Orofacial pain symptoms and associated disability and psychosocial impact in community-dwelling and institutionalized elderly in Hong Kong.

OBJECTIVE: The study investigated the experience of orofacial pain (OFP) symptoms and associated disability and psychosocial impact in community dwelling and institutionalized elderly people in Hong Kong. METHODS: A community-based cross-sectional survey involving elders aged 60 years and above. Participants were recruited at social centres for the elderly and homes for the aged throughout Hong Kong. Elders who reported OFP symptoms in the previous four weeks took part. Standard questions were asked about OFP conditions in the previous month and the Manchester Orofacial Pain Disability Scale (MOPDS), the Oral Health Impact Profile (OHIP-14) and the General Health Questionnaire (GHQ-12) were administered. The MOPDS was translated and validated for use in Chinese elders. RESULTS: 200 community dwelling and 200 institutionalized elders participated. Toothache was the most common symptom (62.0%) and burning sensation in the tongue was least common (0.5%). The distribution of pain symptoms, pain duration and severity and pain ratings were similar in both groups. The MOPDS (Chinese elders version) had good reliability and construct validity. The MOPDS and OHIP-14 summary scores was significantly higher in the institutionalized elderly (p < 0.001 and p < 0.013, respectively). Psychological distress (GHQ-12 score > or = 4) was more common among the institutionalized elderly (11%) than the community dwelling elderly (4.0%, p = 0.002). CONCLUSIONS: Orofacial pain symptoms were associated with significant disability and had a detrimental impact on psychological distress level and quality of life, particularly in the institutionalized elderly. There is a need to improve access to professional care and health-related outreach services generally for elderly people in Hong Kong.

Widespread pain symptoms and psychological distress in southern Chinese with orofacial pain.

The study investigated the experience of widespread pain (WP) symptoms and psychological distress in southern Chinese with orofacial pain (OFP). A community-based, cross-sectional case-control study involving people aged 35-70 registered with the Hospital Authority/University of Hong Kong Family Medicine Clinic served as the sampling frame. People with recent OFP symptoms and a group without OFP took part. Standard questions were asked about OFP conditions in the previous month. Psychological status was evaluated through depression, and non-specific physical symptoms (NPS) scores were measured with depression and somatization sub-scales of the Symptom Checklist-90. Widespread pain was determined using body outline drawings to identify painful sites prior to a standard clinical examination. Two hundred people with OFP and 200 without OFP participated. Compared with 5.0% in the comparison group (P = 0.005), 13.5% of participants with OFP had WP (OFP/WP). Multiple OFP symptoms were more common in the OFP/WP sub-group than the OFP sub-group without WP (OFP/No WP) (P < 0.002). Sixty-three percent of the OFP/WP sub-group had moderate/severe depression scores compared with 26.0% in the OFP/No WP sub-group (P < 0.001). When pain items were included and excluded, 92.6% and 88.9% of the OFP/WP sub-group had moderate/severe NPS scores, respectively compared with 68.5% and 65.0% in the OFP/No WP sub-group (P = 0.004). Co-morbid WP occurred relatively often in southern Chinese with OFP. Psychological distress was common in OFP sufferers, particularly those with WP. A multidisciplinary approach to treatment including cognitive/behavioural therapy should be considered in Chinese people with OFP as part of a WP pattern.

Agreement between patient and proxy assessments of oral health-related quality of life after stroke: an observational longitudinal study.

This study aimed to assess agreement between patient and proxy assessment of patients' oral health-related quality of life (OHRQoL) during the acute stroke phase and 6 months after hospital discharge. As part of an observational longitudinal study, 161 consecutive patients hospitalized after stroke and their caregivers (CGs) were monitored during acute stroke and 6 months after hospital discharge. Patient-CG agreement of health-related quality of life as assessed by the General Oral Health Assessment Index (GOHAI) and Medical Outcomes Study 12-item Short Form (SF-12) which comprises physical (PCS-12) and mental component summaries (MCS-12) was determined by comparison and correlation analyses. Complete data were available for 65 patients and CGs. Compared with acute stroke, there were improvements in GOHAI and SF-12 scores from patient's and CG's perspective at 6-month follow-up. Caregivers overestimated the impact of stroke on MCS-12 over a period of time (P < 0.01) and underestimated the impact on GOHAI during acute stroke (P < 0.001) and on PCS-12 6 months later (P < 0.05). Patient-CG agreement was substantial to excellent during acute stroke [intra-class correlation coefficient (ICC 0.69-0.86)] and fair-to-moderate 6 months later (ICC 0.28-0.60). Agreement was adequate between patients' and CGs' assessment of patient OHRQoL during acute stroke but it was less reliable 6 months after hospital discharge. These findings suggest that proxy assessment of OHRQoL after stroke is effective in assessing stroke-related oral impairments that affect life quality without placing additional burden on stroke patients themselves to assess OHRQoL.

