The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 19 (page 88)

According to Azpiroz and Malagelada (l990) tonic muscular contraction of the stomach (i.e. gastric tone), determines the balance between gastric accommodation and emptying. Tone is finely regulated by multiple interacting mechanisms; reflexes arising from different regions of the upper gastrointestinal tract may modulate the gastric emptying process (and hence presumably gastric tone).

An unusual but well-documented case of gastric atony was described by Telander et al (l978). This concerned a 5 months old child who presented with massive gastric distension and intractable gastric stasis. No evidence of organic narrowing or occlusion was found at the pylorus during 3 separate exploratory operations. Biopsy of the gastric wall revealed no abnormality of the ganglion cells in the myenteric plexuses and the smooth muscle cells of the tunica muscularis were normal. A gastric pressure-volume response obtained through a gastrostomy revealed no concomitant increase of intragastric pressure during stepwise increments of volume, indicating a complete lack of gastric tone, i.e. gastric atony. The cause was considered to be absence of electrical potential normally coupling electrical and mechanical activity, diminished sensitivity of the gastric smooth muscle to excitatory stimuli and probably an ectopic antral pacemaker. (Chap.16).



Mainly as a result of the investigations of Stadaas and Aune (l97O), Schulze-Delrieu (l983, l986) and Azpiroz and Malagelada (l985) it may now be accepted that the radiographic image of a long, angulated, "fish-hook" stomach with a sagging greater curvature is due to hypotonicity of the gastric musculature. The hypotonic stomach is associated with decreased or absent peristalsis, absent cyclical contractions of the pyloric sphincteric cylinder and delayed emptying of liquid barium in the erect position (Chap. 13, 20). Changing the position of the subject to the left anterior oblique recumbent position, causes immediate, gravitational emptying of liquid barium, showing that pylorospasm is not a factor in these cases (Chap. 20).

In most instances gastric hypotonicity is of idiopathic origin and presumably of little clinical significance. More severe degrees, sometimes progressing to acute gastric dilatation, may occur in a variety of conditions e.g. post-operatively, after severe trauma and in electrolyte disturbances.


A short, transversely situated, "steerhorn" stomach on the other hand, is now known to be the result of gastric hypertonicity. In these cases immediate emptying of liquid barium usually commences in the erect position, before the onset of peristalsis or cyclical contractions of the pyloric sphincteric cylinder (Chap. 13).


  1. Azpiroz F, Malagelada JR. Physiologic variations in canine gastric tone measured by an electronic barostat. Amer J Physiol l985, 248, G229 - G237.
  2. Azpiroz F, Malagelada JR. Intestinal control of gastric tone. Amer J Physiol l985, 249, G501 - G509.
  3. Azpiroz F, Malagelada JR. Perception and reflex relaxation of the stomach in response to gut distension. Gastroenterology l990, 98, ll93 - ll98.
  4. Pernkopf E. Beiträge zur vergleichenden Anatomie des Vertebratenmagens. Zeitschr gesamte Anat l929, 91, 329 - 362.
  5. Schulze-Delrieu K. Volume accommodation by distension of gastric fundus (rabbit) and gastric corpus (cat). Dig Dis Sci l983, 28, 625 - 632.
  6. Schulze-Delrieu K. Selected Summaries: Gastric Tone. Gastroenterology l986, 90, 1298 - 1299.
  7. Stadaas J, Aune S. Intragastric pressure-volume relationship before and after vagotomy. Acta Chir Scand l970, 136, 611 - 615.
  8. Telander RL, Morgan KG, Kreulen DL, et al. Human gastric atony with tachygastria and gastric retention. Gastroenterology l978, 75, 497 - 501.
  9. Torgersen J. The muscular build and movements of the stomach and duodenal bulb. Acta Rad l945, Suppl 45, 1 - 191.

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