Central mechanisms in burning mouth syndrome involving the olfactory nerve: a preliminary study

Phenotypical characterization of exteroceptive sensation and pain symptoms on diabetic patients

BACKGROUD

Diabetic neuropathy (DN) is one of the most common complications of diabetes, affecting about half of individuals with the disease. Among the various symptoms of DN, the development of chronic pain stands out and manifests as exacerbated responses to sensorial stimuli. The conventional clinical treatments used for general neuropathy and associated painful symptoms, still brings uncomplete and unsatisfactory pain relief. Patients with neuropathic pain syndromes are heterogeneous. They present with a variety of sensory symptoms and pain qualities which difficult the correct diagnosis of sensory comorbidities and consequently, the appropriate chronic pain management.

AIMS

Herein, we aimed to demonstrate the existence of different sensory profiles on diabetic patients by investigating epidemiological and clinical data on the symptomatology of a group of patients with DN.

METHODS

This is a longitudinal and observational study, with a sample of 57 volunteers diagnosed with diabetes from outpatient day clinic of Hospital Universitário of the University of São Paulo-Brazil. After being invited and signed the Informed Consent Form (ICF), patients were submitted to clinical evaluation and filled out pain and quality of life questionnaires. They also performed quantitative sensory test (QST) and underwent skin biopsy for correlation with cutaneous neuropathology.

RESULTS

Data demonstrate that 70% of the studied sample presented some type of pain, manifesting in a neuropathic or nociceptive way, what has a negative impact on the life of patients with DM. We also demonstrated a positive association between pain and anxiety and depression, in addition to pain catastrophic thoughts. Three distinct profiles were identified in the sample, separated according to the symptoms of pain: (i) subjects without pain; (ii) with mild or moderate pain; (iii) subjects with severe pain. We also identified through skin biopsy that diabetic patients presented advanced sensory impairment, as a consequence of the degeneration of the myelinated and unmyelinated peripheral fibers. This study characterized the painful symptoms and exteroceptive sensation profile in these diabetic patients, associated to a considerable level of sensory degeneration, indicating, and reinforcing the importance of the long-term clinical monitoring of individuals diagnosed with DM, regarding their symptom profiles and exteroceptive sensitivity.

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.

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.

Emerging Pattern of Post-COVID-19 Parosmia and Its Effect on Food Perception

Olfactory dysfunction is amongst the many symptoms of Long COVID. Whilst most people that experience smell loss post COVID-19 recover their sense of smell and taste within a few weeks, about 10% of cases experience long-term problems, and their smell recovery journey often begins a few months later when everyday items start to smell distorted. This is known as parosmia. The aim of this study was to identify the key food triggers of parosmic distortions and investigate the relationship between distortion and disgust in order to establish the impact of parosmia on diet and quality of life. In this cross-sectional study (n = 727), respondents experiencing smell distortions completed a questionnaire covering aspects of smell loss, parosmia and the associated change in valence of everyday items. There was a significant correlation between strength and disgust (p < 0.0001), and when the selected items were reported as distorted, they were described as either unpleasant or gag-inducing 84% of the time. This change in valence associated with loss of expected pleasure and the presence of strange tastes and burning sensations must certainly lead to changes in eating behaviours and serious longer-term consequences for mental health and quality of life.

Outpatient Oral Neuropathic Pain Management with Photobiomodulation Therapy: A Prospective Analgesic Pharmacotherapy-Paralleled Feasibility Trial

