Effects of surgical treatment for classical trigeminal neuralgia with concomitant persistent facial pain.

PURPOSE: Classical trigeminal neuralgia with concomitant persistent facial pain responds poorly to conservative treatment. The authors describe the effects of microvascular decompression and radiofrequency thermocoagulation for patients with classical trigeminal neuralgia and concomitant persistent facial pain. CASE REPORT: Case 1 was a 61-year-old man with dull, continuous, aching pain in the left maxillary and mandibular molar area. Case 2 was a 68-year-old woman with aching pain in the maxillary right molar. Case 3 was a 67-year-old woman with severe pain in the right upper lip and maxillary right second premolar. Case 4 was a 42-year-old man with orofacial pain of 14 months' duration. Cases 1 and 2 underwent radiofrequency thermocoagulation and reported good relief of symptoms. Cases 3 and 4 underwent microvascular decompression and attained excellent relief. CONCLUSION: Microvascular decompression may be more effective than radiofrequency thermocoagulation for patients with classical trigeminal neuralgia with concomitant persistent facial pain.

Effects of exercise therapy on painful temporomandibular disorders.

Temporomandibular disorders (TMD) are common chronic musculoskeletal pain conditions among orofacial pain. Painful TMD condition such as myalgia and arthralgia can be managed by exercise therapy. However, as it is hard to access actual effect of each modality that is included in an exercise therapy programme due to multiple choice of the management modality, their efficacy remains controversial. Therefore, this review focused on the effects of exercise therapy for the management of painful TMD. The aims of this review were to summarise the effects of exercise therapy for major symptoms of painful TMD and to establish a guideline for the management of painful TMD, resulting in higher quality and reliability of dental treatment. In this review, exercise modalities are clearly defined as follows: mobilisation exercise, muscle strengthening exercise (resistance training), coordination exercise and postural exercise. Furthermore, pain intensity and range of movements were focused as outcome parameters in this review. Mobilisation exercise including manual therapy, passive jaw mobilisation with oral appliances and voluntary jaw exercise appeared to be a promising option for painful TMD conditions such as myalgia and arthralgia. This review addressed not only the effects of exercise therapy on various clinical conditions of painful TMD shown in the past, but also an urgent need for consensus among dentists and clinicians in terms of the management of each condition, as well as terminology.

Characteristics of Glutamate-Evoked Pain in the Masseter Region: Differences Between Targeted Injections in Subcutaneous, Muscle, and Bone Tissues.

AIMS: To investigate whether glutamate-evoked pain in the masseter region differs between three different depths of injection, targeting subcutaneous, muscle, and bone tissues. METHODS: A total of 16 healthy volunteers participated and, in a randomized order, received injections of glutamate (1.0 M, 0.2 mL) and isotonic saline (0.9%, 0.2 mL) in the masseter region that targeted subcutaneous, intramuscular, and bone surface tissues. Following injection, pain intensity was measured using electronic visual analog scale (eVAS) and numeric rating scale (NRS) scores of unpleasantness, tiredness, tension, soreness, and stiffness. Pressure pain sensitivity (PPS), pain drawing areas, and McGill Pain Questionnaire (MPQ) scores were also assessed. Repeated-measures analysis of variance, McNemar test, and Tukey post hoc tests were used for statistical analyses. P < .05 was considered statistically significant. RESULTS: Overall, subcutaneous injections induced significantly more unpleasantness and pain than intramuscular injections, and PPS scores evoked after glutamate injection at the surface of the bone were significantly higher than after intramuscular glutamate injection. Subcutaneous glutamate injections were more often described as "sharp" and "pinching." CONCLUSION: The subcutaneous injection was more painful and unpleasant than the intramuscular injection. The glutamate injection at the surface of the bone sensitized the deep pain tissues to pressure stimulation. Clinically, it may be difficult to differentiate between the source or site of pain originating from the masseter region, but the specific quality and word descriptors could assist in differential diagnosis.

Comparison of masseter muscle referred sensations after mechanical and glutamate stimulation: a randomized, double-blind, controlled, cross-over study.

