12 Pseudo-obstruction syndromes

Chronic intestinal pseudo-obstruction (CIP) is a clinical syndrome characterized by symptoms and signs of intestinal occlusion, in absence of any mechanical obstruction of the gut lumen. It causes impaired transit of intestinal contents and is determined by abnormalities of motor activity. The term CIP is used to indicate a heterogeneous group of disorders with many different pathogenic mechanisms. The defect in the regulation of intestinal transit can be at any level of motility control. Two main types of CIP are recognized, termed respectively myogenic (when smooth muscle cells are affected) and neurogenic (caused by abnormalities of extrinsic and/or intrinsic nervous supplies). Both types may be secondary to a variety of recognizable diseases or idiopathic. In myogenic CIP, intestinal transit is impaired because of lack of propulsive strength; in the neurogenic form, contractions are powerful but not sufficiently co-ordinated to propel intestinal contents aborally in an organized fashion. CIP belongs to the large and loosely defined group of digestive functional disorders. These disorders probably share common pathogenic mechanisms but with different expressiveness. The reasons why only some patients present recurrent symptomatological bouts resembling mechanical occlusion has not been clarified. This aspect is of great clinical relevance and deserves attention, as CIP patients, unlike other patients with severe functional disorders, may undergo repeated, useless and potentially dangerous operations. The diagnosis of CIP may be suggested by clinical features and is based on radiological, endoscopic, manometric, and histological findings. Recent technological improvements facilitate the recognition of this intriguing syndrome. In particular, manometric recording of the small bowel motility, which has long been considered an important research technique, can now also be regarded as a useful diagnostic tool.