Neuralgia and the Diseases that Resemble it

(1) The first and most essential characteristic of a true neuralgia is, that the pain is invariably either frankly intermittent, or at least fluctuates greatly in severity, without any sufficient and recognizable cause for these changes.

(2) The severity of the pain is altogether out of proportion to the general constitutional disturbance.

(3) True neuralgic pain is limited with more or less distinctness to a branch or branches of particular nerves; in the immense majority of cases it is unilateral, but when bilateral it is nearly always symmetrical as to the main nerve affected, though a larger number of peripheral branches may be more painful on one side than on the other.

(4) The pains are invariably aggravated by fatigue or other depressing physical or psychical agencies.

The above are characteristics which every genuine neuralgia possesses, even in its earliest stages; if they be not present, we must at once refer the diagnosis to one or other of the affections described in Part II. of this work.

Supposing the above symptoms to be present, we expect to find —

(5) In by far the largest number of instances that the patient has either previously been neuralgic, or liable to other neuroses, or that he comes of a family in which the neurotic disposition is well marked. Failing this, we are strongly to doubt the neuralgic character of the malady, unless we detect that there has been —

(6) A poisoning of the blood by malaria (but this very rarely causes neuralgia, save in the congenitally predisposed); or —

(7) A powerfully operating or very long-continued peripheral irritation centripetally directed upon the sensory nucleus of the painful nerve; which irritation may be (a) "functional," as where the eye has been persistently and severely over-strained and trigeminal pain results, or a sudden severe shock has been received; or, (b) coarsely material, as where inflammation, ulceration, etc., of surrounding tissues involve the periphery of the painful nerves in a perpetually morbid action, or chronic but profoundly depressing psychical influences; or —

(8) A constitutional syphilis. In this case there will either be marked syphilitic local affection of the trunk of a nerve, or if, as is more common, the syphilitic change is in the nerve-centre, there will most likely be other syphilitic centric mischiefs, leading to scattered motor or vaso-motor paralyses, characteristic modifications of special sense-functions, etc.

If the neuralgia be of some standing and a certain degree of severity, there will inevitably be found —

(9) Some of the fixed tender points of Valleix, in such situations as have been described in Chapter I.; and —

(10) Secondary affections (a) of secreting glands, or (b) vaso-motor nerves; or (c) of nutrition of tissues; or secondary localized paralyses of muscles, or localized anæsthesia of a somewhat decided though not complete kind, as described in Chapter II.; any one or any number of these various complications may be present.

I must insist that the above picture includes only the essentials for a diagnosis of neuralgia; if the painful affection will not answer to the conditions therein included, we have no right to call it a neuralgia – it belongs, for every practical purpose, to some other category of disease. Let me add one more essential characteristic, which is, that the pain begins and assumes its characteristic type before any other of the phenomena appear, with the single and partial exception of anæsthesia.

There are some special modes of diagnosis of the varieties of neuralgia, developed of late years, that require notice here; they are chiefly the result of the researches of Moriz Benedikt.

