The role of sensory input of the chorda tympani nerve and the number of fungiform papillae in burning mouth syndrome

WWOM VII: Effectiveness of topical interventions in the management of burning mouth syndrome: A systematic review

OBJECTIVES

To assess the effectiveness of topical interventions in the management of burning mouth syndrome (BMS), based on the core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT).

METHODS

A systematic literature review of RCTs on topical interventions for the management of BMS, published in PubMed, Web of Science, PsycInfo, Cochrane Database/Central, and Google Scholar through May 2021 was performed.

RESULTS

Eight RCTs (n = 358 study participants) were included in this study. Due to underreporting of IMMPACT domains, publication bias, high degree of heterogeneity between studies, meta-analysis was not undertaken. Based on changes in visual analogue pain scores (ΔVAS), the most reported outcome, the effectiveness of the topical interventions was demonstrated; however, it is low level of evidence.

CONCLUSIONS

High levels of variability (interventions, outcomes, outcome measurement tools, and intervention effects evaluated), heterogeneity, publication bias, and underreporting of IMMPACT domains were observed across the RCTs. This systematic review highlights the need for application of standardized outcome measures to future RCTs. At the present time, there is lack of moderate-strong evidence on short- and long-term outcomes to support or refute the use of any particular topical intervention in managing BMS. Future RCTs with standardized outcome measures are needed.

A review of psychocutaneous disorders from a psychotherapeutic perspective—Toolkit for the dermatologist

Introduction

The study of psychocutaneous disorders requires a multidisciplinary approach. It is of paramount importance that dermatologists understand the psychiatric premise for these disorders. Mental health professionals can also benefit from a better understanding of the dermatologic manifestations of psychiatric disorders they may encounter in their practice.

Aim

The aim of this study is to elevate the level of understanding regarding psychotherapeutic treatment of psychocutaneous disorders.

Methods

We performed a literature review using the major databases. Four researchers reviewed English, full text, peer-reviewed articles that were published after 2000 using our specific search terms and inclusion/exclusion criteria.

Results

The majority of psychocutaneous disorders seem to be clustered among three DSM-5 disorders: depressive disorders, anxiety disorders, and obsessive-compulsive related disorders.

Conclusions

Better recognition of the underlying psychiatric comorbidities may lead to improved patient outcomes.

Relationship between subjective taste sensations and taste strip test in patients with taste disorders with and without burning mouth syndrome

Background/purpose

Both subjective and objective evaluations are required to assess taste function. Evaluation of taste function has important clinical significances in patients with burning mouth syndrome (BMS) due to pain-taste interactions. The purpose of this study was to investigate the relationship between subjective and objective taste evaluations in patients with taste disorders based on the presence of BMS.

Materials and methods

Fifty–one patients with taste disturbances were included. The patients completed questionnaires on subjective taste sensations. The taste strip test was performed to examine objective taste function. The patients were divided into two groups: subjects with BMS (n = 24, 3 males and 21 females) and without BMS (n = 27, 8 males and 19 females).

Results

Significant differences were not observed in age, age distribution, and gender distribution between the groups. There were no significant differences in self-reported taste abilities based on the presence of BMS. However, the taste strip test showed higher correct answer rates for bitterness (P = 0.027) in the patients with BMS. In addition, a significant difference (P = 0.034) was observed in the distribution of objective types of taste disorders between the groups. A significant correlation between the subjective and objective evaluation results was observed only in patients with BMS.

Conclusion

In patients with taste disorders, patients with BMS had significant correlations between subjective and objective evaluations and different distributions in the types of taste disorders compared with those without BMS. The presence or absence of BMS should be evaluated in the diagnosis and management of taste disorders.

