Neuralgia and the Diseases that Resemble it

I ask the reader to dwell with fixed attention on this fact of the exclusiveness, or almost exclusiveness, with which the neuralgias of the anterior part of the head are represented during the period of bodily development, and especially in the years just succeeding puberty, by migraine or by clavus. When this fact has thoroughly entered the mind, we can hardly help joining with it that other and most important fact already noticed, of the close connection between the predisposition to migraine and the predisposition to epilepsy, and reflecting further on the strong tendency which epilepsy likewise shows to infest the earlier years of sexual life. In view of these things, it is difficult to avoid the inference that both the epileptic and the neuralgic affections of this critical period of life are the expression of a morbid condition of the medulla oblongata, in which the sensory root of the trigeminus has its origin; and further, that this morbid condition (tending to explosive and atactic manifestations of nerve-force) must have its basis in defective nutrition. For, be it remembered, the epoch of sexual development is one in which an enormous addition is being made to the expenditure of vital energy; besides the continuous processes of the growth of the tissues and organs generally, the sexual apparatus, with its nervous supply, is making by its development heavy demands upon the nutritive powers of the organism; and, it is scarcely possible but that portions of the nervous centres, not directly connected with it, should proportionally suffer in their nutrition, probably through defective blood-supply. When we add to this the abnormal strain that is being put on the brain, in many cases, by a forcing plan of mental education, we shall perceive a source not merely of exhaustive expenditure of nervous power, but of secondary irritation of centres like the medulla oblongata, that are probably already somewhat lowered in power of vital resistance, and proportionably irritable. Let us suppose, then, that to all these unfavorable conditions there was added the circumstance that the structure of the medulla oblongata, or of parts of it, was congenitally weak and imperfect; then surely it would be scarcely possible for these loci minimæ resistentiæ to escape being thrown into that state of weak and disorderly commotion which eminently favors pain in the sensory, and convulsion in the motor apparatus.

2. We have so far been mainly considering the relations to the production of neuralgia of certain conditions of the central nervous system which indisputably are inherent from birth. Let us now pass quite to the other extreme, and consider a class of momenta which take a decided part in producing many neuralgiæ, but which are altogether accidental and factitious, and cannot be included among the necessary hostile conditions of life. To push the contrast to the utmost, let us inquire first, what amount of influence in the production of neuralgia can be given by such a purely "functional" influence as educational misdirection of intellect and emotion?

It is somewhat strange, though every one accepts as a mere truism the maxim that sudden emotional shock may produce almost any degree or variety of nervous disorder, the slower but far surer influence of long-continued mental habit is often practically ignored. It cannot, indeed, be left out of sight as a cause of disorders of the mind itself, nor are there many who would deny that such diseases as cerebral softening are, in a considerable number of cases, the premature ending to a life that has been broken down by harassing work and anxiety. But what is far less appreciated is the tendency of certain unfortunate mental surroundings and modes of mental life to produce a generally neurotic condition, which may express itself in a variety of functional disorders, among which not the least common is neuralgia.

