Intermittent intracranial condylar dislocation with minimal functional sequelae.

Degenerative changes of the temporomandibular joint (TMJ) present with a broad spectrum of morphological alterations. However, erosions leading to a glenoid fossa defect and condylar impingement of the temporal lobe are a rare finding. A 77-year-old female patient presented with limited mouth opening and pre-auricular pain during mastication on the left side. She denied any neurological dysfunction. Her medical history included poliomyelitis, multiple cancers, and osteonecrosis of the left tibial plateau. Computed tomography revealed advanced degeneration of both TMJs. On the left side, a glenoid fossa fragment was elevated towards the left middle cranial fossa. Real-time dynamic magnetic resonance imaging (MRI) showed repetitive intracranial condylar dislocation during mouth closure. She declined surgery and received instructions for self-management. At the 12-month follow-up, she reported resolution of the pain and normal masticatory function. A control MRI showed a stable radiographic appearance. This report illustrates that intermittent dislocation of the mandibular condyle into the middle cranial fossa can be successfully managed conservatively. The self-limiting nature of the TMJ degenerative joint disease, patient preference, and the patient's general health status require consideration when advising patients on the therapeutic strategy.

Quality of life, chronic pain, insomnia, and jaw malfunction in patients after alloplastic temporomandibular joint replacement: a questionnaire-based pilot study.

Studies of patients undergoing alloplastic total temporomandibular joint replacement seldom report on quality of life (QoL) and sleep. The aim of this pilot study was to assess these factors in such a patient cohort using validated psychometric questionnaires. Data were collected via online surveys comprising the following six questionnaires: Short Form-12 Health Survey (SF-12), Patient Health Questionnaire-15, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30, Insomnia Severity Index, Graded Chronic Pain Scale, and Jaw Disability List. Pain intensity, limitation in nutrition, and treatment satisfaction were assessed using numerical rating scales. Mouth opening was measured at follow-up. The SF-12 Physical Composite Score was markedly lower than that of the age-matched general population, whereas the Mental Composite Score did not differ significantly. Participants indicated a low somatization level and low level of disability due to pain, but reduced QoL. Clinically relevant insomnia was reported by 36% of participants. In conclusion, the results of this pilot study indicate that QoL and sleep in patients with a total temporomandibular joint replacement differ from those in the general population, indicating the need for a comprehensive outcome assessment utilizing validated psychometric tools in accordance with the current biopsychosocial model of chronic disorders.

[Validation of the German-language version of the Injustice Experience Questionnaire (IEQ) in five outpatient clinics]. / Validierung der deutschen Übersetzung des Injustice Experience Questionnaire (IEQ) in 5 ambulanten Schmerzbehandlungseinrichtungen.

INTRODUCTION: Occupational and social rehabilitation can be influenced by perceived injustice that results from pain. Currently, the Injustice Experience Questionnaire (IEQ), the tool most commonly used to assess perceived injustice, is not available in German. The aim of this study was the validation of the German-language version of the IEQ. MATERIALS AND METHODS: The validation of the IEQ was carried out via a web-based survey. For this purpose, participants completed the IEQ and construct-related scales analogous to the original study Tampa Scale of Kinesiophobia (TSK), Depression scale of the Depression Anxiety and Stress Scales (D-DASS), Pain Disability Index (PDI), and McGill Pain Questionnaire (MPQ). In addition, the participants completed questions on their socioeconomic status and on the cause of their pain, taken from the German Pain Questionnaire. RESULTS: Of 223 respondents, 134 (60.1%) returned a completed questionnaire and were included in the study. In all, 26.1% of participants reported suffering from pain resulting from accidents. None of the reviewed one- to three-factor solutions for the IEQ's structure achieved a good model fit. The best results were found for a two-factor solution, whereby the exploratory factor analysis revealed almost all items loaded highly on both factors and the confirmatory factor analysis showed high correlations between the factors. These findings are consistent with previous studies. The IEQ correlated highly and significantly with the other psychological instruments. There were no floor or ceiling effects. Cronbach's α for the German IEQ version was 0.93 and thus attests a high level of internal consistency. CONCLUSION: The analyses attest the excellent psychometric properties of the German translation of the IEQ and so the German-language version of the IEQ can be used as a validated questionnaire to screen for perceived injustice.

