Hyperalgesia against capsaicin in persons with uninvestigated dyspepsia: potential as a new diagnostic test

Lack of understanding of the pathogenesis of functional dyspepsia is one reason for the paucity of effective treatment options. Whereas mechanical sensitivity in persons suffering from dyspepsia might be impaired, chemically induced hypersensitivity has received little attention. Aim: To evaluate whether vanilloid receptors stimulated by capsaicin are hypersensitive in persons with dyspepsia. Methods: Six volunteers with uninvestigated dyspepsia who never had consulted a physician (4 women, age 26.2 +/- 4.1 years) and six controls (3 women, age 27.5 +/- 5.9 years) underwent jejunal perfusion with capsaicin. All participants swallowed a tube with an infusion site at the ligament of Treitz and 7 cm distally a barostat balloon that was used for pressure-controlled distension. Capsaicin solution (40 mu g/ml, 2.5 ml/min) was infused for 60 minutes or until discomfort was induced. Perceptions of seven different sensations were evaluated using a graded questionnaire during capsaicin infusion and jejunal distension. Results: During infusion of capsaicin, the length of time until occurrence of the first sensation (P < 0.01) and discomfort (P < 0.001) was significantly shorter in those with dyspepsia than in the control group. Mechanical distension induced first sensation and discomfort at lower balloon volumes in those with dyspepsia but this difference was not significant. Conclusion: Jejunal sensitivity to capsaicin is increased in persons with uninvestigated dyspepsia, and vanilloid receptors might be involved in the pathophysiology of this condition. Patients with hypersensitivity to chemical stimuli may represent a distinct sub-population based on the underlying pathophysiology and may require specific treatment to restore normal visceral sensitivity.