Burning Mouth Syndrome (BMS)—Treatment with Verbal and Written Information, B Vitamins, Probiotics, and Low-Level Laser Therapy: A Randomized Clinical Trial

Background: The objective of this study was to determine the most effective treatment option for burning mouth syndrome. Methods: Informative treatment alone, B vitamin injections, oral cavity probiotics, and low-level laser therapy were evaluated and compared. The study included new patients diagnosed with burning mouth syndrome, who were randomly allocated into one of four treatment groups. The primary outcome was improvement in patient’s quality of life as determined by a self-perceived Oral Health Impact Profile-14 (OHIP-14) quality of life questionnaire before and after therapy. The secondary outcome was determination of mucosal symptom intensity according to visual analog scale (VAS) grading from 0 to 10. Data were submitted to statistical analysis. Results: A total of 62 patients completed the study. Oral cavity probiotics and LLLT scores for OHIP-14 resulted in a statistically significant difference before and after therapy. Standardized effect sizes between OHIP scores before and after treatment were the greatest for patients who had received oral cavity probiotics. Conclusions: Oral cavity probiotics and LLLT were the most effective treatment for improvement in quality of life. Further investigation on a larger group of patients is required.

Dysgeusia: A review in the context of COVID-19

Background

Taste disorders in general, and dysgeusia in particular, are relatively common disorders that may be a sign of a more complex acute or chronic medical condition. During the COVID-19 pandemic, taste disorders have found their way into the realm of general as well as specialty dentistry, with significance in screening for patients who potentially may have the virus.

Types of Studies Reviewed

The authors searched electronic databases (PubMed, Embase, Web of Science, Google Scholar) for studies focused on dysgeusia, ageusia, and other taste disorders and their relationship to local and systemic causes.

Results

The authors found pertinent literature explaining the normal physiology of taste sensation, proposals for suggested new tastes, presence of gustatory receptors in remote tissues of the body, and etiology and pathophysiology of taste disorders, in addition to the valuable knowledge gained about gustatory disorders in the context of COVID-19. Along with olfactory disorders, taste disorders are one of the earliest suggestive symptoms of COVID-19 infection.

Conclusions

Gustatory disorders are the result of local or systemic etiology or both. Newer taste sensations, such as calcium and fat tastes, have been discovered, as well as taste receptors that are remote from the oropharyngeal area. Literature published during the COVID-19 pandemic to date reinforces the significance of early detection of potential patients with COVID-19 by means of screening for recent-onset taste disorders.

Practical Implications

Timely screening and identification of potential gustatory disorders are paramount for the dental care practitioner to aid in the early diagnosis of COVID-19 and other serious systemic disorders.

Role of Photobiomodulation Therapy in Neurological Primary Burning Mouth Syndrome. A Systematic Review and Meta-Analysis of Human Randomised Controlled Clinical Trials

Mitochondrial homeostasis is crucial for energy production and neuronal survival in neurological primary burning mouth syndrome (npBMS). Photobiomodulation therapy (PBMT) has been utilised in npBMS management, however, its role of intervention remains controversial. The aim of this systematic review and meta-analysis of CRD 42020198921 PROSPERO registration reference was to oversee and determine the efficacy of PBMT in patients with npBMS, identifying the gaps and bridge them by proposing recommendations for future studies purposes. PRISMA guidelines and Cochrane Collaboration recommendations followed. Various search engines employed to analyse a total of 351 studies of which 12 were included. A wide range of utilised PBM wavelengths was between 635-980 nm and the power output ranged between 30 mW and 4000 mW. A high risk of bias (RoB) was noted in 7 out of 12 included studies (58.3%), as results of qualitative analysis. Meta-analysis findings of 4 out of 12 studies showed statistically significant intergroup differences (SSID) for visual analogue scale (VAS) values (MD = -1.47; 95% CI = -2.40 to -0.53; Z = 3.07 (p = 0.002) whereas meta-analysis on 5 out of 12 studies revealed SSID for anxiety/depression and quality of life (MD = -1.47; 95% CI = -2.40 to -0.53; Z = 3.07 (p = 0.002), favouring PBMT group to the control treatment strategies. Despite the inconsistency and diversity in PBM parameters (wavelength, power, light source, spot size, emission mode, energy per point, total energy) and treatment protocols (exposure time, number of sessions, time interval between sessions, treatment duration)-majority of the included studies showed positive PBM results. The high RoB and meta-analytical heterogeneity in the eligible studies warrant the necessity to perform well-designed and robust RCTs after acknowledging the drawbacks of the available scientific literature and addressing our suggested recommendations highlighted in our review.

