Multimodal pain stimulation of the gastrointestinal tract

Table 2 Multimodal comparison of clinical experimental data obtained in the esophagus from patient with different GI diseases

Patient group	Mechanical stimuli	Heat stimuli	Cold stimuli	Electrical stimuli	Sensitization with acid
Non-cardiac chest pain[41]	No differences to single stimuli, but increased pain to repeated stimuli and increased referred pain area, reflecting central hyperexcitability.	Not done	Not done	Not done	Increased sensation to mechanical stimulations after acid in patients only.
Esophagitis[31]	Patients were hyposensitive but with larger and more widespread referred pain. The distension induced more reactive contraction.	Patients were Hypersensitive probably via increased activation of TRPV1 receptors.	No differences	Not done	Not done
Non-erosive reflux disease (Reddy et al unpublished data)	Patients were hyposensitive to mechanical stimuli. The distensions induced more reactive contractions in the esophagus in the patients and they had larger referred pain areas. Patients with pathological 24-h pH-measurement were more hyposensitive than the patients with normal pH profile.	The patients were hypersensitive to heat with increased referred pain areas to this modality.	No differences between patients and controls	Not done sensitivity score unpublished data)	Patients had a higher sensitivity score to acid perfusion.
Diabetes (Frøkjær et al, unpublished data)	Patients had hyposensitivity to distension, but increased referred pain areas, reflecting peripheral neuropathy and central hyperexcitability. Increased stiffness of the gut wall in diabetes.	As mechanical stimulations	Not done	As mechanical stimulations	Not done
Chronic pancreatitis (Dinmcevski et al, unpublished data)	No differences in sensation. No differentiated effect on morphine and oxycodone in attenuation of mechanical pain.	No differences in sensation Oxycodone attenuated heat pain better than morphine.	Not done	Larger referred pain area in the patients. Opioids were not better than placebo in attenuating electrical pain	Not done unpublished data)