Myxomas often occur upon the peripheral nerves, and are frequently multiple, their points of predilection being the larger trunks, as the sciatic, ulnar, etc. They show their characteristic soft structure, and are usually spindle-shape, assuming a rounder form as they attain a large size. The various forms of sarcoma occasionally form tumors upon the nerves, attacking generally the large trunks. Carcinomatous tumors beginning upon the nerves sometimes occur, but as a rule these growths involve the nerve by extension to it from adjacent parts.
Syphilitic gummata have been found almost exclusively upon the intracranial portion of the cranial nerves.
Gliomas appear to affect only the optic and acoustic nerves. Lepra nervorum (lepra anæsthetica) produces usually a spindle-form thickening upon the nerve-trunks, but sometimes there are more distinct knots, which may be felt beneath the skin, bead-like, along the course of the nerves of the extremities.
Like the true neuromas, the false neuromas, developing from the neurilemma and perineurium, may involve the whole or only a part of the fibres of a nerve, or the nerve-fibres may run at the side of the tumor—different conditions, which may alter materially the effects produced upon the nerve.
Neuromas, both false and true, may occur not only singly, but often in large numbers, many hundreds having been counted upon an individual. Sometimes they are numerous upon a single nerve-trunk and its branches, and again they may appear scattered over nearly all of the nerves of the body, even to the cauda equina and roots of the nerves. According to Erb,9isolated neuromas are more frequent in females, while multiple neuromas are found almost exclusively in men. Neuromas vary greatly in size, as we might expect from the very great difference of their nature and structure; sometimes no larger than a pea, they may attain the size of a child's head.
9Ziemssen's Handbuch.
ETIOLOGY.—In cases of multiple neuromata it would seem as if there was a constitutional condition or diathesis as the foundation of the affection. This we may the more readily believe as there appears good evidence to show that the tendency to the formation of these nerve-tumors is sometimes hereditary, and some of them are congenital.
Idiots and cretins have been observed to suffer in undue proportion with multiple neuromas. We find a direct exciting cause of neuromas in mechanical injuries of nerves, wounds, blows, pressure, etc. Thus, as has been already seen, true neuromas occur in the divided ends of the nerves after amputations or otherwise where a nerve-trunk has been divided (cicatricial neuroma). As such neuromas are in some degree the result of inflammation, it is probable that they may sometimes be caused by chronic neuritis.
For a large number of neuromas no cause can be assigned, and we must at present consider them as originating spontaneously.
SYMPTOMS.—The position and connections of neuromas being so different, sometimes simply in contact with the nerve; sometimes situated in the thickness of the nerve-trunk, the fibres being pressed aside and spread out upon the surface of the tumor; sometimes involving in their tissue a part or the whole of the nerve-fibres,—we cannot but expect avery marked difference in their clinical history. Not a few cases occur in which the presence of neuromas, even in large numbers, gives rise to no symptoms during life, and their existence has been revealed only upon a post-mortem examination.
The symptom most common to neuromas, and one to be expected from their mechanical interference with the nerves, is neuralgic pain—sometimes extreme, local or shooting along the course of the nerves, stubborn, and hardly to be alleviated by remedies. It is paroxysmal, notwithstanding the unvarying character of its cause, in consonance with the tendency to periodical activity which prevails in the nervous system. Sometimes the pain is increased notably by atmospheric changes. The pain may sometimes be arrested by firm pressure upon the nerve above the seat of the tumor. In some cases pressure upon the neuroma, or even handling it, causes great pain. The intensity of the pain does not depend upon the size of the tumor, some of the smallest having earned the appropriate name of tubercula dolorosa. The continued irritation of a neuroma sometimes produces a condition of general nervous excitability, which shows itself in hysterical and even in true epileptic convulsions. Occasionally there are abnormal sensations (paræsthesiæ), formication, numbness, etc., in the distribution of the nerve affected, and when from pressure or histological changes the fibres are destroyed anæsthesia results.
The interference with the conductivity of the motor fibres, which occurs less frequently than alterations of sensation, shows itself in cramps, tumors, paresis, and paralysis, according to its degree.
