Grouped under the term "hay fever" there are probably as many different affections as there are under the term "chronic rheumatism." There are [{369}] people who, in the springtime, as soon as the weather gets warm, suffer from what is popularly called hay fever. This is often called "spring catarrh" or "rose cold" and seems often to be associated with the pollen of flowers. Then there are people whose hay fever, as it is called, develops about the first of June and continues to be bothersome until the middle of July, when there is a remission of symptoms, though in dry prolonged hot periods after that the affection may recur. It seems as if, at the beginning of the heated term, the warm, dry dusty air irritates their nostrils very much, while after some weeks they gradually become used to this and the reaction is not so violent. Then there are the regular hay-fever patients whose affection occurs principally in haying time, during August and September, though most of them have not been near hay pollen, and the disease is an affection of dwellers in cities rather than in the country, of indoor livers more than of farming people, who might be expected to suffer most from the supposed cause, hay pollen. Even where pollen is directly concerned in its causation it is probably oftener the pollen of the rag weed rather than that of hay that is responsible for it.
There are two elements in the disease apparently of equal importance. One of these is a strictly local condition interfering with respiration in some way, or with the circulation to the mucous membrane of the nose and the lachrymal ducts. The other is an individual over-sensitiveness so that there is an exaggerated reaction to irritation. Some of this is mental, that is, is due to expectancy, or to the persuasion that this reaction is sure to occur under certain circumstances. As a consequence, attacks of hay fever are reported even after a distant view of a hayfield, or of rose cold due to the sight of an artificial rose, and of other recurrences that show the power of the mind to bring about at least a beginning of symptoms.
While the first or physical element in the etiology of dust catarrh can be treated successfully by various means, it is important to get the mind of the individual in a favorable state so as to enable him to obtain better control over his vaso-motor system which is so much influenced by emotions and thoughts. It is this latter element in the causation of the disease that has been successfully treated by the many remedies that for a time have had reported success in the cure of hay fever yet afterwards proved to be of no benefit because they had lost their influence over the patients' minds.
In a review of Morell MacKenzie's book "Hay Fever, with an Appendix on Rose Cold," Dr. J. N. MacKenzie [Footnote 31] has some paragraphs on hay fever which, though written twenty-five years ago, are worth recalling for a proper understanding of the disease. He preferred to call the disease rhinitis sympathetica or coryza vaso-motoria periodica, names which are much better descriptive terms and have no unsubstantiated suggestions of etiology in them.
[Footnote 31: American Journal of Medical Sciences, 1886.]
According to our conception, the so-called nasal reflex neuroses, whether taken singly or collectively, as the cause of the ensemble of phenomena known as "hay fever," may be regarded as the protean manifestation of a morbid condition to which we have given the name rhinitis sympathetica, and which is characterized by a hyperesthetic condition of the vaso-motor nerve centers linked to a peculiar excitability of the nasal cavernous tissue. For, if we inquire what condition or conditions is common to them all, and what morbid process is capable of producing them, either singly or in combination; how phenomena apparently [{370}] so widely different in character and anatomical sphere of operation may be traced to a solitary source, we find the answer in certain more or less clearly defined changes in the nasal apparatus and in a certain exalted state of the sympathetic nervous system, to which latter we instinctively turn as the organ most conspicuously concerned in the evolution of purely reflex acts. In whatever relation the local nasal affection and the condition of the sympathetic stand to each other in the matter of cause and effect, they must both be regarded as inseparable factors in the production of the phenomena under consideration. It matters not to what hypothesis the path of speculation may lead. Of this we can be reasonably sure, that in the production of the characteristic symptoms of this disease, a certain excitability of the nasal passages is necessary, plus an exalted state of the central nervous system.
Dr. MacKenzie calls attention particularly to the erectile character of the tissues mainly involved in all these forms of dust catarrh and dwells on the rôle that mental influence always plays in the phenomena noted in such tissues. This with the vaso-motor elements in the affection which are so largely also under the control of the emotional nature make it clear that the pathology of the affection must be considered from this standpoint and, therefore, its therapy also.
Dr. MacKenzie continues:
From our present knowledge of the disease, it seems difficult to escape the conclusion that its pathology is intimately interwoven with a morbid condition of the vaso-motor sympathetic, and probably a hypersensitive state of the nerve centers themselves. When we recall the fact that in the famous section of the sympathetic in the neck by Claude Bernard, symptoms similar to, or closely allied to, the phenomena of hay fever were produced; when we reflect upon the results reached by Prevost in his experiments on the spheno-palatine ganglion, is there not a clue to lead us through the labyrinth of our difficulties to a rational solution of the question? . . .
. . .In the human body, wherever erectile tissue is found, it is intimately related to reflex or sympathetic acts; there seems to be connected with it a certain receptivity to reflex producing impressions, a certain power of reflex excitability dependent upon its structure and functions. It is thus peculiarly a tissue of sympathy in which we may most satisfactorily study the mechanism of purely reflex or sympathetic acts. Now it seems to us that, as the nasal corpora cavernosa belong to this class of sympathetic tissues, there will be little difficulty in explaining the rôle which they play in the paroxysms of an affection which is probably connected with, if not dependent upon, an excitation of the sympathetic nerve centers, and in more clearly defining the intimate relation which its erection bears to the reflex manifestations of the disease under review.
These considerations explain the heredity of the affection in many cases, since it is dependent on defects that may be family traits, yet they also enable us to understand how slight lesions of the nasal mucous membrane may be the center from which radiate the underlying pathological conditions of the disease.