[32] Patients often report that their symptoms are worsened during periods of psychological stress. The etiology of the condition is unclear, although recent studies

have suggested the presence of a small-fiber sensory neuropathy, thus suggesting it is a form of neuropathic pain,[33, 34] but others propose a steroid dysregulation mechanism.[35] The condition can be difficult to manage, and a variety of RCTs have been reported, which include drug therapies and cognitive behavior therapy.36-38 Research on this condition is difficult to conduct in part due to its rarity and a lack of animal models; however, studies are being undertaken JQ1 datasheet that indicate evidence of central changes on functional magnetic resonance imaging (MRI), thus supporting the hypothesis that there are definite neurophysiological elements

to this condition, rather than it being a psychosomatic condition as has been previously suggested. TMDs are the most common causes of orofacial pain, affecting 10-15% of the population.[39, 40] Presenting features include pain localized to the pre- and post-auricular areas, the angle and ramus of the Protein Tyrosine Kinase inhibitor mandible, and the temporal region. There may be associated clicking, sticking, or locking of the temporomandibular joints. The pain may be intermittent or continuous, and is usually described as dull, aching, or throbbing, or in the words of patients: “weight on the side of the face getting heavier and heavier,” “pressure feeling,” “elastic band that is too tight,” or “needles digging in.” Some patients experience pain that is sharp or shooting in character, intermixed with dull continuous pain. The pain commonly radiates into the temporal or occipital regions into the neck and across the malar region of the face; it can be unilateral or bilateral, and of varying severity. There may be an associated bruxing or clenching habit. The pain is typically aggravated by opening the mouth wide, yawning, or chewing. There may be limitation of mouth opening.[41] TMD has historically been classified using the Research Diagnostic Criteria into myofascial pain, disc displacement, and other disorders,[42, 43] 上海皓元医药股份有限公司 as the International

Classification of Headache Disorders (ICHD)-II of TMD was not useful in clinical settings.[2] Newer classification criteria refer to myalgia, myofascial pain with referral, and myalgia with disc involvement.[41] A large prospective cohort study is currently underway in the USA investigating the prognostic factors related to the development of TMD.44-46 Participants with and without TMD participate in a battery of psychometric, biometric, and genetic tests. Baseline data on the psychological characteristics of the TMD cases demonstrate that this population shows higher levels of distress, catastrophizing, and increased somatic awareness compared with non-TMD controls. A number of other studies have reported similar findings.