The Mystery of "Metal Mouth" in Chemotherapy

Of all the oral sensations that are experienced, "metallic" is one that is rarely reported in healthy participants. So why, then, do chemotherapy patients so frequently report that "metallic" sensations overpower and interfere with their enjoyment of food and drink? This side-effect of chemotherapy-often referred to (e.g., by patients) as "metal mouth"-can adversely affect their appetite, resulting in weight loss, which potentially endangers (or at the very least slows) their recovery. The etiology of "metal mouth" is poorly understood, and current management strategies are largely unevidenced. As a result, patients continue to suffer as a result of this poorly understood phenomenon. Here, we provide our perspective on the issue, outlining the evidence for a range of possible etiologies, and highlighting key research questions. We explore the evidence for "metallic" as a putative taste, and whether "metal mouth" might therefore be a form of phantageusia, perhaps similar to already-described "release-of-inhibition" phenomena. We comment on the possibility that "metal mouth" may simply be a direct effect of chemotherapy drugs. We present the novel theory that "metal mouth" may be linked to chemotherapy-induced sensitization of TRPV1. Finally, we discuss the evidence for retronasal olfaction of lipid oxidation products in the etiology of "metal mouth." This article seeks principally to guide much-needed future research which will hopefully one day provide a basis for the development of novel supportive therapies for future generations of patients undergoing chemotherapy.

Chemosensory Function in Burning Mouth Syndrome a Comparative Cross-Sectional Study

Taste and smell are considered to be functions that contribute to the maintenance of good nutritional status. The present study evaluates taste and smell function in patients with burning mouth syndrome (BMS) versus a control group. A cross-sectional study was made of 36 consecutive patients with BMS and 56 healthy patients. Smell was assessed using the Sniffin' Sticks test, while taste was evaluated with Taste Strips. Oral quality of life was assessed with the Oral Health Impact Profile-14 (OHIP-14), and the severity of dry mouth with the Thompson Xerostomia Inventory. The patients with BMS had a mean age of 60.4 0 ± 10.5 years, while the controls had a mean age of 61.3 ± 19 years. No significant differences in smell were recorded between the two groups. In contrast, significant differences in taste function were observed between the patients with BMS and the controls. In the patients with BMS, 44.4% suffered taste alterations compared with the 3.4% healthy controls. Further studies in such patients are needed to allow improved management of the chemosensory problems, mouth dryness, and oral health-related quality of life in BMS.

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.

Developing a research diagnostic criteria for burning mouth syndrome: Results from an international Delphi process

OBJECTIVE

To develop a beta version of a preliminary set of empirically derived research diagnostic criteria (RDC) for burning mouth syndrome (BMS) through expert consensus, which can then be taken into a test period before publication of a final RDC/BMS.

DESIGN

A 6 round Delphi process with twelve experts in the field of BMS was used. The first round formed a focus group during which the purpose of the RDC and the definition of BMS was agreed upon, as well as the structure and contents. The remaining rounds were carried out virtually via email to achieve a consensus of the beta version of the RDC/BMS.

RESULTS

The definition of BMS was agreed to be 'an intraoral burning or dysaesthetic sensation, recurring daily for more than 2 hours per day over more than 3 months, without evident causative lesions on clinical examination and investigation'. The RDC was based upon the already developed and validated RDC/TMD and formed three main parts: patient self-report; examination; and psychosocial self-report. A fourth additional part was also developed listing aspirational biomarkers which could be used as part of the BMS diagnosis where available, or to inform future research.