Neuromas may destroy life by the continued excessive pain, which wears down the strength and depresses the vitality. Death may be caused by their peculiar situation; as, for instance, upon the cauda equina, where they produce paraplegia, paralysis of the sphincter and bladder, and trophic changes.
TheDIAGNOSISof neuromas can only be made when they are sufficiently superficial to be recognized by the touch, and along with the symptoms above detailed the tumor is situated upon the known course of a nerve, to which, moreover, its attachment allows a lateral movement.
The onlyTREATMENTavailable for neuromas is extirpation, which must be conducted with a view to sparing any fibres of the nerve not involved in the tumor. Where it is necessary to divide the nerve in the removal of the tumor, as small a portion as possible must be excised, with the hope of a regeneration and reuniting of the cut ends. The success of extirpation depends largely upon the nature of the neuroma. The true neuromas, while they often show a strong tendency to recur after removal, are benign and show no metastasis. For the false neuromas the prognosis will be in accordance with their benign or malignant character.
BYJ. J. PUTNAM, M.D.
BYJ. J. PUTNAM, M.D.
DEFINITION.—It is customary to describe as neuralgic those pains for which no adequate cause can be assigned in any irritation of the sensory nerves from outside, which recur paroxysmally, are unattended by fever, and are distributed along the course of one or more nerves or nerve-branches.
The general use of the term neuralgia further implies the common belief that there is a disease or neurosis, not covered by any other designation, of which these pains are the characteristic symptom. Of the pathological anatomy of such a disease, however, nothing is known; and if it could be shown for any given group of cases that the symptoms which they present could be explained by referring them to pathological conditions with which we are already familiar, these cases would no longer properly be classified under the head of neuralgia.
The attempt has frequently been made, and on good grounds, in obedience to this reasoning, to cut down the list of the neuralgias, strictly so called, and to account for many of the groups of symptoms usually classified under that head by referring them to anæmia or congestion of the sensory nerves, to neuritis, etc.
One of the best and most recent statements of this view is that of Hallopeau,1who, although he does not wholly deny the existence of a neurosis which may manifest itself as neuralgia, goes so far as to maintain that the gradual onset and decline and more or less protracted course so common in the superficial neuralgias, such as sciatica, suggest rather the phases of an inflammatory process than the transitions of a functional neurotic outbreak, and that, in general terms, a number of distinct affections are often included under the name of neuralgia which are really of different origin, one from the other, and resemble each other only superficially. This subject will be discussed in the section on Pathology, and until then we shall, for convenience' sake, treat of the various neuralgic attacks as if they were modifications of one and the same disease.
1Nouveau Dict. de Méd. et de Chir. pratiques, art. “Névalgies.”
GENERALSYMPTOMATOLOGY.—The neuralgias may be conveniently divided into—1, external or superficial; 2, visceral; 3, migraine and the migrainoid headaches.
The most prominent symptom of a neuralgic attack of the superficialnerves is of course the pain, and sometimes, from first to last, no other sign of disease is present. In an acute attack the pain is usually ushered in by a sense of discomfort, which the patient vainly tries to shake off, or by a feeling of weight and pressure or of numbness and prickling, or of itching. Sometimes, though far less often than in the case of migraine, there are prodromal signs of a more general character, such as a feeling of thirst2or of mental depression or drowsiness.
2Spoken of by Mitchell's patient with neuralgia of the stump (see below).
A dart of pain may then be felt, which soon disappears, but again returns, covering this time a wider area or occupying a new spot as well as the old. The intensity, extension, and frequency of the paroxysms then increase with greater or less rapidity, but, as a rule, certain spots remain as foci of pain, which radiates from them in various directions, principally up or down in the track of the nerve-trunk mainly implicated. The pain rarely or never occupies the whole course and region of distribution of a large nerve or plexus, but only certain portions, which may be nearly isolated from one another.
In an acute attack the affected parts may at first look pale and feel chilly, and later they frequently become congested and throb. Mucous surfaces or glandular organs in the neighborhood often secrete profusely, sometimes after passing through a preliminary stage of dryness.
