Chronic myofascial temporomandibular pain is associated with neural abnormalities in the trigeminal and limbic systems
From: Pain. 2010 May;149(2):222-8. Epub 2010 Mar 16.
Myofascial pain of the temporomandibular region is a common, but poorly understood chronic disorder. It is unknown whether the condition is a peripheral problem, or a disorder of the central nervous system. To investigate possible central nervous system substrates of myofascial temporomandibular pain, the authors compared the brain morphology of 15 women with myofascial temporomandibular pain to that of 15 age- and gender-matched healthy controls. High-resolution structural brain and brainstem scans were carried out using magnetic resonance imaging (MRI), and data were analyzed using a voxel-based morphometry approach.
The myofascial temporomandibular pain group evidenced decreased or increased gray matter volume compared to controls in several areas of the trigeminothalamocortical pathway, including brainstem trigeminal sensory nuclei, the thalamus, and the primary somatosensory cortex. In addition, myofascial temporomandibular pain individuals showed increased gray matter volume compared to controls in limbic regions such as the posterior putamen, globus pallidus, and anterior insula. Within the myofascial temporomandibular pain group, jaw pain, pain tolerance, and pain duration were differentially associated with brain and brainstem gray matter volume. Self-reported pain severity was associated with increased gray matter in the rostral anterior cingulate cortex and posterior cingulate. Sensitivity to pressure algometry was associated with decreased gray matter in the pons, corresponding to the trigeminal sensory nuclei. Longer pain duration was associated with greater gray matter in the posterior cingulate, hippocampus, midbrain, and cerebellum. The pattern of gray matter abnormality found in myofascial temporomandibular pain individuals suggests the involvement of trigeminal and limbic system dysregulation, as well as potential somatotopic reorganization in the putamen, thalamus, and somatosensory cortex.
The association between neck disability and jaw disability
From: J Oral Rehabil. 2010 May 27. [Epub ahead of print]
The association between cervical spine disorders (CSD) and temporomandibular disorders (TMD) has been extensively investigated. However, no studies investigating the relationship between the level of jaw disability and neck disability have been published. Therefore, the objective of this study was to determine whether there was a relationship between neck disability measured using the neck disability index and jaw disability measured through the jaw function scale. A sample of 154 subjects who attended the TMD/Orofacial Pain clinic and students and staff at the University of Alberta participated in this study. All subjects were asked to complete the neck disability index, the jaw function scale, the jaw disability checklist (JDC), and the level of chronic disability of temporomandibular disorders (chronic pain grade disability questionnaire used in the RDC/TMD). Spearman rho test was used to analyse the relationship between neck disability and jaw disability. Multiple regression analysis was used to determine the association between the level of chronic disability of temporomandibular disorders and neck disability.
A strong relationship between neck disability and jaw disability was found. A subject with a high level of temporomandibular disorders disability (grade IV) increased by about 19 points on the neck disability index when compared with a person without temporomandibular disorders disability. These results have implications for clinical practice. If patients with temporomandibular disorders have neck disability in addition to jaw disability, treatment needs to focus on both areas because the improvement of one could have an influence on the other.
Jaw symptoms and signs and the connection to cranial cervical symptoms and post-traumatic stress during the first year after a whiplash trauma.
From: Disabil Rehabil. 2010 May 8. [Epub ahead of print]
The purpose of this study is to estimate the prevalence of jaw symptoms and signs during the first year after a neck sprain in a car collision. Further, to determine their relationships to the localisation and grade of the initial neck symptoms and signs, headache, post-traumatic stress and crash characteristics.
One hundred and forty-six adult subjects and crash characteristics were prospectively investigated in an in-depth study during 1997-2001. Head, neck, and jaw symptoms and signs were recorded within 5 weeks and after 1 year. Acute post-traumatic stress was estimated with the Impact of Event Scale-Revised (IES-R).
