When Pain Outruns Pathology: Toward a Bidirectional Model of Illness in Burning Mouth Syndrome

Burning Mouth Syndrome (BMS) is a chronic orofacial pain condition characterized by persistent burning sensations in the absence of consistently identifiable pathology. This mismatch between severe symptoms and inconclusive findings challenges conventional diagnostic reasoning, which presumes that subjective complaints reflect underlying biological lesions—leading to repeated investigations, diagnostic delay, and uncertainty about symptom legitimacy. This paper uses BMS as a paradigmatic case to question a core assumption of clinical reasoning: that objective pathology constitutes primary evidence. In this Perspective, drawing on phenomenology and medical anthropology, we argue that when pathology is indeterminate, illness—the lived experience of suffering—must be treated as primary clinical evidence rather than as a secondary expression of disease. We propose a bidirectional conceptual framework in which physiological processes, psychological states, and lived experience interact dynamically, with symptoms actively participating in the maintenance of the condition. This framework explains persistent diagnostic uncertainty, heterogeneous treatment responses, and the clinical significance of validation and meaning-making. Reframing BMS in this way supports earlier recognition, reduces reliance on exclusion-based strategies, and justifies multimodal interventions addressing both biological and experiential dimensions of pain. More broadly, it suggests that clinical reasoning must expand to incorporate lived experience as indispensable evidence wherever pathology is indeterminate.