I may fairly hope to be acquitted of any predisposition to lay exaggerated stress on this kind of influence in the production of neuralgia, considering all that I have said of the importance of that inevitable cause, the neurotic inheritance, and all that I shall have to say presently as to the effects of a variety of external influences of a totally different kind. But I confess that, with me, the result of close attention given to the pathology of neuralgia has been the ever-growing conviction that, next to the influence of neurotic inheritance, there is no such frequently powerful factor in the construction of the neuralgic habit as mental warp of a certain kind, the product of an unwise education. This work is not intended as a treatise either on religion or psychology, and yet it is impossible for me to avoid some few words that may seem to trench on the province of each: for I believe that there are certain emotional and spiritual and intellectual grooves into which it is only too easy to direct the minds of young children, and which conduct them too often to a condition of general nervous weakness, and not unfrequently to the special miseries of neuralgia. As regards the working of the intellect, it is easier to speak in a free and unembarrassed manner than respecting the other matters. There can be no doubt that, of intellectual work, that sort which exhausts and harasses the nervous system is the forced, the premature, and the unreal kind; and this it is which predisposes, among other nervous maladies, to neuralgia. It is more difficult to speak the truth about emotional influences generally, and especially about those which are concerned with the highest spiritual matters; but I should do wrong were I to suppress the statement of my convictions on this point. I believe that a most unfortunate, a positively poisonous influence upon the nervous system, especially in youth, is the direct result of efforts, dictated often by the highest motives, to train the emotions and aspirations to a high ideal, especially to a high religious ideal. It is not the object that is bad, but the machinery by which it is sought to be attained. In modern society there are two principal methods which are popularly employed for this purpose; I shall describe them, by two epithets which are selected with no offensive intention, as the Conventual and the Puritan methods of spiritual training. By the former is meant that kind of education which deliberately dwarfs the nervous energy, with the hope of preserving the mind from the contamination of unbelief and of sinful passion. It is a system which is not peculiar to the Roman Church, nor even to the Christian religion, and it need the less detain our attention, as its effects, so far as they are evil, are mainly seen in general nervous and mental enfeeblement, rather than in the outbreak of explosive nervous disorders, such as convulsion, insanity, or neuralgia. There are doubtless exceptions to the rule; but that is the rule. It is far otherwise with the spiritual education which is here called Puritan, but which is confined to no party in the Church. This is a system which seeks to purify and exalt the mind, not by enforcing obedience to a series of spiritual rules for which another mind is responsible, but by compelling it to a perpetual introspection directed to the object of discovering whether it comes up to a self-erected spiritual standard. The reader will understand that I have not the remotest intention to depreciate either a true and manly self-restraint in obedience to the direction of "pastors and masters," or an honest watchfulness over one's own conduct and thoughts. But the lessons which our psychologists are rapidly learning, as to the evil effects on the brain of an education that promotes self-consciousness, are sorely needed to be applied to the pathology of nervous diseases generally, and of neuralgia among the rest. Common sense and common humanity, when united with the physician's knowledge, cry out against the system under which religious parents and teachers subject the feeble and highly mobile nervous systems of the young to the tremendous strain of spiritual self-questioning upon the most momentous topics. More especially is such a practice to be condemned in the case of boys and girls who are passing through the terrible ordeal of sexual development – an epoch which, as we have already seen, is peculiarly favorable to the formation of the neurotic habit, and I must emphatically state my belief that among the seriously-minded English middle classes, more especially, whose life is necessarily colorless and monotonous, the mischief thus worked is both grave and widely spread.

Perhaps the maximum of damage that can be inflicted through the mind upon the sensory nervous centres is effected when to the kind of self-consciousness that is generated by an excessive spiritual introspection there is added the incessant toil of a life spent in sedentary brain-work, and checkered with many anxieties, and many griefs which strike through the affections. Doubtless, such a combination of morbid mental influences is sufficient of itself to generate the neuralgic disposition in its severest forms, without any hereditary neurotic influence, and without any other peripheral irritations; I have more than one such instance in my mind at this moment. But, if they can do this, much more can such influences arouse inherent tendencies to neuralgia; to persons who are predisposed in this manner they are most highly deleterious.

3. We come now to the peripheral influences which in a more obvious manner become factors in the production of neuralgia. Of such influences there are an immense variety, and the only common quality that can be predicated of all is the tendency directly to depress the life of the sentient centre upon which their action impinges.