As regards the quality of the pain, Benedikt says that the curve of intensity has an intimate relation to the locus in quo of the neuralgia (i. e., whether in the periphery, trunk, or roots). An inflammatory irritation set up at the periphery of a nerve (by a joint-inflammation, for instance) produces a continuous pain; the same kind of irritation, attacking a nerve-trunk (e. g., in the bony canals), produces a paroxysmal pain; an inflammation spreading from the vertebræ to the nerve-roots or the cord-centres produces momentary lancinating pains. The latter characteristic he supposes to be especially characteristic of the centrally-produced neuralgias; and I may observe, as so far confirmatory of this idea, that this is especially the character of the pains in locomotor ataxy. There are sundry special cases to be considered, however: thus, Benedikt himself remarks that the pain set up by the pressure of a pulsating aneurism is, from the nature of things, lancinating from moment to moment. Eulenburg,32 moreover, says that Benedikt's tests of the locality of the primary mischief only hold good under the following circumstances: (1) When the irritability and the exhaustibility of the nerves are in a normal condition during the neuralgia; (2) when the irritation that calls forth the paroxysm is either identical with the original cause of the disease, or at least operates upon the same spot. The two conditions, however, do not concur. The irritability and exhaustibility may be sometimes excessive in neuralgias, sometimes normal, and perhaps, in certain cases, beneath the normal standard; by which means the form of the curve of intensity must be considerably modified. Moreover, the irritation that provokes an attack may from the periphery attack the primary seat of the disease, even when this is central, on account (says Eulenburg) of exaggerated conductivity of the nerves (his second cause33 of "hyperæsthesia"), as is, in fact, very frequently the case. He also thinks the distinction between paroxysmal and lancinating pains too indefinite to serve as a sufficiently reliable basis of diagnosis, especially considering the endless nuances of the form which the pain is apt to take. I agree with Eulenburg upon this point; and am convinced, from my own observations, that such a distinction as that between lancinating and paroxysmal pains is illusory, [I have taken some pains to investigate the character of the pains, not only in neuralgia, but in locomotor ataxy. It is true that the lancinating character predominates, on the whole, in the latter disease; but there are great differences in different individuals, and even in the same patient at various times, which plainly depend on subjective influences. Compare for instance, Dr. Headlam Greenhow's report on an ataxic patient, with a report on the same man by Dr. Buzzard and myself. ("Trans. Clin. Soc.," vol. i., 1868, pp. 152-162.)] the two kinds being frequently found alternate in the same case. The only useful distinction, in my opinion, is Benedikt's first one: he is probably right in saying that, where such an affection as an inflamed joint forms the source of peripheral irritation that immediately provokes a neuralgia, the pain is apt to be unusually continuous.

The extent to which the pain of neuralgia spreads into different termini of the same nerve has been made the basis of distinctions as to the seat of the original mischief. For example, it has been said that pain in the mental branch of the third division of the trigeminus, which does not invade the auriculo-temporal branch, can hardly depend on an irritation operating on the trunk of the inferior dental; it must be distinctly peripheral, or else it must act upon limited portions of the central origin of the fifth nerve. But the fact seems rather to be that, whether the neuralgia was excited by lesions at the periphery, in the nerve-trunk, or in the centre, it is equally possible that either a small or a large part of the peripheral expanse of the nerve may become the seat of the pain: this almost necessarily follows from the entire independence of individual fibres in nerves.

As regards the evidence afforded by the motor, vaso-motor, and trophic complications, there is this very positive diagnostic value in them – that they enable us to say, with greater assurance than we could otherwise do, that the disease is a real neuralgia. But, the only evidence that they afford as to the situation of the mischief is, that they uniformly point to the central end of a particular nerve; and accordingly I have already shown, in the chapter on Pathology, that the attentive study of these very complications furnishes us with some of the most powerful arguments upon which rests my theory that in neuralgia there is always centric mischief. What share in the production of the malady, in any given case, has been taken by the centric disease, and what if any by a peripheral irritation, the existence of these complications in no way helps us to determine; far less does it enable us to localize a peripheral lesion which may have acted as a concomitant cause; on the contrary, I believe that there is no more fertile source of erroneous judgment on this very point, than some of these complications, especially the vaso-motor and trophic. I suspect that it has happened, in hundreds of instances, that a localized congestion or inflammation, which is a mere secondary phenomenon, produced in the centrifugal manner already so fully explained, has been taken for the veritable fons et origo of the malady: hence the neuralgia has been confidently reckoned as one peripherally produced, and, what is even worse, the whole energy of treatment has been directed to a mere outlying symptom, under the idea that the primary source of mischief was being attacked.

