Assessment of Somatosensory Function, Pain, and Unpleasantness in Two Surrogate Models of Trigeminal Nerve Damage: A Randomized, Double-Blind, Controlled Crossover Study.

AIMS: To assess the pain and/or unpleasantness and the somatosensory changes caused by two experimental models of trigeminal nerve damage (topical application of capsaicin and local anesthetics) in healthy participants using extensive evaluation tools. METHODS: This double-blinded, randomized, placebo-controlled, crossover study included 20 healthy adult participants who underwent three separate sessions of testing. In each session, the psychophysical quantitative sensory testing (QST) and the electrophysiologic electrically evoked trigeminal "nociceptive-specific" blink reflex (nBR) investigations were performed at baseline. Following a 15-minute topical application of 0.1% capsaicin, 5% EMLA, or Vaseline (placebo) agents, the maximum numeric rating scale pain and unpleasantness scores were recorded. Additionally, qualitative sensory testing and somatosensory mapping were performed. The QST and nBR investigations were repeated immediately after each application. Data were analyzed using repeated-measures analysis of variance. RESULTS: Capsaicin application was associated with significantly higher pain and unpleasantness scores when compared to EMLA and Vaseline (P < .001), with varied bidirectional somatosensory changes among the participants and significant loss of thermosensory function (P < .030). EMLA application induced loss of thermal and mechanical somatosensory function (P < .030) and a significant reduction in electrically evoked pain scores on nBR investigation (P < .001). No significant changes were seen in the electrophysiologic component of the nBR after any of the applications (P = .922). CONCLUSION: Topical capsaicin and EMLA application mimicked certain aspects of somatosensory changes seen in trigeminal nerve damage patients and may be used as surrogate models of such changes.

Cross-cultural differences in types and beliefs about treatment in women with temporomandibular disorder pain.

OBJECTIVES: Women with temporomandibular disorder (TMD) pain from three cultures were assessed for type of treatment received and core illness beliefs. METHODS: In a clinical setting, 122 women patients with chronic TMD pain (39 Saudis, 41 Swedes and 42 Italians) were evaluated for patient characteristics, type of practitioner, type of treatment received and beliefs about TMD prior to consultation in TMD specialist centres. Measures included a survey of treatments received and a belief scale regarding contributing, aggravating and treatment-relevant factors related to the pain. All questionnaires were translated from English and culturally adapted. Comparisons among cultural groups were performed using a linear regression model for continuous variables and logistic regression model for dichotomous variables. A P-value < 0.05 was considered statistically significant. RESULTS: The study found no significant associations between cultures and the type of practitioners consulted previously. Treatments differed among cultures: Swedes most commonly received behavioural therapy, acupuncture and an occlusal appliance; Saudis most commonly received Islamic medicine; and Italians most commonly received an antidepressant. Swedes were significantly more likely than Saudis and Italians to believe that TMD pain treatment should address behavioural factors. CONCLUSIONS: Among Saudi, Italian and Swedish women with chronic TMD pain, culture does not influence the type of practitioner consulted before visiting a TMD specialist or their beliefs about contributing and aggravating factors for their pain. However, treatment types and beliefs concerning mechanisms underlying the pain differed cross-culturally, with local availability or larger cultural beliefs also probably influencing the types of treatments that TMD patients pursue.

A new protocol to evaluate the effect of topical anesthesia.

This double-blind, placebo-controlled, randomized cross-over clinical experimental study tested the reliability, validity, and sensitivity to change of punctuate pain thresholds and self-reported pain on needle penetration. Female subjects without orofacial pain were tested in 2 sessions at 1- to 2-week intervals. The test site was the mucobuccal fold adjacent to the first upper right premolar. Active lidocaine hydrochloride 2% (Dynexan) or placebo gel was applied for 5 minutes, and sensory testing was performed before and after application. The standardized quantitative sensory test protocol included mechanical pain threshold (MPT), pressure pain threshold (PPT), mechanical pain sensitivity (MPS), and needle penetration sensitivity (NPS) assessments. Twenty-nine subjects, mean (SD) age 29.0 (10.2) years, completed the study. Test-retest reliability intraclass correlation coefficient at 10-minute intervals between examinations was MPT 0.69, PPT 0.79, MPS 0.72, and NPS 0.86. A high correlation was found between NPS and MPS (r = 0.84; P < .001), whereas NPS and PPT were not significantly correlated. The study found good to excellent test-retest reliability for all measures. None of the sensory measures detected changes in sensitivity following lidocaine 2% or placebo gel. Electronic von Frey assessments of MPT/MPS on oral mucosa have good validity.

Somatosensory sensitivity in patients with persistent idiopathic orofacial pain is associated with pain relief from hypnosis and relaxation.

