RECENT FINDINGS: Disordered immune reactions and release of cytokines with resultant gut inflammation and dysfunction appear to be key features of PI-IBS. Disordered brain-gut-microbiota interactions, type of infecting agent, and host-genetic susceptibility are risk factors but also are reasons for the varying spectrum of clinical severity. Although prognosis is generally good, symptoms and inflammation may persist for a long time. Symptomatic relief with antidiarrheals, antispasmodics, 5HT3 antagonists, mesalamine, probiotics, and low-dose antidepressants remain the primary approaches, but in some difficult cases, a combination of drugs that target the pathophysiology may be helpful. PI-IBS has many overlapping features with IBS-D and shares similar pathophysiology and management approaches.
Methods: Patients with chronic constipation (Rome III) were evaluated for DD with HRPT and WM during bearing-down "on-bed" without inflated rectal balloon and "on-commode (toilet)" with 60-mL inflated rectal balloon. Eleven healthy volunteers were also evaluated.
Results: Ninety-three of 117 screened participants (F/M = 77/16) were included. Balloon expulsion time was abnormal (＞ 60 seconds) in 56% (mean 214.4 seconds). A modest correlation between HRPT and WM was observed for sphincter length (R = 0.4) and likewise agreement between dyssynergic subtypes (κ = 0.4). During bearing down, 2 or more anal pressure-segments (distal and proximal) could be appreciated and their expansion measured with HRPT but not WM. In constipated vs healthy participants, the proximal segment was more expanded (2.0 cm vs 1.0 cm, P = 0.003) and of greater pressure (94.8 mmHg vs 54.0 mmHg, P = 0.010) during bearing down on-commode but not on-bed.
Conclusions: Because of its better resolution, HRPT may identify more structural and functional abnormalities including puborectal dysfunction (proximal expansion) than WM. Bearing down on-commode with an inflated rectal balloon may provide additional dimension in characterizing DD.