Scandinavian Center for Orofacial Neuroscience

Stockholm, Sweden

Scandinavian Center for Orofacial Neuroscience

Stockholm, Sweden

Time filter

Source Type

Christidis N.,Karolinska Institutet | Christidis N.,Scandinavian Center for Orofacial Neuroscience | Kang I.,University of British Columbia | Cairns B.E.,University of British Columbia | And 9 more authors.
Journal of Headache and Pain | Year: 2014

Background: Previous studies have shown that 5-HT3-antagonists reduce muscle pain, but there are no studies that have investigated the expression of 5-HT3-receptors in human muscles. Also, tetrodotoxin resistant voltage gated sodium-channels (NaV) are involved in peripheral sensitization and found in trigeminal ganglion neurons innervating the rat masseter muscle. This study aimed to investigate the frequency of nerve fibers that express 5-HT3A-receptors alone and in combination with NaV1.8 sodium-channels in human muscles and to compare it between healthy pain-free men and women, the pain-free masseter and tibialis anterior muscles, and patients with myofascial temporomandibular disorders (TMD) and pain-free controls.Methods: Three microbiopsies were obtained from the most bulky part of the tibialis and masseter muscles of seven and six healthy men and seven and six age-matched healthy women, respectively, while traditional open biopsies were obtained from the most painful spot of the masseter of five female patients and from a similar region of the masseter muscle of five healthy, age-matched women. The biopsies were processed by routine immunohistochemical methods. The biopsy sections were incubated with monoclonal antibodies against the specific axonal marker PGP 9.5, and polyclonal antibodies against the 5-HT3A-receptors and NaV1.8 sodium-channels.Results: A similar percentage of nerve fibers in the healthy masseter (85.2%) and tibialis (88.7%) muscles expressed 5-HT3A-receptors. The expression of NaV1.8 by 5-HT3A positive nerve fibers associated with connective tissue was significantly higher than nerve fibers associated with myocytes (P <.001). In the patients, significantly more fibers per section were found with an average of 3.8 ± 3 fibers per section in the masseter muscle compared to 2.7 ± 0.2 in the healthy controls (P =.024). Further, the frequency of nerve fibers that co-expressed NaV1.8 and 5-HT3A receptors was significantly higher in patients (42.6%) compared to healthy controls (12.0%) (P <.001).Conclusions: This study showed that the 5-HT3A-receptor is highly expressed in human masseter and tibialis muscles and that there are more nerve fibers that express 5-HT3A-receptors in the masseter of women with myofascial TMD compared to healthy women. These findings indicate that 5-HT3-receptors might be up-regulated in myofascial TMD and could serve as potential biomarkers of chronic muscle pain. © 2014, Christidis et al.; licensee Springer.


Sato H.,Keio University | Sato H.,Kawasaki Municipal Kawasaki Hospital | Castrillon E.E.,University of Aarhus | Castrillon E.E.,Scandinavian Center for Orofacial Neuroscience | And 10 more authors.
European Journal of Pain (United Kingdom) | Year: 2016

Background This study was conducted to determine whether glutamate-evoked jaw muscle pain is modulated by the acidity and temperature of the solution injected. Methods Thirty two participants participated and received injections of high-temperature acidic (HT-A) glutamate (pH 4.8, 48 C), high-temperature neutral (HT-N) glutamate (pH 7.0, 48 C) and neutral temperature neutral (NT-N) glutamate (pH 7.0, 38 C) solutions (0.5 mL) into the masseter muscle. Pain intensity was assessed with an electronic visual analogue scale (eVAS). Numerical rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, mechanical sensitivity and pressure pain thresholds (PPT) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). One or two way ANOVAs were used for data analyses. Results Injection of HT-A glutamate solutions significantly increased the area under the VAS-time curve compared with injection of HT-N glutamate and NT-N glutamate solution (p < 0.040). The duration of glutamate-evoked pain was significantly longer when HT-A glutamate was injected than when NT-N glutamate was injected (p < 0.017). No significant effects of acidity were detected on pain drawings, NRS unpleasantness and heat perception, but there was a significant effect of acidity on MPQ scores and mechanical sensitivity. Conclusion Acidity and temperature modulate glutamate-evoked jaw muscle pain suggesting an interaction between acid sensing and glutamate receptors which could be of importance for understanding clinical muscle pain conditions. © 2015 European Pain Federation - EFIC®.


