Journal of Oral & Facial Pain and Headache, 02/2004

Chronic orofacial pain represents a diagnostic and treatment challenge for the clinician. Some conditions, such as atypical facial pain, still lack proper diagnostic criteria, and their etiology is not known. The recent development of neurophysiological methods and quantitative sensory testing for the examination of the trigeminal somatosensory system offers several tools for diagnostic and etiological investigation of orofacial pain. This review presents some of these techniques and the results of their application in studies on orofacial pain and sensory dysfunction. Clinical neurophysiological investigation has greater diagnostic accuracy and sensitivity than clinical examination in the detection of the neurogenic abnormalities of either peripheral or central origin that may underlie symptoms of orofacial pain and sensory dysfunction. Neurophysiological testing may also reveal trigeminal pathology when magnetic resonance imaging has failed to detect it, so these methods should be considered complementary to each other in the investigation of orofacial pain patients. The blink reflex, corneal reflex, jaw jerk, sensory neurography of the inferior alveolar nerve, and the recording of trigeminal somatosensory-evoked potentials with near-nerve stimulation have all proved to be sensitive and reliable in the detection of dysfunction of the myelinated sensory fibers of the trigeminal nerve or its central connections within the brainstem. With appropriately small thermodes, thermal quantitative sensory testing is useful for the detection of trigeminal small-fiber dysfunction (Aδ and C). In neuropathic conditions, it is most sensitive to lesions causing axonal injury. By combining different techniques for investigation of the trigeminal system, an accurate topographical diagnosis and profile of sensory fiber pathology can be determined. Neurophysiological and quantitative sensory tests have already highlighted some similarities among various orofacial pain conditions and have shown heterogeneity within clinical diagnostic categories. With the aid of neurophysiological recordings and quantitative sensory testing, it is possible to approach a mechanism- based classification of orofacial pain. Keywords: neurophysiological diagnostic techniques, neuropathy, orofacial pain, quantitative sensory testing, trigeminal nerve

Aims: To evaluate the effect of temporomandibular arthralgia on mandibular mobility, chewing, and bite force. Methods: Twenty female patients (ages 19 to 45 years) with unilateral temporomandibular joint (TMJ) pain during chewing (49 ± 27 mm on a 100-mm visual analog scale) and provocation, as well as TMJ tenderness, were studied. The TMJ conditions were classified as disc derangement disorders (n = 9), osteoarthritis (n = 7), and inflammatory disorders (n = 4). The patients were compared with matched healthy volunteers without orofacial pain or tenderness. Exclusion criteria were the presence of fewer than 24 teeth or malocclusion. The methods used were (1) algometric assessment of the pressure pain threshold (PPT) over the TMJ; (2) clinical recordings of maximum jaw opening; (3) computerized kinematic assessment of maximum vertical distance, velocity, and cycle duration during chewing of soft gum; and (4) measurement of unilateral molar bite force. Results: The mean (± SD) PPT in the patients¡¯ painful side (69 ± 20 kPa; P = .000001) was significantly lower than in the control subjects (107 ± 22 kPa). Jaw opening was also significantly less (P = .00003) in the patients (42 ± 9 mm) than in the controls (52 ± 4 mm). Chewing cycle duration and maximum closing velocity were significantly different (P = .03) in the patients (948 ± 185 milliseconds and 142 ± 46 mm/s, respectively) versus the controls (765 ± 102 milliseconds and 173 ± 43 mm/s, respectively), and bite force was significantly lower (P = .000003) in the patients (238 ± 99 N) than in the controls (394 ± 80 N). Both bite force and jaw opening in patients were significantly correlated (P = .02) with PPT (r = 0.53 and 0.63, respectively). Conclusion: These systematic findings supplement results from acute pain experiments and confirm indications from unspecified patient groups that the clinical presence of long-standing TMJ pain is associated with marked functional impairment. This impairment might be a result of reflex adaptation and long-term hypoactivity of the jaw muscles. Keywords: bite force, jaw kinematics, mastication, orofacial pain, temporomandibular joint

Aims: To compare the short-term efficacy of patient education only versus the combination of patient education and home exercises for the treatment of myofascial pain of the jaw muscles. Materials and Methods: Seventy myogenous temporomandibular disorder patients were assigned to 2 treatment groups. One group received patient education supplemented by general information about self-care of the jaw musculature. The other group received both education and a home physical therapy program. Treatment contrast, calculated from the mean normalized relative changes in anamnestic and clinical scores, was used to determine treatment success. Clinical outcome measures included pressure pain threshold (PPT) of the masseter, anterior temporalis, and Achilles tendon; pain-free maximal jaw opening; and pain on chewing, spontaneous muscle pain, and headache as rated on visual analog scales. Results: After 3 months the success rate was 57% for the group that received education only and 77% for the group that received both education and home physical therapy (P = .157). The patients were then redivided into 2 groups: successfully treated patients and unsuccessfully treated patients. In the unsuccessfully treated group, pain-free maximal jaw opening increased significantly more among those who had been in the education and physical therapy group than among those who had been in the education-only group (P = .019). The change in PPT was significantly greater in successfully treated patients than in unsuccessfully treated patients (.009 P .039), independent of the treatment modality, with higher PPTs among successful patients. There were no significant differences between the successfully and unsuccessfully treated groups or between treatment modalities for any other variable. Conclusion: Over a period of 3 months, the combination of education and a home physical therapy regimen, as used in this protocol, is slightly more clinically effective than education alone for the treatment of myofascial pain of the jaw muscles. Keywords: myofascial pain, patient education, physiotherapy, pressure pain threshold, randomized clinical trial