The skin often becomes acutely sensitive to the touch, even though firm, deep pressure may relieve the suffering. Movement of the painful parts, whether active or passive, is apt to increase the pain. When the attack is at its height, the pain is apt to be felt over a larger area than at an earlier or a later period, and may involve other nerves than those first attacked. Thus, a brachial becomes a cervico-brachial neuralgia or involves also the mammary or intercostal nerves. A peculiarly close relationship exists between the neuralgias of the trigeminal and of the occipital nerves. It is said that when the attack is severe the corresponding nerves of the opposite side may become the seat of pain. This is perhaps remotely analogous to the complete transference of the pain from one side to the other which is so characteristic of periodical neuralgic headaches, especially if they last more than one day.
Some cutaneous neuralgias pass away after a few hours' or a night's rest, after the manner of a migraine or a headache, and patients in whom this takes place are, as a rule, constitutionally subject to neuralgia or other neuroses. Toward the end of such an attack there is often a copious secretion of pale, limpid urine. In a large class of cases, on the other hand, the attack is of several days' or weeks', or even months' or years', duration, with remissions or intermissions and exacerbations, which may be either periodical or irregular.
The most marked periodicity of recurrence is seen with the neuralgias of malarial origin, which may take on any one of the typical forms of that disease.
These malarial neuralgias affect pre-eminently, though not exclusively, the supraorbital branch of the fifth nerve; but it should not be forgotten that there is also a typically periodical supraorbital neuralgia of non-malarial origin, of which the writer has seen several pronounced examples, the pain usually recurring regularly every morning at eight or nine o'clock and passing away early in the afternoon. The same periodicityis seen, though less often, in other neuralgias. Thus, Trousseau3speaks of neuralgic attacks from cancer of the uterus in a young woman, which recurred daily at exactly the same hour. Some of the traumatic neuralgias show the same peculiarity to a marked degree.
3Clin. Méd.
In many neuralgias, on the other hand, the exacerbations are worse at night, like the pains of neuritis. In the intervals between the attacks the pain may be wholly absent, or may persist, usually as a dull aching.
After a neuralgia has lasted a few days—sometimes, indeed, from the outset if the attack is severe—it is usually found that definite spots of tenderness have made their appearance at certain limited points on the course of the nerve. These are the famous points douloureux which Valleix described with such minute accuracy, believing them to be invariably present in true neuralgias. This is certainly not strictly the case, though they are very common. They are not necessarily coincident with the foci of spontaneous pain, as Valleix supposed, but do correspond in general to the points at which the affected nerve emerges from its bony canal or from deep muscles and fascia, and to portions of its area of distribution in the skin. The spinous process corresponding to an affected spinal nerve may also become tender, but this is probably to be looked on, like the same symptom in so-called spinal irritation, not as a sign of local disease, but as due to a general reaction on the part of the nervous system, and as a fact of a different order from the tenderness along the nerve.
The termination of an acute neuralgic attack is usually gradual, like its onset, although in some cases of headache, and in other neuralgias to a less degree, there comes a moment when the patient suddenly declares that he is free from pain.
Neuralgic attacks are usually characterized, besides the pain, by a highly-interesting series of symptoms, which are in part transitory and functional, and in part due to structural changes in the tissues.4
4See Notta,Arch. gén. de Méd., 1854; Anstie,Neuralgia and its Counterfeits.
The spasm and subsequent dilatation of blood-vessels in the affected area have already been alluded to. A disturbance of secreting organs in the neighborhood of the painful region, the lachrymal gland, the skin, the mucous membranes, the salivary glands, is of equally common occurrence, and is probably in great measure due to direct irritation of the glandular nerves, since the increased secretion is said to occur sometimes unattended by congestion.
The hair may become dry and brittle and inclined to fall out, or may lose its color rapidly, regaining it after the attack has passed.
The increased secretion of urine already alluded to attends not only renal neuralgias, but those of the fifth pair, intercostal, and other nerves. There may be unilateral furring of the tongue (Anstie).
