Pain and biomechanical responses to distention of the duodenum in patients with systemic sclerosis

Abstract

Background & Aims: Abnormalities of the small intestine have been indicated in systemic sclerosis. The aim was to use a new method to study the active-passive mechanical and sensory properties of the duodenum in these patients. Methods: A volume-controlled ramp-distention protocol was used in the duodenum in 9 patients and 8 healthy controls. The nonpainful/painful sensations, pressure, cross-sectional area, wall tension, and strain were evaluated. Using butylscopolamine for muscle relaxation, the active (contractile muscular component) and passive (other mechanical tissue components) were computed. Results: The contraction amplitude was smaller and the cross-sectional area higher in the patients ( P < 0.05). Both the active and passive tension as function of strain was translated to the left in the patients, indicating a stiffer wall. The maximum active tension and the corresponding strain were 62% and 69% lower in the patients ( P < 0.05). An association was found between the duration of the disease and the strain ( P < 0.05). The perception score was higher as function of pressure, tension, and strain ( P = 0.01, P = 0.03, and P < 0.01, respectively) in the patients than in the controls, with strain as the most sensitive variable to describe the sensory response. In 5 patients who complained of regular clinical symptoms, the referred pain area to distention was enlarged. Conclusions: Systemic sclerosis resulted in increased stiffness and impaired muscle function of the duodenum. The pain evoked by a controlled strain of the gut was increased and can explain many of the symptoms reported in the clinic.