[German transcultural translation of the Injustice Experience Questionnaire]. / Deutsche transkulturelle Übersetzung des Injustice Experience Questionnaire.

BACKGROUND: Occupational and social rehabilitation is influenced by perceived injustice as a result of injury. To assess perceived injustice, the Injustice Experience Questionnaire (IEQ) has been developed and is available in English. The aim of this study was to translate and culturally adapt the English version of the IEQ into German. MATERIALS AND METHODS: The IEQ was translated into German according to the criteria for the transcultural adaptation of self-assessment tools. The translation was examined in a sample of 19 pain patients as to whether the translated items were comprehensible, unacceptable or offensive, and what their meaning and the reason for the chosen response were. Data were assessed using nonparametric statistical methods. RESULTS: The German translation of the IEQ showed a high degree of comprehensibility. The items' meanings and participants' selected answer options were rated as highly plausible by two raters and the wording of the items was assessed as being neither unacceptable nor offensive by participants. Because of the slightly increased values with regard to Item 3, whose meaning was unrecognized by the raters, the term "Unachtsamkeit" was replaced by "Unaufmerksamkeit." CONCLUSION: The study attests to the cultural and linguistic intelligibility and precision of the German translation of the IEQ. In a follow-up study, the translation should be validated in a larger sample of pain patients.

Alloplastic total temporomandibular joint replacements: do they perform like natural joints? Prospective cohort study with a historical control.

The aim of this study was to qualitatively and quantitatively describe the biomechanics of existing total alloplastic reconstructions of temporomandibular joints (TMJ). Fifteen patients with unilateral or bilateral TMJ total joint replacements and 15 healthy controls were evaluated via dynamic stereometry technology. This non-invasive method combines three-dimensional imaging of the subject's anatomy with jaw tracking. It provides an insight into the patient's jaw joint movements in real time and provides a quantitative evaluation. The patients were also evaluated clinically for jaw opening, protrusive and laterotrusive movements, pain, interference with eating, and satisfaction with the joint replacements. The qualitative assessment revealed that condyles of bilateral total joint replacements displayed similar basic motion patterns to those of unilateral prostheses. Quantitatively, mandibular movements of artificial joints during opening, protrusion, and laterotrusion were all significantly shorter than those of controls. A significantly restricted mandibular range of motion in replaced joints was also observed clinically. Fifty-three percent of patients suffered from chronic pain at rest and 67% reported reduced chewing function. Nonetheless, patients declared a high level of satisfaction with the replacement. This study shows that in order to gain a comprehensive understanding of complex therapeutic measures, a multidisciplinary approach is needed.

[Distinctive features of orofacial pain perception]. / Besonderheiten der orofazialen Schmerzempfindung.

BACKGROUND: In the widely used German pain questionnaire, qualitative pain characteristics are assessed by the Schmerzbeschreibungsliste (SBL). In clinical practice these adjectives insufficiently cover the spectrum of orofacial pain perceptions (OFP) and have not been proven by data. The aim of this study was the analysis of a questionnaire focussing on OFP (ZZM-FB) in which nine additional pain descriptors were amended to the SBL (SBL-OF). OBJECTIVES: The objectives of this work were to (1) compare selection frequencies between the items of the SBL and the SBL-OF and (2) test the null hypothesis that the SBL and SBL-OF item selection is not influenced by gender, age, pain features (intensity, duration, time pattern, distribution), hospital anxiety and depression scale (HADS) and diagnosis. MATERIAL AND METHODS: A total of 224 patients consecutively referred to the interdisciplinary OFP unit between 2010 and 2012 completed a ZZM-FB. The corresponding diagnosis was obtained from the clinical reports. In all, 209 OFP-Q were anonymized and data retrospectively analysed at a significance level of p ≤ 0.01. RESULTS: The descending rank order of the 12 most frequently selected items was as follow: pressing (SBL), dull (SBL), pulling (SBL), stinging (SBL), dreadful (SBL), miserable (SBL), exhausting (SBL-OF), grueling (SBL-OF), agonizing (SBL-OF), atrocious (SBL), horrible (SBL), pulsating (SBL). The null hypothesis was rejected for all parameters except for age. The selection frequency was significantly influenced by gender, pain intensity, duration and distribution, time pattern, HADS values and diagnosis. CONCLUSIONS: In this cohort, some ADD descriptors were selected more frequently than some SBL items, indicating that the SBL does not adequately capture the characteristics of OFP. These results will be considered in the construction of a revised ZZM-FB, which is currently in development.