The muscles supplied by the branches of the affected nerve or of related nerves may be the seat of spasm, or, on the other hand, may become paretic; and this is true even of the large muscles of the extremities.
Vision may be temporarily obscured or lost in the eye of the affected side in neuralgia of the fifth pair, and hearing, taste, and smell are likewise deranged, though more rarely. I am not aware that distincthemianopsia is observed except in cases of true migraine, where it forms an important prodromal symptom.
In connection with these disorders of the special senses the occasional occurrence of typical anæsthesia of the skin of one-half of the body should be noted, which several observers have found in connection with sciatica. The writer has seen a cutaneous hyperæsthesia of one entire half of the body in a case of cervico-occipital neuralgia of long standing. These symptoms are probably analogous to the hemianæsthesia which comes on after epileptic or other acute nervous seizures, or after concussion accidents, as has lately been observed both in this country and in Europe, and it is perhaps distantly related to the hemianæsthesia of hysteria. Local disorders of the sensibility in the neuralgic area are far more common than this, and, in fact, are usually present in some degree. The skin is at first hyperæsthetic, but becomes after a time anæsthetic; and this anæsthesia offers several interesting peculiarities. When this loss of sensibility is well marked, areas within which the anæsthesia is found are apt to be sharply defined, but they may be either of large size or so small as only to be discovered by careful searching (Hubert-Valleroux). The sensibility within these areas may be almost wanting, but in spite of this fact it can often be restored by cutaneous faradization around their margins, and the functional or neurosal origin of the anæsthesia is thus made apparent. Where the anæsthesia is due, as sometimes happens, to the neuritis with which the neuralgia is so often complicated, it is more lasting, but usually less profound and less sharply defined.
These changes may be transient, or, if a neuralgia is long continued and severe, they may pass into a series of more lasting and deeper affections of the nutrition.
The skin and subjacent tissues, including the periosteum, from being simply swelled or œdematous may become thickened and hypertrophied. The writer has known a case of supraorbital neuralgia, at first typically intermittent, to lead to a thickening of the periosteum or bone over the orbit, which even at the end of several years had not wholly disappeared.
Neuralgias of the fifth pair, which are as remarkable in their outward results as they are in their severity and their relation to other neuroses, are said to give rise to clouding and ulceration of the cornea, to iritis, and even to glaucoma.
Herpetic eruptions on the skin sometimes occur, of which herpes zoster is the most familiar instance.
Muscular atrophy is very common, especially in sciatica, and in some cases this occurs early and goes on rapidly, while in others it may be only slight and proportioned to the disease and relaxation of the muscles, even where the neuralgia has lasted for weeks or months.
Neuritis of the affected nerve is a common result or attendant of neuralgia, and may remain behind for an indefinite period after the acute pain has gone, manifesting itself by subjective and objective disorders of sensibility, by occasional eruptions on the skin, or by muscular atrophy.
It is plain that in this list of symptoms a variety of conditions have been described which would never all be met with in the same case, and which, as will be shown in the section on Pathology, are probably due to different pathological causes.
These neuralgias are less definitely localized by the sensations of the patient than those of the superficial nerves, and it is not definitely known what set of nerves are at fault.
They are deep-seated and are referred to the general neighborhood of the larynx, œsophagus, heart, or one of the abdominal or genital organs, as the case may be.
The pain is usually of an intense, boring character, and does not dart like the pain of superficial neuralgia, but is either constant or comes in waves, which swell steadily to a maximum and then die away, often leaving the patient in a state of profound temporary prostration.
Deep pressure often brings relief. A patient of the writer, who is subject to attacks of this kind in the right hypochondrium, will bear with her whole weight on some hard object as each paroxysm comes on, or insist that some one shall press with his fists into the painful neighborhood with such force that the skin is often found bruised and discolored.