If we search among the external influences which contribute to the production of neuralgia for one that is apparently trivial as to the amount of material disturbance which it can cause, and yet is very frequently effective, we may select the agency of cold. The effect of a continuous cold draught of air impinging on the naked skin for some time is comparatively frequently seen in the provocation of neuralgic attack: we say comparatively, because this influence is more frequently effective than blows, wounds, or temporary irritations of any kind, applied to the peripheral ends of sensory nerves. But if neuralgia be a more frequent consequence of cold than of these other influences, a moment's reflection will show that it is by no means an absolutely common result. One has only to think of the numerous omnibus-drivers, engine-drivers, cab-drivers, etc., etc., who pass their whole working lives in presenting the (more or less) naked expanse of their trigeminal and their cervico-occipital nerves to every variety of wind, to perceive that, were this sort of influence very potent in itself, male neuralgic patients should swarm as thick as bees in our hospital and dispensary out-patient rooms; which is notoriously quite contrary to the fact. The same remarks, in both directions, may be applied to the direct influence of atmospheric moisture, either with or without the effect of wind (of course I am not speaking of the more recondite effects of damp soil on the persons who live about it). [Among the hundred patients who formed the basis of the inquiries mentioned in this work, forty-one accused external cold of producing the attack, but many of these produced insufficient evidence that such was the case.] In short, the direct effects of atmospheric cold would seem to be these. Mere lowness of temperature goes for something, but not much; [The most marked instance of the effect of cold, per se, that I have seen, was exhibited by a young lady who was under my care during the past severe winter (1870-'71). During much of the time she was confined to a carefully-warmed apartment, on penalty of a violent paroxysm if she left it.] for about as much, perhaps, as it does in the way of aggravating all neurotic tendencies. Cold joined with wind is much more powerful. And the maximum of ill-effect seems reached by very cold wind mingled with sleet or driving rain, which keeps the skin sodden. But the conclusion at which I long ago arrived is, that none of these influences ever take more than a small (though it is sometimes an important) part in the production of neuralgia; and that in the majority of cases there is no pretence for supposing that they had the slightest share in its causation.

A word or two must be said as to the modus operandi of cold and cold wind, as these are the most frequent of external, so-called "exciting" causes. The popular use of such phrases as the latter has an extraordinary influence in disguising the plain fact, which is, that these influences operate wholly in the direction of robbing the nerves of force. The continuous abstraction of heat from the surface, which of course is materially aided by rapid movement of the air, must necessitate a readjustment of the distribution of energy, the only result of which must be to drain the sensory nervous centre of its reserve of force. But, in fact, there is an experiment, ready performed to our hands, which may amply satisfy us as to the kind of influence exerted by cold on superficial nerves, viz., the sensations experienced in recovering from frost-bite, which has been severe enough to paralyze the nerves without causing actual gangrene of the tissues. The passage of the nerves back from temporary death to full functional life is marked by a half-way stage in which there is agonizing pain.

4. We must next consider the effects of a class of peripheral influences which act, where they exist, in a more constant manner than any others; viz., those in which the trunk or periphery of a sensory nerve either receives a severe injury, or becomes more or less engaged in inflammatory processes, or compressed or otherwise damaged by the growth of tumors or the spread of destructive ulcerations.

With regard to ordinary nerve-wounds as a cause of neuralgia, we have already said (vide Chapter II.) nearly as much as it is necessary to say; we need only here point out that, like the influence of cold applied to superficial nerves, that of wounds must necessarily be a depressing one to the centre with which the wounded nerve is connected, and the resulting neuralgia must be regarded as an expression of impeded and imperfect nerve-energy, not of heightened nerve-function. The pain is set up during the process of nerve-healing; that is to say, at a stage intermediate between those of abolished function and completely restored function; and there can be little doubt that the obstinacy with which it is often protracted is due to the slowness with which a wounded nerve recovers its full functional activity; when once the latter is completely restored there is an end of neuralgic pain. It is exactly analogous to the course of events in recovery from freezing.