Depression and diffuse physical symptoms in southern Chinese with temporomandibular disorders.

The study investigated the experience of depressive symptoms and the relationship with diffuse physical symptoms reporting in southern Chinese seeking professional care for temporomandibular disorders (TMD) in Hong Kong. Eighty-seven new patients [77 females/10 males; mean age 39.3 years (SD 12.7)] referred to the specialist TMD clinic at the Prince Philip Dental Hospital, Hong Kong participated in this study. The Research Diagnostic Criteria (RDC)/TMD history questionnaire was used to derive Axis II psychological data. Psychological status was assessed through depression and non-specific physical symptoms (NPS) scores (pain items included and excluded) measured with RDC/TMD Axis II instruments; 42.5% of patients experienced moderate/severe depression symptoms; 59.8% and 57.5% had moderate/severe NPS scores when pain items were included and excluded, respectively. Strong, positive and statistically significant correlations were noted between depression scores and the NPS scores that included pain items (r = 0.80) and those that did not (r = 0.80). The correlations remained consistent and were of similar magnitude when male patients were excluded from the computation and also when the possible effect of patient age was controlled. While taking into account the modest patient sample which was related to a low rate of treatment seeking, depressive symptoms were common and similar to other western and Chinese patient groups. NPS reports were higher than in Singapore Chinese patients. There appeared to be a clear association between depression and diffuse physical symptoms. The findings should be considered in the holistic care of Chinese people with TMD.

The efficacy of cevimeline hydrochloride in the treatment of xerostomia in Sjögren's syndrome in southern Chinese patients: a randomised double-blind, placebo-controlled crossover study.

Cevimeline hydrochloride, a specific agonist of the M3 muscarinic receptor, is beneficial in the treatment of symptoms of xerostomia and xerophthalmia associated with Sjögren's syndrome (SS). Cevimeline has not been evaluated in southern Chinese patients. Furthermore, the effects of cevimeline on health-related quality of life and oral health status are not known. In this randomised, double-blind, placebo-controlled crossover study, patients received cevimeline 30 mg or matched placebo three times per day over 10 weeks followed by a 4-week washout period before treatment crossover. Participants self-completed the following questionnaires: Xerostomia Inventory (XI), the General Oral Health Assessment Index (GOHAI), the Ocular Surface Disease Index (OSDI) and the Medical Outcomes Short Form (SF-36). Clinical assessments included sialometry, examination of the oral cavity for the degree of xerostomia and dental complications of xerostomia. Fifty patients (22 primary SS and 28 secondary SS) were enrolled in the trial. Forty-four patients completed the study. There was a significant improvement in the XI and GOHAI scores as well as the objective rating of xerostomic signs of the oral cavity after treatment with cevimeline. However, there was no improvement in salivary flow rates and dry eye symptoms. SS patients had lower SF-36 scores, but these did not improve after treatment with cevimeline.

Diagnostic sub-types, psychological distress and psychosocial dysfunction in southern Chinese people with temporomandibular disorders.

The study aimed to assess the distribution of temporomandibular disorders (TMD) sub-types, psychological distress and psychosocial dysfunction in southern Chinese people seeking treatment for TMD using Research Diagnostic Criteria for TMD (RDC/TMD) and investigate potential cross-cultural differences in sub-type prevalence and psychosocial impact. Eighty-seven consecutive patients (77 females; 10 males) with a mean age of 39.3 years (s.d. 12.8) newly referred to the specialist TMD clinic at the Prince Philip Dental Hospital, Hong Kong over a 20-month period took part in the study. RDC/TMD history questionnaire and clinical assessment data were used to derive Axis I and II findings. Group I muscle disorders were the most common and found in 57.5% of patients. Group II (disc displacement) disorders were found in 42.5% and 47.1% of the right and left temporomandibular joints (TMJ) respectively. Group III disorders (arthralgia/arthrosis/arthritis) were revealed in 19.5% and 23.0% of right and left TMJ's respectively. In the Axis II assessment, 42.5% of patients had moderate/severe depression scores, 59.7% had moderate/severe somatization scores and based on graded chronic pain scores 15.0% had psychosocial dysfunction (grade III and IV). While acknowledging the small sample size, the distribution of RDC/TMD Axis I and II diagnoses was fairly similar in Chinese TMD patients compared with Western and other Asian patient groups. However, in Chinese patients, myofascial pain with limited jaw opening and TMJ disc displacement with reduction were more common and a significant number experienced psychological distress and psychosocial dysfunction. The findings have implications for the management of TMD in Chinese people.

