Abdominal Pain Sensitization Connected With Upper but Not Lower Abdominal Pain in Adults With Gastroparesis.

INTRODUCTION: Although pain is recognized as an important symptom in gastroparesis, it has not been well studied and characterized. Quantitative sensory testing (QST) is a psychophysical method that has the potential to provide a measure of pain processing, as well as insight into pain pathophysiology and the prediction of response to specific therapies. We aimed to characterize somatic QST in a well-characterized cohort of patients with gastroparesis. METHODS: Adults with scintigraphically defined gastroparesis underwent abdominal QST with assessment of mechanical pain: pain sensitivity (thresholds and tolerance) and pain facilitation (temporal summation). The Patient Assessment of Upper GI Symptoms (PAGI-SYM) upper and lower abdominal pain scales were used. RESULTS: QST was performed on 264 participants (87% female; age = 18-78 years). In both the upper and lower abdomen, smaller pain thresholds and lower pain tolerance were significantly associated with greater PAGI-SYM upper abdominal pain severity (b's = 0.07-0.15; p's = 0.007-0.02), but not lower abdominal pain severity. Scores on the PAGI-SYM upper and lower abdominal pain scales were moderately correlated (r = 0.48, p < 0.0001). No significant associations were found for temporal summation. CONCLUSIONS: Our findings suggest self-reported upper abdominal pain severity correlated with both lower and upper abdominal mechanical pain sensitivity-possibly reflecting secondary sensitization of the abdominal wall, due to viscerosomatic convergence in upper abdominal somatic segments. Lower abdominal pain severity association with only upper (but not lower) abdominal QST may be due to cross-organ sensitization. Further investigations are needed to test the clinical utility of abdominal QST in gastric sensorimotor disorders. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01696747.