Burning mouth syndrome: Is it a neuropathic condition?

Abstract: Burning mouth syndrome (BMS) is one of the most typical orofacial pain conditions that is characterized by ongoing burning or tingling pain mostly in tongue, labial mucosa and the palate. Classifications have defined that the diagnosis should exclude any known systemic or peripheral pathologies that can cause pain in the oral cavity, which means BMS is a pain condition with unknown etiology. BMS has long been recognized to be associated with menopause and depression / anxiety and has been studied from a hormonal or a psychological point of view. Recent morphological studies, however, have revealed pathological changes of small nerve fibers in the tongue epithelium that explain taste disturbance and psychophysical and electrophysiological changes observed in BMS patients. This small nerve fiber degeneration may be involved in the peripheral and the central pain modulation mechanisms, which induce continuous burning pain and hyperalgesia against hot foods. Further, lack of neuroactive steroids is reported to play a pivotal role in nerve degeneration and exertion of neuropathic pain. Imaging studies have suggested the dysregulated pain modulation system in the brain of BMS patients that showed reduced pain inhibition against noxious pain stimuli and strengthened connectivity in the salience network in the resting state of the BMS brain. These studies suggest a possible relationship between menopause and psychosocial distress, taste disturbance and dysregulation of the peripheral and the central pain modulation systems. Taken together, these findings lead to a suspect that BMS is a neuropathic condition, although current consensus on classification of BMS remains that BMS is an idiopathic orofacial pain. My talk will include recent findings in literature and from our studies. (269 words excluding name and affiliation)