Reliability of an intraoral extension for intraoral palpation and assessment of mechanical sensitivity of the temporal tendon.

BACKGROUND: The temporal tendon is a structure often compromised in patients suffering from temporomandibular disorders (TMD), yet its intraoral location makes a standardised assessment difficult. OBJECTIVES: To evaluate the variability and accuracy to target force of a newly designed intraoral extension for a palpometer device (Palpeter, Sunstar Suisse) when compared to manual palpation, in addition to clinically assessing the mechanical sensitivity and referred sensations of the temporal tendon in healthy individuals. METHODS: Experiment 1: 12 individuals were asked to target on a scale 0.5, 1 and 2 kg, for 2 and 5 s by using five different methods (Palpeter, Palpeter with three different extension shapes and manual palpation). Experiment 2: 10 healthy participants were recruited for a randomised double-blinded assessment by applying pressure of 0.5, 1 and 2 kg to the right temporal tendon with the three extensions and manual palpation. Participants rated the intensity of their sensation/pain on a 0-50-100 numeric rating scale (NRS), unpleasantness on a 0-100 NRS, and if present, they rated and drew the location of referred sensations. Repeated measures analysis of variance (ANOVA) was used in both experiments to compare differences between palpation methods. Tukey's HSD tests were used for the post hoc comparisons, and p values below .05 were considered significant. RESULTS: Experiment 1: The extensions showed no significant differences between them regarding reliability and accuracy for all forces and durations (p > .05). The manual method was significantly less reliable and accurate when compared to the other methods (p < .05). Experiment 2: There were no significant differences between the Palpeter extensions regarding pain intensity or unpleasantness NRS scores (p > .05), but all the extensions had significantly increased pain intensity and unpleasantness when compared to manual palpation (p < .05). Similarly, the frequency of referred sensations was similar between extensions but increased when compared to manual palpation. CONCLUSIONS: The new Palpeter extensions proved to be significantly more accurate and have lower test-retest variability than the manual method in a non-clinical setting. Clinically, they showed no significant differences in NRS scores for pain intensity nor unpleasantness, with no major differences in referred sensations, making any of the extensions suitable for clinical testing of the temporal tendon in future studies.

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

Temporomandibular disorders (TMD) patients can present clinically significant jaw pain fluctuations which can be debilitating and lead to poor global health. The Graded Chronic Pain Scale evaluates pain-related disability and its dichotomous grading (high/low impact pain) can determine patient care pathways and in general high-impact pain patients have worse treatment outcomes. Individuals with low-impact TMD pain are thought to have better psychosocial functioning, more favorable disease course, and better ability to control pain, while individuals with high-impact pain can present with higher levels of physical and psychological symptoms. Thereby, there is reason to believe that individuals with low- and high-impact TMD pain could experience different pain trajectories over time. Our primary objective was to determine if short-term jaw pain fluctuations serve as a clinical marker for the impact status of TMD pain. To this end, we estimated the association between high/low impact pain status and jaw pain fluctuations over three visits (≤ 21-day-period) in 30 TMD cases. Secondarily, we measured the association between jaw pain intensity and pressure pain thresholds (PPT) over the face and hand, the latter measurements compared to matched pain-free controls (n = 17). Jaw pain fluctuations were more frequent among high-impact pain cases (n = 15) than low-impact pain cases (n = 15) (OR 5.5; 95% CI 1.2, 26.4; p value = 0.033). Jaw pain ratings were not associated with PPT ratings (p value > 0.220), suggesting different mechanisms for clinical versus experimental pain. Results from this proof-of-concept study suggest that targeted treatments to reduce short-term pain fluctuations in high-impact TMD pain is a potential strategy to achieve improved patient perception of clinical pain management outcomes.

Assessment of Pain Modulatory and Somatosensory Profiles in Chronic Tension-Type Headache Patients.