The application of electricity as a test of the nature of a neuralgia has been employed by Benedikt,34 who lays down certain laws as the result of his researches. He says that (a) in idiopathic peripheral neuralgias the nerves are not sensitive to the current; (b) in neuralgias dependent on neuritis or hyperæmia of the nerve-sheath there is general electric tenderness of the nerve; (c) in cases where the pain has been set up by morbid processes in tissues surrounding the nerve, there is electric tenderness only at the site of these changes. I may, in general terms, express concurrence in these statements; but I must add that, as diagnostic rules they apply only to the early stages of neuralgia; for the occurrence of secondary complications may and does altogether change the condition of electric sensitiveness. It need hardly be said that the above remarks on diagnosis apply for the most part only to the superficial neuralgias, which, however, include an immense majority of the cases of neuralgias. The diagnosis of visceral neuralgias is, it need hardly be said, in most cases, a far more difficult and complicated matter. In these diseases we have often little more to guide us, in the actual symptoms, than (a) the intermittence of the pain, and (b) the absence of commensurate constitutional disturbance, especially the complete freedom from sense of illness in the intervals between the pains. We shall be obliged to rely greatly on such historical facts as the presence or absence of neurotic tendencies in the patient and his family; the possibility of his having been exposed to blood-poisoning (e. g., from malaria or chronic alcoholic excess, or extreme over-smoking); the circumstance that he has been habitually overworked, or greatly exposed to agitating psychical influences; perhaps that he has been subject to a combination of several of these morbific momenta. To say truth, the diagnosis of visceral neuralgias must, at the best of times, be a difficult and anxious matter, and we can hardly ever thoroughly satisfy ourselves until we have procured some decided results from treatment; fortunately, however, it happens tolerably often that we can do this, and sometimes in a very striking way.

Prognosis.– The prognosis of neuralgia varies exceedingly, according to the form and situation of the disease, and many other considerations. There are, of course, in the first place, certain neuralgias in which the prospect is perfectly hopeless as to cure; such are the cases in which the nerve is involved in a continuously growing tumor (especially within a rigid cavity, like the skull), or a slow but persistent ulcerative process.

Supposing, however, that the case is none of these, the very first prognostic consideration is that of age.

Of the neuralgias of youth, the majority either disappear altogether after a first attack, or recur a certain number of times during some years, the neuralgic tendency either disappearing or becoming greatly mitigated when the process of bodily consolidation is over. In another group the neuralgic tendency is never lost, but the form of the attacks changes, and there is far less spontaneity in the manner of their production. It is exceedingly common to see delicate boys and girls between puberty and the age of eighteen or twenty, attacked with typical migraine, which recurs regularly every three or four weeks for perhaps two or three years, then ceases to occur at regular periods, then loses the tendency to stomach complication; and, by the age of twenty-five or somewhat later, has left, as its only relic, a tendency to attacks of ophthalmic neuralgia, which come on when the patient is excessively fatigued, or encounters the close air of a theatre, or undergoes an unusual strain of mental excitement or anxiety, etc.; but which never come on without some such special provocation. So, again, there is a variety of sciatica which belongs mainly to the period between puberty and the twenty-fifth to thirtieth year, and which seems really to belong, pathologically, to the age of unsettled and irregular sexual function, the tendency to it usually disappearing after the patient has settled down happily in married life. Ovarian and mammary neuralgia have very commonly a similar history.

On the other extreme we find the neuralgias of the period of bodily decay: these are of very bad prognosis. A neuralgia which first develops itself after the arteries and capillaries have begun to change decidedly in the direction of atheroma is extremely likely, even if apparently cured for a time, to recur again and again, with ever-increasing severity, and to haunt the patient for the remainder of his days. It therefore becomes exceedingly important, in a prognostic point of view, to assure ourselves as soon as possible whether this arterial degeneration has decidedly commenced; and for this purpose I am in the habit of insisting to pupils on the great importance of sphygmographic examination for all neuralgic patients who have passed the middle age. Where we get the evidence which is furnished by the formation of a distinctly square-headed radial pulse-curve, even though there be no palpable cord-like rigidity of superficial arteries, we are bound to be exceedingly cautious of giving a favorable prognosis.

In women the period of involution of the sexual apparatus forms a crisis which, in regard to neuralgias, is of great prognostic importance. On the one hand, if the general vital status be good, and the arterial system fairly unimpaired, we may look to the completion of the process of involution as a probable time of deliverance from neuralgic troubles that have hitherto beset a woman; we know that she will probably suffer a temporary aggravation of her pains, but we hope to see her lose them altogether. On the other hand, if it should happen that she enters on the period of sexual involution with her general nutrition considerably impaired and her arterial system decidedly invaded by atheroma, it is only too likely that neuralgias recurring now, or attacking her for the first time, will assume the worst and least manageable type.