The functions and secretions of the visceral organs are apt to be greatly disordered during a neuralgic attack, and it is often difficult or impossible to tell with certainty which of these conditions was the parent of the other. Undoubtedly, either sequence may occur, but the pain excited by disorder of function, or even organic disease of any organ, is not necessarily felt in that immediate neighborhood. Thus I have known the inflammation around an appendix cæci, of which the patient shortly afterward died, to cause so intense a pain near the edge of the ribs that the passage of gall-stones or renal calculus was at first suspected.
There seems to be as much variation as to modes of onset and duration among the visceralgias as among the superficial neuralgias, but the tendency to short typical attacks of frequent recurrence seems to be greater with the former.
The visceral neuralgias are quite closely enough related to certain of the superficial neuralgias to show that they belong in the same general category. The two affections are often seen in the same person, and not infrequently at the same time or in immediate succession. Thus in the case of the patient just alluded to above, the attacks of deep-seated neuralgia in the neighborhood of the right flank are at times immediately preceded by severe neuralgia of the face or head. Similarly, intercostal neuralgia may occur in immediate connection with neuralgias of the cardiac or gastric nerves.
The phenomenon of tender points is not entirely wanting in the visceralgias, though less constant and definite than in the superficial neuralgias.
The liver and the uterus especially become the seat of more or less localized tenderness, and possibly the tenderness in the ovarian region which is so common, and so often unattended by real inflammation, is, in part, of this order.
The secondary results of the visceralgias are not easy to study. Besides the disorders of secretion and function above alluded to, swelling of the liver with jaundice and paresis of the muscular walls of the hollow viscera may be mentioned as having been ascribed to neuralgia.
It is not known to what degree neuritis occurs as a cause orcomplication of these neuralgias, and this is a question which is greatly in need of further study.
This is often classified as an affection of a different order from the neuralgias, but there seem to be no real grounds for this distinction.
The superficial neuralgias themselves are probably not one, but a group of affections, with the common bond of severe and paroxysmal pain.
Neither is what is called migraine always one and the same disease.
Although in its most typical form it presents very striking characteristics, such as a marked preliminary stage, with peculiar visual and sensory auras, sometimes occupying one entire half of the body, a short and regular course and periodical return, deep-seated pain without tender points, and prominent unilateral vascular disorders, yet these symptoms shade off by imperceptible degrees into those of neuralgia of the fifth pair, or more often into one or another form of unilateral neuralgic headache which stands midway between the two.
The vascular phenomena of migraine are believed by various observers, as is well known, to constitute the primary and essential pathological feature of the disease, and to be the cause of the pain. But this is a pure hypothesis, and as a matter of fact the cases are abundant in which no greater vascular changes are present than in other neuralgias of equal severity.
Migraine seems to occupy an intermediate position between the grave neuroses, especially epilepsy, and the neuralgias of neurosal origin.
The symptomatology will be described at greater length below.
GENERALETIOLOGY.—The causes of neuralgia may be divided into predisposing and exciting causes.
The most important of the first group are—
1. Hereditary tendencies;
2. The influences associated with the different critical periods of life;
3. The influences attached to sex;
4. The action of constitutional diseases, such as phthisis, anæmia, gout, syphilis, diabetes, nephritis, malarial poisoning, metallic poisoning.
The most important of the second group of causes are—
1. Atmospheric influences and the local action of heat and cold;
2. Injuries and irritation of nerves;
3. Irritation of related nerves (so-called reflex and sympathetic neuralgias);
4. Acute febrile diseases.
In most cases more than one cause is to blame, and each should be separately sought for.
PREDISPOSINGCAUSES.—1. Hereditary Tendencies.—It is generally admitted as beyond question that neuralgias are most common in families in which other signs of the neuropathic taint are prominent. Such affections as hysteria, neurasthenia, epilepsy, asthma, chorea, dipsomania, and even gout and phthisis as it would seem, are akin to the neuralgic tendency.
The neuropathic family is thought to contain, in fact, a much larger number of members than this,5but there is danger of exaggerating the importance of an influence of which we know as yet so little.
5Féré,Arch. de Névrologie, 1884, Nos. 19 and 20, “La famille névropathique.”
It should be remembered, moreover, that even where an inherited taint is present its influence may be but slight as compared with that of some special exciting cause.