CONCLUSION

This Delphi process has created a beta version of an RDC for use with BMS. This will allow future clinical research within BMS to be carried out to a higher standard, ensuring only patients with true BMS are included. Further validation studies will be required alongside refinement of the RDC as trialling progresses.

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.

Relationships between subjective taste sensations and electrogustometry findings in patients with taste disorders

This study aimed to examine the relationships between subjective taste sensations and electrogustometry (EGM) findings in patients with taste disturbances according to the presence of burning mouth (BM) symptoms. Forty-six patients were included and asked to complete a questionnaire that contained questions on subjective taste sensations for the four basic taste qualities and the pattern of taste disorders such as ageusia, hypogeusia and dysgeusia. EGM was performed to measure detection thresholds. To examine the influence of BM symptoms, patients were divided into two groups: patients with and without BM symptoms. The patients consisted of 11 men and 35 women. The group without BM symptoms (n=26) had significantly lower degrees of subjective taste sensations for all taste qualities and higher correlation levels between subjective taste sensations and EGM thresholds than the group with BM symptoms (n=20). The patterns of taste disorders also showed more significant associations with the levels of subjective taste sensations in the patients without BM symptoms compared with those with BM symptoms. In conclusion, patients with taste disorders without BM symptoms had more severe taste disturbances than those with BM symptoms. The pathophysiology of taste disturbances differs according to the presence or absence of BM symptoms.

Psychophysical characterisation of burning mouth syndrome-A systematic review and meta-analysis

BACKGROUND

Primary burning mouth syndrome (BMS) is an oro-facial disease with neuropathic characteristics. Psychophysics, such as quantitative sensory testing (QST), is used to sub-classify neuropathic pain syndromes, but their usefulness in characterising BMS is not yet clear.

OBJECTIVE

The aim of this study was to summarise and to quantitatively and qualitatively analyse the available information about QST findings in BMS, and to reflect on possible mechanisms of disease.

METHODS

In this systematic review and meta-analysis, different search strategies were used to screen for articles in PubMed, Embase, EBSCOhost, Cochrane Library, Web of Science, Google Scholar and two sources of conference abstracts. Primary clinical studies focused on QST assessment in patients with BMS were included. Data were synthesised qualitatively and quantitatively. Risk of bias was assessed following the AHRQ guidelines.

RESULTS

Thirteen articles with low to moderate risk of bias and one conference abstract were selected from 45 unique articles that were identified. Individually, the studies reported combinations of thermal and mechanical sensory impairments measured by QST. The meta-analysis showed significant sensory differences between patients and controls in warmth (effect size = 0.683; P < .05) and cold detection thresholds (effect size = -0.580; P < .001).

CONCLUSION

The results indicate that thermal sensitivity seems to be altered in patients with BMS compared to controls, suggesting a small-fibre neuropathy. However, study protocols were highly variable and heterogeneous. Therefore, studies with better designs and complete reporting of results should be performed to bring value to the use of psychophysics in the assessment of BMS.

Time-dependent responses in brain activity to ongoing hot stimulation in burning mouth syndrome

Burning mouth syndrome (BMS) is classified into idiopathic orofacial pain conditions. Although central and peripheral neuropathic mechanisms are believed to be involved, the etiology remains to be fully elucidated. The present study examined temporal brain responses to an ongoing hot stimulus to investigate the pain modulating system in patients with BMS. The thermal stimulation sequence comprised baseline (32°C, 40 s) to warm (40°C, 32 s) to baseline (32°C, 40 s) to hot (49°C, 32 s), which was repeated four times using a Peltier thermode. These warm and hot stimuli were applied on the right palm and right lower lip in two separate sessions. Functional magnetic resonance imaging data were acquired by recording echo-planar images with a block design. Brain activity induced by purely hot stimulation (49°C vs. 40°C) applied to the palm was more pronounced than that induced by lip stimulation and in patients with BMS compared with controls. Comparison of brain activity between the first 16 s and second 16 s of the stimulus revealed pronounced time-dependent facilitation in patients with BMS during lip stimulation. These findings indicate that the pain modulating system in patients with BMS is dysregulated and that the brain in BMS is highly sensitized to pain information originating from the trigeminal system.

