Purpose: Burning mouth syndrome（BMS） is a type of chronic orofacial pain, which is challenging to diagnose and treat. This study looked at recent international review articles, and tried to confirm the recent international underatnding of the pathophysiologies, diagnosis, classifications and treatments of BMS.
Study selection: PubMed/MEDLINE, EMBASE, EBSCO, and WEB of SCIENCE databases were reviewed and evaluated to identify articles about BMS, written in English from 2010 to 2018.
Results: Fifty-nine review articles were identified. The first authors of the 59 review articles belonged to 19 countries and eight clinical departments. Forty of the 59 articles（68％） subtyped BMS as primary and secondary BMS, and 45（76％） of the 59 articles revealed that the primary pathophysiology of BMS was the pain of neuropathic origin. Only four review articles（7％）demonstrated significant relationships between BMS and psychological factors. In the 59 review articles, 70 treatment modalities, including systemic, local, and psychological methods were described. In the 36 modalities from 16 reviews with systematic review or meta-analysis, cognitive-behavioral therapy, topical clonazepam, and oral gabapentin were considered as possible effective treatments.
Conclusion: International consensus of BMS about pathophysiologies, diagnosis, classifications, and treatents are controversial even now. However, some evidence-based findings may support the patients with BMS in the near future.

View full abstract

Purpose: Pharmacotherapy for non-odontogenic pain may result in side effects. The purpose of this study was to investigate the side effects of pharmacotherapy for non-odontogenic pain retrospectively and to identify drugs that are at risk of causing side effects.
Methods: The patients’ backgrounds, use of medications, and side effects were extracted from their medical records at the Orofacial Pain Relief Center, Kanagawa Dental University Hospital from November 2018 to March 2020. Logistic regression analysis was performed, with the presence or absence of side effects at below the initial dose as the dependent variable. The independent variables were use of pain medications （amitriptyline hydrochloride, carbamazepine, Ca^2＋ channel α2δ ligands, tramadol hydrochloride）. Model performance was assessed with the Model Chi-square test, the Hosmer-Lemeshow test, Nagelkerke’s R² explained variance, and percentage of correct classifications. Bootstrapping techniques were used to internally validate our model.
Results: Of 123 patients, side effects occurred in 30 patients （24.4％）. A higher risk of side effects in pharmacotherapy for non-odontogenic pain included the use of Ca^2＋ channel α2δ ligand （p＝0.001, odds ratio （OR）: 5.61, 95％ confidence interval （CI）: 2.01-15.7）, and the use of carbamazepine （p＝0.022, OR: 4.02, 95% CI: 1.22-13.3）.
Conclusions: These results suggest that Ca^2＋ channel α2δ ligands （such as pregabalin and myrogabalin besylate） and carbamazepine may have a high risk of developing side effects even at initial doses below those listed in the package insert.

View full abstract

Purpose: The objective of this study was to investigate the prevalence of headache, facial pain, and bruxism in Japanese undergraduate dental school students.
Methods: Total 304 （104 for Class 2011, 111 for Class 2012, and 89 for Class 2013） third year dental school students at Nihon University School of Dentistry at Matsudo participated in this study. Patients History Questionnaire （PHQ） and Clinical Examination Form of Research Diagnostic Criteria for Temporomandibular Disorders （RDC/TMD） were completed during their mandatory class in temporomandibular disorders and orofacial pain. All students were required to input their data into database via an e-learning system. The answers of question #3 Have you had pain in the face, jaw, temple, in front of the ear, or in the ear in the past month?, #15c: Have you been told, or do you notice that you grind your teeth or clench your jaw while sleeping at night?, #15d: During the day, do you grind your teeth or clench your jaw?, and #18 During the last 6 months have you had a problem with headache or migraines? of PHQ were extracted from the database to investigate the prevalence of headache, facial pain, and bruxism in Japanese dental school students.
Results: The prevalence of headache and facial pain was 51.6％ and 4.6％, respectively. Also, eighty-three subjects （27.3％） reported the bruxism during sleep and 38 subjects （12.5％） reported the bruxism during wakefulness. Multiple regression analysis revealed significant relevance between headache/ facial pain and bruxism.
Conclusion: The prevalence of headache was higher than that of facial pain. Bruxism during sleep in Japanese dental school students was estimated remarkably high compared to adolescent group. Although this prevalence was estimated by self-repot, it was suggested that headache/ facial pain may be affected by bruxism.

