Circadian rhythms variation of pain in burning mouth syndrome

Burning mouth syndrome: Analysis of diagnostic delay in 500 patients

OBJECTIVES

To assess the diagnostic delay, the number and type of referrals and the clinical and psychological profile in a wide sample of patients with Burning Mouth Syndrome (BMS).

MATERIALS AND METHODS

Data on the disease onset, oral symptoms, type and number of practitioners consulted, misdiagnoses, and the presence of medically unexplained extraoral physical symptoms were recorded in 500 BMS patients. Potential predictors of diagnostic delay were also evaluated.

RESULTS

The mean diagnostic delay was 29.71 ± 47.19 months. An average of 2.61 ± 1.65 practitioners were consulted by each patient, the most frequent being the general physicians (287; 57.4%), maxillofacial surgeons (111; 22.2%), and otolaryngologists (104; 20.8%). The mean number of misdiagnoses was 3.54 ± 1.85. Nonspecific stomatitis, candidiasis, and gastroesophageal reflux were the most common misdiagnoses. Higher age, low education, the presence of dysgeusia, and a previous history of psychiatric illness were predictors of a longer diagnostic delay (p-value: 0.028, 0.050, 0.007, 0.034, respectively).

CONCLUSIONS

The lack of knowledge among specialists, the high rate of misdiagnosis, and the diagnostic delay of BMS highlight the need to introduce educational interventions in all medical specialties in order to promote an early and appropriate diagnosis, thereby improving the prognosis and quality of life of the patients.

Trigeminal neuralgia and trigeminal neuropathic pain

It is very important that the dental team are aware of the varied presentations of pain in the mouth, face and other parts of the trigeminal region which are not directly caused by teeth or oral structures. Our understanding of underlying causes in this complex area is evolving. Ultimately, patients who present with what may at first seem to be oral or dental problems will require specialist input in secondary care with potential for use of systemic medications. This article reviews the common non-dental pains encountered in the orofacial region related to dysfunction of the trigeminal nerve.

Single-nucleus transcriptome analysis reveals transcriptional profiles of circadian clock and pain related genes in human and mouse trigeminal ganglion

Introduction

Clinical studies have revealed the existence of circadian rhythms in pain intensity and treatment response for chronic pain, including orofacial pain. The circadian clock genes in the peripheral ganglia are involved in pain information transmission by modulating the synthesis of pain mediators. However, the expression and distribution of clock genes and pain-related genes in different cell types within the trigeminal ganglion, the primary station of orofacial sensory transmission, are not yet fully understood.

Methods

In this study, data from the normal trigeminal ganglion in the Gene Expression Omnibus (GEO) database were used to identify cell types and neuron subtypes within the human and mouse trigeminal ganglion by single nucleus RNA sequencing analysis. In the subsequent analyses, the distribution of the core clock genes, pain-related genes, and melatonin and opioid-related genes was assessed in various cell clusters and neuron subtypes within the human and mouse trigeminal ganglion. Furthermore, the statistical analysis was used to compare the differences in the expression of pain-related genes in the neuron subtypes of trigeminal ganglion.

Results

The present study provides comprehensive transcriptional profiles of core clock genes, pain-related genes, melatonin-related genes, and opioid-related genes in different cell types and neuron subtypes within the mouse and human trigeminal ganglion. A comparative analysis of the distribution and expression of the aforementioned genes was conducted between human and mouse trigeminal ganglion to investigate species differences.

Discussion

Overall, the results of this study serve as a primary and valuable resource for exploring the molecular mechanisms underlying oral facial pain and pain rhythms.