The human brain response to dental pain relief.

Local anesthesia has made dental treatment more comfortable since 1884, but little is known about associated brain mechanisms. Functional magnetic resonance imaging is a modern neuroimaging tool widely used for investigating human brain activity related to sensory perceptions, including pain. Most brain regions that respond to experimental noxious stimuli have recently been found to react not only to nociception alone, but also to visual, auditory, and other stimuli. Thus, presumed functional attributions have come under scrutiny regarding selective pain processing in the brain. Evidently, innovative approaches are warranted to identify cerebral regions that are nociceptive specific. In this study, we aimed at circumventing known methodological confounders by applying a novel paradigm in 14 volunteers: rather than varying the intensity and thus the salience of painful stimuli, we applied repetitive noxious dental stimuli at constant intensity to the left mandibular canine. During the functional magnetic resonance imaging paradigm, we suppressed the nociceptive barrage by a mental nerve block. Brain activity before and after injection of 4% articaine was compared intraindividually on a group level. Dental pain extinction was observed to correspond to activity reduction in a discrete region of the left posterior insular cortex. These results confirm previous reports demonstrating that direct electrical stimulation of this brain region-but not of others-evokes bodily pain sensations. Hence, our investigation adds further evidence to the notion that the posterior insula plays a unique role in nociceptive processing.

Fear-learning deficits in subjects with fibromyalgia syndrome?

BACKGROUND: Fibromyalgia syndrome (FMS) is frequently associated with psychiatric conditions, particularly anxiety. Deficits in contingency learning during fear conditioning have been hypothesized to increase anxiety and, consequently, pain sensation in susceptible individuals. The goal of this study was to examine the relationship between contingency learning and pain experience in subjects with FMS and rheumatoid arthritis (RA). METHODS: Fourteen female FMS subjects, 14 age-matched female RA subjects and 14 age-matched female healthy controls (HCs) were included in a fear-conditioning experiment. The conditioned stimulus (CS) consisted of visual signs, the unconditioned stimulus (US) of thermal stimuli. CS- predicted low-temperature exposure (US), while CS+ was followed by low or high temperature. RESULTS: In the FMS group, only 50% of the subjects were aware of the US-CS contingency, whereas 86% of the RA subjects and all of the HCs were aware of the contingency. CS+ induced more anxiety than CS- in RA subjects and HCs. As expected, low-temperature exposure was experienced as less painful after CS- than after CS+ in these subjects. FMS subjects did not show such adaptive conditioning. The effects of the type of CS on heart rate changes were significant in the HCs and the aware FMS subjects, but not in the unaware FMS subjects. CONCLUSIONS: Contingency learning deficits represent a potentially promising and specific, but largely unstudied, psychopathological factor in FMS. Deficits in contingency learning may increase anxiety and, consequently, pain sensation. These findings have the potential to contribute to the development of novel therapeutic approaches for FMS.

Quantitative sensory testing of intraoral open wounds.

Wound healing is an important aspect of oral and maxillofacial surgery. Positive sensory signs (allodynia, hyperalgesia) and negative sensory signs (hypoesthesia, hypoalgesia) may be encountered. Quantitative sensory testing (QST) has moved from bench to bedside for the detection, therapy selection and monitoring the recovery of individuals with sensory disturbances. Tracking somatosensory changes during normal and abnormal wound healing has not previously been reported. This report presents data obtained by a novel, automated, non-contact psychophysical method for assessment of wound sensitivity after standardized oral mucosal biopsy. By directing graded air puffs towards palatal biopsy wounds, thresholds for sensory detection, pain detection and pain tolerance were repeatedly assessed across 19 days, demonstrating high reliability. Participants recorded daily spontaneous and chewing-evoked maximum pains. Pain detection and tolerance thresholds increased linearly across time. Comparison between air puff evoked pain detection threshold and chewing-evoked pain demonstrated a strong correlation. Thus, for the first time, this study tracked the time course of somatosensory sensitivity of wounds induced by oral biopsies. The psychophysical data on wound healing obtained by this automated, contact-free stimulation method can be utilized as a surrogate marker for clinical pain improvements and standardized assessment of intraoral pain sensitivity, for example in oral mucositis.

