfunction of endogenous pain modulation mechanisms and brain‐related pain amplification following dentoalveolar mechanical painful stimulus (Moana‐Filho et al, ; Nasri‐Heir et al, ) similarly to other proposed COPCs such as TMD (Moana‐Filho, Herrero Babiloni, & Nisley, ; Moana‐Filho, Herrero Babiloni, & Theis‐Mahon, ) and fibromyalgia (O'Brien, Deitos, Trinanes Pego, Fregni, & Carrillo‐de‐la‐Pena, ; Sawaddiruk, Paiboonworachat, Chattipakorn, & Chattipakorn, ).…”

Temporomandibular disorders cases with high-impact pain are more likely to experience short-term pain fluctuations

“…Data reported here were collected as part of a parent study conducted at the University of Minnesota School of Dentistry (UMN SOD) assessing somatosensory characteristics and neuroimaging outcomes from participants with chronic TMD pain and pain-free controls 44 , 45 . Of the 52 female participants enrolled in the parent study, five had partial data missing which prevented them to be considered for the present study.…”

“…All participants were informed in detail about the experimental protocol and gave oral and written informed consent before entering the study. Full description of the experimental protocol can be found elsewhere 44 , 45 . Briefly, data were collected during three experimental visits, each of them separated by a 2–4 day period which is defined here as “short-term”.…”