Thermography as a Non-Ionizing Quantitative Tool for Diagnosing Burning Mouth Syndrome: Case-Control Study

Objectives: Thermography is an imaging technique based on the acquisition and analysis of thermal data. The present study evaluates the use of tongue infrared thermography (IRT) as a tool for the diagnosis of burning mouth syndrome (BMS). Material and methods: An IRT study was carried out in patients diagnosed with BMS according to the criteria of the International Association for the Study of Pain (n = 32) and in healthy controls (n = 35). Burning sensations, dry mouth and taste disturbances were assessed, and three temperature values were recorded for each tongue surface (dorsal, right lateral, left lateral and tip), along with body temperature and environmental temperature. Results: A statistically significant difference was recorded in the temperature of the dorsal surface of the tongue between the BMS group and the controls (p = 0.01). The area under the curve (AUC) was 0.731 (95% CI: 0.402–0.657; p = 0.003). The sensitivity and specificity obtained was 62% and 77%, respectively. Conclusions: Infrared thermography appears to be useful as a complementary tool for the diagnosis of BMS, though further studies are needed in this field.

Intraoperative Pain Sensation During Cataract Surgery: Why Does Timing Matter?

Purpose: To investigate whether timing influences pain perception during cataract surgery and to investigate the possible mechanisms.Methods: Patients scheduled for cataract surgery both in the morning and afternoon were consecutively enrolled. Questionnaires to evaluate anxiety, including the Simplified State-Trait Anxiety Inventory, Amsterdam Preoperative Anxiety and Information Scale, and a visual analogue scale (VAS) for anxiety, were completed preoperatively, whereas a VAS for pain and the Wong-Baker FACES® Pain Rating Scale questionnaire were completed after surgery. Preoperative blood pressure and heart rate were recorded. Blood samples were acquired before surgery, and plasma cortisol, adrenocorticotropic hormone, adrenalin, and noradrenalin were tested.Results: Fifty-five patients underwent uneverntful cataract surgery (28 in the morning and 27 in the afternoon) were included in the final analysis. Greater intraoperative pain perception during cataract surgery was reported in the afternoon than in the morning. Overall anxiety levels were significantly higher in the afternoon. Plasma adrenalin levels were significantly higher in the afternoon. Cortisol levels were higher in the afternoon. Preoperative anxiety levels were closely related to intraoperative pain perception. Both adrenalin and cortisol correlated positively with preoperative anxiety, but only adrenalin correlated significantly with the pain scores.Conclusions: Patients undergoing cataract surgery in the afternoon showed more preoperative anxiety, which may have increased their relevant stress hormones. Both the patient's emotional state and hormone levels may together aggravate his/her perceived pain in the afternoon. Monitoring preoperative anxiety levels, blood pressure, and heart rate should help to identify patients at higher risk of perceived intraoperative pain.Clinical trial registration:Trial registration number: NCT02182921Registration site: clinicaltrials.gov.

Burning mouth syndrome: An update

Background:

Burning mouth syndrome (BMS) is a chronic and debilitating oral pain of the normal oral mucosa. It mainly affects women in their fifth to seventh decade. Its aetiopathogenesis remains unclear and is probably of multifactorial origin, with increasing evidence that BMS may be a neuropathic disorder. BMS is classified as an idiopathic (nociplastic) orofacial pain with or without somatosensory changes by International Classification of Orofacial Pain (ICOP 2020). The diagnosis of BMS, having excluded ‘oral burning mouth symptoms’, has evolved from basic intraoral exclusion screening to extensive clinical and laboratory investigations, which include the screening of comorbidities and other chronic pains and somatosensory testing. There is no standardised treatment in managing BMS, but a proposed combination of supportive and pharmacological treatment has been recommended.

Aim:

To review the current concepts of BMS definitions, classifications, aetiopathogenesis, diagnosis techniques, and evidence-based treatments in managing BMS patients.

