Reply to Musella et al.

Dear Editor,

We sincerely appreciate the constructive comments provided by Musella et al. ¹ in our letter to the editor.

First, we do not consider it optimal to subsume all idiopathic oral symptoms under the blanket term “dysaesthesia.” We designate relatively mild abnormal sensations—such as slight discomfort or unpleasant oral sensations—as “dysaesthesia.” In contrast, more pronounced and specific abnormalities, including oral dysmorphism and foreign-body sensations, are more appropriately classified as “cénestopathies” (cenestopathy) in accordance with Dupré's original definition. ² Recent tightening of the diagnostic criteria for burning mouth syndrome (BMS) has created a gap whereby patients who present with dysaesthesia alone—without the characteristic burning pain—no longer fit within the traditional category of oral dysaesthesia and, as Musella et al. have noted, risk remaining undiagnosed. Consequently, in our clinical practice, we provisionally treat such cases as oral cenesthopathy (OC). ³

In light of these considerations, the view that cenesthopathic manifestations—such as oral dysmorphism, phantom taste, and oral foreign-body sensation—represent “distorted perception caused by malfunction of central sensory processing” is entirely consistent with our previous work, including the report by Umezaki et al., ⁴ and we fully agree.

Moreover, we highly value the concept of oral dysesthetic and perceptual disorder (ODPD), proposed to embrace patients who fall outside the current diagnostic framework for BMS. ⁵ ODPD accurately captures the symptom spectrum that clinicians frequently encounter.

In routine practice, patients often present with concomitant BMS and OC. When OC manifestations are mild, overlap with BMS becomes likely, and—because OC still lacks unified diagnostic criteria—differential diagnosis is challenging. Consequently, the term oral dysesthesia is employed with multiple meanings, which risks confusion and misclassification between BMS and OC. Paradoxically, such apparent inconsistency may imply that both disorders are divergent phenotypes of a single underlying pathophysiology.

The frequent diagnostic overlap and marked symptomatic commonality between the two conditions provide the strongest support for this hypothesis. Whereas BMS is characterized primarily by burning pain and OC tends to foreground foreign-body or bizarre sensations, patients with either disorder complain of oral pain/discomfort, and their subjective symptom profiles overlap extensively. Furthermore, we frequently observe that the chief complaint is oral pain at the initial visit; once pharmacotherapy effectively alleviates this pain, oral cenesthopathic manifestations—such as dysgeusia or a foreign-body sensation—tend to emerge.

Indeed, among 1501 consecutive new patients seen at our clinic between April 2021 and August 2024, we identified 667 cases of BMS alone, 281 of OC alone, and 112 with overlapping diagnoses. Despite the low prevalence of both disorders in the general population, this high overlap rate supports the hypothesis that BMS and OC reside on a continuous pathophysiological spectrum.

While the nomenclature “ODPD” itself warrants further scrutiny, we recognize that its intent—to encompass patients excluded by the current BMS criteria—runs parallel to our own endeavor. However, we hold a different view on including, oral dyskinesia, and halitophobia within ODPD. The primary pathology in oral dyskinesia appears to stem from dysregulation of the basal ganglia–thalamocortical control loop. Halitophobia has historically been regarded as a subtype of taijin kyofusho (anthropophobia). ⁶ In our opinion, these conditions should be considered pathophysiologically distinct from the “pain and sensory abnormalities” that ODPD is designed to address.

We also believe that subdividing ODPD into “dysaesthetic” and “perceptual” dimensions with three clinical profiles (dysaesthesia-dominant, perception-dominant, and mixed type) requires cautious deliberation at present because (i) dimensional allocation of individual symptoms lacks sufficient empirical validation; (ii) objective diagnostic methods enabling such classification have yet to be developed; and (iii) evidence linking the proposed classification directly to current therapeutic decision-making is limited. Diagnostic frameworks acquire real clinical value only when they are coupled to treatment approaches. Multicenter collaborative studies aimed at identifying biomarkers and treatment responses within each dimension are therefore needed to test the practical utility of this proposal.

The concept of ODPD advanced by Musella et al. and our perspective on a BMS–OC symptom spectrum share a common aim: to rescue patients currently marginalized by existing criteria. ¹ We look forward to continued exchange of knowledge so that both approaches may contribute to better care for patients with chronic oral pain and intra-oral sensory disorders.