Pain reduction in burning mouth syndrome (BMS) may be associated with selective improvement of taste: a retrospective study

OBJECTIVE

The aim of this study was to examine taste function in patients who reported improvement in their pain level after treatment to determine if pain reduction is associated with change in taste function in patients with burning mouth syndrome (BMS).

STUDY DESIGN

This retrospective study of patients with BMS was conducted at a private oral medicine clinic.

RESULTS

Thirty-nine patients with BMS (31 females and 8 males; mean age 56.1 ± 9.4 years) reported improvement in their pain in 1 to 22 months after the initial visit (mean 5.13 ± 4.18). The most commonly used medication was clonazepam 0.25 to 0.5 mg/day. Twenty-eight patients were treated with a combination of medications. "Salt" and "bitter" responses at the fungiform papillae were increased after treatment (P = .026 and P = .044, respectively). "Salt" responses at the circumvallate papillae also increased (P < .001). Pain reduction was significant after treatment in the morning (P = .002) and in the evening (P < .001).

CONCLUSIONS

Treatment of BMS can significantly decrease pain symptoms, resulting in improvement in taste function. Pain reduction often requires a combination of medications.

Topical application in burning mouth syndrome

Background/purpose

Intraoral and perioral burning sensations may be sequelae of burning mouth syndrome (BMSD) or burning mouth symptoms (BMSP), which present a diagnostic challenge. The aims of the study were to evaluate the efficacy of a topical anesthetic as a diagnostic test to differentiate BMSD from BMSP and to assess the comorbidities and responses to various pharmacologic treatments in BMSD and BMSP patients.

Materials and methods

A total of forty-four charts of patients with burning mouth that visited the Rutgers School of Dental Medicine Orofacial Pain Clinic between January 1st, 2000 and November 1st, 2014 were retrospectively reviewed. Twenty patients were diagnosed with BMSD, and 24 patients were diagnosed with BMSP attributed to local and systemic causes. The diagnosis was determined per the guidelines of the International Association for the Study of Pain and American Academy of Orofacial Pain. The main goal of this study was to evaluate the effect of topical anesthetic medication applied to the burning site.

Results

The percentage of change in pain reduction following topical anesthetic application in the BMSP group was significantly higher than that of the BMSD group (p < 0.05). In the BMSD group, 77% of females and 27% of males responded to clonazepam. One third of the females in the BMSP group also suffered from hypertension.

Conclusion

Topical anesthetics can be used as a simple, swift and efficient chair-side diagnostic tool to differentiate BMSD and BMSP. Females have a better response to clonazepam in BMSD.

Impact of Fungiform Papillae Count on Taste Perception and Different Methods of Taste Assessment and their Clinical Applications: A comprehensive review

Fungiform papillae are raised lingual structures which contain taste buds and thus play an important role in taste perception. These structures vary in number due to their relative sensitivity to a range of systemic and local factors which affect the dorsum of the tongue. Taste sensation can be measured using both chemical and electrical methods; however, the number of fungiform papillae has a direct effect on chemogustometric and electrogustometric values during evaluation. This review provides a general overview of fungiform papillae, their quantification methods and the various factors which may affect these structures. In addition, numerous methods of recording taste sensation and their clinical applications are highlighted.