Some neuralgias are more closely associated with the inherited neuropathic diathesis than others. The connection is especially close in the case of migraine;6then follow other forms of periodical headache and the visceral neuralgias. Even the superficial neuralgias7are more or less subject to this influence. This is thought to be especially true of the facial neuralgias.
6There is a witty French saying (quoted by Liveing), “La migraine est le mal des beaux esprits;” which might be rendered, “The disease of nervous temperaments.”
7For tables of illustrative cases see Anstie,Neuralgia and its Counterfeits, and J. G. Kerr,Pacific Med. and Surg. Journ., May, 1885.
Reasons will be offered later for suspecting that many cases usually classed as neuralgia, and characterized by gradual onset and protracted course, are essentially cases of neuritis; and there is need of further inquiry as to how far hereditary influences are concerned in producing them, and whether such influences act by increasing the liability of the peripheral nerves to become inflamed, or only by increasing the excitability of the sensory nervous centres.
2. Age.—Neuralgia is oftenest seen in middle life and at the epochs marked by the development and the decline of the sexual functions. The affection, when once established, may run over into advanced age, but cases beginning at this period are relatively rare and very intractable (Anstie).
Childhood is commonly said to be almost exempt from neuralgia, but, in fact, there seems no sufficient reason for withholding this term from the so-called growing pains of young children8so long as it is accorded to the almost equally irregular neuralgias of anæmia in the adult. The same remark applies to the attacks of abdominal pain in children, which often seem to be entirely disconnected from digestive disorders.
8Probably due to anæmia or imperfect nutrition (see Jacobi, “Anæmia of Infancy and Childhood,”Archives of Med., 1881, vol. v.).
Adolescents and children also suffer from periodical headaches, both of the migrainoid and of the neuralgic type. These are obstinate and important affections.9Migraine especially, coming on in early life, points to a neuropathic constitution, and will be likely to recur at intervals through life, or possibly to give place to graver neuroses.
9Blache,Revue mensuelle de l'enfance, Mar., 1883, and Keller,Arch. de Névroloqie. 1883.
3. Sex.—Women show a stronger predisposition than men to certain forms of neuralgia, as to the other neuroses, but it is generally conceded that whereas neuralgias of the fifth and occipital and of the intercostal nerves are met with oftenest among them, the brachial, crural, and sciatic neuralgias are commoner among men. This probably indicates that the neurosal element is of greater weight in the former group, the neuritic element in the latter.
4. Constitutional Diseases.—The blood-impoverishment of phthisis and anæmia, the poison of malaria, syphilis, and gout, and the obscurerforms of disordered metamorphosis of tissue, undoubtedly predispose to neuralgia and the other neuroses, as well as to neuritis and others of the direct causes of neuralgic attacks.
Anstie regards the influence of phthisis as so important as to place it fairly among the neuroses. Gout is likewise reckoned by some observers among the neuroses,10but we tread here upon uncertain ground. Anstie does not regard gout as a common cause of neuralgia, but most writers rate it as more important, and gouty persons are certainly liable to exhibit and to transmit an impaired nervous constitution, of which neuralgia may be one of the symptoms. The neuralgias of gout are shifting, irregular in their course, and sometimes bilateral.
10Dyce-Duckworth,Brain, vol. iii., 1880.
Syphilitic patients are liable to suffer, not only from osteocopic pains and pains due to the pressure of new growths, but also from attacks of truly neuralgic character. These may occur either in the early or the later stages of the disease. They may take the form of typical neuralgias, as sciatica or neuralgia of the supraorbital nerve (Fournier11), or they may be shifting, and liable to recur in frequent attacks of short duration, like the pains from which many persons suffer under changes of weather, anæmia, or fatigue.
11Cited by Erb inZiemssen's Encyclopædia.
There are other obscure disorders of the nutrition, as yet vaguely defined, in connection with which neuralgia of irregular types is often found. Some of these are classed together under the name of lithæmia, and are believed to be due to imperfect oxidation of albuminoid products.12
12See DaCosta,Am. Journ. of Med. Sciences, Oct., 1881, and W. H. Draper,New York Med. Record, Feb. 24, 1883.