Referred sensations (RS) are commonly found in various musculoskeletal pain conditions. Experimental studies have shown that RS can be elicited through glutamate injection and mechanical stimulation. Despite this, differences and similarities between these modalities in RS outcomes remain unclear. The aim of this study was to assess differences between mechanical-induced and glutamate injection-induced RS in the trigeminal region. The present randomized, double-blind, controlled, cross-over study recruited 60 healthy participants who were assessed in 2 different sessions. In both sessions, pressure was applied to the masseter muscle with 4 different forces (0.5, 1, 2, and 4 kg), and glutamate (1 mol/L or 0.25 mol/L) was injected into the same area. Participants rated their perceived masseter sensations and rated and drew any RS they experienced. No difference was found in number of participants reporting RS after glutamate injection compared with mechanical stimulation. More participants reported RS when the stimulus was painful compared with a nonpainful stimulus. Furthermore, it was shown that the more intense the stimulus, the higher the frequency of RS. Finally, RS centre-of-gravity location was similar between the 2 sessions. In summary, RS was elicited in healthy individuals through both modalities, and no differences in frequency of RS were observed in the orofacial region. Hence, RS does not seem to be modality-dependent, and only the painfulness of the stimulus caused an increase in frequency of RS. Finally, RS location for each participant was similar in both sessions possibly indicating a preferred location of referral. These findings may have implications for our understanding of RS in craniofacial pain conditions.

Intraoral chemical burn in an elderly patient with dementia.

We describe the case of a 77 year-old Japanese woman who was referred to the Department of Oral and Maxillofacial Surgery at Tokyo Women's Medical University Hospital with symptoms of spontaneous intraoral pain and dysphagia evoked by accidental alkaline (calcium oxide) ingestion. The stomach and esophagus were examined under endoscopy, but no evidence of burns or ulceration associated with the calcium oxide was apparent in the upper gastrointestinal tract. Oral care, antibacterial therapy (cefmetazole sodium) and nutritional management were performed after hospitalization. Mucosal erosions, dysphagia and pneumonia were almost resolved after 16 days of oral care and antibacterial treatment. Re-burn of the oral mucosa associated with accidental ingestion was not reported after discharge. Oral management may have potential to improve the management of intraoral chemical burns, but symptomatic treatment remains the only strategy for burn management. Accidental ingestion of chemicals by patients with impaired cognition may result in dire consequences and prevention is thus more important than burn management.

Assessment of human intraoral thermal sensitivity with simple devices in the clinic: implications for orofacial pain conditions.

AIMS: To use simple thermal devices with different diameters and temperatures to investigate reliability and magnitude of human intraoral thermal sensitivity. METHODS: Sixteen healthy volunteers participated. Six thermal devices with tapered circular ends (stimulus diameter 3, 5, and 10 mm) were used. Three different temperatures (room temperature, heat, and cold) were applied with each of the three diameters, ie, nine combinations. Participants were stimulated in randomized order at nine different sites: tongue, lip, maxillary attached gingiva adjacent to the left and right central incisors (without touching the lip) and to the left and right premolars (with or without touching the lip), and the left and right cheeks extraorally. Participants rated the perceived stimulus intensity on 0-50- 100 numeric rating scales (NRS). The number of paradoxical thermal sensations was also recorded. Ten volunteers were examined twice on the same day and recalled for a second session for assessment with the 5-mm-diameter device of within- and between-session reliability (interclass correlation coefficients [ICC]). The results were analyzed using a three-way analysis of variance. RESULTS: Reliability of NRS scores ranged from poor (ICC = 0.09, with cold stimulation at the premolar region) to excellent (ICC > 0.92, with cold stimulation at the cheek or tongue). NRS values varied with stimulus diameter (P < .050), temperature (P < .001), and sites (P < .001), with significant size x site and temperature x site interactions (P < .001). The tongue was the most sensitive site (P < .001) and the gingiva was the least sensitive site (P < .050). The 10-mm-diameter device produced higher NRS scores than the 3-mm-diameter device. CONCLUSION: The reliability of intraoral thermal sensitivity recorded with the 5-mm-diameter device varied greatly between different sites. Nonetheless, with this caveat in mind, the study did document that semiquantitative assessment of intraoral thermal sensitivity is feasible and applicable for clinical studies in different intraoral pain conditions.

Influence of topical application of capsaicin, menthol and local anesthetics on intraoral somatosensory sensitivity in healthy subjects: temporal and spatial aspects.