Development and evaluation of a questionnaire to evaluate clinical dental teachers (ECDT).

OBJECTIVES: To develop and test the psychometric properties (validity and reliability) of a questionnaire to evaluate clinical dental teachers. METHODS: An item (question) pool was generated with the use of a literature review, feedback from faculty staff, and from focus group discussions with dental students. Following factor analysis the validity and reliability of a revised questionnaire was assessed. This involved 148 dental students and 453 assessments of 29 clinical dental teachers. RESULTS: Effective clinical dental teaching (ECDT) scores were associated with 'global ratings' of the effectiveness of clinical dental teaching (P<0.01), indicating strong criterion validity. In comparison analysis there was strong agreement between students regarding ratings of individual clinical dental teachers, indicating good construct validity. Reliability was assessed by examining internal consistency of sub-scales and overall ECDT scale, and found to be good (Cronbach alpha's > 0.80). CONCLUSION: A valid and reliable measure to evaluate clinical dental teachers has been developed for use in a clinical academia setting, and has potential use as a quality assurance measure.

Location of needle electrode recording sites in the human masseter muscle by magnetic resonance imaging.

A stereotactic method was developed for locating needle electrode recording sites within the human masseter muscle. The method combines a single motor unit (SMU) electromyographic (EMG) technique, magnetic resonance imaging, the 3-dimensional reconstruction of orofacial tissues, and a common reference systems. SMU EMG activity can be recorded from different sites in the masseter muscle, and the location of these sites displayed graphically in 3 dimensions. The technique should be a useful adjunct in future studies of the internal architecture and electrophysiological properties of the human masseter muscle.

Recruitment of motor units in human flexor carpi ulnaris.

In 1949, Denny-Brown reported that the motoneuron pool of the human flexor carpi ulnaris (FCU) muscle was fractionated into subpopulations, each subpopulation being activated during a different voluntary motor task. The following report presents data on motor unit recruitment in the human FCU muscle for the tasks of isometric flexion and ulnar deviation, cocontraction of the forearm muscles and non-isometric flexion of the wrist. These observations show that every FCU motor unit tested reliably, contributed to all four tasks, that is, no separate subpopulations were observed for any of the contractions tested. Furthermore, the order of recruitment was the same for all four tasks.

Effect of experimental pain from trigeminal muscle and skin on motor cortex excitability in humans.

The pathophysiology of many orofacial pain syndromes is still unclear. We investigated the effect of tonic muscle and skin pain on the excitability of the trigeminal motor pathways using transcranial magnetic stimulation (TMS). Motor evoked potentials (MEPs) were recorded in the masseter surface electromyogram (EMG). Magnetic pulses were delivered with a large coil at intensities 1.1 and 1.5 times the motor threshold, and for each intensity, MEPs were recorded at three different clenching levels: 15, 30 and 45% of maximum voluntary contraction (MVC). Baseline, pain and post-baseline recordings were compared in two sessions. Firstly, muscle pain was induced by infusion of hypertonic saline (5.8%) into the left masseter. Secondly, skin pain was induced by topical application of capsaicin (5%) on the left cheek. Muscle and skin pain did not induce significant effects on the amplitude or latency of the MEPs (ANOVAs: P>0.50). In both sessions, the amplitude of the MEPs increased with the increase of the clenching level and stimulus intensity (P<0.0001; P<0.005) whereas the latency was not significantly changed (P>0.05; P=0.11). Muscle pain was associated with an increase in the pre-stimulus EMG activity on the non-painful side compared with baseline (P<0.01), which could be due to compensatory changes in the activation of the painful muscle. The need for voluntary contraction to evoke MEPs in the masseter muscles and compensatory mechanisms both at the brainstem and cortical level might explain the lack of detectable modulation of MEPs. Nonetheless, the present findings did not support the so-called 'vicious cycle' between pain - central hyperexcitability - muscle hyperactivity.

