Chapter 38 (page 193)

The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 38 (page 193)

Relationship to Cyclical Activity of Sphincteric Cylinder

In the present cases as well as in some of those described previously (Keet l952) it is clear that prolapse of gastric mucosa may only occur during maximal contraction of the pyloric sphincteric cylinder. A number of other authors came to essentially similar conclusions, although they used terms such as "antral systole", "gastric systole" and "peristaltic activity" to indicate the concept of contraction of the sphincteric cylinder (Nygaard and Lewitan l948; Fermin l950; Zimmer l950; Levin l97l). According to Bralow and Melamed (l947) prolapse ensued when there was failure of the normal orad movement of the mucosa during "antral systole" as originally described by Golden (l937) (Chap. 13). In our view prolapse almost amounts to expulsion of gastric mucosal folds into the duodenum, together with luminal contents. It is surmized that it may indicate failure of the normal mechanism of "independent but co-ordinated" contractions involving the muscularis externa and mucosa, as described by Forssell (l923, l939) (Chap. 2, 13). It seems as if the occurrence of prolapse depends on the degree of contraction of the pyloric sphincteric cylinder, rather than the position of the patient, in many cases.

On the other hand prolapse of gastric mucosa into the duodenum may also be fickle and unpredictable; its occurrence and extent may vary between examinations and even during a single examination.

The Radiological Differential Diagnosis

Normal. A number of authors have commented on the fact that the base of the duodenal bulb may normally have a semicircular or concave outline, which may easily be mistaken for a semicircular or mushroom-shaped defect due to prolapsed mucosa (Scott 1946; Bralow and Melamed 1947; Manning and Highsmith 1948; Hawley et al. 1949; Keet 1952; Todd and Brennan 1957). The concave defect often becomes more prominent during maximal contraction of the pyloric sphincteric cylinder (Chap. 13).

Depending on the direction of the pyloro-duodenal axis, the circular indentation of the base of the bulb caused by the normal pyloric ring, may sometimes appear to be exaggerated. This is especially evident when the bulb is seen obliquely from the base. If, in addition the sphincteric cylinder is contracted, producing longitudinal mucosal folds running toward the aperture, the appearance may mimic prolapse closely. In one of the illustrations of Rappaport et al. (1952), a round defect of the base of the bulb with radial striae of barium was said to indicate prolapse of gastric mucosa; however, this could just as well have been a normal stage of contraction of the cylinder. There seems to be little doubt that in many instances, and perhaps even in the majority of non-verified cases, the radiological diagnosis rested upon faulty interpretation of these normal appearances, leading to false positive diagnoses.

Adult Hypertrophic Pylorid Stenosis. A number of authors mentioned adult hypertrophic pyloric stenosis in the differential diagnosis (Pendergrass and Andrews 1935; Scott 1946; Hawley et al. 1949; Keet 1952). In this condition the hypertrophied musculature of the pyloric sphincteric cylinder indents the base of the duodenal bulb, producing a concave defect which may be mistaken for prolapse. The narrowed pyloric canal contains longitudinal mucosal folds converging on the aperture, again mimicking prolapse (Chap. 24). In adult hypertrophic pyloric stenosis the bulbar defect is due to pressure from without, and tends to be constant. In prolapse there is an intraluminal bulbar defect which tends to change in size and shape. Differences are also seen in the motility of the cylinder in the two conditions. Whereas the cylinder may contract and expand normally in prolapse, it remains more or less permanently contracted in hypertrophic stenosis. A complicating factor is that prolapse of gastric mucosa may co-exist with adult hypertrophic pyloric stenosis or narrowing and constriction of the cylinder (Pendergrass and Andrews 1935; Archer and Cooper 1939; MacKenzie et al. 1946; Zacho 1948; Manning and Gunter 1950; Keet 1952).

Prolapsed Benign Pedunculated Gastric Polyps. Prolapsed polyps have long been known to produce rounded defects in the duodenal bulb (Eliason et al 1926; Pendergrass and Andrews 1935). Short and Young (1968) collected 30 cases from the literature and found the majority to be benign adenomas. However, prolapsing lipomas, myomas, fibromyomas and other types of benign gastric polyps may occur. A feature of these defects is that they may vary in position, at times being seen in the confines of the sphincteric cylinder and at other times in the duodenal bulb.

Prolapsed Primary Gastric Carcinoma. Occasionally a prolapsed primary gastric carcinoma may produce a rounded intraluminal filling defect in the first part of the duodenum. Joffe et al. (1977) described 4 cases of this nature, all gastric adenocarcinomas, 2 being pedunculated and 2 sessile (Chap. 33).