There remain for consideration, however, (a) a small class of cases of nerve-wounds in which the healing process is not simple; but the lesion is followed by the development of a tumor of the kind denominated true neuroma. The process consists of hyperplastic changes in the nerve-fibres; its commonest examples are seen in the extraordinarily painful swellings that occur on the ends of nerves left in stumps after amputations; but, in fact, a neuroma of this kind may occur after any kind of severe nerve-injury, as, e. g., a cut from broken glass, the impaction of foreign bodies, etc. The true neuromata are composed mainly of nerve-tissue, with a relatively small element of connective tissue: the nerve-fibres can be traced directly to the nerve-tumor. Besides the traumatic neuromata which form permanent tumors, incapable of being got rid of except by actual excision, a minor variety of the same kind of change has in several cases been known to take place in consequence of an abiding local irritation from the impaction of a foreign body, on the removal of which the neuromatoid enlargement completely disappeared. (b) There are likewise a certain number of cases in which a tumor is developed from the neurilemma, and does not consist of nervous tissue; these are distinguished as false neuromata, and may be of various kinds, the fibromatous and gliomatous being far the most common, but cysts and cystic tumors also sometimes occurring.

The case of the neuromata is well worth reflecting upon, in the course of our endeavors to clear up the Pathology and Etiology of Neuralgia. If ever we could find a merely peripheral influence which would of itself be invariably competent to excite neuralgic pains, it would surely be found in neuroma; but the case is not merely not so, it is strikingly contrary. Just as wounded and inflamed nerves frequently go through the whole processes of disease and recovery without once eliciting a neuralgic pang, so is it with neuromata; they are not unfrequently quite indolent, and neither excite neuralgia, nor are themselves at all particularly tender to the touch. And what is most remarkable is, that, as Eulenburg correctly remarks, among the pseudo-neuromata the kind of tumor which is most frequently associated with neuralgia is by no means the dense fibroma or glioma, which might be expected by its mechanical pressure to excite inevitable neuralgic pain, but the far softer and more yielding cystic tumors. I do not know how the facts may affect the reader, but to me they suggest the strongest possible arguments against the belief that peripheral irritation can of itself produce neuralgia without the intervention of some centric change. The tendency to such change (from inherent constitution) in the sensory root of the nerve must surely be the reason why neuroma causes neuralgia in a given number of subjects, instead of letting them go scot-free, as it does other persons.

The same remarks apply to the result of observations on the effect of tumors commencing in tissues altogether unconnected with the nerve, and merely coming to involve it, secondarily, in pressure. It has been often noted that, among these tumors, fluid-containing cysts and soft medullary cancers are far more frequently the cause of decided and distressing neuralgia than the denser and less yielding neoplasms. Of kinds of tumors that are specially apt to produce severe and even intolerable neuralgia by the pressure on nerves, it has been remarked that aneurisms are among the worst: here every pulsation often sends a dart of agony through the nerve. There is a reason here, however, which is often left out of sight; not merely is the perpetually varying pressure specially harassing and exhausting to the nerve, but in many of these cases there is general arterial degeneration, and the sensory root of the nerve is exceedingly likely to be very badly nourished. [This result will be more directly brought about when the aneurism happens to press on the ganglion of a posterior root.] We pass now to the consideration of the influence exerted by other great series of peripheral impressions in the production of neuralgia. These impressions are connected chiefly with the functions of the digestive and of the genito-urinary organs, the functions of the eye, and the nutrition of the teeth.