Jaw symptoms were initially reported by three men (5%) and three women (4%), and subsequently developed in eight women (10%) during the following year. Jaw signs were noted initially in 53 subjects (37%) and in 28 subjects (24%) after 1 year, without difference between sexes, and more often after low-speed impacts. Headache in females, cranial cervical symptoms, pronounced neck problems, post-traumatic stress and whiplash associated disorders (WAD) grade II-III after rear-end impacts were related to jaw signs during the acute phase. After 1 year, jaw signs were related to residual neck problems, headache and post-traumatic stress.
Jaw symptoms are seldom reported during the acute phase after a whiplash trauma. Women more often than men develop jaw symptoms during the first year. Jaw symptoms and signs may develop also after low-speed impacts, especially after rear-end collisions. Jaw symptoms and signs should be observed after whiplash trauma, especially in those with headache, pronounced neck problems, cranial neck symptoms and post-traumatic stress.
Cardiovascular and muscle activity during chewing in whiplash-associated disorders (WAD).
From: Arch Oral Biol. 2010 Apr 20. [Epub ahead of print]
The present study aimed to elucidate possible physiological mechanisms behind impaired endurance during chewing as previously reported in whiplash associated disorders. We tested the hypothesis of a stronger autonomic reaction in whiplash associated disorders than in healthy subjects in response to dynamic loading of the jaw and neck motor system.
Cardiovascular reactivity, muscle fatigue indicies of EMG, and perceptions of fatigue, exhaustion and pain were assessed during standardised chewing. Twenty-one whiplash associated disorders subjects and a gender/age matched control group participated. Baseline recordings were followed by two sessions of alternating unilateral chewing of a bolus of gum with each session followed by a rest period.
More than half of the whiplash associated disorders subjects terminated the test prematurely due to exhaustion and pain. In line with our hypothesis the chewing evoked an increased autonomic response in whiplash associated disorders exhibited as a higher increase in heart rate as compared to controls. Furthermore, we saw consistently higher values of arterial blood pressure for whiplash associated disorders than for controls across all stages of the experiment. Masseter EMG did not indicate muscle fatigue nor were there group differences in amplitude and mean power frequency. Pain in the whiplash associated disorders group increased during the first session and remained increased, whereas no pain was reported for the controls.
More intense response to chewing in whiplash associated disorders might indicate pronounced vulnerability to dynamic loading of the jaw and neck motor system with increased autonomic reactivity to the test. Premature termination and autonomic involvement without EMG signs of muscle fatigue may indicate central mechanisms behind insufficient endurance during chewing.
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Sleep continuity and architecture: associations with pain-inhibitory processes in patients with temporomandibular joint disorder.
From: Eur J Pain. 2009 Nov;13(10):1043-7. Epub 2009 Jan 24
Recent research suggests bi-directional interactions between the experience of pain and the process of sleep; pain interferes with the ability to obtain sleep, and disrupted sleep contributes to enhanced pain perception. Our group recently reported, in a controlled experimental study, that sleep fragmentation among healthy adults resulted in subsequent decrements in endogenous pain inhibition. The present report follows up that observation by extending this line of research to a sample of patients experiencing persistent pain. Patients with chronic temporomandibular joint disorder pain were studied using polysomnography and psychophysical evaluation of pain responses. The authors assessed whether individual differences in sleep continuity and/or architecture were related to diffuse noxious inhibitory controls, a measure of central nervous system pain inhibition. Among 53 temporomandibular joint disorder patients, higher sleep efficiency and longer total sleep time were positively associated with better functioning of diffuse noxious inhibitory controls. These results suggest the possibility that disrupted sleep may serve as a risk factor for inadequate pain-inhibitory processing and hint that aggressive efforts to treat sleep disturbance early in the course of a pain condition might be beneficial in reducing the severity or impact of clinical pain.
Related:
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Development of temporomandibular disorders is associated with greater bodily pain experience
From: Clin J Pain. 2010 Feb;26(2):116-20
The aim of this study is to examine the difference in the report of bodily pain experienced by patients who develop temporomandibular disorders and by those who do not develop temporomandibular disorders over a 3-year observation period.
