Acta Medica Scandinavia. Vol. CXL, fasc. I, 1951.

From the Medical Clinic (Head: Professor Ask-Upmark) of the Royal Academic Hospital of the University of Upsala, Sweden

The Region of the Solar Plexus as a Trigger Zone in Clinical Medicine'

BY

ERIK ASK-UPMARK, M.D.

(Submitted for publication October 9, 1950)

From topographical point of view the region of the solar plexus is closely con- nected with the big arteries of the abdominal cavity, with the stomach and with the innervation of the subdiaphragmatic structures. Whilst the physiologist may be able to distinguish the trigger zone for various reflexes from this region in the aninial experiment, the physician will as a rule not be in the same position but only be able to register various clinical phenomena elicited by means of a reflex from striictures of the epigastrium. The present paper is going briefly to review sonie such phenomena.

Mater id 'The material is represented by numerous clinical observations, three of which

may be briefly quoted as examples. Case 1. Engineer, aged 38, was able to bring about a considerable distension of the

abdominal circumference by means of two methods: on the one hand by partaking of food or fluid when tired, on the other hand by pressing the tip of his finger in dorsal direction towards the abdominal wall in the very midline, immediately below the lower end of the sternal bone. This bloating syndrom has been described in detail by Alvarez and by ourselves and the case here in question has been reported by our colleague Frantzell and ourselves in a recent paper. I t turned out to be due to a descendence of the diaphragm.

Case 2 . Physician, aged 48. In the earlier history disturbances along the line of peptic ulcer. The present history dates back since 24 years and consists in fainting spells, appear- ing in connection with the deglutition when the food was about to pass into the stomach.

Presented to the 1st International Congress of Cardiology, Paris 1950.

THE REGION OF T H E SOLAH PLEXUS AS A TRIGGER ZONE IN CLINICAL MEDICINE 29

These attacks did appear particularly if he was tired or if his clothes were very tight and especially on partaking of certain kind of foods such as salt herring or certain drinks such as Swedish brandy or carbonated water. The sequence of events runs as follows: he turns intensely pale, feels dizzy and faints. Physical examination, roentgen examination of oesophagus and stomach and duodenum, electrocardiograms under stress and in connec- tion with the partaking of food were negative throughout, i t being conceived that no attack was possible to provoke during the examination.

Case 3. Engineer, aged 52. Earlier disturbances of the pre-ulcer type, is said to have had a duodenitis(?). Once in a while fainting spells in connection with meals, not least so if enjoying cold drinks. Physical examination, roentgen examination of oesophagus and gastroduodenal system, electrocardiograms, glucose tolerance test etc. all normal, although a t the time of the examination no attack was to be provoked.

Discussion

There are various syndromes connected with the introduction of food and (or) drinks into the stomach:

1. 'The gastrocolic reflex is, of course, well known and entirely normal. I t may be exaggerated if the trigger zone is particularly susceptible as in gastritis with lack of hydrochloric acid or if the colon is irritable, as in colitis. I t is awe11 known fact that the intentional suppression of this reflex represents one of the most important causes of constipation.

2. The acute abdominal distension or bloating syndrome may be elicited in different ways. References are to be had in the important paper of Alvarez as well as in the report of Ask-Upmark and Frantzell. The first case here quoted was remarkable because 1. i t was a man, 2. a definite trigger point was to be ascertained and 3. a familiar occurrence was to be noted, since two of his children temporarily had suffered from the same disorder. There are reasons to believe in the nerb ous system as instrumental for the appearance of the attacks.

3. The Hoemheld syndrome with its well known cardiac disturbances is due to the distension of the stomach, as demonstrated by Hochrein and others. I t may serve to stress the necessity in cardiac disorders, not least so in coronary insufficiency, to serve only small meals to the patient. On the other hand it is a well known fact that vomiting may put an end t o an attack of paroxysmal tachycardia. 'That acute dilatations of the stomach may be connected with cardiac and vasomotor disturbances is well known as well and the same goes for several instances of diaphragmatic herniation.

4. Fainting spells in connection with the swallowing of food have been described by Weiss and collaborators in cases where a traction diverticle of the oesophagus has been about. In the present cases (2) and (3) no such abnormalities of the oesophagus were to be registered. Since it was not possible t o examine the patients during the attack the behaviour of the heart in these cases is of course impossible to judge. There are, however, two other series of observations available which may or may not be connected with the phenomenon here observed. One of them is

30 KRIK ASK-UPMARK

the so-called ice-cream headache, which has been studied recently by Kinsella and which quite obviously has nothing to do with impulses from the oral cavity but should be considered as a vasomotor response to the passage of the cool ice- creani through the lower part of the oesophagus (cfr the auriculotemporalis syndrome, which, however, is elicited from the oral cavity). 'The second series of observations is represented by the peculiar fainting spells of young women with an aneurysm of the splenic artery during the last part of gestation. Just why these fainting spells do occur we do not know but the neighbourliood to the solar plexus on the one hand, the presence of barosensible trigger zones in the corresponding arterial segments on the other (Heymans, Rein) make i t tempting to assume a similarity to the carotid sinus syncope syndrom.

5. The dumping syndrome, finally, is encountered after resections of the stomach. II'e have had our attention focussed upon this topic for a t least 12 years. Originally I was inclined to agree with those who believed in a hypoglykemia as the cause, all the more since the carbohydrate metabolism is apt to present disturbances in the peptic ulcer syndrome itself. Eventually, however, this explana- tion has had to be discarded but for a few exceptional cases and the essential mechanism calling forth the various symptoms (vasomotor etc.) seems to be the distension of the intestinal loop. I t seems entirely reasonable, owing to the oliservations of Meurling in IJpsala and others, that allergic factors may be involved as well. I t is instructive to note the observation of Bleurling that the administration of procain in water before meals (5 centigrams or more) is apt to bring relief, a fact stressing the importance of some kind of trigger mechanism.

Summary. l h e introduction of food and (or) fluid in the upper part of the gastrointestinal

tract may call Iorth certain clinical disturbances. In some instances the trigger zone may be found in the oesophagus (for example the ice cream headache), in other instances in the intestinal system (dumping syndrom) and in still other instances in the stomach itself or its neighhourhood (for instance the acute ah- dominal distension syndrome). I t is possible that a comnion trigger zone is to be found in the arterial system supplying the corresponding gastrointestinal structures. IVhy the result in one case may be headache, in another case bloating in still another case fainting cannot be said.

Refenences

Alvarez: Arch. Int . Med. 1949:84:217. - Ask-Upmark, E.: Svenska Lakartidn., 1945. - Ask-Upmark, E. and A. Frantzell: Acta Radiolog. 1950:23:104.