To take the least important of these first, I may surprise some readers by the statement, which I nevertheless make with much confidence, that irritation of any part of the alimentary canal is, on the whole, a rare concurrent cause, even in the production of neuralgia. There are, as has been already fully explained, cases of neuralgia seated in these viscera themselves (or the plexuses in their immediate neighborhood), although their number is immensely smaller than that of the neuralgias of superficial nerves. But it is not at all common – it is even exceedingly rare – for irritation conveyed from the alimentary canal to take any important part in setting up neuralgia of a distant nerve, even when that nerve has close connections, through the centres, with those coming from the irritated portion of the alimentary canal. Valleix had the great merit to perceive this, even in the case of neuralgias of the head, where appearances are so likely to lead the observer to a contrary opinion. And it is not a little remarkable that this should be the case, when we consider the close central connections which the vagus, the great sensory nerve of a large portion of the alimentary canal, has with the sensory root of the trigeminus. In fact, however, there are certain peculiar forms of gastric irritation which do react upon the trigeminus; for instance, a lump of unmelted ice, suddenly swallowed, almost invariably produces acute pain in the supra-orbital branch of the fifth, on one side or the other, and occasionally (as in a case cited by Sir Thomas Watson) in other nerves. But that common dyspeptic troubles at all frequently or importantly contribute to the production of neuralgia, I do not for a moment believe: it needs some very powerful irritation, such as that just mentioned, or as impaction of great masses of scybalæ in the intestines, or severe irritation from worms, to produce such an effect.

It is far otherwise with the genito-urinary apparatus; in a large number of cases, irritations proceeding from these organs do undoubtedly contribute to the production of neuralgia, though by no means in the important degree which many authors seem to have assumed. There can be no doubt, for example, that the irritation of a calculus, either within the kidney itself, in the ureter, or in the bladder, may set up violent neuralgia, which for the most part is localized in the branches of the lumbo-abdominal nerves. The instance of the eloquent Robert Hall is an example of renal calculus acting in this way: he suffered the most excruciating agony for years, and was obliged to take enormous quantities of opium in order to make life endurable. An instance of calculus impacted in the ureter, in a gentleman somewhat past middle age, occurred in my own practice; the lumbo-abdominal neuralgia occurred in frequent paroxysms of dreadful severity; and another case, already referred to was that of a woman, in whom ovarian neuralgia was undoubtedly in great part due to the irritation of an impacted calculus in the ureter. These cases, however, are very rare in comparison with others in which the peripheral source of the neuralgia is either the uterus or ovary, or the external genitals. I have no means of ascertaining, with anything like accuracy, the frequency with which the internal sexual organs are the starting-point of neuralgia, because the majority of such cases pass, naturally, to the care of physicians who practice chiefly in the diseases of women, and consequently not adequately represented either in my hospital or my private practice; still, I have seen a good many of these affections, and, though I speak with the reserve necessitated by the circumstances just named, I am much inclined to believe that even such powerful centripetal influences as those of the states of commencing puberty, of pregnancy, of the change of life, and uterine diseases generally, are very rarely the cause of true unilateral neuralgia, except in subjects with congenital tendencies to neuralgia. But in predisposed subjects there can be no doubt that these influences assist most powerfully in producing the malady.

Of the power of irritation of the external genitalia to act as a so-called "exciting cause" of neuralgia, there is abundant evidence. I would especially call attention to the remarkable monograph of M. Mauriac, ["Etude sur les Nevralgies Reflexes symptomatiques de l'Orchi-epididymite blenorrhagique" Par C. Mauriac, Medecin de l'Hospital du Midi. Paris, 1870.] on the neuralgias consecutive to blenorrhagic orchi-epididymitis, as illustrating this with a force that was to me, for one, surprising. I shall, perhaps, have further occasion to these researches; here it will be enough to mention that M. Mauriac's enormous experience of blenorrhœa and orchitis at the Midi has shown that, in an exceedingly large number of cases, certainly not less than four per cent., this combination is followed by reflex neuralgias, of which a large number are not seated in the genital apparatus, but affect the track of some distant sensory nerve, through the intermediation of the spinal centres; and that with these reflex pains there is often profound general disturbance, including very often an extremely profound general anæmia. The most frequent kind of these neuralgias is rachialgia, i. e., pain in the superficial posterior branches of spinal nerves; next comes lumbo-abdominal neuralgia; then sciatic and crural, visceralgic (abdominal), etc.; and besides all these there are numerous instances of neuralgia in the testis. As to the nervous "reflection," more hereafter.