OBJECTIVES: In a recent study hypnosis has been found to relieve persistent idiopathic orofacial pain. Quantitative sensory testing (QST) is widely used to evaluate somatosensory sensitivity, which has been suggested as a possible predictor of management outcome. The objectives of this study were to examine: (1) possible associations between clinical pain relief and baseline somatosensory sensitivity and (2) the effect of hypnosis management on QST parameters. METHODS: Forty-one patients with persistent idiopathic orofacial pain completed this randomized controlled study in 1 of 2 groups: hypnosis (hypnotic analgesia suggestions) or control (relaxation). QST at 2 intraoral (pain region and contralateral mirror image region) and 3 extraoral (hand and both cheeks) sites was performed at baseline and after the hypnosis/control management, together with pressure pain thresholds and pressure pain tolerance thresholds determined bilaterally at the masseter and temporalis muscles, the temporomandibular joints, and the third finger. RESULTS: Degree of pain relief was negatively correlated with a summary statistic of baseline somatosensory sensitivity (summed z-score), that is, high baseline somatosensory sensitivity was associated with low pain relief (r=-0.372, P=0.020). Hypnosis had no major effect on any QST measure compared with relaxation (P>0.063). CONCLUSIONS: High pain sensitivity at baseline may predict poor pain management outcome. In addition, despite clear clinical pain relief, hypnosis did not significantly or specifically influence somatosensory sensitivity. Future studies should further explore QST measures as possible predictors of different management response in orofacial pain conditions.

Efficacy of botulinum toxin type A for treatment of persistent myofascial TMD pain: a randomized, controlled, double-blind multicenter study.

Evidence of an effect by botulinum toxins is still lacking for most pain conditions. In the present randomized, placebo-controlled, crossover multicenter study, the efficacy of botulinum toxin type A (BTX-A) was investigated in patients with persistent myofascial temporomandibular disorders (TMD). Twenty-one patients with myofascial TMD without adequate pain relief after conventional treatment participated. A total of 50 U of BTX-A or isotonic saline (control) was randomly injected into 3 standardized sites of the painful masseter muscles. Follow-up was performed after 1 and 3 months, followed by a 1-month washout period, after which crossover occurred. Pain intensity at rest was the primary outcome measure, while physical and emotional function, global improvement, side effects, and clinical measures were additional outcome measures. There was no main difference between drugs (ANOVA; P=.163), but there was a significant time effect (P<.001), so BTX-A reduced mean (SD) percent change of pain intensity by 30 (33%) after 1 month and by 23 (30%) after 3 months compared to 11 (40%) and 4 (33%) for saline. The number of patients who received a 30% pain reduction was not significantly larger for BTX-A than after saline at any follow-up visit. The number needed to treat was 11 after 1 month and 7 after 3 months. There were no significant changes after treatment in any other outcome measures, with the exception of pain on palpation, which decreased 3 months after saline injection (P<.05). These results do not indicate a clinical relevant effect of BTX-A in patients with persistent myofascial TMD pain.

A follow-up study of subjective symptoms of temporomandibular disorders in patients who received acupuncture and/or interocclusal appliance therapy 18-20 years earlier.

OBJECTIVE: To evaluate the presence of symptoms of temporomandibular disorders (TMDs) in patients referred to a specialist clinic because of muscular problems 18-20 years earlier and who had received mainly acupuncture and/or interocclusal appliance therapy. MATERIAL AND METHODS: Sixty-five subjects who had received therapy at a TMD specialist clinic 18-20 years earlier were mailed a questionnaire with questions about TMD symptoms, their attitude towards the therapy, and their opinion about the outcome. Fifty-five subjects (85%) answered and returned the questionnaire. RESULTS: Before therapy, 87% had had severe TMD symptoms, but this figure decreased to 38% at the long-term follow-up. The mean values of the subjects' complaints at worst and at best before treatment, measured with a visual analog scale, were 66 (range 26-100) and 31 (range 0-100), respectively. The corresponding figures at the long-term follow-up were 32 (range 0-96) and 16 (range 0-70). Headache at least once a week was originally reported by 73% of the women and by 77% of the men. Headache prevalence 18-20 years later was 35% in women and 54% in men. The majority of patients were positive about the therapy they had received, and would recommend it to a friend with similar complaints. CONCLUSIONS: A majority of the patients reported a lasting improvement in their symptoms. Patients' overall opinions of the therapy received were positive.

Treatment of temporomandibular disorders among adolescents: a comparison between occlusal appliance, relaxation training, and brief information.

In a randomized trial the effects of occlusal appliance and relaxation therapy, each combined with brief information, were compared with brief information only, in adolescents with temporomandibular disorder (TMD) pain. One-hundred-and-twenty-two adolescents (93 F and 29 M aged 12-18 years) were randomly assigned to one of the following 3 groups: brief information + occlusal appliance (BI + OA), brief information + relaxation therapy (BI + RT), or brief information (BI). Included were subjects reporting pain once a week or more often, in addition to receiving a diagnosis of TMD according to the Research Diagnostic Criteria (RDC/TMD). They were evaluated before and after treatment and at a 6-month follow-up by means of self-reports and clinical assessment. The result revealed a significantly higher reduction in frequency of pain, in pain intensity (visual analog scale [VAS]), and in a composite pain index (intensity x frequency) for patients treated with BI + OA compared with those treated with BI alone. In the BI + OA group, 60% of the patients attained a clinically significant improvement (at least 50% or more) on the pain index, a significantly higher proportion compared to that obtained in the other 2 treatment groups. Analgesic consumption was also significantly more reduced in the BI + OA group compared to the BI group. However, no significant differences were found between the treatment groups in jaw opening or in muscle and TMJ tenderness scores. Occlusal appliance was found to be superior to both relaxation therapy and brief information regarding pain reduction and can therefore be recommended when treating adolescents with TMD pain.