Journal of Oral & Facial Pain and Headache, 02/2012

Aims: To investigate the relationship of headache frequency with patient-reported physical functioning and emotional functioning in temporomandibular disorder (TMD) subjects with concurrent temple headache. Methods: The Research Diagnostic Criteria for TMD (RDC/TMD) Validation Project identified, as a subset of 614 TMD cases and 91 controls (n = 705), 309 subjects with concurrent TMD pain diagnoses (RDC/TMD) and temple headache. The temple headaches were subdivided into infrequent, frequent, and chronic headache according to the International Classification of Headache Disorders, second edition (ICHD-II). Study variables included self-report measures of physical functioning (Jaw Function Limitation Scale [JFLS], Graded Chronic Pain Scale [GCPS], Short Form-12 [SF-12]) and emotional functioning (depression and anxiety as measured by the Symptom Checklist-90R/SCL-90R). Differences among the three headache subgroups were characterized by increasing headache frequency. The relationship between ordered headache frequency and physical as well as emotional functioning- was analyzed using linear regression and trend tests for proportions. Results: Physical functioning, as assessed with the JFLS (P .001), SF-12 (P .001), and GCPS (P .001), was significantly associated with increased headache frequency. Emotional functioning,- reflected in depression and anxiety, was also associated with increased frequency- of headache (both P .001). Conclusion: Headache frequency- was substantially correlated with reduced physical functioning and emotional functioning in subjects with TMD and concurrent temple headaches. A secondary finding was that headache was precipitated by jaw activities more often in subjects with more frequent temple headaches. Keywords: health-related quality of life, jaw function, psychosocial status, temporomandibular disorders, tension-type headache

Aims: To determine whether shared genetic influences are responsible for the association between pain from temporomandibular disorders (TMD) and migraine headache. Methods: Data were -obtained from 1,236 monozygotic and 570 dizygotic female twin pairs from the University of Washington Twin Registry. TMD pain was assessed with a question about persistent or recurrent pain in the jaw, temple, in front of the ear, or in the ear. The presence of migraine headache was determined by self-report of doctor--diagnosed migraine. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental influences. Results: The best fitting univariate models indicated that additive genetic effects contributed 27% of the variance in TMD pain (95% confidence interval = 15% to 38%) and 49% of the variance in migraine headache (95% confidence interval = 40% to 57%). The best-fitting bivariate model revealed that 12% of the genetic component of TMD pain is shared with migraine headache. Conclusion: These preliminary findings suggest that the association between TMD pain and migraine headache in women may be partially due to a modest shared genetic risk for both conditions. Future studies can focus on replicating these findings with symptom- and diagnosis-based instruments.

Aims: To carry out a randomized clinical trial to compare the effect of palmitoylethanolamide (PEA) versus ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), for pain relief in temporomandibular joint (TMJ) osteoarthritis or arthralgia. PEA acts as an endogenous agent with an autacoid local inflammation antagonism and modulates mast cell behavior controlling both acute and chronic inflammation. Methods: A triple-blind randomized clinical trial was conducted on 24 patients (16 women and 8 men) aged 24 to 54 years and suffering from TMJ osteoarthritis or arthralgia. The patients were enrolled from a group of 120 consecutive patients referred to the University of Bologna's Department of Orthodontics. Patients were randomly divided into two groups: group A (12 subjects) -received PEA 300 mg in the morning and 600 mg in the evening for 7 days and then 300 mg twice a day for 7 more days. Group B (12 subjects) received ibuprofen 600 mg three times a day for 2 weeks. Every patient recorded the intensity of spontaneous pain on a visual analog scale twice a day. Maximum mouth opening was recorded by a blind operator during the first visit and again after the 14th day of drug treatment. A t test was used for data comparisons. Results: Pain decrease after 2 weeks of treatment was significantly higher in group A than in group B (P = .0001); maximum mouth opening improved more in group A than in group B (P = .022). Conclusion: These data suggest that PEA is effective in treating TMJ inflammatory pain. Keywords: NSAIDs, palmitoylethanolamide, TMJ arthralgia, TMJ osteoarthritis, TMJ pain

Aims: To investigate the influence of noxious stimulation of the temporomandibular joint (TMJ) on conditioned pain modulation (CPM) and the possible influence of gender on such CPM effects in the craniofacial region of humans. Methods: Twenty healthy men and 20 healthy women participated in two sessions. Conditioning stimulation (CS) was standardized mechanical stimulation of pericranial muscles at a pain level of 5 on a 0 to 10 visual analog scale (VAS). Intra-articular electrical stimuli were applied to the left TMJ with an intensity around VAS = 5 (painful session). No electrical stimulation was applied in the control session. Pressure pain threshold (PPT) and pressure pain tolerance threshold (PPTol) were used as responses to pressure (test) stimuli and were assessed in the right masseter muscle and left forearm before and during TMJ stimulation in addition to the CS (during, immediately after, and 10 minutes after CS). PPT and PPTol were analyzed by multilevel analysis of variance. Results: The parameters were not dependent on gender, assessment site, or session, but were dependent on time (PPT, PPTol: P .001) with session-time interactions (PPT: P .001, PPTol: P = .002). CS triggered increases in PPT and PPTol (hypoalgesia) in both sessions and without significant differences between sessions or assessment sites during CS (painful session: 49.2 ± 3.7%, control session: 46.0 ± 3.4% for PPT and painful session: 17.7 ± 3.2%, control session: 21.4 ± 3.5% for PPTol). Conclusion: Acute noxious stimulation of the TMJ does not alter the magnitude of CPM effects on masseter muscle pain in either gender. It is suggested that deficiencies in CPM in persistent pain conditions are most likely more related to the duration of clinical pain than the pain per se. Keywords: conditioned pain modulation (CPM), experimental craniofacial pain, gender differences, human volunteers, trigeminal system