Classifying orofacial pains: a new proposal of taxonomy based on ontology.

We propose a new taxonomy model based on ontological principles for disorders that manifest themselves through the symptom of persistent orofacial pain and are commonly seen in clinical practice and difficult to manage. Consensus meeting of eight experts from various geographic areas representing different perspectives (orofacial pain, headache, oral medicine and ontology) as an initial step towards improving the taxonomy. Ontological principles were introduced, reviewed and applied during the consensus building process. Diagnostic criteria for persistent dento-alveolar pain disorder (PDAP) were formulated as an example to be used to model the taxonomical structure of all orofacial pain conditions. These criteria have the advantage of being (i) anatomically defined, (ii) in accordance with other classification systems for the provision of clinical care, (iii) descriptive and succinct, (iv) easy to adapt for applications in varying settings, (v) scalable and (vi) transferable for the description of pain disorders in other orofacial regions of interest. Limitations are that the criteria introduce new terminology, do not have widespread acceptance and have yet to be tested. These results were presented to the greater conference membership and were unanimously accepted. Consensus for the diagnostic criteria of PDAP was established within this working group. This is an initial first step towards developing a coherent taxonomy for orofacial pain disorders, which is needed to improve clinical research and care.

Tracing toothache intensity in the brain.

Identification of brain regions that differentially respond to pain intensity may improve our understanding of trigeminally mediated nociception. This report analyzed cortical responses to painless and painful electrical stimulation of a right human maxillary canine tooth. Functional magnetic resonance images were obtained during the application of five graded stimulus strengths, from below, at, and above the individually determined pain thresholds. Study participants reported each stimulus on a visual rating scale with respect to evoked sensation. Based on hemodynamic responses of all pooled stimuli, a cerebral network was identified that largely corresponds to the known lateral and medial nociceptive system. Further analysis of the five graded stimulus strengths revealed positive linear correlations for the anterior insula bilaterally, the contralateral (left) anterior mid-cingulate, as well as contralateral (left) pregenual cingulate cortices. Cerebral toothache intensity coding on a group level can thus be attributed to specific subregions within the cortical pain network.

Guidelines and recommendations for assessment of somatosensory function in oro-facial pain conditions--a taskforce report.

The goals of an international taskforce on somatosensory testing established by the Special Interest Group of Oro-facial Pain (SIG-OFP) under the International Association for the Study of Pain (IASP) were to (i) review the literature concerning assessment of somatosensory function in the oro-facial region in terms of techniques and test performance, (ii) provide guidelines for comprehensive and screening examination procedures, and (iii) give recommendations for future development of somatosensory testing specifically in the oro-facial region. Numerous qualitative and quantitative psychophysical techniques have been proposed and used in the description of oro-facial somatosensory function. The selection of technique includes time considerations because the most reliable and accurate methods require multiple repetitions of stimuli. Multiple-stimulus modalities (mechanical, thermal, electrical, chemical) have been applied to study oro-facial somatosensory function. A battery of different test stimuli is needed to obtain comprehensive information about the functional integrity of the various types of afferent nerve fibres. Based on the available literature, the German Neuropathic Pain Network test battery appears suitable for the study of somatosensory function within the oro-facial area as it is based on a wide variety of both qualitative and quantitative assessments of all cutaneous somatosensory modalities. Furthermore, these protocols have been thoroughly described and tested on multiple sites including the facial skin and intra-oral mucosa. Standardisation of both comprehensive and screening examination techniques is likely to improve the diagnostic accuracy and facilitate the understanding of neural mechanisms and somatosensory changes in different oro-facial pain conditions and may help to guide management.

Insula-specific responses induced by dental pain. A proton magnetic resonance spectroscopy study.

