SummaryUntil recently, visceral pain has been a subject without precise basis, which we are reduced to study directly on the sick man.In spite of the ease which anesthetic infiltrations offer us, these do not have the accuracy of surgical sections in which we cut only one nerve path in each operative time, thus allowing for a better understanding of the phenomena.When a visceral disease is accompanied by acute pain, we do not feel visceral pain only but miscellaneous painful sensations.We must distinguish three different kinds of pain which can be felt at the same moment, but which have very different properties.1. Pains of the parietal serous membrane :They are of cerebro-spinal origin and are very acutely felt.They are due to the irritating contacts which the viscera may develop with the peritoneum, whether through their distension (mecanical stimulus) or by way of lymphangitis (chemical stimulus).They are not affected by the infiltration of the splanchnic nerve.2. The pain proper to the splanchnic organs :It is a fact and it is well perceived at the site of the diseased organ. It is apt to make itself felt even in the absence of all irritation of the parietal peritoneum, but it can only respond to special irritations, the so-calledadequate irritations(i.e. distension, spasm, ischemia, inflammation). It is a dull, imprecise, confuse pain and is relieved by the infiltration of the splanchnie nerve.3. The radiated pains :They are frequently felt in ill-defined areas, varying from one moment to another. They are annoying and hard to bear. They are usually present in acute attacks but can exist on their own.When involving the bile-ducts, these radiated pains offer the picture of a real phrenic neuritis. This is best explained by the connections which exist between the nerve endings supplying the peritoneum under the diaphragm and the endings of the phrenic nerve which also takes part in the innervation of the same area of the peritoneum.From the therapeutic point of view, two types of anesthetic infiltrations have been tried. I have used them in several sorts of biliary colics.1. Intradermal infiltrations of Lemaire(Louvain 1926) :It is given in the cutaneous area where the referred pain is perceived. It abolishes the cutaneous hyperesthesia which adds its own sufferings to the visceral pain, the latter persisting entirely with its character of deep, vague, imprecise pain. It does not modify the pain of peritoneal origin or that due to the phrenic neuritis.2. Infiltration of the right Splanchnic Nerve :It reaches at the same time the splanchnic nerve, the sympathetic chain and the right phrenic nerve which runs at 3 to 4 cm. from the point of infiltration.In fact, it abolishes the visceral pain and the phrenic neuritis, but leaves the pain due to the peritoneal irritation.3. Infiltration of the 12th right intercostal nerve :This has never been described before. I had noticed that every patient suffering from a painful or functional disorder of the bile-ducts had a spot sensitive to finger pressure. This point is exactly located under the inferior border of the 12th right rib where it crosses the external border of the lumbar muscular mass (fig. 4).I have noticed the existence of that painful spot with such regularity that I am now in the habit of considering this fact as a revealing sign of biliary disease.Since 1941, I have systematically practised infiltrations of that painful point and have noticed that if the needle penetrated exactly under the lower edge of the 12th rib, good results were regularly obtained. Pain of peritoneal origin and phrenic neuritis is instantly abolished. The visceral-algy does not appear to be influenced at that precise moment. But on the following day, we notice disappearance of functional disorders and at the same time, gradual disappearance of the visceral sensibility. All this happens as if this anesthesia blocked certain centripetal paths of reflexes whose answer, whether motor, vaso-motor or secretory, unfavorously modified the functions of the gall-bladder and the bile-ducts. Once this vicious circle is broken, the disorders completely disappear.So convinced am I of this fact, that when events do not seem to bear it out, I believe that the diagnosis must be revised and that we must investigate the possibilities of an anatomical lesion (blocking gall-stones or tumour).