Salivary and serum levels of substance p, neurokinin A and calcitonin gene related peptide in burning mouth syndrome

Oxidative stress-mediated proapoptosis signaling: A novel theory on the mechanism underlying the pathogenesis of burning mouth syndrome

BACKGROUND

Burning mouth syndrome (BMS) is a chronic oral pain disorder characterized by a generalized burning sensation in the oral mucosa without apparent medical or dental causes. Despite various hypotheses proposed to explain BMS pathogenesis, a clear understanding of the cellular-level events and associated histologic and molecular findings is lacking. Advancing our understanding of BMS pathogenesis could facilitate the development of more targeted therapeutic interventions.

TYPES OF STUDIES REVIEWED

The authors conducted an extensive literature search and review of cellular mechanisms, focusing on evidence-based data that support a comprehensive hypothesis for BMS pathogenesis. The authors explored novel and detailed mechanisms that may account for the characteristic features of BMS.

RESULTS

The authors proposed that BMS symptoms arise from the uncontrolled activation of proapoptotic transmembrane calcium permeable channels expressed in intraoral mucosal nerve fibers. Elevated levels of reactive oxygen species or dysfunctional antiapoptosis pathways may lead to uncontrolled oxidative stress-mediated apoptosis signaling, resulting in upregulation of transmembrane transient receptor potential vanilloid type 1 and P2X 3 calcium channels in nociceptive fibers. Activation of these channels can cause nerve terminal depolarization, leading to generation of action potentials that are centrally interpreted as pain.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The authors present a novel hypothesis for BMS pathogenesis, highlighting the role of proapoptotic transmembrane calcium permeable channels and oxidative stress-mediated apoptosis signaling in the development of BMS symptoms. Understanding these underlying mechanisms could provide new insights into the development of targeted therapeutic interventions for BMS. Additional research is warranted to validate this hypothesis and explore potential avenues for effective management of BMS.

Salivary biomarkers in burning mouth syndrome: A systematic review and meta-analysis

The objective of this systematic review was to evaluate which salivary biomarkers are altered in patients with burning mouth syndrome (BMS) compared to a control group (CG). A comprehensive literature search was conducted in four databases. Case-control studies evaluating salivary biomarkers in BMS patients were included. Risk of bias was assessed using the Newcastle-Ottawa tool. RevMan was used for meta-analysis. Seventeen studies were selected. The included studies collected 54 different biomarkers. Of these biomarkers, only three (cortisol, α-amylase, and dehydroepiandrosterone) were analyzed in three or more studies. Dehydroepiandrosterone obtained contradictory results among the studies. However, cortisol and α-amylase levels were found to be higher in BMS patients. Cortisol was the only biomarker which could be included for meta-analysis. Cortisol levels were significantly higher in the BMS group compared to the CG (Mean Difference = 0.39; 95% CI [0.14-0.65]; p = 0.003). In conclusion, different studies investigated salivary biomarkers in patients with BMS compared to a CG, with controversial results. Meta-analysis, confirmed by trial-sequential analysis, showed how cortisol levels were significantly higher in BMS. Cortisol emerges as an interesting salivary biomarker in BMS, but future properly designed studies are needed to evaluate its role in diagnosis and/or response to treatment.

Salivary characteristics in burning mouth syndrome: a systematic review

INTRODUCTION

Compare through case-control studies, the salivary characteristics of patients with and without BMS.

EVIDENCE ACQUISITION

Searches in Embase, PubMed, Web of Science, Scopus, Cochrane, and BIREME were conducted for the identification of case-controls studies reported.

EVIDENCE SYNTHESIS

Thirty-three studies were included, of which 26 articles evaluated OSB, 17 SRF, and 7 SE. Nineteen organic biomarkers showed higher levels in BMS patients, the two most indicated being α-amylase and cortisol. Ten organic biomarkers, including Tumor Necrosis Factor-alpha (TNF-α) and IL-6, showed lower levels in BMS patients. Regarding salivary flow rate (SFR), five articles indicated that BMS patients have less unstimulated SFR (uSRF)Two articles indicate that stimulated SFR (sSRF) is lower in BMS patients nevertheless, but eight did not show differences. Sialochemical analysis revealed that sodium (Na), chloride (Cl), potassium (K), sodium (Na), and calcium (Ca), showed higher levels in BMS patients according to three studies, but two studies did not establish any differences. Two study established that BMS patients have lower Mg salivary levels.

CONCLUSIONS

Qualitative salivary characteristics suggest that BMS has neuropathic, inflammatory, emotional, immune, and hormonal involvements. BMS can be associated with changes in salivary biomarkers of inflammation and oxidative stress, is related to anxiety and degree of pain.