OBJECTIVES: To evaluate whether induced dental pain leads to quantitative changes in brain metabolites within the left insular cortex after stimulation of the right maxillary canine and to examine whether these metabolic changes and the subjective pain intensity perception correlate. METHODS: Ten male volunteers were included in the pain group and compared with a control group of 10 other healthy volunteers. The pain group received a total of 87-92 electrically induced pain stimuli over 15 min to the right maxillary canine tooth. Contemporaneously, they evaluated the subjective pain intensity of every stimulus using an analogue scale. Neurotransmitter changes within the left insular cortex were evaluated by MR spectroscopy. RESULTS: Significant metabolic changes in glutamine (+55.1%), glutamine/glutamate (+16.4%) and myo-inositol (-9.7%) were documented during pain stimulation. Furthermore, there was a significant negative correlation between the subjective pain intensity perception and the metabolic levels of Glx, Gln, glutamate and N-acetyl aspartate. CONCLUSION: The insular cortex is a metabolically active region in the processing of acute dental pain. Induced dental pain leads to quantitative changes in brain metabolites within the left insular cortex resulting in significant alterations in metabolites. Negative correlation between subjective pain intensity rating and specific metabolites could be observed.

Interindividual differences in the perception of dental stimulation and related brain activity.

For identical diagnoses in the trigeminal innervation territory, individual differences have been clinically observed among the symptoms reported, such as dysesthesia and pain. Different subjective perceptions of unpleasantness and pain intensity may have different cortical substrates. The aim of this study was to identify brain areas in which activation depends on the subjective perception (intensity and unpleasantness) of electric dental stimulation. Electrical stimuli of increasing intensity were applied to maxillary canines in 14 healthy volunteers. Ratings for stimulus intensity and unpleasantness perceived across the stimulation session were reported postscan on 11-point numerical scales. The rating values were then included as covariates in the functional magnetic resonance imaging (fMRI) group analysis. Interindividual differences of intensity ratings were reflected in differential activity of the following brain areas: superior parietal lobule, superior temporal gyrus/anterior insula, inferior and middle temporal gyrus, lingual gyrus, anterior cingulate, and caudate nucleus. Differences related to unpleasantness ratings were reflected in the lingual gyrus. In conclusion, differences of perceived intensity between individuals are reflected in the differential activity of a set of brain areas distinct from those regions, reflecting rating differences of unpleasantness.

Stereometric assessment of TMJ space variation by occlusal splints.

Occlusal splints are used for the management of temporomandibular disorders, although their mechanism of action remains controversial. This study investigated whether insertion of an occlusal splint leads to condyle-fossa distance changes, and to mandibular rotation and/or translation. By combining magnetic resonance images with jaw tracking (dynamic stereometry), we analyzed the intra-articular distances of 20 human temporomandibular joints (TMJs) before and after insertion of occlusal splints of 3 mm thickness in the first molar region. For habitual closure, protrusion, and laterotrusion in the contralateral joint, occlusal splints led to minor--yet statistically significant--increases of global TMJ space and to larger increases at defined condylar areas. Condylar end rotation and translation in habitual closure were reduced. Hence, the insertion of a 3-mm-thick occlusal splint led to a change in the topographical condyle-fossa relationship, and therefore to a new distribution of contact areas between joint surfaces.

Cortical activation resulting from painless vibrotactile dental stimulation measured by functional magnetic resonance imaging (FMRI).

There have been few investigations on hemodynamic responses in the human cortex resulting from dental stimulation. Identification of cortical areas involved in stimulus perception may offer new targets for pain treatment. This initial study aimed at establishing a cortical map of dental representation, based on non-invasive fMRI measurements. Five right-handed subjects were studied. Eight maxillary and 8 mandibular teeth were stimulated after the vibratory perception threshold was determined for each tooth. Suprathreshold stimulation was repeated thrice per session, in a total of three sessions performed on three consecutive days. Statistical inference on cluster level identified increased blood-oxygen-level-dependent signal during vibratory dental stimulation, primarily in the insular cortex bilaterally and in the supplementary motor cortex. No significant brain activation was observed in the somatosensory cortex with this stimulation protocol. These results agree with previous findings obtained from invasive direct electrical cortical stimulation of the human insula.