Anatomical stability of human fungiform papillae and relationship with oral perception measured by salivary response and intensity rating

Fungiform papillae house taste buds on the anterior dorsal tongue. Literature is inconclusive as to whether taste perception correlates with fungiform papillae density (FPD). Gustatory reflexes modulate the amount and composition of saliva subsequently produced, and thus may be a more physiologically objective measure of tastant-receptor interactions. Taste perception fluctuates with time but the stability of individual fungiform papillae is unclear. This study followed ten healthy volunteers longitudinally at baseline, one and six months. FPD, diameter and position were measured and participants rated intensity perception of sucrose, caffeine, menthol and capsaicin solutions. Salivary flow rate, protein concentration and relative changes in protein composition were measured following each tastant. FPD, diameter and position were unchanged at six months. FPD did not correlate with intensity rating for any taste. FPD did correlate with changes in salivary protein output following sucrose (ρ = 0.72, p = 0.02) and changes in levels of proline-rich protein and mucin 7 following capsaicin (ρ = 0.71, p = 0.02, ρ = 0.68, p = 0.04, respectively). These results suggest that over six months fungiform papillae are anatomically stable, playing a greater role in mediating the physiological salivary response to stimuli rather than determining the perceived intensity of taste.

An updated review on pathophysiology and management of burning mouth syndrome with endocrinological, psychological and neuropathic perspectives

Burning mouth syndrome (BMS) is a chronic oro-facial pain disorder of unknown cause. It is more common in peri- and post-menopausal women, and sex hormone dysregulation is believed to be an important causative factor. Psychosocial events often trigger or exacerbate symptoms, and persons with BMS appear to be predisposed towards anxiety and depression. Atrophy of small nerve fibres in the tongue epithelium has been reported, and potential neuropathic mechanisms for BMS are now widely investigated. Historically, BMS was thought to comprise endocrinological, psychosocial and neuropathic components. Neuroprotective steroids and glial cell line-derived neurotrophic factor family ligands may have pivotal roles in the peripheral mechanisms associated with atrophy of small nerve fibres. Denervation of chorda tympani nerve fibres that innervate fungiform buds leads to alternative trigeminal innervation, which results in dysgeusia and burning pain when eating hot foods. With regard to the central mechanism of BMS, depletion of neuroprotective steroids alters the brain network-related mood and pain modulation. Peripheral mechanistic studies support the use of topical clonazepam and capsaicin for the management of BMS, and some evidence supports the use of cognitive behavioural therapy. Hormone replacement therapy may address the causes of BMS, although adverse effects prevent its use as a first-line treatment. Selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs) may have important benefits, and well-designed controlled studies are expected. Other treatment options to be investigated include brain stimulation and TSPO (translocator protein 18 kDa) ligands.

Is burning mouth syndrome a neuropathic pain condition?

Primary burning mouth syndrome (BMS) is defined as an "intraoral burning or dysaesthetic sensation, recurring daily… more than 3 months, without clinically evident causative lesions" (IHS 2013). In addition to pain, taste alterations are frequent (dysgeusia, xerostomia). Although lacking clinical signs of neuropathy, more accurate diagnostic methods have shown neuropathic involvement at various levels of the neuraxis in BMS: peripheral small fiber damage (thermal quantitative sensory testing, electrogustatometry, epithelial nerve fiber density), trigeminal system lesions in the periphery or the brainstem (brainstem reflex recordings, trigeminal neurography, evoked potentials), or signs of decreased inhibition within the central nervous system (deficient brainstem reflex habituation, positive signs in quantitative sensory testing, neurotransmitter-positron emission tomography findings indicative of deficient striatal dopamine function). Abnormalities in electrogustatometry indicate the involvement of the small Aδ taste afferents, in addition to somatosensory small fibers. According to these findings, the clinical entity of BMS can be divided into 2 main subtypes compatible with either peripheral or central neuropathic pain, which may overlap in individual patients. The central type does not respond to local treatments and associates often with psychiatric comorbidity (depression or anxiety), whereas the peripheral type responds to peripheral lidocaine blocks and topical clonazepam. Burning mouth syndrome is most prevalent in postmenopausal women, having led to a hypothesis that BMS is triggered as a consequence of nervous system damage caused by neurotoxic factors affecting especially vulnerable small fibers and basal ganglia in a setting of decrease in neuroprotective gonadal hormones and increase in stress hormone levels, typical for menopause.