Neuropathic pain (NP) can be challenging to treat effectively as analgesic pharmacotherapy (MED) can reduce pain, but the majority of patients do not experience complete pain relief. Our pilot approach is to assess the feasibility and efficacy of an evidence-based photobiomodulation (PBM) intervention protocol. This would be as an alternative to paralleled standard analgesic MED for modulating NP intensity-related physical function and quality of life (QoL) prospectively in a mixed neurological primary burning mouth syndrome and oral iatrogenic neuropathy study population (n = 28). The study group assignments and outcome evaluation strategy/location depended on the individual patient preferences and convenience rather than on randomisation. Our prospective parallel study aimed to evaluate the possible pre/post-benefit of PBM and to allow for a first qualitative comparison with MED, various patient-reported outcome measures (PROMs) based on Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT-II) were used for up to a nine-month follow-up period in both intervention groups (PBM and MED). The PBM protocol applied to the PBM group was as follows: λ810 nm, 200 mW, 0.088 cm2, 30 s/point, 9 trigger and affected points, twice a week for five consecutive weeks, whereas the MED protocol followed the National Institute of Clinical Excellence (NICE) guidelines. Our results showed that despite the severe and persistent nature of the symptoms of 57.50 ± 47.93 months at baseline in the PBM group, a notably rapid reduction in PISmax on VAS from 7.6 at baseline (T0) to 3.9 at one-month post-treatment (T3) could be achieved. On the other hand, mean PISmax was only reduced from 8.2 at baseline to 6.8 at T3 in the MED group. Our positive PBM findings furthermore support more patients' benefits in improving QoL and functional activities, which were considerably impaired by NP such as: eating, drinking and tasting, whereas the analgesic medication regimens did not. No adverse events were observed in both groups. To the best knowledge of the authors, our study is the first to investigate PBM efficacy as a monotherapy compared to the gold standard analgesic pharmacotherapy. Our positive data proves statistically significant improvements in patient self-reported NP, functionality, psychological profile and QoL at mid- and end-treatment, as well as throughout the follow-up time points (one, three, six and nine months) and sustained up to nine months in the PBM group, compared to the MED group. Our study, for the first time, proves the efficacy and safety of PBM as a potent analgesic in oral NP and as a valid alternative to the gold standard pharmacotherapy approach. Furthermore, we observed long-term pain relief and functional benefits that indicate that PBM modulates NP pathology in a pro-regenerative manner, presumably via antioxidant mechanisms.

Burning mouth syndrome: a review of therapeutic approach

Burning mouth syndrome (BMS) is described by an intense burning sensation of the tongue or other oral areas without a clear etiopathology. The diagnosis of BMS is challenging due to variations of manifestations. The management of BMS is complicated due to the complex etiology of the disease. Many medications and treatment methods have been recommended for BMS management, but no one confirmed as the standard method. In this study, the therapeutic approaches of BMS were evaluated. The data of the article was obtained from PubMed/MEDLINE, Cochrane Library, and Web of Science. The following terms including "burning mouth syndrome", "therapy", and "treatment" were used for search in the databases. A wide range of articles about the therapeutic approach of BMS was searched and reviewed. Pharmacological and non-pharmacological approaches have been used for BMS management. Pharmacological treatments are including Capsaicin, Clonazepam, Low-dose aripiprazole, Alpha-lipoic acid, Duloxetine, Amitriptyline, Gabapentin, and Pregabalin, and ultra-micronized palmitoylethanolamide. Non-pharmacological therapies for BMS are cognitive therapy, Electroconvulsive therapy, Laser therapy, Acupuncture and auriculotherapy, Transcranial Magnetic Stimulation (rTMS), Salivary Mechanical Stimulation, and Botulinum Toxin. A detailed assessment of the etiology and pathophysiology of BMS, and having information about novel therapeutic interventions are essential for the management of BMS.

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.

Neuropathic and Psychogenic Components of Burning Mouth Syndrome: A Systematic Review

The pathophysiology of primary burning mouth syndrome (BMS) has been extensively debated but is poorly understood despite a large number of hypotheses attempting to explain its etiopathogenic mechanisms. The aim of the present work was to systematically review papers that could provide arguments in favour of the neuropathic and psychogenic components of primary BMS for a better understanding of the disease. This systematic review (SR) was registered in PROSPERO (CRD42021224160). The search was limited to articles in English or French from 1990 to 01 December 2020. A total of 113 articles were considered for data extraction. We divided them into four subgroups: pharmacological and nonpharmacological management studies (n = 23); neurophysiological studies (n = 35); biohistopathological studies (n = 25); and questionnaire-based studies (n = 30). Several of these studies have shown neuropathic involvement at various levels of the neuraxis in BMS with the contribution of quantitative sensory testing (QST), functional brain imaging, and biohistopathological or pharmacologic studies. On the other hand, the role of psychological factors in BMS has also been the focus of several studies and has shown a link with psychiatric disorders such as anxiety and/or depression symptoms. Depending on the patient, the neuropathic and psychogenic components may exist simultaneously, with a preponderance of one or the other, or exist individually. These two components cannot be dissociated to define BMS. Consequently, BMS may be considered nociplastic pain.

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.

Co-occurrence of Pain Symptoms and Somatosensory Sensitivity in Burning Mouth Syndrome: A Systematic Review

Background

Burning mouth syndrome (BMS) is a chronic and spontaneous oral pain with burning quality in the tongue or other oral mucosa without any identifiable oral lesion or laboratory finding. Pathogenesis and etiology of BMS are still unknown. However, BMS has been associated with other chronic pain syndromes including other idiopathic orofacial pain, the dynias group and the family of central sensitivity syndromes. This would imply that BMS shares common mechanisms with other cephalic and/or extracephalic chronic pains. The primary aim of this systematic review was to determine whether BMS is actually associated with other pain syndromes, and to analyze cephalic and extracephalic somatosensory sensitivity in these patients.