Conclusion:

As BMS is a diagnosis by exclusion, thus a stratified approach is required for assessment of patients presenting BMS. A BMS diagnosis protocol is desired using a standardised screening to distinguish BMS from patient’s presenting with ‘oral burning symptoms’, and evaluation of comorbid chronic pain disorders or other medical comorbidities, which will include haematological, fungal, salivary flow, and qualitative sensory testing. Axis II and other additional quantitative sensory testing may further elucidate the causes of this condition. For future BMS prediction and prevention, will be based upon research on the relationship between other chronic pain disorders and familial history, environmental and genetic information.

Burning Mouth Syndrome

Burning mouth syndrome is a chronic condition characterized by an intraoral burning sensation in the absence of a local or systemic cause.

The Clinical Features of Painful Small-Fiber Neuropathy Suggesting an Origin Linked to Primary Sjögren's Syndrome

OBJECTIVE

We attempted to determine whether clinical features could differentiate painful small-fiber neuropathy related to primary Sj€ogren's syndrome (pSS-SFN) from idiopathic SFN (idio-SFN).

METHODS

Validated clinical questionnaires and neurophysiological investigations specific for pain and SFN assessment were performed in 25 patients with pSS-SFN and 25 patients with idio-SFN.

RESULTS

Patients with idio-SFN had more frequent severe burning sensations and higher mean anxiety scores and daily pain intensity compared to patients with pSSSFN. Conversely, patients with pSS-SFN had reduced electrochemical skin conductance measured by Sudoscan_, and almost half of them had the sensation of walking on cotton wool.

CONCLUSION

Our results suggest that idio-SFN more specifically involved small sensory fibers than pSS-SFN, in which subtle dysfunction of larger sensory fibers and damage of distal autonomic sudomotor innervation may occur. A practical algorithm is proposed to help to differentiate SFN associated with pSS from idio-SFN, based on information very easy to obtain by clinical interview.

Emerging relevance of circadian rhythms in headaches and neuropathic pain

Circadian rhythms of physiology are the keys to health and fitness, as dysregulation, by genetic mutations or environmental factors, increases disease risk and aggravates progression. Molecular and physiological studies have shed important light on an intrinsic clock that drives circadian rhythms and serves essential roles in metabolic homoeostasis, organ physiology and brain functions. One exciting new area in circadian research is pain, including headache and neuropathic pain for which new mechanistic insights have recently emerged. For example, cluster headache is an intermittent pain disorder with an exceedingly precise circadian timing, and preliminary evidence is emerging linking several circadian components (eg, Clock and Nr1d1) with the disease. In this review, we first discuss the broad metabolic and physiological relevance of the circadian timing system. We then provide a detailed review of the circadian relevance in pain disease and physiology, including cluster headache, migraine, hypnic headache and neuropathic pain. Finally, we describe potential therapeutic implications, including existing pain medicines and novel clock-modulating compounds. The physiological basis for the circadian rhythms in pain is an exciting new area of research with profound basic and translational impact.

Recent Advances in the Etiology and Treatment of Burning Mouth Syndrome

Burning mouth syndrome (BMS) is a debilitating condition that has a striking female predilection. Although the oral mucosa is normal in appearance, patients with BMS experience oral burning that most commonly localizes to the lips and tongue. BMS is a diagnosis of exclusion, and all underlying pathoses associated with allodynia must be ruled out prior to rendering the diagnosis. The etiopathogenesis of BMS remains poorly understood, and thus patient management is challenging. Data indicate that oral and systemic factors both contribute to the development and persistence of the condition. Of particular interest, emerging work identifies structural and functional deficits within the nervous system that may lead to a more mechanistic understanding of BMS pathology. In addition, several novel findings suggest that circadian rhythm dysfunction may be a previously unappreciated yet clinically significant driver of disease. Circadian rhythm controls pain perception, mood, and sleep and plays a key role in the regulation of the hypothalamic-pituitary-adrenal axis. Since these are altered in patients with BMS, this may be reflective of underlying circadian dysfunction. While evidence-based treatment strategies for BMS are lacking, current treatment approaches consist of local and systemic medications, such as clonazepam, alpha lipoic acid, capsaicin, low-level laser therapy, gabapentin, and amitriptylin. In addition, the use of cognitive behavioral therapy is reported. This review provides an overview of the recent literature related to the etiology and treatment of BMS and identifies current challenges facing researchers and clinicians alike.