Aims: To assess the prevalence of subjective symptoms of pain and/or temporomandibular disorder (TMD) dysfunction and their association with psychosomatic (PS) symptoms in a longitudinal follow-up study of Finnish young adults over an 8-year period. Methods: One hundred twenty-eight Finnish young adults (60 men and 68 women) were assessed longitudinally at the ages of 15, 18, and 23 years using routine stomatognathic methods and a standardized questionnaire. Results: The prevalence of reported TMD symptoms ranged from 6% to 12% for pain symptoms, from 12% to 28% for dysfunctional symptoms, and from 4% to 7% for a combination of these 2 types of symptoms. The prevalence of PS symptoms, which were constantly present in many of the patients who reported them, ranged from 7% to 11%. A significant correlation (P .05) was found between TMD pain and PS symptoms at the ages of 15 and 18 years. PS symptoms were not significantly correlated to TMD dysfunction symptoms or to experiencing no symptoms at any age. The majority of subjects in all age groups with both TMD and PS symptoms were female, in a ratio of approximately 2 to 1. Conclusion: The prevalence of TMD and PS symptoms was low in adolescence and young adulthood, and there was a significant association, although relatively weak, between PS symptoms and reports of either TMD pain or a combination of TMD pain and dysfunction symptoms. Keywords: longitudinal studies, prospective studies, psychosomatic symptoms, temporomandibular disorders

Aims: To study in a randomized placebo-controlled design the efficacy of the antidepressant venlafaxine, a serotonin and a weak noradrenaline reuptake inhibitor, in the treatment of atypical facial pain (AFP). Methods: The study was a randomized, doubleblind, crossover comparison of venlafaxine and a placebo. It consisted of 2 treatment periods, each of 4 weeks' duration, separated by a 2-week washout period. Thirty patients suffering from chronic pain who had been diagnosed with AFP after a thorough clinical examination were recruited. Pain intensity and pain relief were registered at 6 visits. Anxiety, depression, and adverse effects were recorded. Venous blood samples were collected at the end of each treatment period for the determination of serum levels of venlafaxine and its metabolites. Results: Twenty patients completed the trial. Eight patients discontinued because of adverse effects and 2 patients were excluded because of noncompliance. Two patients completed the trial but were excluded from the analysis because they experienced no pain at the baseline visit. There was no significant difference in pain intensity reduction between the maximum tolerated dose of venlafaxine (75 mg in most cases) and the placebo. Pain relief was significantly greater with venlafaxine than with the placebo treatment. Significantly more escape medication was consumed during the placebo period compared with the venlafaxine period. No significant correlation was found between the serum concentration of the drug and the response to treatment. Anxiety and depression scores did not differ between venlafaxine and placebo treatment. Adverse effects were equally common during both treatments. Conclusion: Venlafaxine was only modestly effective in the treatment of AFP. Keywords: antidepressants, atypical facial pain, chronic pain, neuropathic pain, venlafaxine

Aims: To compare the results of 3 methods of recognizing internal derangements with a clicking sound on condylar movement: 2 function-based methods (clinical examination and condylar movement recording) and 1 anatomy-based method (magnetic resonance imaging [MRI]). Methods: For the recognition of an anterior or posterior disc displacement with reduction and of hypermobility within the temporomandibular joint (TMJ), 42 participants underwent a clinical examination, an opto-electronic movement recording, and an MRI scan. The examinations were executed in a single-blind design, with different experienced examiners for each technique. In addition, for 10 randomly chosen participants, the condylar movement recordings and the MRI scans were carried out twice. Without the examiners' knowledge, these second recordings were added to the other data. Results: Intraobserver reliability for the recognition of internal derangements was excellent for condylar movement recording (κ = 0.86) and fair to good for MRI (κ = 0.73). Intermethod agreement was fair to good (κ = 0.59) between the 2 function-based techniques. However, intermethod agreement between the anatomy-based MRI technique and either of the 2 function-based techniques was poor (for condylar movement recording, κ = 0.15; and for clinical examination, κ = 0.12). Conclusion: There is a great discrepancy between the diagnoses for internal derangements based upon anatomical TMJ characteristics and those based on functional TMJ characteristics. For a function-based diagnosis, there is probably no need for the sophisticated technique of condylar movement recording, since that method shows fair to good agreement with a carefully performed clinical examination. Keywords: clinical criteria, condylar movement recordings, internal derangements, magnetic resonance imaging, temporomandibular joint

Aims: To investigate whether condylar morphological changes influence the condyle position in the glenoid fossa as well as the amount of condylar movement from the intercuspal position (IP) to the reference position (RP). Methods: Helical computed tomography was used for precise measurement of the joint spaces at IP and RP in 22 subjects (mean age 22.7 years). Subjects were divided into 2 groups, those without condylar bone changes (n =11) and those with condylar bone changes (n = 11). The latter group was further subdivided into a flattening subgroup and an osteophyte subgroup, according to the type of condylar bone change. Results: There were no significant differences in the width of the anterosuperior or posterosuperior joint spaces at IP between either the 2 groups or the 2 subgroups. On the other hand, during condylar movement from IP to RP, the condyles moved significantly more superiorly and posterosuperiorly in the bone-change group than in the no-bone-change group. There was also greater absolute horizontal condylar movement between IP and RP in the bone-change group. In addition, within the bone-change group, the type of condylar bone change influenced the amount of condylar movement. Joints with osteophyte formation showed the most superior, posterosuperior, and absolute horizontal movement from IP to RP. Conclusion: The findings that condyles of the bone-change group, especially those with osteophyte formation, were located significantly more anteroinferiorly in the glenoid fossa at IP than RP than the condyles of the no-bone-change group suggest that condylar IP-RP positional changes might be related to condylar shape alteration. Keywords: condylar bone change, helical computed tomography, osteophyte formation