OBJECTIVE: The aim of this study was to thoroughly phenotype a group of chronic tension-type headache (CTTH) patients. METHODS: Fifteen CTTH patients diagnosed according to the International Classification of Headache Disorders-3 and 15 healthy controls were included in this study. Furthermore, 70 healthy controls were included to establish normative values. Quantitative sensory testing (QST), including temporal summation of pain (TSP), conditioned pain modulation (CPM), and psychological and sleep variables, was assessed in a single session. TSP and CPM were then combined to build pain modulation profiles (PMP) for each individual. RESULTS: No difference was found between groups for PMP, TSP, and CPM. However, 10 CTTH patients showed a pronociceptive PMP, with 8 related to a deficient CPM and 2 to both a deficient CPM and increased TSP. Increased cold detection thresholds were the most common sensory disturbance found in CTTH patients. Significant differences were seen between groups for pain catastrophizing, depression, and sleep quality although not all patient's scores were above the clinically meaningful cutoffs. CONCLUSIONS: In summary, CTTH patients presented with different PMP. These PMP may be related to increased TSP, deficient CPM, alterations in thermal detection that may be related to autonomic dysregulation, or a combination of all three. Overall, this suggests that due to their heterogeneous pathophysiology, CTTH patients should be managed according to their underlying pathophysiology and not with a one-size-fits-all approach.

Systematic Mapping of Pressure Pain Thresholds of the Masseter and Temporalis Muscles and Assessment of Their Diversity Through the Novel Application of Entropy.

AIMS: To assess the diversity of pressure pain thresholds (PPTs) within the masseter and temporalis muscles by using the novel concept of entropy and to assess the differences in PPT scores between different sites of the masseter and temporalis muscles. METHODS: In this randomized, single-blinded study, the left and right masseter and temporalis muscles of 14 healthy volunteers were divided into 15 sites each, and the PPT was assessed for each of these sites. PPT assessments were performed in two different sessions. Entropy and center of gravity (COG) values were calculated for the PPTs of each muscle. Repeated measures analysis of variance was used to assess differences between muscles, sides, and sites for PPT, entropy, and COG scores. RESULTS: The main findings were: (1) PPT scores varied significantly between the masseter and temporalis muscles and within each of these muscles; (2) entropy values of PPT scores were not different between the masseter and temporalis muscles; and (3) COG values of PPT scores varied statistically, but these changes do not seem to be clinically relevant. CONCLUSION: The results of this study suggest that the anatomical layout of the masseter and temporalis muscles has implications for mechanical pain sensitivity and that areas have different sensitivities within these muscles. Furthermore, reference values for the entropy of PPTs in healthy individuals have been estimated, and comparing these values with those of patients with muscle-related pain conditions can provide quantitative information about the spatial heterogeneity of mechanical pain sensitivity, which may be a valuable clinical outcome measure.

Entropy of Masseter Muscle Pain Sensitivity: A New Technique for Pain Assessment.

AIMS: To test whether manipulation of mechanical pain sensitivity (MPS) of the masseter muscle is reflected in quantitative measures of entropy. METHODS: In a randomized, single-blinded, placebo-controlled design, 20 healthy volunteers had glutamate, lidocaine, and isotonic saline injected into the masseter muscle. Self-assessed pain intensity on a numeric rating scale (NRS) was evaluated up to 10 minutes following the injection, and MPS was evaluated after application (at 5 minutes and 30 minutes) of three different forces (0.5 kg, 1 kg, and 2 kg) to 15 different sites of the masseter muscle. Finally, the entropy and center of gravity (COG) of the pain sensitivity scores were calculated. Analysis of variance was used to test differences in means of tested outcomes and Tukey post hoc tests were used to adjust for multiple comparisons. RESULTS: The main findings were: (1) Compared with both lidocaine and isotonic saline, glutamate injections caused an increase in peak, duration, and area under the NRS pain curve (P < .01); (2) A pressure of 2 kg caused the highest NRS pain scores (P < .03) and entropy values (P < .02); (3) Glutamate injections caused increases in entropy values when assessed with 0.5 kg and 1.0 kg but not with 2.0 kg of pressure; and (4) COG coordinates revealed differences between the x coordinates for time (P < .01) and time and force for the y coordinates (P < .01). CONCLUSION: These results suggest that manipulation of MPS of the masseter muscle with painful glutamate injections can increase the diversity of MPS, which is reflected in entropy measures. Entropy allows quantification of the diversity of MPS, which may be important in clinical assessment of pain states such as myofascial temporomandibular disorders.