Abstract
OBJECTIVE: To investigate the pain threshold and the referred pain areas to electrical stimulation of the prepyloric region of the stomach, and the cutaneous sensibility in the referred pain areas.DESIGN: Eight healthy males volunteered for the study. To identify the area of referred pain, all subjects participated in a study using the same model four months previously. During gastroscopy, repeated electrical burst stimuli were delivered in four adjacent prepyloric sites of the stomach, and the pain detection thresholds (PDTs) together with the area of pain referral were determined. Before, during and after continuous electrical painful stimuli delivered in the prepyloric region, the cutaneous sensitivities in the referred pain area and a control area on the chest were characterized using electrical, heat, touch and pinprick stimuli.RESULTS: The PDTs in the four prepyloric areas were not different and the location of the referred pain was reproducible. During the nociceptive visceral stimuli, hyperalgesia to heat stimulation was detected in the referred pain area compared with the control area, but the thresholds for electrical, touch and pinprick stimulations did not change.CONCLUSIONS: The reproducible pain thresholds in adjacent prepyloric sites make future analysis in patient groups possible because the precise site of stimulation can vary without changing the sensibility. The modality-specific somatosensory changes in the referred pain areas further indicate that visceral pain can cause differentiated sensory changes. Modality-specific sensibility changes are also seen in referred areas to muscle pain. Thus, the model may increase the information on viscerocutaneous convergence phenomena in humans.