A case-control evaluation of fungiform papillae density in burning mouth syndrome

HYPOTHESIS

It has been hypothesized that high fungiform papillae density may be a risk factor for developing the taste and pain alterations characteristic of burning mouth syndrome.

OBJECTIVE

Evaluate whether fungiform papillae density, taste sensitivity, and mechanical pain sensitivity differ between burning mouth syndrome cases and controls.

STUDY DESIGN

This case-control study compared cases diagnosed with primary burning mouth syndrome with pain-free controls.

METHODS

Participants (17 female cases and 23 female controls) rated the intensity of sucrose, sodium chloride, citric acid, and quinine applied separately to each side of the anterior tongue and sampled whole mouth. Mechanical pain sensitivity was assessed separately for each side of the tongue using weighted pins. Digital photographs of participants' tongues were used to count fungiform papillae.

RESULTS

Burning mouth syndrome cases had increased whole mouth taste intensity. Cases also had increased sensitivity to quinine on the anterior tongue, as well as increased mechanical pain sensitivity on the anterior tongue. Fungiform papillae density did not differ significantly between cases and controls. Fungiform papillae density on the left and right sides of the tongue were correlated in controls; however, there was no left/right side correlation in cases.

CONCLUSION

Cases had increased pain and taste perception on the anterior tongue. The lack of correlation between left and right fungiform papillae density in cases may be an indication of asymmetrical lingual innervation in these patients.

LEVEL OF EVIDENCE

3b. Laryngoscope, 128:841-846, 2018.

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.

Comparison of Taste Threshold in Smokers and Non-Smokers Using Electrogustometry and Fungiform Papillae Count: A Case Control Study

INTRODUCTION

Smoking in long term is not only responsible for cancerous changes but is also one of the reasons of altered taste sensation in smokers. These taste changes are hypothesized to be due to reduction in density of fungiform papillae on the dorsum of the tongue.

AIM

The aim of this study was to assess the relationship between fungiform papillae count, blood Red Cell Distribution Width (RDW) and electrogustometric thresholds in smokers and non-smokers.

MATERIALS AND METHODS

Fungiform papillae count was assessed using digital photography and imaging software while electrogustometric thresholds were assessed using modified Transcutaneous Electric Nerve Stimulation (TENS) machine in 30 smokers and 30 non-smokers. The subjects also underwent RDW evaluation. The data collected was analyzed using Pearson's correlation coefficient.

RESULTS

Fungiform papillae counts in smokers were less than those of non-smokers and an inverse relationship was detected between smoking and fungiform papillae count. Electrogustometric thresholds were more in smokers than non-smokers and showed direct relationship with smoking. RDW was significantly more in smokers compared to non-smokers. An inverse relationship was observed between fungiform papillae count and RDW.

CONCLUSION

Our results suggest that smokers have a high taste threshold because of decrease in the number of fungiform papillae on the tongue and RDW values do show an inverse relationship with fungiform papillae density which depicts subclinical nutritional deficiency bringing atrophic changes in tongue.

Burning mouth syndrome: Current concepts

Burning mouth syndrome (BMS) is a chronic pain condition. It has been described by the International Headache Society as "an intra-oral burning or dysesthetic sensation, recurring daily for more than 2 h/day for more than 3 months, without clinically evident causative lesions." BMS is frequently seen in women in the peri-menopausal and menopausal age group in an average female/male ratio of 7:1. The site most commonly affected is the anterior two-thirds of the tongue. The patient may also report taste alterations and oral dryness along with the burning. The etiopathogenesis is complex and is not well-comprehended. The more accepted theories point toward a neuropathic etiology, but the gustatory system has also been implicated in this condition. BMS is frequently mismanaged, partly because it is not well-known among healthcare providers. Diagnosis of BMS is made after other local and systemic causes of burning have been ruled out as then; the oral burning is the disease itself. The management of BMS still remains a challenge. Benzodiazepines have been used in clinical practice as the first-line medication in the pharmacological management of BMS. Nonpharmacological management includes cognitive behavioral therapy and complementary and alternative medicine (CAM). The aim of this review is to familiarize healthcare providers with the diagnosis, pathogenesis, and general characteristics of primary BMS while updating them with the current treatment options to better manage this group of patients.

