Pain, Central Sensitization and Psychoemotional State in Patients With Chronic Masticatory Muscle Pain

The aim of this study is to investigate the relationship of psychological aspects, selected blood parameters, pain, central sensitization, and muscle electromyography activity in patients with chronic masticatory muscle pain.

In this prospective cohort study, the study group will consist of 51 people with masticatory muscle pain lasting longer than 3 months, while the control group will involve 51 people without such disorder. Muscle type of temporomandibular disorders will be diagnosed on the basis of validated and standardized DC/TMD protocol. Additionally potential headaches will be assessed according to the ICHD-3, since coexistence of chronic masticatory muscle pain and headache is often observed. Psychological aspects will be analyzed using validated questionnaires regarding depression (PHQ-9), anxiety (GAD-7), perceived stress (PSS-10), satisfaction with life (SWLS), type D personality (DS-14) and coping with stress (Mini-COPE). Central Sensitization will be assessed using the Central Sensitization Inventory. Following blood substances will be assessed: serotonin, dopamine, Gamma-aminobutyric acid (GABA), Tumor Necrosis Factor α (TNF-α), CGRP, SERT, interleukin 1B, interleukin 6, interleukin 8, interleukin 10 and interleukin 17A. Additionally two polymorphisms of genes encoding proteins for serotonin receptors HTR2A - rs4941573 in intron 3 and dopamine DRD3 - rs6280 (Ser9Gly) will be analyzed. Pain assessment will be done using a validated and standardized questionnaire regarding chronic pain (GCPS) and an algometer and will include the measurement of pressure pain threshold in masseter and temporal muscles. In addition, potential autonomic disorders will be assessed using Autonomic Symptoms Questionnaire proposed by Low. Electromyographic muscle activity will be assessed by tetany test. The results of the study will allow for deeper understanding of the complex nature of orofacial pain of muscle origin and its connection with the mechanism of central sensitization, headache and muscle electromyographic activity. Measurement of blood parameters will provide more accurate information on the pathophysiology of these disorders and the use of validated questionnaires will provide valuable information about the mental state of patients.