Of almost or quite equal importance with the question of the physiological age of the patient is that of his personal and family history with regard to the tendency to neuralgia and to other severe neuroses. Upon this subject I have dwelt so very fully in other parts of this work, that it is merely necessary here to repeat, that the balance of chances is most heavily swayed to the bad side by all evidence tending to prove congenital neurotic tendencies in the patient and vice versa.

Of prognostic hints that are to be gathered from our knowledge of the immediate causes of the attack, there are none so valuable as those which we gather from the detection of a malarial or a syphilitic factor in the production of the malady. In the former case, we hope to cure the patient either with quinine or arsenic, with almost magical certainty and rapidity; in the latter, we expect an almost equally brilliant result from iodide of potassium.

The particular nerve in which the neuralgia is seated does not so decidedly influence the prognosis, according to my experience, as is stated by some authors; nevertheless, there are differences of this kind. For instance, sciatica, though by no means so frequently a mild and trifling complaint as Eulenburg would make it to be, is certainly, on the whole, more curable than the trigeminal neuralgias taken as a group. I, however, cannot share Eulenburg's opinion as to the rarity of a central cause for sciatica, nor his consequent explanation of its more frequent curability; the latter I explain by the fact that it is possible far more completely to remove the concomitant causes in sciatica than in trigeminal neuralgia. By simply keeping a sciatic patient in the prone posture, shielded from cold and from pressure on the nerve, we have it in our power to remove nearly all peripheral sources of irritation; but in trigeminal neuralgia there are many influences, particularly psychical ones, which cannot be shut out, and which will continue to act with disastrous effect in many cases. With all this, however, we see a sufficiently large number of incurable sciaticas, on the one hand, and of severe trigeminal neuralgia cured on the other. It is only the genuine epileptiform tic, occurring in subjects whose arterial system is an advanced stage of degeneration, that stands out clearly and unmistakably pre-eminent among neuralgias for rebelliousness to treatment of every kind.

CHAPTER V.

TREATMENT OF NEURALGIA

I now approach what is really the most difficult portion of my task; for, although it would be easy enough to write copiously on the treatment of neuralgia, it is extremely difficult to keep a just medium between the opposite extremes of undue meagreness and of useless profusion of detail in the handling of this subject. There are also difficulties connected with the present uncertain and transitional state of opinion, even among high authorities, as to the value of particular remedies, and even of large groups of remedial agents, altogether there has been more hesitation in my mind as to this part of the present work than about any other, and the present chapter has been rewritten more than once. I mention this only to account for what there may very likely be found in it – an imperfect literary style such as too commonly marks work which has been repeatedly patched and corrected. At the same time, it should be said that my hesitation does not apply to the main principles of treatment which will be recommended below; it proceeds rather from the fear of seeming to ignore from carelessness modes of treatment which are still much used, but which I have really rejected, because, after full trial, they appeared to me valueless. Space is, after all, limited, and a complete account of all the remedies for neuralgia in vogue, in English and Continental clinics, would of itself fill a large volume.

The treatment of neuralgia may be divided into four branches: (1) Constitutional remedies; (2) narcotic-stimulant remedies; (3) local applications; (4) prophylaxis.

1. Constitutional treatment must be subdivided, as (a) dietetic, (b) anti-toxic, and (c) medicinal tonic.

(a) The importance of a greatly-improved diet for neuralgic patients is a matter which is more fully appreciated by the English school of medicine than by either the French or the German; it has, for instance, very much surprised me to notice the almost entire silence of Eulenburg on this topic. For my part, the opinions expressed three years ago35 on this matter have only been modified in the direction of increasing certainty; I have learned by further experience that the principle is even more extensively applicable than I had supposed.