Neuropathic Pain in Patients with Burning Mouth Syndrome Evaluated Using painDETECT

Objective

This study set out to identify the neuropathic component of pain experienced by burning mouth syndrome (BMS) patients evaluated using painDETECT, a diagnostic tool that could easily be introduced into clinical practice.

Materials and Methods

This study included 64 patients (33 BMS and 31 suffering nociceptive pain). Each completed the painDETECT neuropathic pain questionnaire, the Hospital Anxiety and Depression Scale, and pain intensity was also measured using a visual analogue scale (VAS).

Results

Pain among BMS patients (evaluated by VAS) was 6.1 ± 1.9, and 4.3 ± 1.7 among nociceptive patients ( P  < 0.001). PainDETECT obtained total scores ≥ 19 in 21% of BMS patients, indicating the presence of neuropathic pain. When painDETECT pain descriptors were analyzed comparing the BMS group with nociceptive pain subjects, statistically significant differences were found for burning sensation ( P  < 0.010), prickling ( P  < 0.001), electric shock-like sensation ( P  = 0.046), thermal sensation ( P  < 0.001), and numbness ( P  = 0.002). Logistic regression analysis found that VAS scoring was the strongest determinant predicting neuropathic pain.

Conclusion

The present study suggests that almost a third of BMS patients present neuropathic pain, which is strongly associated with the intensity of pain measured using VAS. These data could provide the basis for further research.

Clinical characterization of women with burning mouth syndrome in a case-control study

OBJECTIVE

Burning mouth syndrome (BMS) is a chronic orofacial pain disorder that is defined by a burning sensation in the oral mucosa. The aim of this study was to investigate the underlying factors, clinical characteristics and self-reported oral and general health factors associated with BMS.

MATERIAL AND METHODS

Fifty-six women with BMS (mean age: 67.7) and their age-matched controls were included in the study. A general questionnaire, an OHRQL index and BMS-specific questionnaires were used. Each subject underwent an oral examination.

RESULTS

The mean severity of the BMS symptoms (VAS, 0-100) was 66.2 (SD 19.7). Overall, 45% of the patients reported taste disturbances. More of the patients than the controls rated their general health, oral health and life situation as 'less satisfactory'. The patients also reported more frequently on-going medications, diseases/disorders, xerostomia, allergy and skin diseases. Except for more bruxofacets among the patients, there were no significant differences regarding signs of parafunction. In a multiple logistic regression analysis, xerostomia and skin diseases showed the strongest prediction for BMS and no significant effect was found for medication, allergy or bruxofacets.

CONCLUSIONS

Skin diseases and xerostomia but not parafunction were strongly associated with BMS. Our findings provide the basis for additional studies to elucidate the causal factors of BMS.

Burning mouth syndrome

Objective

To review the clinical entity of primary burning mouth syndrome (BMS), its pathophysiological mechanisms, accurate new diagnostic methods and evidence-based treatment options, and to describe novel lines for future research regarding aetiology, pathophysiology, and new therapeutic strategies.

Description

Primary BMS is a chronic neuropathic intraoral pain condition that despite typical symptoms lacks clear clinical signs of neuropathic involvement. With advanced diagnostic methods, such as quantitative sensory testing of small somatosensory and taste afferents, neurophysiological recordings of the trigeminal system, and peripheral nerve blocks, most BMS patients can be classified into the peripheral or central type of neuropathic pain. These two types differ regarding pathophysiological mechanisms, efficacy of available treatments, and psychiatric comorbidity. The two types may overlap in individual patients. BMS is most frequent in postmenopausal women, with general population prevalence of around 1%. Treatment of BMS is difficult; best evidence exists for efficacy of topical and systemic clonazepam. Hormonal substitution, dopaminergic medications, and therapeutic non-invasive neuromodulation may provide efficient mechanism-based treatments for BMS in the future.

