A burning sensation in the mouth may be a primary condition, or secondary to identifiable causes (Fig. 38.1). Burning mouth ‘syndrome’ (BMS) – also known as glossopyrosis, glossodynia, oral dysaesthesia or stomatodynia – is the term used when symptoms described usually as a burning sensation, exist in the absence of clinically identifiable oral mucosal disease, when a medical or dental cause has been excluded. BMS is a medically unexplained symptom (MUS). The International Association for the Study of Pain define it as: ‘A distinctive nosological entity characterized by unremitting oral burning or similar pain in the absence of detectable mucosal changes’.
use of drugs, such as cytotoxics, angiotensin converting enzyme (ACE) inhibitors, clonazepam, antidepressants, hormone replacement therapy, proton pump inhibitors (PPIs) or protease inhibitors (PIs) (Algorithm 38.1)
BMS has been associated with immunological changes; it has been hypothesized that the presence of low levels of CD28 cells suggests that BMS might be a pre-autoimmune disease. Cytokines IL-2 and TNF-alpha might play a role in the pathogenesis.
BMS may be a neuropathic disorder of reduced pain and sensory thresholds. It can follow damage to the cauda tympani nerve and is increased in frequency in Parkinson’s disease. BMS patients are often ‘super-tasters’ – they have raised sensitivity to taste. Nerve growth factor (NGF) peptide and tryptase activity appear significantly and persistently raised in saliva in BMS. Hypotheses include that BMS is a sympathetic activity-mediated neuropathic disorder induced by traumatic trigeminal nerve injury or varicella-zoster virus infection, or due to:
BMS most frequently affects the anterior tongue, but it can also affect the palate or, less commonly, the lips or lower alveolus. Three types of BMS have been described on the basis of the pattern of symptoms of burning sensation (Table 38.1).