Chapter 26 (page 121)

The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 26 (page 121)

Chapter 26

Nausea, Retching and Vomiting

The mechanism of vomiting in mammals is complex and in spite of experimental studies some aspects are still not fully understood. It is usually accepted that the vomiting sequence consists of 3 successive phases: nausea initially, followed by retching, often leading to forcible expulsion of gastric contents through the mouth, i.e. ejection or vomiting. During these stages a co-ordinated sequence of movements occurs, involving, amongst others, the upper small bowel, stomach, oesophagus, diaphragm, voluntary abdominal muscles and glottis.

The complex movements of the ejection phase occur with extreme rapidity. Some features visible during radiographic investigation of this phase have been described by Lumsden and Holden (l969); as these involve the proximal stomach, the gastro- oesophageal junction, oesophagus and laryngo-pharynx, the details fall outside the scope of the present investigation.

Nausea

During radiological examinations Barclay (l936) noted absence of gastric peristalsis in cases of nausea, as well as sagging of the lowermost part of the greater curvature which he attributed to loss of gastric tone. Lumsden and Holden (l969) described a similar, sudden descent of the greater curvature in a number of patients with nausea; they had no radiographic record of the occurrence.

During routine barium studies in the erect position, one of our patients would occasionally complain of nausea after having swallowed the first few mouthfuls of the suspension. Under these circumstances the following was seen: the lower part of the greater curvature sagged, causing an increase in the diameter of the distal part of the stomach, indicating loss of tone (Chap. 19). Simultaneously peristaltic contractions in the body of the stomach, cyclical contractions of the pyloric sphincteric cylinder and gastric emptying ceased. The appearance of the stomach was similar to that seen after administration of anticholinergic agents. The following is an example of what is usually observed in cases of nausea:

Case Report

Case 26.1. G.C., male aged 24 years, was referred for barium study because of vague upper gastrointestinal symptoms. Having swallowed the first 3 mouthfuls of barium, the patient complained of feeling nauseous; there was no retching but he was unable to continue drinking. Initially the stomach appeared to have a normal tone, but the greater curvature sagged, moderate gastric dilatation occurred and peristaltic activity and cyclical contractions of the pyloric sphincteric cylinder ceased. A trickle of barium had entered the duodenal bulb but no further gastric emptying occurred (Fig. 26.1). He was advised to sit down. After 15 minutes the nausea disappeared and the examination could be resumed. Gastric tone, peristalsis, sphincteric cylinder activity and emptying became normal; no organic lesion was detected.

Fig. 26.1. Case G.C. Moderate dilatation of stomach, sagging of greater curvature, and absence of peristalsis and cyclical activity of pyloric sphincteric cylinder

According to Monges et al. (l974) the first electromyographic phenomena of nausea are the disappearance of spiking activity in the stomach and small intestine, and the slowing, decrease in amplitude and disturbance in propagation of the basal electrical rhythm (BER). These events may occur before the patient experiences nausea.

You et al. (l980) recorded gastric myoelectric activity in control subjects and in a group of patients with unexplained nausea, epigastric bloating and vomiting; the technique entailed the use of a peroral suction electrode. As no mention was made of actual retching or vomiting during the investigations, it would appear that recordings were obtained during the phase of nausea. One of the electrodes was attached to the gastric mucosa 1.0 cm orally to the pyloric ring, and another 3.0 cm orally to the ring, i.e. within the confines of the pyloric sphincteric cylinder (others were attached further orally, and 2 were located in the duodenum). In contrast to the normal, regular pacesetter potential (PP) with a frequency of 3 to 4 cycles per minute, all 9 patients showed abnormal "antral" myoelectric activity, characterized by tachygastria or tachyarrhythmia and propagation of the PP in either the orad or aborad direction.