The next acquired condition to which I would invite your attention, which may act as a cause of pain, is the presence of certain poisonous compounds in the blood or system. These are more especially the poisons of malaria, of syphilis, of gout and rheumatism, of alcohol, of certain drugs, and lastly of certain metallic poisons, as mercury, phosphorus, lead and arsenic.
Although this group includes a tolerable number of members all together, it is less important than either the preceding division of nontoxic malnutrition of the nervous tissues, or of our first class, in which heredity plays the main role.
Still the toxic cases are sufficiently common. What we have already said as to treatment here holds good, but we must superadd the means of combating the particular poison.
In the malarial cases the pain is often entirely relieved by quinine or one of its substitutes; on this all are agreed, whether homeopaths or allopaths, or outside of any regular path. It is quite curious how the malarial neuralgias preferably locate in the first division of the fifth. But one word of caution, the mere fact of recurrence or periodicity, more or less regular, does not suffice to establish the diagnosis of malaria, for all neuralgias are apt to be more or less periodic. You must get definite symptoms of chill or fever before you can be sure. Once sure, the treatment is plain: efficient doses of the antiperiodic.
When we come to the syphilitic cases we enter more debateable territory. The pains about the head, especially the teeth, are sometimes not due to the disease, but to the means taken to combat it. I do not intend here to take up the question of the treatment of the secondary stage, except to enter my protest as to the harm done, especially to the teeth, by routine overdosing with mercury. Fortunately this abuse of a most valuable remedy is much lessening. In the third stage of syphilis you sometimes get most remarkable pain manifestations, and I had one in my practice that I cannot refrain from quoting.
A gentleman, aged between 40 and 45, had suffered for years from recurrent attacks of pain of great severity. When I saw him the pain, although more or less present constantly, had very marked exacerbations every afternoon. It was located in the great occipital nerves, especially on right side. Had formerly had considerable pain in distribution of right inferior dental nerve. His occupation was sedentary and involved considerable mental application. He stated on questioning that some eighteen years before he contracted syphilis. From this he believed himself cured. He had subsequently married, but had no children. Having suffered for six or eight years from these attacks of pain at varying intervals, he had consulted numerous physicians with only temporary benefit. He was very despondent; his sufferings were very intense, and only the most powerful anodynes gave relief. After some investigation, I made up my mind that the syphilitic dyscrasia lay at the bottom of his suffering. I therefore began specific treatment with iodide of potash. Prof. Seguin, who saw him in consultation, concurred in both diagnosis and the line of treatment. He suggested pushing the iodide until its therapeutic limit was reached. This was done; but it was not until the enormous dose of one-half ounce thrice daily was reached that the pain yielded. During one week this patient took over one pound of iodide of potash.
A course of mercury in small doses completed the cure. Two years have now elapsed, and the patient has had no recurrence of pain.
Gout and rheumatism were formerly ascribed a much more important role in the production of pain than they now occupy. Leaving out of account the acute manifestations of these diseases, their influence is slight as predisposing causes in the production at least of facial pain. There is perhaps one disease of the dental apparatus to which I shall allude later on, in which gout may act as an efficient cause.
On the other hand, the class of pains due to the action of the chronic abuse of certain therapeutic agents is unhappily an increasing one; I allude to alcohol, opium, cocaine, chloral and other drugs, originally taken for the relief of pain, which induce a pernicious habit in their unfortunate victims, of which pain is one of the main expressions. It is an undoubted fact that this class of sufferers is on the increase. Much of this tendency is due to the excessive wear and tear and the unhealthy competition of our modern civilization. It has always been the refuge of the weak, the attempt to escape from the moral evils of our lot by means of something that will temporarily dull our consciousness of the trials we have gone through and the apparently greater trials that lie ahead of us. The moment the competition for existence and for wealth becomes keener, the greater will be the temptation of the unsuccessful or depraved to seek oblivion for their failure in some narcotic, which will for the time being quiet their disappointed consciousness. When in addition you have an inherited weakness on the part of your patient in his susceptibility to pain, or in a condition of pain actually existing, can you wonder that so many fall by the way? It seems to me that a terrible responsibility lies upon us all, especially upon us physicians, lest by our treatment we encourage this tendency. Nor do I think that as a profession we can be altogether acquitted of carelessness, to put it mildly, in this regard. It is so much easier to relieve the symptom pain, when called to a sufferer, by a dose of morphine, and then when the next attack comes on to repeat it, than to analyze the complex group of phenomena on which that pain depends. You will perceive that the question with which we started as to the nature of pain is of vital importance in this regard.
The last group of constitutional agents which act as pain disposers is one with which you are all familiar, namely, the action of certain metallic poisons; of these the most important are mercury and phosphorus. It is highly significant that they have their main action in the structural changes they cause in the periosteum of bones, the peridental membranes.