This is a 3-year prospective study of 266 females aged 18 to 34 years initially free of temporomandibular disorders pain. All patients completed the Symptom Report Questionnaire (SRQ) at baseline and yearly intervals, and at the time they developed temporomandibular disorders (if applicable). The SRQ is a self-report instrument evaluating the extent and location of pain experienced in the earlier 6 months. Statistical analysis was carried out using repeated measures ANOVA.
Over the 3-year period, 16 patients developed temporomandibular disorders based on the Research Diagnostic Criteria for temporomandibular disorders. Participants who developed temporomandibular disorders reported more headaches, muscle soreness or pain, joint soreness or pain, back pain, chest pain, abdominal pain, and menstrual pain than Participants who did not develop temporomandibular disorders at both the baseline and final visits. Participants who developed temporomandibular disorders also reported significantly more headache, muscle soreness or pain, and other pains when they were diagnosed with temporomandibular disorders compared with the baseline visit.
The development of temporomandibular disorders was accompanied by increases in headaches, muscle soreness or pain, and other pains that were not observed in the Participants who did not develop temporomandibular disorders. Participants who developed temporomandibular disorders also report higher experience of joint, back, chest, and menstrual pain at baseline.
Does a dose-response relation exist between spinal pain and temporomandibular disorders?
From: BMC Musculoskelet Disord. 2009 Mar 2;10:28
Temporomandibular disorders are musculoskeletal pain conditions characterised by pain and dysfunction in the jaw-face muscles and/or the temporomandibular joint. Musculoskeletal pain conditions occurring at various locations may share pathophysiological mechanisms. Co-morbidity between temporomandibular disorders, headaches and neck/shoulder pain has been reported in temporomandibular disorders patient samples as well as in samples drawn from the general population. Low back pain, one of the most common pain conditions in humans, has been associated with other pains such as neck pain and headaches, which has been interpreted as a tendency for symptoms to cluster in some individuals. The source of these patterns is not known, but neurobiological sensitization processes, genetically determined vulnerability and psychological factors are commonly given as possible explanations. Results of a 3-year prospective study showed a significantly increased risk of developing a new pain condition with presence of a pain condition at baseline. A more recent prospective study based on patients with non-painful temporomandibular disorders indicated a dose-response relationship between the number of pain sites at baseline (head, back, chest, stomach) and the risk of onset of dysfunctional temporomandibular disorders pain among women. Frequency of headaches was found to have a dose-response relationship with occurrence of musculoskeletal symptoms (e.g. pain in neck, shoulders and low back) in a Norwegian population.
The authors have recently shown that patients with long-term spinal pain (neck, shoulder and/or low back) significantly more often have signs and symptoms of temporomandibular disorders than do matched controls. The associations remained statistically significant also after exclusion of those who reported jaw pain. It is not known whether co-morbidity between temporomandibular disorders and neck pain, shoulder pain and/or low back pain occurs within the whole range of variation in symptom frequency and severity. Most analyses in this field have involved dichotomized samples, not taking variations of symptom severity into consideration. The aim of the present study was to test whether a reciprocal dose-response relation exists between frequency and severity of neck pain, shoulder pain and/or low back pain and temporomandibular disorders. The authors tested the following null hypotheses:
1. Occurrence of frequent temporomandibular disorders symptoms and headaches does not differ significantly between study groups with varying frequency and severity of neck pain, shoulder pain and/or low back pain.
2. Presence of frequent neck pain, shoulder pain and/or low back pain does not differ significantly between study groups with varying frequency and severity of temporomandibular disorders symptoms.
