Burning mouth syndrome at menopause: Elusive etiology.

Burning mouth syndrome (BMS), as a clinical condition though described for a long time, remains poorly understood.[1] BMS is a diagnosis of exclusion. Establishing the diagnosis of BMS in a given patient requires exclusion of oral pathological lesions, certain systemic diseases, vitamin deficiencies, and intake of drugs known to cause dryness and burning of mouth.[2] In the current issue, the authors provide a list of drugs that cause BMS in the article “Prevalence of Burning Mouth Syndrome in middle aged and elderly postmenopausal women: A clinical Research.”[3] Some of these medications will be a part of the multipill treatment for management of cardiovascular problem in menopausal women. Hence a careful enquiry should be done as to the onset of BMS vis-ô-vis initiation of the medications.

BMS is also known as stomatodynia and the International Association for the Study of Pain has defined it as “all forms of burning sensation in the mouth, including complaints described as stinging sensation or pain, in association with an oral mucosa that appears clinically normal in the absence of local or systemic diseases or alterations.”[4]

BMS largely occurs as a chronic burning painful condition of the tongue (glossodynia) in peri-/post-menopausal women with or without dryness of mouth (xerostomia). Its prevalence is estimated as 18-33% in postmenopausal women.[2] Misra et al. also report nearly 21% of 105 postmenopausal women having BMS; a fairly high prevalence.[3]

There may be other associated “dynia” or painful conditions like vulvostomatodynia.[5] Since both BMS and vulvodynia occur more frequently in menopausal women, estrogen deficiency could be considered as a common pathological mechanism of these clinical conditions. Estrogen receptors are also identified in both the tongue and the vaginal mucosa besides having microscopic similarity.[67] However, hormone replacement therapy (HRT) has not been majorly found to be useful and thus estrogen deficiency is generally not accepted as causal.[8] There are conflicting reports about the use of HRT in menopausal women with BMS.[8] However, there are strong views expressed against the psychogenic nature of BMS at menopause in view of the dramatic drop in sex steroid levels at the menopausal transition.[9]

Currently neuropathic etiology is being evolved as possibly causal for BMS.[1011] Reductions in the number of unmyelinated fibers associated with taste papilla and a reduction in number of intraepithelial fibers have been shown in studies of tongue biopsy from patients of BMS.[1012] Functional MRI (fMRI) studies in limited patients have revealed that patients of BMS may have neurodysregulation of afferent pain stimuli.[13] Some studies have hinted at genetic component based on a higher prevalence of BMS in high tasters.[14]

Studies have also been conducted on saliva as hyposalivosis or dry mouth (xerostomia) may be a part of BMS. Salivary glands also have estrogen receptors.[8] Salivary secretion flow rate and its biochemical composition in postmenopausal women before and during HRT have been detailed.[8] However; even here there is a lack of convincing evidence for the therapeutic role of HRT in xerostomia.

In view of uncertain etiology and a lack of definite criteria of diagnosis of BMS, treatment remains empirical. Misra et al. quotes a study of Geri Forte in 75 postmenopausal women with symptoms of burning mouth; 47 of these were symptom free at the end of 6-week treatment. One would like to also know about the safety of the formulation in view of its herbo-mineral composition. In a recent double blind placebo-controlled study of Catuama (a formulation of multiple plants from Brazil), a significant reduction was observed in the symptoms of BMS.[15]

In an extensive systematic review of drugs used for treatment of BMS, the authors detail effectiveness and safety of several interventions that include local anesthetics, antidepressants, benzodiazepines, topical clonazepam, benzydamine hydrochloride, dietary supplements, and hormone replacement therapy (HRT) in postmenopausal women.[2] Outcome of cognitive behavioral therapy (CBT) is also reviewed. However, the authors mention that no good-quality studies for CBT were found. A randomized placebo-controlled study of topical clonazepam showed significant benefit with treatment compared to placebo in patients having BMS.[16]

In conclusion, though BMS is prevalent in menopausal women, approaches for evaluation and management are still not standardized as etiology remains enigmatic. There is also a great scope for well-designed clinical studies using reverse pharmacological approach[17] for evaluating alternative therapeutic modalities from AYUSH and traditional systems of medicine in treatment of the syndrome.