Saliva flow rates and clinical characteristics of patients with burning mouth syndrome: A case-control study

Burning mouth syndrome (BMS) is a chronic pain condition that most commonly affects postmenopausal women older than 50 years of age. Xerostomia is a common complaint among BMS patients. However, previous studies showed inconsistent findings regarding saliva flow rate reduction. This study examined saliva flow rates, degree of mucosal hydration, xerostomia, and clinical characteristics in BMS patients compared with healthy controls. Unstimulated whole saliva (USWS) was collected through passive drooling; residual mucosal saliva (RMS) was collected using filter paper strips. Stimulated whole saliva (SWS) was collected while chewing on gum base. Oral exam and self-report data were collected. A total of 50 women (22 BMS cases and 28 healthy controls) aged 50 years or older were included in the analysis of this study. Mean age was 62 years for cases and 56 years for controls (P=0.05). Compared with controls, cases had significantly lower USWS flow rates (P<0.001) and had a higher prevalence of xerostomia (P=0.001), gastrointestinal disease (P<0.001), and vaginal dryness (P=0.01). These data show that oral and vaginal dryness are common among BMS patients. Further studies are needed to investigate potential pathophysiological mechanisms related to the quality of saliva and mucosal barrier status among these patients.

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.

Calcitonin gene-related peptide and pain: a systematic review

BACKGROUND

Calcitonin gene-related peptide (CGRP) is widely distributed in nociceptive pathways in human peripheral and central nervous system and its receptors are also expressed in pain pathways. CGRP is involved in migraine pathophysiology but its role in non-headache pain has not been clarified.

METHODS

We performed a systematic literature search on PubMed, Embase and ClinicalTrials.gov for articles on CGRP and non-headache pain covering human studies including experimental studies and randomized clinical trials.

RESULTS

The literature search identified 375 citations of which 50 contained relevant original data. An association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain was found. In 13 out of 20 studies in somatic pain conditions, CGRP levels had a positive correlation with pain. Increased CGRP levels were reported in plasma, synovial and cerebrospinal fluid in subjects with musculoskeletal pain. A randomized clinical trial on monoclonal antibody, which selectively binds to and inhibits the activity of CGRP (galcanezumab) in patients with osteoarthritis knee pain, failed to demonstrate improvement of pain compared with placebo. No studies to date have investigated the efficacy of monoclonal antibodies against CGRP receptor in non-headache pain conditions.

CONCLUSION

The present review revealed the association between measured CGRP levels and somatic, visceral, neuropathic and inflammatory pain. These data suggest that CGRP may act as a neuromodulator in non-headache pain conditions. However, more studies are needed to fully understand the role of CGRP in nociceptive processing and therapy of chronic pain.

Salivary changes in oral mucosal diseases

Saliva is a unique biological fluid that can be easily collected and analyzed with low cost and low morbidity. Therefore, there is a growing attention for using salivary biomarkers in the diagnosis and monitoring of disease progress and response to treatment. Salivary changes have been described in relation to oral mucosal diseases. This article discusses the causes and consequences of salivary hypofunction and presents a review of the literature related to changes in salivary parameters in various oral mucosal diseases and in systemic diseases with possible oral mucosal involvement.

Burning mouth syndrome: a review and update

Burning mouth syndrome (BMS) is characterized by the presence of burning sensation of the oral mucosa in the absence of clinically apparent mucosal alterations. It occurs more commonly in middle-aged and elderly women and often affects the tongue tip and lateral borders, lips, and hard and soft palate. In addition to a burning sensation, the patients with BMS may also complain unremitting oral mucosal pain, dysgeusia, and xerostomia. BMS can be classified into two clinical forms: primary and secondary BMS. The primary BMS is essential or idiopathic, in which the organic local/systemic causes cannot be identified and a neuropathological cause is likely. The diagnosis of primary BMS depends mainly on exclusion of etiological factors. The secondary BMS is caused by local, systemic, and/or psychological factors; thus, its diagnosis depends on identification of the exact causative factor. When local, systemic or psychological factors are present, treatment or elimination of these factors usually results in a significant clinical improvement of BMS symptoms. Vitamin, zinc, or hormone replacement therapy has been found to be effective for reducing the oral burning or pain symptom in some BMS patients with deficiency of the corresponding factor. If patients still have the symptoms after the removal of potential causes, drug therapy should be instituted. Previous randomized controlled clinical trials found that drug therapy with capsaicin, alpha-lipoic acid, clonazepam, and antidepressants may provide relief of oral burning or pain symptom. In addition, psychotherapy and behavioral feedback may also help eliminate the BMS symptoms.

Topirimate-induced burning mouth syndrome

Burning mouth syndrome is a chronic pain condition characterized by burning, painful sensations within the oral cavity. A patient developed symptoms of burning mouth syndrome after initiating topiramate treatment for headache prevention. The symptoms resolved when the medication was discontinued, and the association was replicated upon re-challenge of the drug.