View full abstract

Patients: Patients suffering from dry mouth often complain of tongue pain. In this study, we elucidated the profile of phosphorylation of extracellular signal-regulated kinase （ERK） in trigeminal spinal subnucleus caudalis （Vc） neurons of the dry-tongue model rat in response to cold stimuli.
Methods: The dry-tongue model rats were developed by receiving tongue exposure in the dry air for 2 hr per day for 1-14 days under light anesthesia （2% isoflurane）. The nocifensive behavior to cold stimulation and phosphorylation of ERK in the Vc were compared between sham and dry-tongue model rats. In addition, we evaluated effects of continuous intrathecal （i.t.） administration of MEK inhibitor PD98059 on the nocifensive behavior and expression of pERK immunoreactive （IR） cells in Vc.
Results: Head-withdrawal threshold （HWT） to cold stimulation of the tongue significantly decreased on day 7 compared to sham rats （dry tongue model, 3.27±1.12℃; sham, −3.39±0.58℃）. The number of pERK-IR cells in the Vc significantly increased in comparison to that of sham rats on day 7 （dry tongue model, 41.2±3.6; sham; 23.0±3.6）. The decrement in the cold HWT were blocked by PD98059 （PD98059, −3.5±0.3℃; Vehicle, 3.2±0.4℃. In addition, PD98059 blocked an increase in the number of pERK-IR cells （PD98059, 27.6 ± 2.7; Vehicle; 39.1 ± 3.1）.
Conclusions: The present study demonstrated that cold hyperalgesia occurs in the dry-tongue rats and suggested that cold tongue pain in the dry-tongue model rats correlates with ERK phosphorylation in Vc neurons.

View full abstract

Patient: A 59-year-old man had experienced intense left facial pain at the beginning of and after meals. No apparent abnormal finding was detected by the clinical examination, panoramic radiography, MRI, ultrasonography except for tenderness of the left parotid gland and submandibular gland. We diagnosed idiopathic first bite syndrome （FBS）. At the same time, we found hyperglycemia in his laboratory data. He was referred to a diabetes specialist and underwent treatment for diabetes.　The beginning of and after meals pain improved as the decrease of blood glucose level.
Discussion: In this case, pain at the beginning of and after meals improved significantly after the diabetes treatment, and the severe postprandial pain disappeared. Although idiopathic FBS has been suggested to be associated with diabetes, the experience of this case indicates that hyperglycemia may be strongly involved in the pain of idiopathic FBS.
Conclusions: When diagnosing idiopathic FBS, it may be necessary to confirm the history of diabetes and laboratory data.

View full abstract

Most cases of trigeminal neuralgia are caused by neurovascular compression. We report a rare case of trigeminal neuralgia due to large cerebral arteriovenous malformation （AVM）.
Patient: The patient is a 62-year-old male. His chief complaint was electric shock-like pain on the left mandibul, and he was referred to our department from general practitioner. At the first visit, we suspected trigeminal nerve pain, and prescribed carbamazepine 100mg/day. The electric shock-like pain diminished. Head CT scan and MRI showed arteriovenous malformation（AVM） in the left occipital lobe. Under a diagnosis of secondary trigeminal neuralgia, the pain subsided within the range of self-control, after increasing the dose of the carbamazepine 400mg/day. Currently, the patient has been followed in the Department of Neurosurgery in our hospital, and the pain is controlled.
Discussion: The case was diagnosed secondary trigeminal neuralgia due to large cerebral arteriovenous malformation. Since the treatment method for AVM differs depending on Spetzler-Martin classification, it is important to cooperate with other related departments.
Conclusion: We report a rare case of trigeminal neuralgia due to large cerebral AVM. In this case, carbamazepine was effective for trigeminal neuralgia. If pain in the trigeminal region are present, we should differentially diagnose secondary trigeminal neuralgia attributed to intracranial lesions.

View full abstract