Motor-unit reflex inhibition in different regions of the human masseter muscle.

Regional localization of reflexes is common in anatomically complex limb muscles, but it is uncertain whether this occurs in the multipinnate human jaw-elevator muscles. In this study, motor-unit (MU) inhibitory reflex behaviour was examined in different regions of the human masseter using a strictly controlled method in which stimulus conditions, MU firing frequency, and motor task were matched. All MUs were inhibited by a non-noxious electrical stimulus delivered to the oral mucosa. Although there were significant differences between MUs in the duration of inhibition, this was not dependent on the location of the MUs within the muscle. It was concluded that MU inhibitory reflex behaviour in the masseter is not region specific.

Motor-unit territory in the human masseter muscle.

Motor-unit territories in human masseter are reportedly focal and related to putative subvolumes of muscle. However, in the absence of a reliable method of locating needle-electrode recording sites within the muscle in three dimensions and due to inherent weaknesses in electromyographic recording techniques, the limits of motor-unit territory in the masseter may have been underestimated. Single motor-unit responses were recorded as time-locked events from 32 paired-needle recording sites throughout the masseter muscles of three subjects. Recording sites were located stereotactically with an optical system, magnetic resonance imaging, and a common reference, then displayed graphically in three dimensions. The mean linear separation of the paired recording sites was 8.8 +/- 3.4 mm. The putative territories had a preferred orientation in the antero-posterior axis. Motor-unit territories were larger than described previously and appeared to be related to anatomical compartments. The restriction of these territories to discrete regions of the muscle provides an anatomical substrate for selective regional motor control of the human masseter muscle.

Task-related behavior of motor units in different regions of the human masseter muscle.

Muscle activity patterns appear to vary regionally in the human masseter. However, studies of motor-unit (MU) behaviour in the masseter have been hampered by the absence of a reliable technique for locating needle-electrode recording sites. Here, voluntary MU behaviour patterns were examined in verified regions of the muscle. Activity was recorded from 50 stereotactically mapped masseter MUs. Initially, the task specificity of each MU was determined. Then for each task, the lowest sustainable firing frequency (LSFF) was reached by slow increases and decreases in voluntary firing rate, followed by sustained firing at the lowest possible rate. Pulse-discrimination and digital sampling of consecutive interspike intervals were used to measure the LSFF for each task to which the MU contributed. All MUs fired continuously during the performance of 2-6 separate tooth-contact and postural tasks. There were significant differences between LSFFs for the tasks performed by 47 units. Masseter MU task profiles appear to vary regionally, and are dependent on jaw position, the bite point along the tooth row, and the direction of effort. Descending neural drive to masseter MUs thus seems to be highly task dependent, even when the unit firing rate is controlled voluntarily at its LSFF.

Effect of motor tasks on the cortical topography of the human masseter muscle.

Non-invasive magnetic stimulation of the brain was earlier used to reveal the corticomotor representation of the human masseter muscle but it is unclear how motor tasks affect this map. An experimental approach incorporating transcranial magnetic stimulation of verified locations on the scalp, surface electromyography, and controlled muscle facilitation was used to disclose the corticomotor output map of the masseter during three isometric tooth-contact tasks, viz., tooth clenching in the intercuspal position, biting on the left molar teeth, and biting on the incisors. Map area was significantly different for all tasks, and map height and volume were also different for biting on the incisor teeth (p<0.05). There was evidence of task-related modulation of corticobulbar activity that appeared to be mainly of corticomotoneuronal origin, although the role of differential, task-associated peripheral afferent input from orofacial receptors could not be discounted.

Transcranial magnetic-stimulation mapping of the cortical topography of the human masseter muscle.

The cortical topography of several limb and trunk muscles has been disclosed using transcranial magnetic stimulation, but the corticomotor representation of the human jaw muscles has not yet been described. An experimental paradigm incorporating transcranial magnetic stimulation of verified sites on the scalp was used (a) to determine the cortical topography of the human masseter muscle and (b) to assess the reproducibility of the motor map, in seven healthy individuals. The results showed that the masseter was discretely represently on the motor and premotor cortex with interindividual variation in map area, volume and height (p < 0.05). Coefficients of variation and reliability were low (15-18%) and high (89-96%), respectively, for motor maps obtained at experimental sessions 2 weeks apart, indicating high reproducibility. The findings have clinical relevance in the management of patients with cerebral injury involving corticobulbar projections to the masseter.

