The taste of trigeminal sensations: relation between taste, lingual tactile acuity, and spicy perception in patients with taste dysfunction

In the oral cavity, oral stereognosis and chemesthesis refer to the abilities to recognize shapes and detect noxious substances, respectively, through various receptors distributed on the tongue. The absence of standardized methods to assess oral somatosensory perception has led to a lack of consensus regarding the relationship between taste and trigeminal sensations. While some studies reported lower trigeminal perception in taste disorders, others did not confirm this correlation. To analyze somatosensation in quantitative and qualitative taste problems, 28 patients (21 females, mean age 59.2 yr) with taste disturbance and 32 participants (20 females, mean age 42.3 yr) with normogeusia identified 3D shapes and letters, sized from 2 to 18 mm, with the anterior part of their tongue, in a threshold test. Additionally, participants rated the intensity of increasing amounts of chili. Gustatory and olfactory functions were also tested. Analyses revealed that patients with taste dysfunction had significantly higher thresholds for lingual tactile sensitivity compared to controls (P < 0.001). Moreover, patients rated the intensity of chili significantly lower than controls (P < 0.001), particularly at higher concentrations. Oral stereognosis threshold scores were negatively correlated with gustatory and olfactory functions, and decreased with increasing age, while intensity for chili correlated with taste scores (P ≤ 0.009). The findings of this study suggest that taste dysfunction is associated with low oral mechanosensory and chemesthetic functions. The testing methods used in this study could be valuable in clinical practice for assessing and monitoring sensory impairments.