Diabetes seems also to be an occasional cause of neuralgia, especially sciatica, and Berger,13who has recently described them, says that they are characterized by limitation of the pain to single branches of the sacral nerves, by a tendency to occur at once on both sides of the body, by the prominence of vaso-motor symptoms, and, finally, by their long duration and obstinacy. There may not, at the moment, be any of the characteristic symptoms of diabetes present.
13Neurologisches Centralblatt, 1882, cited in theCentralbl. für Nervenheilk., etc., 1882, p. 455.
Chronic nephritis also causes neuralgia, either directly or indirectly; and severe neuralgic attacks may accompany the condition, which is as yet but imperfectly known, characterized pathologically by a general arterio-fibrosis and by increased tension of the arterial system.
True rheumatism does not appear to be a predisposing cause of neuralgia.
Anæmia, both acute and chronic, is a frequent cause of neuralgia, both through the imperfect nutrition of the nervous tissues, to which it leads, and, it is thought, because the relatively greater carbonization of the blood increases the irritability of the ganglionic centres.
Even a degree of anæmia which might otherwise be unimportant becomes of significance in the case of a patient who is otherwise predisposed to neuralgia; for such persons need to have their health kept at its fullest flood by what would ordinarily seem a surplus of nourishment and care.
Under the same general heading comes the debility from acute andchronic diseases, and the enfeeblement of the nervous system from moral causes, such as anxiety, disappointment, fright, overwork and over-excitement, and especially sexual over-excitement, whether gratified or suppressed (Anstie), or, on the other hand, too great monotony of life; also from the abuse of tea, coffee, and tobacco.
Lead, arsenic, antimony, and mercury may seriously impair the nutrition of all the nervous tissues, and in that way prepare the way for neuralgia.
IMMEDIATECAUSES.—1. Atmospheric and Thermic Influences.—Neuralgia is very common in cold and damp seasons of the year, in cold and damp localities, and in persons whose work entails frequent and sudden changes of temperature. Exposures of this sort may at once excite twinges of pain here and there over the body, and may eventually provoke severe and prolonged attacks of neuralgia.
The action of damp cold upon the body is complicated, and it exerts a depressing influence on the nervous centres in general which is not readily to be explained. One important factor, however, is the cooling of the superficial layers of the blood, which occurs the more easily when the stimulus of the chilly air is not sufficiently sharp and sudden to cause a firm contraction of the cutaneous vessels, while the moisture rapidly absorbs the heat of the blood. From this result, indirectly, various disorders of nutrition of the deeper-lying tissues or distant organs; and, among these, congestion and neuritis of the sensitive nerves.
Neuralgia often coincides with the presence or advent of storms. A noteworthy and systematic study of this relationship was carried on through many years under the direction of S. Weir Mitchell14by a patient of his, an officer who suffered intensely from neuralgia of the stump after amputation of the leg. The attacks of pain were found to accompany falling of the barometer, yet were not necessarily proportionate to the rapidity or amount of the fall. Saturation of the air with moisture seemed to have a certain effect, but the attacks often occurred when the centre of the storm was so remote that there was no local rainfall. It was impossible to study the electrical disturbances of the air with accuracy, but a certain relationship was observed between the outbreak of the attacks and the appearance of aurora borealis.
14Am. Journ. of Med. Sci., April, 1877, andPhilada. Med. News, July 14, 1883.
This patient's neuralgic attacks were almost certainly of neuritic origin, and it is possible that the exacerbations were due to changes of blood-tension in and around the nerve-sheaths. It is also possible that they were the result of circulatory changes and disordered nutrition of the nervous centres, already in a damaged condition from the irritation to which they had been exposed.
2. Injuries and Irritation of Nerves.—Wounds and injuries of nerves15and the irritation from the pressure of scars, new growths, and aneurisms are prolific causes of neuralgic pain, partly by direct irritation, partly by way of the neuritis which they set up. Neuralgias are likewise common during the period of the healing of wounds, as Verneuil long since pointed out. The pain may be near the wound itself or in some distant part of the body.