Naganawa T.,Tokyo Women's Medical University | Sakuma K.,Tokyo Women's Medical University | Kumar A.,University of Aarhus | Kumar A.,Scandinavian Center for Orofacial Neuroscience | And 3 more authors.
Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology | Year: 2015

Disseminated intravascular coagulation (DIC) is a condition causing severe bleeding, which requires hemostatic measures be taken after surgical treatment. However, there is no clear method to assess coagulation and bleeding after surgical treatment. Here, we describe a rare case of intracranial hemorrhage after tooth extraction in a patient with chronic DIC associated with aortic dissection. A 76-year old Japanese male reported spontaneous pain in the upper front teeth region. Tooth extraction was performed based on a diagnosis of severe periodontitis. Four hours after the extraction, re-bleeding from the tooth socket was reported. Moreover, 10 and 20 h after extraction, bleeding occurred from the tooth socket again. In both situations, the bleeding was successfully controlled by pressure hemostasis. Three and 5 days after the extraction, the patient reported to the emergency outpatient care with post extraction hemorrhage. Twelve days after the extraction, the patient complained of spontaneous severe headache. Computed tomography (CT) of the head was taken and hemorrhage was observed in his left frontal lobe. Thirty-eight days after tooth extraction, brain hemorrhage was spontaneously evoked again. It must be noted that bleeding may occur in any part of the body in patients with DIC and not only at the surgical site. © 2015 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI.


Naganawa T.,University of Aarhus | Naganawa T.,Tokyo Medical University | Baad-Hansen L.,University of Aarhus | Baad-Hansen L.,Scandinavian Center for Orofacial Neuroscience | And 4 more authors.
Experimental Brain Research | Year: 2015

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). © 2015, Springer-Verlag Berlin Heidelberg.


Louca S.,Karolinska Institutet | Louca S.,Scandinavian Center for Orofacial Neuroscience | Christidis N.,Karolinska Institutet | Christidis N.,Scandinavian Center for Orofacial Neuroscience | And 9 more authors.
Journal of Headache and Pain | Year: 2014

Background: Chronic myalgia is associated with higher muscle levels of certain algesic biomarkers. The aim of this study was to investigate if hypertonic saline-induced jaw myalgia also leads to release of such biomarkers and if there were any sex differences in this respect.Methods: Healthy participants, 15 men and 15 aged-matched women (25.7 ± 4.3 years) participated. Intramuscular microdialysis into masseter muscles was performed to sample serotonin (5-HT), glutamate, lactate, pyruvate, glucose and glycerol. After 2 hours 0.2 mL hypertonic saline (58.5 mg/mL) was injected into the masseter on one side and 0.2 mL isotonic saline (9 mg/mL) into the contralateral masseter close to the microdialysis catheter. Microdialysis continued for 1 hour after the injections. Pressure pain thresholds (PPT) and pain were assessed before and after injections.Results: The median (IQR) peak pain intensity (0–100 visual analogue scale) after hypertonic saline was 52.5 (38.0) and after isotonic saline 7.5 (24.0) (p < 0.05). 5-HT, glutamate and glycerol increased after hypertonic saline injection (p < 0.05). Lactate, pyruvate and glucose showed no change. PPT after microdialysis was reduced on both sides (p < 0.05) but without side differences. Pain after hypertonic saline injection correlated positively to 5-HT (p < 0.05) and negatively to glycerol (p < 0.05).Conclusions: 5-HT, glutamate and glycerol increased after a painful hypertonic saline injection into the masseter muscle, but without sex differences. Since increased levels of 5-HT and glutamate have been reported in chronic myalgia, this strengthens the validity of the pain model. Glycerol warrants further investigations. © 2014, Louca et al.; licensee Springer.