Aims: To characterize pain related to primary burning mouth syndrome (BMS) in terms of intensity, interference, and distress caused by the pain, as well as factors influencing the pain across a period of 2 weeks, and to study the use of coping and management strategies on a daily basis. Methods: Fifty-two female patients with primary BMS completed a 2-week pain diary. Pain intensity, interference, distress, and mood on a 0 to 10 numeric rating scale (NRS), as well as pain amplifying and alleviating factors, were recorded three times a day. The use of treatments (medication or other means) and coping strategies were recorded at the end of each day. Coefficient of variation, repeated measures analysis of variance, and correlative methods were used to assess the between- and within-subject variation, pain patterns, and associations between various pain scores. Results: The overall mean pain intensity score of the 14 -diary days was 3.1 (SD: 1.7); there was considerable variation in pain intensity between patients. Most patients experienced intermittent pain. On average, pain intensity increased from the morning to the evening. Intercorrelations between pain intensity, interference, distress, and mood were high, varying between rs = .75 and rs = .93 (P .001). Pungent or hot food or beverages, stress, and tiredness were the most frequently mentioned pain-amplifying factors. The corresponding pain-alleviating factors were eating, sucking pastilles, drinking cold beverages, and relaxation. Thirty (58%) patients used pain medication and 35% reported using other means to alleviate their BMS pain. There was large variation in the use of coping strategies -between subjects. Conclusion: There were considerable differences in pain, in factors influencing the pain, and in pain behavior across BMS patients. This indicates that patient information and education as well as treatment of BMS pain should be individualized. Keywords: burning mouth syndrome, pain behavior, pain coping, pain diary, stomatodynia

Aims: To evaluate the concordance among different pain scales for evaluation of pain in toothache patients and to assess the influence of oral health on the quality of life of those patients. Methods: Ninety-two patients seeking treatment for toothache were evaluated before and after treatment. At baseline and 1 week after the dental treatment, the patients were requested to fill out the Oral Health Impact Profile Inventory (OHIP-14) as well as the following pain scales: the visual analog scale (VAS), numeric scale (NS), verbal rating scale (VRS), and Faces Pain Scale-Revised (FPS-R). The data were analyzed by Pearson correlation, Student t test, and analysis of variance for repeated measurements, with a significance level of 5%. Results: Patients were, on average, 34.4 years old. The sample was composed of 50 women and 42 men. Fifty-eight patients had dental pain of pulpal origin, and 34 had pain of periodontal origin. The mean OHIP score was 20.83 at baseline and 5.0 at 1 week after the completion of the dental treatment. The mean values of the scales at baseline were 50.7 mm, 56.7 mm, 52.2 mm, and 52.9 mm for the VAS, NS, VRS, and FPS-R, respectively. One week after the treatment, these values were 7.5 mm, 9.4 mm, 10.9 mm, and 8.7 mm. A positive correlation was detected between all four scales at baseline and also 1 week after the treatment (P .05). At baseline, the NS was significantly different from the other scales. This difference, however, was not detected at the end of the trial. Conclusion: All scales were able to detect differences in the pain reported after dental treatment and may be valid and reliable for use in clinical dental practice. The NS, however, returns higher scores at baseline when assessing the pain. Keywords: pain assessment, pain intensity, pain scale, quality of life, toothache

Aims: To investigate nociceptive behavior and the immunoreactivity of microglia and phosphorylated-p38 (p-p38) mitogen-activated protein kinase (MAPK) following intracisternal administration of SB203580, a p38 MAPK inhibitor, or minocycline, a microglia -inhibitor, in rats with temporomandibular joint (TMJ) inflammation. Methods: The number of nociceptive behavioral responses was recorded for nine successive 5-minute intervals following formalin injections into the left TMJ. SB203580 or minocycline was administered intracisternally 2 hours prior to the formalin injection. Statistical analysis used one-way analysis of variance followed by least significant difference post-hoc analysis. Results: The intra-articular injection of formalin increased the expression of p-p38 MAPK in the ipsilateral medullary dorsal horn. Most of the p-p38 MAPK co-localized with OX42, a microglial marker, but not with GFAP, an astrocyte marker. Intracisternal injections of SB203580 (0.5, 1, or 5 µg) attenuated the number of nociceptive behavioral responses and the expression of p-p38 MAPK in the medullary dorsal horn. Intracisternal injections of minocycline (25 or 50 µg) also attenuated the responses and the expression of OX42 and p-p38 MAPK in the medullary dorsal horn. Conclusion: These findings suggest that p38 MAPK in microglia plays an important role in the central processing of inflammatory TMJ nociception in rats. The data further indicate that a targeted blockade of the microglial p38 MAPK pathway is a potentially important new treatment strategy for inflammatory TMJ nociception. Keywords: formalin, microglia, p38 MAPK, pain, TMJ

This article reports an unusual case of neuropathic orofacial pain secondary to leprosy. To the authors' knowledge, it is the first case of leprosy reported in the Western literature that was initially thought to be dental pain, then mistaken as a temporomandibular disorder before the correct diagnosis was made. The patient had migrated to Australia from India 24 years previously and was otherwise healthy without any overt features suggestive of infection. A review of the literature revealed that the trigeminal nerve is frequently involved in leprosy, usually associated with sensory loss rather than neuropathic pain. Even in Western countries, patients originally from countries where leprosy is endemic may develop symptoms of the disease many years later. The possibility of leprosy should be considered in the diagnosis of neuropathic orofacial pain in such patients. Keywords: leprosy, neuropathic pain, orofacial pain