Evidence for Central Sensitization in Patients with Temporomandibular Disorders: A Systematic Review and Meta-analysis of Observational Studies.

OBJECTIVES: Several authors have evaluated different pain measurements, including quantitative sensory testing (QST), temporal summation (TS), and conditioned pain modulation (CPM) in order to determine the presence of central sensitization (CS) and its influence on patients with temporomandibular disorders (TMD). Since there are no convincing studies about this topic, the purpose of this study was to conduct a review of the studies involving CS-related measures in TMD patients. METHODS: A meta-analysis of case-control and cohort/cross sectional studies was conducted. Standardized mean differences (SMD) and 95% confidence intervals (CIs) were calculated for relevant QST outcomes and pooled in a meta-analysis using the random effects model. Twenty-two studies (eleven case-control and eleven cross sectional studies) met the inclusion criteria; eight were included in the meta-analysis (five cross-sectional and three case-control). Patients with TMD had decreased pressure pain thresholds in both trigeminal (five studies; n = 1,985; SMD = -1.55, 95% CI -2.23 to -0.77; P < 0.01) and remote areas (five studies; n = 1,985; SMD = -1.92, 95% CI -2.95 to -0.89; P < 0.01). When analyzing for thermal hyperalgesia (hot and cold pain thresholds), differences were not found in trigeminal areas or remote areas in patients with TMD. The TS qualitative analysis showed strong evidence of spinal hyperexcitability for mechanically evoked pain. CONCLUSION: These meta-analyses support the existence of differences in widespread pressure pain sensitivity in patients with TMD when compared with asymptomatic subjects. Spinal and central hyperexcitability can be found in TMD patients as shown by an increase in mechanical TS.

EFFECTIVENESS OF A MOTOR CONTROL THERAPEUTIC EXERCISE PROGRAM COMBINED WITH MOTOR IMAGERY ON THE SENSORIMOTOR FUNCTION OF THE CERVICAL SPINE: A RANDOMIZED CONTROLLED TRIAL.

BACKGROUND: Motor control therapeutic exercise (MCTE) for the neck is a motor relearning program that emphasizes the coordination and contraction of specific neck flexor, extensor, and shoulder girdle muscles. Because motor imagery (MI) improves sensorimotor function and it improves several motor aspects, such as motor learning, neuromotor control, and acquisition of motor skills, the authors hypothesized that a combination of MCTE and MI would improve the sensorimotor function of the cervical spine more effectively than a MCTE program alone. PURPOSE: The purpose of this study was to investigate the influence of MI combined with a MCTE program on sensorimotor function of the craniocervical region in asymptomatic subjects. STUDY DESIGN: This study was a single-blinded randomized controlled trial. METHODS: Forty asymptomatic subjects were assigned to a MCTE group or a MCTE+MI group. Both groups received the same MCTE program for the cervical region (60 minutes), but the MCTE+MI group received an additional intervention based on MI (15 minutes). The primary outcomes assessed were craniocervical neuromotor control (activation pressure value and highest pressure value), cervical kinesthetic sense (joint position error [JPE]), and the subjective perception of fatigue after effort. RESULTS: Intra-group significant differences were obtained between pre- and post interventions for all evaluated variables (p<0.01) in the MCTE+MI and MCTE groups, except for craniocervical neuromotor control and the subjective perception of fatigue after effort in the MCTE group. In the MCTE+MI group a large effect size was found for craniocervical neuromotor control (d between -0.94 and -1.41), cervical kinesthetic sense (d between 0.97 and 2.14), neck flexor muscle endurance test (d = -1.50), and subjective perception of fatigue after effort (d = 0.79). There were significant inter-group differences for the highest pressure value, joint position error (JPE) extension, JPE left rotation, and subjective perception of fatigue after effort. CONCLUSION: The combined MI and MCTE intervention produced statistically significant changes in sensorimotor function variables of the craniocervical region (highest pressure value, JPE extension and JPE left rotation) and the perception of subjective fatigue compared to MCTE alone. Both groups showed statistically significant changes in all variables measured, except for craniocervical neuromotor control and the subjective perception of fatigue after effort in the MCTE group. LEVEL OF EVIDENCE: 1b.