Predictors of pain reduction following a program of manual therapies for patients with temporomandibular disorders: A prospective observational study.

BACKGROUND: Clinical guidelines recommend conservative treatment for the management of temporomandibular disorders (TMD), and manual therapy (MT) is commonly applied to reduce pain and improve function. OBJECTIVES: To identify predictors of pain reduction and functional improvement following a program of manual therapies (MTP) in patients with TMD and develop a first screening tool that could be used in clinical practice to facilitate decision-making. DESIGN: A cohort of 102 adults with a diagnosis of TMD were treated with four weekly sessions within a MTP applied to craniomandibular structures. Candidate predictors were demographic variables, general health variables, psychosocial features, TMD characteristics and related clinical tests. A reduction of pain intensity by at least 30% after the MTP was considered a good outcome. Logistic regression was adopted to develop the predictive model and its performance was assessed considering the explained variance, calibration, and discrimination. Internal validation of the prediction models was further evaluated in 500 bootstrapped samples. RESULTS: Patients experiencing pain intensity greater than 2/10 during mouth opening, positive expectations of outcome following a MTP, pain localized in the craniocervical region, and a low Central Sensitization Inventory score obtained a good outcome following the MTP. Predictive performance of the identified physical and psychological variables was characterized by high explained variance (R2 = 58%) and discrimination (AUC = 89%) after internal validation. A preliminary screening clinical tool was developed and presented as a nomogram. CONCLUSIONS: The high discrimination of the prediction model revealed promising findings, although these need to be externally validated in future research. TRIAL REGISTRATION NUMBER: NCT03990662.

Predictors of pain reduction following manual therapy in patients with temporomandibular disorders: a protocol for a prospective observational study.

INTRODUCTION: Temporomandibular disorders (TMDs) are principally characterised by pain in the craniomandibular area and probable limitations of jaw opening. Manual therapy, like other recommended conservative treatments included in clinical guidelines, is commonly used to treat patients with TMD to reduce pain and improve function. However, outcomes may be variable. The aim of this study is to identify predictors associated with pain reduction in patients with TMD following manual therapy by analysing a combination of patient-reported outcome measures and clinical tests. Such knowledge will support a more personalised management approach by facilitating clinical decision-making. METHODS/ANALYSIS: An observational prospective design will recruit a cohort of 100 adults with a diagnosis of TMD (according to Axis I of the Diagnostic Criteria for TMD) at a Dental Hospital in Italy. Patients will be treated with four weekly sessions of manual therapy applied to craniomandibular structures. An array of predictors has been chosen based on previous research on prognostic factors for TMD and altered pain modulation in musculoskeletal disorders. Candidate predictors including demographic variables, general health variables, psychosocial features, TMD characteristics and clinical tests of the temporomandibular joint and masticatory muscles will be collected at baseline. Definition of good outcome is a clinically significant reduction of pain intensity over the last week (≥30% reduction Visual Analogue Scale) immediately following the four week intervention. Exploratory factor analysis will be applied to analyse factor loading of candidate predictors for good outcome at four weeks. Subsequently, a logistic multivariable regression model will be performed to calculate low and high risk of good outcome. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the 'Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico' and University of Birmingham Ethics Committee. The results will be submitted for publication in a peer-reviewed journal and presented at conferences. TRIAL REGISTRATION NUMBER: NCT03990662; Pre-results.

Cognitive training with action-related verbs induces neural plasticity in the action representation system as assessed by gray matter brain morphometry.

Embodied cognition theories of semantic memory still face the need for multiple sources of converging evidence in support of the involvement of sensory-motor systems in action-related knowledge. Previous studies showed that training manual actions improves semantic processing of verbs referring to the trained actions. The present work aimed to provide complementary evidence by measuring the brain plasticity effects of a cognitive training requiring sustained lexical-semantic processing of action-related verbs. We included two groups of participants, namely the Proximal Group (PG) and the Distal Group (DG), which underwent a 3-week training with verbs referring to actions involving the proximal and the distal upper limb musculature, respectively. Before and after training, we measured gray matter voxel brain morphometry based on T1 structural magnetic resonance imaging. By means of this 2 (Group: PG, DG) × 2 (Time: pre-, post-training) factorial design, we tested whether sustained cognitive experience with specific action-related verbs induces congruent brain plasticity modifications in target regions of interest pertaining to the action representation system. We found significant post- versus pre-training gray matter volume increases, specifically for PG in the left dorsal precentral gyrus, and for DG in the right cerebellar lobule VIIa. These preliminary results suggest that a cognitive training can induce structural plasticity modifications in brain regions specifically coding for the distal and proximal motor actions the trained verbs refer to.