That neuralgic patients require and are greatly benefited by a nutrition considerably richer than that which is needed by healthy persons, is a fact which corresponds with what may be observed respecting the chronic neuroses in general; and it gives me much satisfaction to point out this position of neuralgia as belonging to this large class of disorders, not merely by its pathological affinities, but by its nutritive demands. In a very excellent and suggestive paper by Dr. Blandford36 it is stated, as the result of a large experience in mental and other nervous disorders, that the greater number of chronic insane and hypochondriacal cases, as well as neuralgic patients, are remarkably benefited by what might seem at first sight almost a dangerously copious diet. Occasionally it happens that the patients discover this by the teaching of their own sensations, and the apparent excesses in eating which some epileptic and hypochondriacal persons habitually commit are looked on by many practitioners as the mere indications of a morbid bulimia which represents no real want, but only the craving of a perverted sensation which ought to be interfered with and allayed rather than encouraged. It is now many years since I began to doubt the justice of this opinion; the particular instance which called my attention to it being that of epilepsy, of which disease I saw a considerable number of cases, within a short period of time, that were distinguished by the presence of enormous appetite for food; and I finally came to the conclusion that, so far from this symptom being of evil augury, and likely to lead to mischief, it is, with certain limitations, a most fortunate occurrence. It is hardly necessary to say that over-eating, such as produces dyspepsia and distention of a torpid intestine with masses of fæces, may distinctly aggravate the convulsive tendency; but the truth is that, with a little careful direction and management of the unusual appetite, these bulimic patients can in most cases be allowed to satisfy their desires without harm of this kind following; a larger portion of food really gets applied to the nutritive needs of the body, and the nervous system unmistakably benefits thereby, the tendency to atactic disorder being visibly held in check.

That which I have thus observed in the case of epilepsy, and which Dr. Blandford more particularly affirms concerning chronic mental diseases and the large number of neuroses that hover on the verge of insanity, has been most distinctly verified in my experience of the treatment of neuralgia. It is, unfortunately, by no means a frequent occurrence that the sufferer from this malady is inclined to eat largely, but the few patients of this type that I have seen were, in my judgment, distinctly the better for it. Far more common in neuralgia is a disposition of the patient to care little for food, to become nice and dainty, and in particular to develop an aversion – partly sensational and partly the result of morbid fear about indigestion – for special articles of diet. Dr. Radcliffe pointed out the special tendency of neuralgics to neglect all kinds of fat; partly from dislike, and partly because they believe it makes them "bilious;" and I have had many occasions to observe the correctness of this observation. In fact, by the time patients have become sufficiently ill with neuralgia to apply to a consulting physician, they have already, in the great majority of cases, got to reject all fatty foods, and have cut down their total nutriment to a very sufficient standard. Young ladies suffering from migraine are especially apt to mismanage themselves, to a lamentable extent, in this direction: this is natural enough, because the stomach disorder seems to them the origin of the pain, instead of being, as it is, a mere secondary consequence of the neurosis. But it is not only the sufferers from sick-headache in whom we find this tendency to insufficient eating, especially of fat; not to mention that all severe pain usually tends to disorder appetite and make it fastidious, there is nearly always some wiseacre of a friend at hand, ready to suggest that neuralgia is something very like gout, that gout is always aggravated by good living, and, ergo, that the patient should be "extremely cautious as to diet;" the end of which is that the poor wretch becomes a half-starved valetudinarian, but, so far from his pain getting better, it steadily becomes worse. I cannot too strongly express the benefits that I have seen accrue, in the most various kinds of neuralgic cases, from persistent efforts to remedy this state of things, and to convert the patient from a valetudinarian to a hearty eater; and I wish particularly to say that this success has always been most marked when I have from the first insisted on fat forming a considerable element of the food. Cod-liver oil is the form in which I much prefer to give it, if this be possible; there can be no mistake about the relatively greater power of this than of any other fatty matter, I believe simply from its great assimilability. But the very cases in which we most urgently desire to give fat are often those in which the patient's fantastic stomach openly revolts at the idea of the oil; we must then try other fats; and we should go on trying one thing after another – butter, plain cream, Devonshire cream, even olive or cocoanut oil (though these are the poorest things of the sort we can use) – till we get the patient well into the way of taking a considerable, if possible a decidedly large, daily allowance of fat, without provoking dyspepsia. It is surprising what can be done in this way by perseverance and tact, and it is no less striking to observe the good effects of the treatment. Nothing is more singular than to see a girl, who was a peevish, fanciful, and really very suffering migraineuse, brought to a state in which she will eat spoonful after spoonful of Devonshire cream, and at the same time lose her headaches, lose her sickness, and develop the appetite of a day-laborer; and, though such very marked instances as this are uncommon, they do sometimes occur, and a minor but still important degree of improvement is very frequent.