Chapter 32 (page 160)

The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 32 (page 160)

Discussion

There can be little doubt that the pyloric sphincteric cylinder is contracted in some cases of hiatus hernia, both in infants and in adults. It may occur in sliding, irreducible, and combined (sliding and rolling) types of hiatus hernia. All our cases also had gastro-oesophageal reflux. (Comment: It should be pointed out that there is a tendency to equate persistent, symptomatic gastro-oesophageal reflux with sliding hiatus hernia. Criteria for diagnosing a sliding hernia in our cases was firstly, free and persistent gastro-oesophageal reflux, and secondly, demonstration of the gastro-oesophageal junction at a higher level than normal).

In a series of 134 consecutive cases of hiatus hernia in adults we (Keet and Heydenrych l97l) found radiographic evidence of contraction of the cylinder, to greater or lesser extent, in 14 percent. In a second series of 128 cases, contraction of the pyloric sphincteric cylinder was seen in 28 percent. Why the incidence should differ in the two series, is not clear; it is presumed that the criteria for diagnosing a contracted cylinder were stricter in our first series, only cases with moderate to severe contraction being included.

Contraction of the pyloric sphincteric cylinder may vary from very severe as in hypertrophic pyloric stenosis (Fig. 32.1A), through pseudo- hypertrophic pyloric stenosis (Fig. 32.2B) to moderate and mild degrees of contraction (Fig. 32.4B, 32.5B). A common factor in all is that normal cyclical activity of the pyloric sphincteric cylinder, i.e. the full range of normal rhythmical contraction and relaxation, occurring at a rate of approximately 3 cycles per minute, is absent.

Behar and Ramsby (l978) studied the gastric emptying rate of the liquid phase of a meal, and the fasting "antral" contractility, in 13 patients with gastroesophageal reflux and normal controls. Gastric emptying half-time was no different from that of controls but "antral" contractility (the number of antral contractions and the cumulative antral activity) was lower in reflux oesophagitis patients than in controls. It was concluded that the motility disorder in gastroesophageal reflux was not necessarily confined to the lower oesophageal sphincter, but that it might also involve the "antrum". Hillemeier et al. (l98l) noted delayed gastric emptying in infants with gastro-oesophageal reflux. Valenzuela et al. (l98l) studied gastric emptying of liquids and solids by means of a double isotope technique in l9 patients with oesophagitis and normal controls. Ten patients had delayed gastric emptying of liquids, and 7 of solids; it was concluded that patients with oesophagitis might have delayed gastric emptying. None of these authors based their findings on the concept of the pyloric sphincteric cylinder.

The pathophysiology caused by contraction of the cylinder will vary, depending on the degree of contraction. In our view this may explain some of the above findings. With severe contraction, as in hypertrophic pyloric stenosis (Fig. 32.1A) or pseudo-hypertrophic stenosis (Fig. 32.2B), partial gastric outlet obstruction may be expected; cases of this nature are in the minority. Most cases show mild to moderate degrees of contraction of the pyloric sphincteric cylinder (Fig. 32.4B, 32.5B). This often results in "fixing" the pyloric aperture in the open position, with consequent rapid or normal emptying of liquids. Diminished cyclical activity of a partially contracted pyloric sphincteric cylinder on the other hand, may delay the emptying of solids (Chap. 18) and hamper trituration (Chap. 18).

It is of interest to note that in animal experiments Gillison et al. (l972) found that oesophagitis rarely occurred with reflux of pure gastric juice; when gastric juice containing bile was allowed to reflux into the oesophagus, different degrees of oesophagitis were produced. Stol et al. (l974) found that the concentration of bile acids in the stomach was increased in symptomatic hiatus hernia cases as compared with normal controls, indicating duodenogastric reflux in these cases.

Kaye and Showalter (l974) measured duodenogastric regurgitation in 10 patients with symptomatic gastro-oesophageal reflux and in normal controls. After a standard liquid meal, bile-salt concentration in aspirated gastric juice was significantly higher in patients than in control subjects; this indicated an abnormal degree of regurgitation of duodenal contents into the stomach in patients with symptomatic gastro-oesophageal reflux. Safaie-Shirazi et al. (l975) found that the addition of bile to hydrochloric acid made the mucosa of the oesophagus much more susceptible to inflammatory change. In their investigations of duodenogastric reflux in cases of symptomatic gastro-oesophageal reflux, none of these authors mentioned the possibility of a sphincteric cylinder at the pylorus.

It has been shown that partial contraction of the pyloric sphincteric cylinder may fix the pyloric aperture in the open position (Chap. 13, 27). The partially contracted cylinder, in the absence of cyclical activity, appears to be a factor facilitating gastroduodenal reflux (Chap. 13, 27). It is suggested that the sequence of events may be as follows: In a certain percentage of cases of hiatus hernia (or symptomatic gastro-oesophageal reflux), the pyloric sphincteric cylinder is partially contracted, fixing the pyloric aperture in the open position. The patent aperture and the rigid, tube-like, partially contracted cylinder facilitate duodenogastric reflux. As a consequence of duodenogastric and gastro- oesophageal reflux, duodenal juice enters the oesophagus, producing biliary oesophagitis.

The mechanism of contraction of the pyloric sphincteric cylinder, seen in some cases of hiatus hernia, may possibly be based on vagal stimulation. In animal experiments Bortoff and Davids (l968) found that electrical stimulation of the cervical vagal trunks produced effects in the gastric "antrum" and duodenum. These included a decrease in the frequency of antral slow waves associated with an increase in their amplitude and duration; if vagal stimulation was continued, spike potentials occurred with antral (and duodenal) slow waves. Keet and Heydenrych (l97l) showed that electrical and mechanical stimulation of the anterior and posterior vagi in the oesophageal hiatus of the diaphragm caused contraction of the pyloric sphincteric cylinder; this probably occurred via the hepatic branches of the vagus, which innervate the region of the cylinder and first part of the duodenum (Chap. 8). It is known that owing to its wide ramification, stimulation of the vagus may produce distant effects; one of these is the phenomenon of earache occurring in association with hiatus hernia (Malherbe l958; Keet l968). In this syndrome stimulation of oesophageal vagal filaments in the hiatus produces referred pain in the external ear via the auricular branch. It is surmized that similar stimuli may produce motor effects via the hepatic branches (Chap. 8).

The reason why there should be an association between hiatus hernia and contraction of the pyloric sphincteric cylinder in some cases and not in others, is not known. We have been unable to establish a clear relationship between oesophagitis and contraction of the cylinder. In our second series of 125 cases, 15 had unequivocal oesophagitis, diagnosed either by endoscopy or radiography, or both; of the 15 cases only 4 had contraction of the sphincteric cylinder. The size of the portion of stomach presenting above the diaphragm, or the extent of shift of the gastro-oesophageal junction in the hiatus, similarly does not appear to be of consequence. Usually irreducible hernias cause a larger portion of the stomach to present above the diaphragm than reducible (i.e. sliding) hernias. In our series of 125 cases, 33 were irreducible hernias, with part of the stomach permanently located above the diaphragm; of these, 9 had a contracted pyloric sphincteric cylinder. Factors which may possibly play a role, but which have not been investigated, are the degree of stretch of the vagi in the hiatus, the presence or absence of peri-oesophageal inflammation, and the duration of the condition.