The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 26 (page 124)


Lang et al. (l986) examined the gastrointestinal motor correlates of vomiting in canines by means of implanted extramural strain gauge transducers. One of the motor responses was a retrograde peristaltic contraction commencing in the middle of the small intestine and moving in an orad direction through the small intestine to the gastric "antrum". Ejection did not occur after a consistent delay following the "antral retrograde peristaltic contraction", i.e. there was no evidence that the antral contraction correlated with vomitus ejection. This was consistent with previous findings that the stomach did not provide the propulsive force for vomitus ejection; it was more likely that the propulsive force was provided by contractions of the abdominal or respiratory muscles. The small intestinal retrograde peristaltic contraction, leading to gastric "antral" contractions, was probably mediated peripherally by muscarinic cholinergic receptors as it was selectively blocked by atropine (which does not readily cross the blood-brain barrier).

During routine barium studies we observed the act of ejection in 5 or 6 patients. Because of violent movements it was usually not possible to obtain satisfactory radiographs. The following is a representative case:

Case Report

Case 26.4. S.S., female aged 42 years. After swallowing two mouthfuls of barium, it accummulated in the pyloric region. Incomplete contractions of the pyloric sphincteric cylinder, not propagating the barium into the duodenum, soon started. Almost immediately the patient felt nauseous and retching commenced. At this stage the pyloric sphincteric cylinder contracted maximally, giving rise to an appearance sometimes called "amputation of the antrum". Immediately afterwards a long spastic contraction occurred in the body of the stomach, associated with ejection. Two contracted areas were then present in the stomach, namely the contracted sphincteric cylinder, and a larger region of contraction of the body of the stomach. At that stage most of the remaining barium was in the upper part of the stomach, above the contracted regions. Subsequent clinical examination revealed no obvious cause for the vomiting.


With the exception of Torgersen (l942), none of the authors quoted above based their descriptions of nausea, retching and vomiting on the muscular anatomy of the stomach as previously determined by Cunningham (l906), Forssell (l913) and Torgersen himself.

Our radiographic observations show that nausea is characterized by loss of gastric tone, absence of peristalsis and cyclical contractions of the pyloric sphincteric cylinder, and lack of emptying of fluid barium in the erect position. A number of authors described the electromyographic phenomena recorded during nausea (Monges et al. l974; You et al. l980, l984; Hamilton et al. l986; Geldof et al. l986). It is probable that some of the electrical arrhythmias may be associated with the appearances seen at radiography. Pressure studies of Kerlin (l989) confirmed that postprandial "antral" hypomotility was a major factor in unexplained nausea.

The representative cases described here show that retching is associated with contraction of the pyloric sphincteric cylinder; this is well seen during radiographic studies. Although Lumsden and Holden (l969) did not base the morphology in their cases on the anatomy as described by Torgersen (l942), accompanying illustrations leave little doubt that the pyloric sphincteric cylinder was contracted in all. Wood and Astley (l952) and others (Chap. 20) described a temporary narrowing in the pyloric region closely resembling infantile hypertrophic pyloric stenosis, in vomiting infants. Judging by the descriptions it involved the pyloric sphincteric cylinder. The endoscopic appearances described by Schindler (l937) also tally with contraction of the sphincteric cylinder.

Radiography shows that the cylinder is contracted during ejection. By means of strain gauge transducers in canines Lang et al. (l986) demonstrated an "antral retrograde peristaltic contraction", which appears to tally with contraction of the cylinder; this contraction, however, did not provide the propulsive force for ejection. Radiographically a second, longer area of contraction was seen in the upper part of the stomach during ejection, in addition to the contraction of the cylinder in one of our cases (Case 26.4).


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