Methods

This report followed the PRISMA Statement. An electronic search was performed until January 2015 in PubMed, Cochrane library, Wiley and ScienceDirect. Searched terms included “burning mouth syndrome OR stomatodynia OR glossodynia OR burning tongue OR oral burning”. Studies were selected according to predefined inclusion criteria (report of an association between BMS and other pain(s) symptoms or of cutaneous cephalic and/or extracephalic quantitative sensory testing in BMS patients), and a descriptive analysis conducted.

Results

The search retrieved 1512 reports. Out of these, twelve articles met criteria for co-occurring pain symptoms and nine studies for quantitative sensory testing (QST) in BMS patients. The analysis reveals that in BMS patients co-occurring pain symptoms are rare, assessed by only 0.8% (12 of 1512) of the retrieved studies. BMS was associated with headaches, TMD, atypical facial pain, trigeminal neuralgia, post-herpetic facial pain, back pain, fibromyalgia, joint pain, abdominal pain, rectal pain or vulvodynia. However, the prevalence of pain symptoms in BMS patients is not different from that in the age-matched general population. QST studies reveal no or inconsistent evidence of abnormal cutaneous cephalic and extracephalic somatosensory sensitivity.

Conclusions

There is no evidence for a high rate of other pain symptoms or somatosensory impairments co-occurring with BMS. These results thus suggest that BMS rather depends on specific mechanisms, likely at the trigeminal level. Nevertheless, more thoroughly conducted research is required to draw definitive conclusion.

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.

Oral adverse events in cancer patients treated with VEGFR-directed multitargeted tyrosine kinase inhibitors

OBJECTIVES

This study characterized the incidence and clinical features of oral adverse events among cancer patients who received VEGFR-directed multitargeted tyrosine kinase inhibitor (VR-TKI) therapies.

METHODS

Electronic medical records of adult cancer patients treated with sunitinib, sorafenib, regorafenib, pazopanib, cabozantinib, imatinib, and bevacizumab therapy at Dana-Farber Cancer Institute from 2009 to 2012 were reviewed. Data collected included patient characteristics, oral and non-oral adverse events, and time to onset. Time oral adverse event-free was the primary outcome.

RESULTS

A total of 747 patients with 806 individual courses of therapy were treated for a median of 3.9months with sunitinib (n=161), sorafenib (n=172), regorafenib (n=15), pazopanib (n=132), cabozantinib (n=23), imatinib (n=144), or bevacizumab (n=159) for lung cancer (21%), gastrointestinal stromal tumor (15%), and metastatic renal cell carcinoma (13%). An oral adverse event was reported in 23.7% of patients at a median of 1.9months after starting therapy. The most commonly reported oral adverse event was oral mucosal sensitivity (dysesthesia), occurring in 12% of patients, typically without clinical findings. Multivariate models showed patients who received VR-TKI therapy were at greater risk of any oral adverse event compared with patients treated with imatinib or bevacizumab. Patients receiving VR-TKI therapy who developed an oral adverse event were also at increased risk for hand-foot skin reaction (15.9%).

CONCLUSIONS

VR-TKI associated oral adverse events are characterized primarily by dysesthesia with lack of clinical signs. Oral dysesthesia is more commonly associated with VR-TKIs than with bevacizumab or imatinib. Management is largely empirical and requires further investigation.

Burning mouth syndrome - a common dental problem in perimenopausal women

Burning mouth syndrome (BMS) is characterized by the presence of burning, paresthesia or pain of the oral mucosa in the absence of pathologic lesions revealed during the clinical examination. Moreover, the pain may be accompanied by oral dryness, hypersensitivity to some food compounds and taste disorders. Etiopathogenesis of this condition remains unclear. Potential local causative factors include among the others mechanical irritation, parafunctions and dysfunctions of the stomatognathic system, contact allergy to dental materials and electro-galvanic phenomena. Potential systemic causes include diabetes mellitus, B group vitamin deficiency (vitamins B1, B2, B6 and B12), folic acid and iron deficiency, hormonal imbalance, gastrointestinal diseases, psychiatric and neurological disorders and drug-induced side effects. The hypothesis concerning the role of hormonal changes in the development of BMS seems to be confirmed by a high incidence of this condition in perimenopausal women. Up to now, due to an unclear etiology of the disease, the treatment is very often ineffective and mainly symptomatic, which may exacerbate patient's anxiety and discomfort. In this paper we present the main etiologic factors of the burning mouth syndrome. We discuss the basic diagnostic and therapeutic methods and the influence of hormonal replacement therapy on the course of BMS based on the current medical reports.

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.