[19] _Journal de la Physiologie, v._

[20] "Ernahrungsstorungen der Augen bei Anaesthesie des Trigeminus."

Mitgetheilt von Dr. v. Hippel in Konigsberg in Preussen. Archiv f.

Ophthalm. Band. xiii.

[21] Zeitsch. f. rat. Med., 1867. There is corroborative evidence, from independent sources, of the truth of Meissner's views. His own observation only proved half the case; but he quotes an observation of b.u.t.tman's in which the exact converse of his own experience happened, the external fibres being affected without the inner band, and anaesthesia without trophic changes being the result. Moreover, Schiff (Gaz. hebdom., 1867) obtained experimental results (in operating on cats and rabbits) which coincide with Meissner's.

[22] London Hospital Reports, vol. iii., p. 305.

[23] Wegner, loc. cit.

[24] Archiv f. Ophthalm., xv., 1.

[25] "Deutsches Archiv f. klin. Med.," ii., 2, 1866. I am not aware whether Piotrowski has at all altered his opinions since the (subsequent) observations of Ludwig and Cyon upon the "depressor" nerve.

[26] "Functional Nervous Disorders." Churchill, 2d edit., 1870.

[27] "Prize Essay of the New York Academy of Medicine." New York: Wood & Co., 1869.

[28] Volkmann's Sammlung klinischer Vortrage, No. 2. "Ueber Reflex Lahmungen," von E. Leyden. Leipzig, 1870.

[29] "Cases of Urinary Paraplegia," Med.-Chir. Trans., 1856.

[30] Wurzburg. Med. Zeitsch., iv., 56-64.

[31] Med. Cent. Ztg. 21, 1860.

CHAPTER IV.

DIAGNOSIS AND PROGNOSIS OF NEURALGIA.

_Diagnosis._--This subject is much simplified and shortened, in regard to our present purpose, by the plan of the present work, which, by separately describing (in Part II.) the other disorders which resemble neuralgia, and are liable to be confounded with it, avoids the necessity for stating here the negative diagnosis of neuralgia itself. We are only concerned here to give a clear picture of the positive signs which it is necessary to verify before we can suppose disease to be neuralgia. The special modes of searching for these are interesting, and in some respects peculiar;

(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 const.i.tutional 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_) coa.r.s.ely 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 const.i.tutional 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 anaesthesia 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 a.s.sumes its characteristic type before any other of the phenomena appear, with the single and partial exception of anaesthesia.

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 ca.n.a.ls), produces a paroxysmal pain; an inflammation spreading from the vertebrae 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 circ.u.mstances: (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 cause[33] of "hyperaesthesia"), 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 a.s.surance 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 hyperaemia 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 const.i.tutional 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 circ.u.mstance 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 p.u.b.erty 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 p.u.b.erty and the twenty-fifth to thirtieth year, and which seems really to belong, pathologically, to the age of unsettled and irregular s.e.xual 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 a.s.sure 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 pa.s.sed 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 s.e.xual 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 s.e.xual 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 a.s.sume 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 a.r.s.enic, with almost magical certainty and rapidity; in the latter, we expect an almost equally brilliant result from iodide of pota.s.sium.

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 p.r.o.ne 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.