Conclusion

We present a novel comprehensive hypothesis of primary BMS, gathering the hormonal, neuropathic, and genetic factors presumably required in the genesis of the condition. This will aid in future research on pathophysiology and risk factors of BMS, and boost treatment trials taking into account individual mechanism profiles and subgroup-clusters.

Is it Sjögren's syndrome or burning mouth syndrome? Distinct pathoses with similar oral symptoms

Sjögren's syndrome (SS) and burning mouth syndrome (BMS) typically occur in postmenopausal women. Although these conditions have significantly different etiopathogeneses, patients with SS or BMS often present with analogous oral complaints. The similarities between the two conditions have led to considerable confusion on the part of medical and dental practitioners, and those with BMS or SS often wait years to receive a diagnosis. Therefore, it is imperative for clinicians to understand the characteristic subjective and objective features of each disease and how these can be used to distinguish them. This review will discuss the proposed etiology, clinical manifestations, histopathology, diagnostic criteria, and patient management of SS and BMS. We also identify key differences between the two pathoses that aid in establishing the correct diagnosis. Recognition of the defining features of each condition will lead to reduced time to diagnosis and improved patient management for these poorly understood conditions.

Opiorphin in burning mouth syndrome patients: a case-control study

OBJECTIVES

Opiorphin is a pentapeptide isolated from human saliva that suppresses pain from chemically induced inflammation and acute physical pain. Burning mouth syndrome (BMS) is a chronic condition of a burning sensation in the mouth, where no underlying dental or medical cause can be identified. We aimed to measure the level of opiorphin in whole unstimulated (UWS) and stimulated (SWS) saliva of patients with BMS.

MATERIALS AND METHODS

Originally developed and validated LC-MS/MS method was used for opiorphin quantification. Samples were obtained from 29 BMS patients and 29 age- and sex-matched controls.

RESULTS

The average concentration of opiorphin in UWS and SWS in the BMS group was 8.13 ± 6.45 and 5.82 ± 3.59 ng/ml, respectively. Opiorphin in BMS patients' UWS was significantly higher, compared to the control group (t = 2.5898; p = 0.0122). SWS opiorphin levels were higher, but not significantly, in BMS patients than in controls.

CONCLUSIONS

Our results indicate that higher quantities of salivary opiorphin in BMS may be a consequence of chronic pain, but we cannot exclude that they occur as a result of emotional and behavioral imbalances possibly associated with BMS. To our knowledge, this is the first original article measuring opiorphin in a pain disorder.

CLINICAL RELEVANCE

Opiorphin may be a measurable biomarker for chronic pain, which could help in objectifying otherwise exclusively a subjective experience. Increased opiorphin could serve as a universal objective indicator of painful conditions. Since opiorphin may also reflect emotional and socio-relational imbalances occurring with BMS, it could as well represent a biomarker for BMS. Knowledge on opiorphin's involvement in pain pathways could contribute to developing new clinical diagnostic methods for BMS.

Mildly Increased Mechanical Nociceptive Sensitivity in REV-ERBα Knock-out Mice

Nociception is one of the most complex senses that is affected not only by external stimulation but also internal conditions. Previous studies have suggested that circadian rhythm is important in modulating nociception. REV-ERBα knock-out (KO) mice have disrupted circadian rhythm and altered mood-related phenotypes. In this study, we examined the role of REV-ERBα in inflammatory nociception. We found that the nociceptive sensitivity of KO mice was partially enhanced in mechanical nociception. However, this partial alteration was independent of the circadian rhythm. Taken together, deletion of REV-ERBα induced a mild change in mechanical nociceptive sensitivity but this alteration was not dependent on the circadian rhythm.