Exploring the pathophysiology of LARS after low anterior resection for rectal cancer with high-resolution colon manometry

Although references to the ‘Low Anterior Resection Syndrome’ (LARS) are omnipresent, the exact pathophysiological mechanisms continue to be an enigma to date. Consequently, for this study, we utilized the state-of-the-art technique of high-resolution colon manometry to explore colonic motor patterns in patients who suffered from varying degrees of LARS. One to two years after restoration of transit, patients after TME were asked to enter the study protocol and undergo high-resolution colon manometry. Colonic motor patterns were analysed and occurrences were compared between nine patients with major LARS and nine patients with no/minor LARS. A differentiation between six different colonic motor patterns was made: (1) + (2) short single propagating motor pattern (antegrade/retrograde), (3) + (4) long single propagating motor pattern (antegrade/retrograde), (5) simultaneous pressure wave and (6) high amplitude propagating contraction (HAPC). Furthermore, the relationship of the motor patterns with the LARS-scores was investigated. Results demonstrated that patients with major LARS showed significantly more cyclic short antegrade motor patterns overall, as well as post-bisacodyl (= a laxative) administration. This type of pattern also showed to be strongly correlated to the LARS-scores. Regarding other patterns, no other significant correlations were found with the LARS-scores. HAPC’s only occurred after the administration of bisacodyl in every patient. Finally, patients with major LARS displayed significantly less HAPC’s that started in the proximal colon and ended in the mid-section of the colon, compared to patients with no/minor LARS."