Improved reproducibility of magnetic stimulation-evoked motor potentials in the human masseter by a new method for locating stimulation sites on the scalp.

In magnetic-stimulation studies where motor-evoked potentials (MEP) are measured on different occasions, accurate relocation of the stimulation site on the scalp is essential. Here a novel method of locating neural stimulation sites was tested and the reproducibility of MEPs in the human masseter assessed. The heads of the participants were immobilized in a plastic mask that incorporated a grid overlying the left cerebral hemisphere. A figure-of-eight coil was oriented with a micromanipulator. Electrodes were placed over the right masseter using a standardized method. Two discrete sites on the grid were stimulated alternately at threshold + 10% whilst participants clenched their teeth. Recordings were repeated after the mask and electrodes had been removed and replaced. Within individual participants, the latency and amplitude of the MEP were reproducible between trials and when the mask and electrodes were replaced. The new method appears to be accurate and practical when recording longitudinal MEP data in the masseter.

Motor potentials evoked by transcranial magnetic stimulation during isometric and dynamic masseter muscle contraction in humans.

The facilitation of muscle motor potentials evoked by transcranial magnetic stimulation (TMS) has been demonstrated convincingly during both isometric and dynamic activity in the limbs but not in the jaw muscles. An experimental design involving TMS, surface electromyography and controlled muscle-activity was employed to investigate the motor response of the human masseter during voluntary isometric and dynamic voluntary conditions. During the isometric condition, an increase in muscle facilitation resulted in a progressive increase in motor-evoked potential (MEP) amplitude that was consistently greater on the side contralateral to that subjected to TMS (P < 0.05). No difference in MEP amplitude or laterality of response was revealed for the two dynamic conditions. The sample size may have been too small to reveal any differences. The modulation of MEPs during isometric activity was probably due to cortical and brainstem mechanisms. Putative variation in masseter MEPs during dynamic conditions cannot be discounted.

Pain-pressure threshold in human gingivae.

The pain-pressure threshold in human tissues such as muscles may be affected by the anatomic location of the recording site and the rate of applied pressure. However, it is uncertain how these variables affect the pain-pressure threshold in healthy oral tissues. In 10 subjects, a custom-made algometer was used to apply pressure at a constant rate to 12 sites on the attached gingivae apical to teeth 11 to 16 and 41 to 46. The pain-pressure threshold was measured at three different rates of applied pressure at weekly intervals for 4 weeks. The pain-pressure threshold was consistently higher at maxillary recording sites. There were, however, no differences in the pain-pressure threshold at different recording sites along the tooth row in the maxilla or mandible. The pain-pressure threshold measurements were consistent between recording sessions. The pain-pressure threshold was affected by the rate of pressure application and appeared to increase linearly with increasing rate. This suggests that the pain-pressure threshold may be measured consistently in attached human gingivae. When measurement of deep sensation in the oral mucosa is planned, the location of the recording site and the rate of applied pressure should be verified.

Pain-pressure threshold in painful jaw muscles following trigger point injection.

Pain and tenderness at trigger points and referral sites may be modified in subjects with myofascial pain in the head and neck region by injecting local anesthetic into active trigger points, but the effect of injection on jaw muscle pain-pressure thresholds has not been measured. The mechanism by which trigger-point injection affects muscle tenderness is also unclear and may be related to the "hyper-stimulation analgesia" induced by stimulation of an acupuncture point. A pressure algometer was used before and after an active trigger point injection in the masseter to measure the pain-pressure threshold in the masseter and temporal muscles of 10 subjects with jaw muscle pain of myogenous origin. The pain-pressure threshold in the masseter and temporal muscles was also measured in a matched control group before and after an acupuncture-point injection in the masseter. The pain-pressure threshold was significantly lower in myofascial pain subjects than in control subjects at all recording sites. Pain-pressure thresholds increased minimally in the masseter after trigger-point injection, whereas the temporal region was relatively unaffected. In the control group, the pain-pressure threshold increased significantly at all recording sites in the masseter after acupuncture-point injection. Although local anesthetic injection acts peripherally at the painful site and centrally where pain is sustained, pain-pressure thresholds were not dramatically increased in myofascial pain subjects, in contrast to controls. This suggests that in subjects with myofascial pain, there was continued excitability in peripheral tissues and/or central neural areas which may have contributed to the persistence of jaw muscle tenderness.