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Relationship between head posture and dentofacial morphology in patients with TMJ osteoarthritis or osteoarthrosis
From: World J Orthod. 2008 Winter;9(4):329-36
To test whether there is a relationship between head and neck posture and dentofacial morphology in patients with temporomandibular joint osteoarthritis or osteoarthrosis. The subjects consisted of 34 Japanese females with temporomandibular joint osteoarthritis or osteoarthrosis (aged 24.7 +/- 6.1 years). Six craniocervical angular measurements were constructed for head posture. Two angular and 6 linear measurements were constructed for the skeletal relationship, while 1 angular and 6 linear measurements were constructed for the dental relationship. Pearson correlation coefficients were calculated between head posture and dentofacial variables.
In the skeletal relationship, increased craniocervical angulations were significantly associated with a more posterior position of the maxilla, a decreased Frankfort to mandibular plane angle, decreased mandibular length, and a decreased lower facial height. In the dental relationship, increased craniocervical angulations were significantly associated with more posterior positions of the anterior teeth to the basal bone and decreased alveolar height of the anterior-posterior teeth. The hypothesis was rejected. These results suggest that an association may exist between head and neck posture and dentofacial morphology in patients with temporomandibular joint osteoarthritis or osteoarthrosis.
The impact of orofacial pain on the quality of life of patients with temporomandibular disorder
From: J Orofac Pain. 2009 Winter;23(1):28-37
To evaluate the relationships between gender, diagnosis, and severity of temporomandibular joint disorders with self-reports of the impact of temporomandibular joint disorders on the quality of life, eighty-three individuals seeking temporomandibular joint disorders treatment at the Dental School of Pontifical Catholic University Minas from May to August 2005 were evaluated by a single examiner who was trained and calibrated for diagnosis according to criteria of Axis I of the Research Diagnostic Criteria for temporomandibular joint disorders. The severity of temporomandibular joint disorders was established by the Temporomandibular Index and the impact on quality of life by the Oral Health Impact Profile. Complete data were available for 78 of the 83 initial patients and evaluated by the Mann-Whitney test and Spearman correlation analysis.
Except for one patient, all individuals showed some impact related to physical pain. Of the seven aspects evaluated on the Oral Health Impact Profile, women presented a greater impact than men only for functional limitations. Patients presenting with diagnoses of muscular disorders (group I) or osteoarthritis (group III) reported a greater impact than those without. The Spearman test demonstrated a significant correlation between impact on quality of life and severity of temporomandibular joint disorders. Orofacial pain had a great impact on the quality of life of individuals with temporomandibular joint disorders, without group difference between genders. The presence of muscular disorders (group I) and osteoarthritis (group III) was related to greater impact on quality of life, which was not observed for diagnoses of disc displacement (group II). A correlation between severity of temporomandibular joint disorders and impact on quality of life was clearly observed.
Correlation between MRI evidence of degenerative condylar surface changes, induction of articular disc displacement and pathological joint sounds in the temporomandibular joint
From: Gerodontology. 2008 Dec;25(4):251-7. Epub 2008 Feb 27
The relationship of bony changes in the condylar surfaces in articular disc displacement without reduction in temporomandibular joint was investigated using diagnostic imaging. The study also evaluated whether the bony changes in the condylar surfaces limit disc and condyle motion, and produce pathological joint sounds.
Thirty seven temporomandibular joints in 28 patients diagnosed with degenerative bony changes in the condylar surfaces radiographically and anterior disc displacement without reduction using magnetic resonance imaging (MRI) were studied. The bony changes were assessed by radiographic examination and classified into two types: pathological bone changes including erosion, osteophyte formation and deformity, and adaptive bone changes including flattening and concavity. MRI was performed on the temporomandibular joint to examine the configuration and position of the discs. Joint sounds in the temporomandibular joint were determined using electrovibratograghy with a joint vibration analysis.
The articular disc motion to the condyle in the pathological bone changes group was smaller than in the adaptive bone changes group irrespective of the configuration of the disc, even though there were no significant differences between the two types of bony changes in the disc position during jaw closing. The joint vibration analysis of the temporomandibular joint showed that joint sounds with a higher frequency were observed in the pathological bone changes group than in the adaptive bone changes group. High energy levels needed to produce the higher frequencies were observed only in the pathological bone changes group.
