Burning mouth syndrome needs to consider the gut-brain axis from three types of pain: nociceptive, neuropathic, and nociplastic pain

Abstract

Burning mouth syndrome needs to consider the gut-brain axis from three types of pain: nociceptive, neuropathic, and nociplastic painTo the Editor,The gut-brain axis (GBA) consists of bidirectional communication between the central nervous system and the intestinal tract, linking emotional centers of the brain with peripheral gut function.The GBA may be involved in the etiology of central painful diseases, but the relationship is not fully understood.I read with great interest the article on the etiology of burning mouth syndrome (BMS) by Russo et al. [1].They showed that BMS has a multifactorial etiopathology, including laryngopharyngeal reflux, hormonal and salivary changes related to aging and menopause, and oral flora, which may induce neurodegeneration in the orofacial region [1].I agree with the perspective that signals from the gastrointestinal tract, including the gut microbiota, influence unexplained chronic pain.However, there is little evidence regarding GBA as the etiology of BMS.Therefore, I propose to organize their LETTERS TO THE EDITORperspectives in three dimensions for future research: receptor, nerve, and brain circuit (Table I).Burning mouth syndrome is an intractable chronic pain disorder of unknown cause characterized by burning sensation without any organic abnormality in the oral mucosa.Pain complaints of BMS patients range from tingling, stickiness, and an indescribable pressure-like pain with discomfort.There are three types of pain: nociceptive pain, neuropathic pain, and nociplastic pain, and the pain of BMS patients includes all of these elements.The review by Russo et al. [1] discusses gastrointestinal disease as a cause of nociceptive pain such as an increase in transient receptor potential vanilloid1 (TRPV1) receptors and neuropathic pain such as neuroinflammation.However, the uncomfortable multifocal widespread pain of BMS patients is classified as nociplastic pain, unlike nociceptive or neuropathic pain.The mechanisms that underlie this type of pain are not entirely understood, but it is thought that augmented central nervous system pain and sensory processing and altered pain modulation play prominent roles [2].Nociplastic pain may be accompanied by gastrointestinal symptoms as well as other symptoms of central nervous system origin, such as fatigue, sleep, memory, and mood problems, Table I.Three types of pain and their mechanisms in burning mouth syndrome

Topics & Concepts