Kumar A.,University of Aarhus | Kumar A.,Scandinavian Center for Orofacial Neuroscience | Svensson K.G.,Karolinska Institutet | Svensson K.G.,Scandinavian Center for Orofacial Neuroscience | And 7 more authors.
Archives of Oral Biology | Year: 2014

Objective To investigate if repeated holding and splitting of food morsel change the variability of force and jaw muscle activity in participants with natural dentition. Methods Twenty healthy volunteers (mean age = 26.2 ± 3.9 years) participated in a single session divided into six series. Each series consisted of ten trials of a standardized behavioural task (total 60 trials) involving holding and splitting a flat-faced tablet (8 mm, 180 mg) placed on a bite force transducer with the anterior teeth. The hold and split forces along with the electromyographic (EMG) activity of the left and right masseter (MAL and MAR), left anterior temporalis (TAL) and digastric (DIG) muscles were recorded. A series (ten trials) of natural biting tasks was also performed before and after the six series of the behavioural task. Results The mean hold force (P < 0.001) but not the mean split force (P = 0.590) showed significant effect of number of series. No significant effect of series was seen on the variability of hold and split force and the EMG activity except for the variability of EMG activity for MAL during the hold phase (P = 0.021) and DIG during the split phase (P < 0.001). The behavioural task had no effect on the EMG activity of the natural biting task. Conclusion There was no evident optimization of jaw motor function in terms of reduction in the variability of bite force values and muscle activity, when this simple task was repeated up to sixty times in participants with normal intact periodontium. © 2014 Elsevier Ltd. All rights reserved.


Naganawa T.,Tokyo Women's Medical University | Naganawa E.,Tokyo Women's Medical University | Kumar A.,University of Aarhus | Kumar A.,Scandinavian Center for Orofacial Neuroscience | And 7 more authors.
Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology | Year: 2016

Motivational interviewing (MI) is a technique for helping clients to recognize and address their problems. This approach is useful for clients who are reluctant to change or who are ambivalent about changing their behaviors. We describe a case of medication non-adherence in a patient with chronic intraoral neuropathic pain. A 54-year-old man visited the Tokyo Women's Medical University Hospital with spontaneous pain on the gingiva and tongue. Although, pharmacotherapy was initiated, pain management was inadequate. The patient was unwilling to take any more medications (medication non-adherence) because of his previous experience, where the medications prescribed were non-effective in controlling his pain. MI was performed for his ambivalent condition (unwilling to take medicine vs. willing to achieve pain relief). The patient's behavior changed after three MI sessions, and then 2 weeks of pharmacotherapy (amitriptyline, 10 mg/day) decreased the pain score from 8 to 4 on the numerical rating scale (0-10). Another 8 weeks on amitriptyline at 20 mg/day further improved pain score from 4 to 0. MI may be effective as a psychological approach for addressing non-adherence to medication in the management of chronic intraoral pain. © 2015 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI.


PubMed | University of Aarhus, Scandinavian Center for Orofacial Neuroscience and Nanjing University
Type: Journal Article | Journal: Experimental brain research | Year: 2016

The aim was to test the hypothesis that short-term oral sensorimotor training of the jaw muscles would increase the precision of task performance and induce neuroplastic changes in the corticomotor pathways, related to the masseter muscle. Fifteen healthy volunteers performed six series with ten trials of an oral sensorimotor task. The task was to manipulate and position a spherical chocolate candy in between the anterior teeth and split it into two equal halves. The precision of the task performance was evaluated by comparing the ratio between the two split halves. A series of hold-and-split tasks was also performed before and after the training. The hold force and split force along with the electromyographic (EMG) activity of jaw muscles were recorded. Motor-evoked potentials and cortical motor maps of the right masseter muscle were evoked by transcranial magnetic stimulation. There was a significant effect of series on the precision of the task performance during the short-term oral sensorimotor training (P<0.002). The hold force during the hold-and-split task was significantly lower after training than before the short-term training (P=0.011). However, there was no change in the split force and the EMG activity of the jaw muscles before and after the training. Further, there was a significant increase in the amplitude of the motor-evoked potentials (P<0.016) and in the motor cortex map areas (P=0.033), after the short-term oral sensorimotor training. Therefore, short-term oral sensorimotor task training increased the precision of task performance and induced signs of neuroplastic changes in the corticomotor pathways, related to the masseter muscle.

Loading Scandinavian Center for Orofacial Neuroscience collaborators
Loading Scandinavian Center for Orofacial Neuroscience collaborators