JAUNDICE AS A RESULT OF ENERVATION.
It is now a well-established fact that all secretions are under the direct influence of the nervous system. Stimulate a nerve supplying a gland, and secretion is accelerated; stop the nervous action, and secretion is as instantaneously arrested. Again, just in the same way as volition can produce or suspend muscular movement, mental influence can hasten or retard glandular secretion. As an illustration of this fact, I need only call to mind the influence the mere sight of food has in exciting the salivary secretion, and the effect of bad news in arresting it. Exactly the same influence as is here alluded to, is exerted by the mind over the biliary function. If, for example, as Bernard first observed, a dog with a biliary fistula be caressed, the secretion of bile is actively continued; if, on the other hand, the animal be suddenly ill-used, the secretion of bile is instantly arrested. If he be again caressed, the secretion is re-established, and the bile flows drop by drop from the end of the cannula. Here the influence is entirely produced through the intervention of the nervous system; and if such effects as are above described occur in the dog, we can surely have little difficulty in understanding how the biliary secretion can be influenced in the highly-developed organization of the human being. Indeed, every one must have felt how quickly sad tidings received during a meal not only destroy the appetite and retard digestion, but occasionally alter the complexion. This effect, that all of us must have experienced in a slight degree in our own persons, several may have observed to a greater extent in the persons of others, even to the production of well-marked jaundice. At this very time I have under my care a young married lady, who during the last two years has twice suffered from an attack of jaundice induced by witnessing her child in convulsions, and this I regard as an example of jaundice from enervation.
One of the reasons, no doubt, why jaundice does not more frequently follow upon mental emotion is simply on account of a certain amount of pigment being required in order to produce a visible tinging of the body, and it seldom happens that the emotional effect on the biliary secretion is sufficiently permanent to permit of the requisite amount of pigment accumulating in the blood. The reason, too, why mental emotion is more apt to cause jaundice immediately after a meal is, as will afterwards be better understood, on account of the congested state of the liver at that time favouring the stoppage of the secretion. A blow on the head, which is now and then observed to be suddenly followed by jaundice, acts, I believe, in the same way as fright, namely, by paralyzing the nerve force required for the continuance of the biliary secretion.
I now pass on to the consideration of the pathology of the second kind of jaundice from suppression, namely, jaundice resulting from hepatic congestion.
JAUNDICE ARISING FROM HEPATIC CONGESTION.
This is one of the most common causes of the disease; but as there are two kinds of hepatic congestion—active and passive—it will be necessary for me to make a further subdivision, and consider each of these separately.
Jaundice the Result of Active Congestion.
The mechanism of jaundice resulting from active congestion of the liver is readily explained on physiological grounds.
The congested condition of any gland is unfavourable to secretion. We all know, for example, that congestion of the kidney is accompanied by a suppression of the urinary secretion, and that the secretion is re-established as the congested condition of the organ diminishes. The suppression of the renal secretion is no doubt due to the engorged capillaries pressing upon the secreting structure, and ultimate ramifications of the urine tubes, and thereby annulling their functions. A similar explanation is equally applicable to the biliary secretion; and just as it happens in the case of the kidney, that it is exceedingly rare for a total suppression of its functions to take place, so with the liver it seldom happens that the congestion is sufficiently severe to induce complete arrest of the biliary secretion. We find, therefore, that although there may be yellowness of the skin and high-coloured urine in such cases, pipe-clay stools are frequently absent, sufficient bile to tinge the fæces still finding its way into the intestines.
Undoubtedly it must have occurred to many of my readers, that jaundice is frequently absent in cases of acute inflammation of the liver, even running on to suppuration, and that the foregoing theory of the pathology of such cases is therefore insufficient. At one time I was puzzled to explain this apparent anomaly, but on subsequent investigation the true cause became apparent, and instead of the above fact detracting from, it tended rather to strengthen the theory. If, for example, we closely examine cases of acute hepatitis without jaundice, we find they are those in which only a portion of the liver is affected. It matters not whether it be one lobe or two, the surface or the centre of the organ, the disease is invariably circumscribed; and there is enough hepatic tissue left in a sufficiently normal condition to prevent the constituents of the bile accumulating in the blood, and producing jaundice. This may even occur, as I have myself observed, when the disease has run on to suppuration.