Challenging the 'Central vs. Peripheral' Classification in Burning Mouth Syndrome: A Critical Analysis of Yang...

To critically evaluate the classification of Burning Mouth Syndrome (BMS) into 'peripheral' or 'central' subtypes based on short-term pain relief (≥ 1 cm on the Visual Analogue Scale, VAS) following lingual nerve block, and to explore how quantitative sensory testing (QST) might refine BMS diagnosis.

We reviewed two recent publications by Yang et al. investigating conditioned pain modulation (CPM) and lingual nerve block efficacy in BMS. We examined their reliance on immediate VAS reductions, sample size, QST findings, and adherence to International Classification of Headache Disorders (ICHD-3) criteria.

Yang et al. reported diminished CPM responses, particularly in the wind-up ratio, among patients classified as central BMS, and highlighted short-term pain relief exclusively in the peripheral subtype. However, categorising patients solely by a ≥ 1 cm VAS reduction may oversimplify the multifactorial nature of BMS, especially when QST findings did not consistently distinguish between groups. Additionally, a small sample size (n = 20) could limit generalisability and obscure subtle pathophysiological differences.

Although Yang et al. appropriately applied standard diagnostic guidelines, we recommend integrating subjective (e.g., McGill Pain Questionnaire, Pain Catastrophizing Scale) and objective (e.g., QST, CPM) assessments to capture the complex interplay of peripheral and central mechanisms in BMS. These findings underscore the difficulty of reducing BMS to a strict dichotomy and highlight the need for nuanced, multidimensional approaches. Larger, more diverse cohorts and multidimensional evaluations may improve patient stratification and treatment targeting, ultimately enhancing clinical outcomes for individuals with BMS.