Neuropathic orofacial pain: cannabinoids as a therapeutic avenue

Neuropathic orofacial pain (NOP) exists in several forms including pathologies such as burning mouth syndrome (BMS), persistent idiopathic facial pain (PIFP), trigeminal neuralgia (TN) and postherpetic neuralgia (PHN). BMS and PIFP are classically diagnosed by excluding other facial pain syndromes. TN and PHN are most often diagnosed based on a typical history and presenting pain characteristics. The pathophysiology of some of these conditions is still unclear and hence treatment options tend to vary and include a wide variety of treatments including cognitive behaviour therapy, anti-depressants, anti-convulsants and opioids; however such treatments often have limited efficacy with a great amount of inter-patient variability and poorly tolerated side effects. Analgesia is one the principal therapeutic targets of the cannabinoid system and many studies have demonstrated the efficacy of cannabinoid compounds in the treatment of neuropathic pain. This review will investigate the potential use of cannabinoids in the treatment of symptoms associated with NOP.

The role of xerostomia in burning mouth syndrome: a case-control study

Objective : To assess the efficacy of anti-xerostomic topical medication (urea 10%) in patients with burning mouth syndrome (BMS). Method : Thirty-eight subjects diagnosed with BMS according to the International Association for the Study of Pain guidelines were randomized to either placebo (5% sodium carboxymethylcellulose, 0.15% methyl paraben, and 10% glycerol in distilled water qsp 100 g) or treatment (urea 10%) to be applied to the oral cavity 3-4 times per day for 3 months. The patients were evaluated before and after treatment with the following instruments: the EDOF-HC protocol (Orofacial Pain Clinic – Hospital das Clínicas), a xerostomia questionnaire, and quantitative sensory testing. Results : There were no differences in salivary flow or gustative, olfactory, or sensory thresholds (P>0.05). Fifteen (60%) patients reported improvement with the treatments (P=0.336). Conclusion : In conclusion, there were no differences between groups, and both exhibited an association between reported improvement and salivation.

Gustatory modulation of the responses of trigeminal subnucleus caudalis neurons to noxious stimulation of the tongue in rats

Certain tastants inhibit oral irritation by capsaicin, whereas anesthesia of the chorda tympani (CT) enhances oral capsaicin burn. We tested the hypothesis that tastants activate the CT to suppress responses of trigeminal subnucleus caudalis (Vc) neurons to noxious oral stimuli. In anesthetized rats, we recorded Vc unit responses to noxious electrical, chemical (pentanoic acid, 200 μm) and thermal (55 °C) stimulation of the tongue. Electrically evoked responses were significantly reduced by a tastant mix and individually applied NaCl, monosodium glutamate (MSG), and monopotassium glutamate. Sucrose, citric acid, quinine and water (control) had no effect. Pentanoic acid-evoked responses were similarly attenuated by NaCl and MSG, but not by other tastants. Responses to noxious heat were not affected by any tastant. Transection and/or anesthesia of the CT bilaterally affected neither Vc neuronal responses to electrical or pentanoic acid stimulation, nor the depressant effect of NaCl and MSG on electrically evoked responses. Calcium imaging showed that neither NaCl nor MSG directly excited any trigeminal ganglion cells or affected their responses to pentanoic acid. GABA also had no effect, arguing against peripheral effects of GABA, NaCl or MSG on lingual nocicepive nerve endings. The data also rule out a central mechanism, as the effects of NaCl and MSG were intact following CT transection. We speculate that the effect is mediated peripherally by the release from taste receptor cells (type III) of some mediator(s) other than GABA to indirectly inhibit trigeminal nociceptors. The results also indicate that the CT does not exert a tonic inhibitory effect on nociceptive Vc neurons.