The aim of this study was to investigate temporal and spatial aspects of somatosensory changes after topical application of capsaicin, menthol and local anesthetics (LA) on the gingiva with the use of intraoral palpometers and thermal devices. Sixteen healthy volunteers (eight male, eight female) participated. Four topical preparations (capsaicin, menthol, LA and Vaseline as a control) were randomly applied to the gingiva around the first premolar in the upper jaw via individual oral templates, which allowed spatial mapping of somatosensory changes at and adjacent to the site of application. The topical drugs were applied for 15 min in a randomized and balanced sequence. The perceived preparation-evoked pain intensity was recorded with the use of 0-10 visual analog scales (VAS). Standardized mechanical and thermal stimuli were applied before, during and up to 30 min after the topical applications, and numerical rating scales (NRS) were used to score the perceived intensity of the stimuli. Peak VAS, area under the curve and mean VAS preparation-evoked pain scores for capsaicin, menthol, LA and control were compared with paired t tests. NRS scores for mechanical and thermal test stimuli were analyzed with four-way repeated measurements analyses of variance. Capsaicin evoked significantly higher VAS pain parameters as well as higher NRS scores to heat stimuli than control (P < 0.029). There were no significant differences in stimulus-evoked NRS scores between the menthol and control conditions (P = 0.518), but LA caused significantly lower stimulus-evoked NRS scores compared with control (P < 0.001). Post hoc tests showed that capsaicin caused sensitization to heat stimuli at and adjacent to the application area. In conclusion, this study for the first time demonstrates the time course of capsaicin-evoked heat hyperalgesia in and outside the site of application at the oral mucosa (primary and secondary hyperalgesia).

Effect of a reversal mirror condition on orofacial mechanical sensitivity.

The aim of this study was to investigate whether watching one's own face being touched in a reversal mirror condition modulates orofacial somatosensory sensitivity. A total of 37 healthy volunteers participated in a pilot study, the main study, and a control experiment. In the main experiment, 16 participants received seven different intensities of pinprick stimuli in the right infraorbital region. The perceived stimulus intensity was rated on a 0-50-100 numerical rating scale (NRS). In addition, the pinprick threshold (PiPT) was evaluated in the same region using an electronic von Frey device. During stimuli, participants were watching their own face in two different conditions (normal and reversal mirror) in randomized order. Subjective experiences during each condition were assessed with a questionnaire containing nine statements. The participants rated their level of agreement with the statements using a 7-item Likert scale. There were significant main effects on NRS scores of stimulus forces (p < 0.001) and experimental condition (p < 0.001). Post hoc analyses showed that stimulation with higher force levels induced significantly higher NRS scores (p < 0.001), but interestingly, there were significantly lower NRS scores in the reversal mirror condition than in the normal mirror condition (p < 0.001). There was no significant main effect of experimental condition on PiPT (p = 0.184). The experimental condition influenced the response to several statements significantly (p < 0.001). The somatosensory sensitivity may be impaired when the location of stimulation is not in accordance with the perception. In conclusion, hypoesthetic effects of a reversal mirror were present for fixed force measures but not for threshold measures. Further studies are now needed to describe the potential implications for other somatosensory modalities and orofacial pain conditions.

Application of a new palpometer for intraoral mechanical pain sensitivity assessment.

AIMS: To investigate the reliability and magnitude of intraoral mechanical pain sensitivity by using a palpometer with add-on devices with different physical properties. METHODS: Sixteen healthy volunteers participated. Three palpometers (0.5, 1.0, and 2.0 kg) were used. Add-on devices were put on the circular metal stamp of the palpometer. Four diameters (3, 4, 5, and 10 mm) and two shapes of the rubber-top (flat and round) of the add-on devices were tested at each force level, ie, a total of 24 combinations. Participants were stimulated at the gingival mucosa around the maxillary central incisors and first molars on both sides by using the palpometers in randomized order. Participants rated perceived stimulus intensity on a 0-50-100 numerical rating scale (NRS). Ten volunteers were examined twice on the same day and recalled for a second session for assessment of within- and between-session reliability. Intraclass correlation coefficients were calculated for reliability measures, and NRS scores were analyzed with analysis of variance. RESULTS: Reliability of NRS scores was excellent (interclass correlation coefficients 0.76 to 0.99). Analysis of NRS values corrected for pressure level revealed that there were main effects of site (P = .006), force (P < .001), size (P < .001), and shape (P < .001) but not side (P = .051). CONCLUSION: Reliability of intraoral novel palpometer measures of pressure sensitivity was excellent, and sensitivity to pressure stimulation was dependent on the applied force and physical properties of the add-on device. The study indicated that semi-quantitative assessment of intraoral mechanical sensitivity is feasible and could be applied in further studies on different intraoral pain conditions.

Altruists are trusted based on non-verbal cues.

The identification of altruists based on non-verbal cues might offer a solution to the problem of subtle cheating. Previous studies have indicated that the ability to discriminate altruists from non-altruists emerges during evolution. However, behavioural differences with regard to social exchanges involving altruists and non-altruists have not been studied. We investigated differences in responses to videotaped altruists and non-altruists with the Faith Game. Participants tended to entrust real money to altruists more than to non-altruists, providing strong evidence that cognitive adaptations evolve as counter-strategies to subtle cheating.