15See S. Weir Mitchell,Injuries of Nerves.
Neuralgia due to the pressure and irritation of tumors, new growths,or aneurisms requires a special word. The pain is apt to be intensely severe, but what is of especial importance is that the symptoms may not present anything which is really characteristic of their origin, except their long continuance; and this should always excite grave suspicion of organic disease.
These attacks of pain may be distinctly periodical; and this is true whether they are felt in the distribution of the affected nerve or of distant nerves.
Not only are direct injuries of nerves a cause of neuralgia, but sudden concussion or jar may have a like effect—whether by setting up neuritis or in some other way is not clear. Ollivier16reports a case where a blow beneath the breast caused a neuralgia which eventually involved a large portion of the cervico-brachial plexus; and the writer has seen a like result from a blow between the shoulders.
16Cited by Axenfeld and Huchard, p. 116.
Peripheral irritations, such as caries of the teeth (see below, under Facial Neuralgia) and affections involving other important plexuses, such as those of the uterine nerves, are a frequent cause of neuralgia, and should always be sought for. They act in part by setting up neuritis, and in part evidently in some more indirect manner, since the neuralgia which they excite may be referred to more or less distant regions, forming the so-called—
3. Reflex and Sympathetic Neuralgias.—The term reflex, as here used, is ill chosen, and the term sympathetic only covers our ignorance of the real processes involved, and which we should seek for in detail. Thus, disease of the uterus or ovaries may cause facial, mammary, intercostal, or gastric neuralgia.
Hallopeau17suggests that some of these results may be brought about by the pressure of enlarged lymphatic glands attached to the affected organ.
17Loc. cit., p. 766.
Another important centre of nervous irritation is the eye. Slight errors of refraction, or weakness of the muscles of fixation, especially the internal recti, are a source of frontal headaches and other nervous symptoms, and even of typical migraine,18to a degree which is not usually appreciated. It is improbable that in the latter case the irritation acts as more than an exciting cause, but it may nevertheless be a conditio sine quâ non of the attack.
18St. Barthol. Hosp. Repts., vol. xix.
Acute and chronic inflammations of the mucous membrane of the frontal sinuses, perhaps even of the nasal membrane, are likewise important; and although it is probable that the opinions sometimes expressed as to the significance of these causes are exaggerated, it is equally true that obstinate and, as it were, illogical persistence in their removal will sometimes be richly rewarded.
It is especially worthy of note that there need be no local sign whatever to call the attention of the patient to the presence of the peripheral irritation.
Nothnagel19has described neuralgias which come on in the first week of typhoid, and are to be distinguished from the general hyperæsthesia of later stages. He describes an occipital neuralgia of this sort which finally disappeared under the use of a blister. Other acute diseases may have a like effect. The writer has seen a severe facial neuralgia in thefirst week of an insidious attack of pneumonia in a person who was not of neuralgic habit, and before the fever or inflammation had become at all severe.
19Virch. Arch., vol. liv., 1872, p. 123.
PATHOLOGY ANDDIAGNOSIS.—In surveying the clinical history of the neuralgias and the circumstances under which they occur, we have grouped together a large number of symptoms of very different character from each other, and we have now to inquire to what extent these symptoms are really united by a pathological bond.
Two opposite opinions have been held concerning the pathology of neuralgic affections. According to one opinion, every neuralgic attack, no matter how it is excited, is the manifestation of a neurosis—that is, of a functional affection of the nervous centres—to which the term neuralgia may properly be applied. This view is based on the resemblance between the different forms of neuralgia, or the apparent absence, in many cases, of any adequate irritation from without, and the fact that the persons in whom neuralgias occur usually show other signs of a neuropathic constitution.
According to the other opinion, the various forms of neuralgia are so many different affections, agreeing only in their principal symptom, and are due sometimes to congestion or anæmia of the nerves or the nerve-centres; sometimes to neuritis, the pressure of tumors, or the irritation of distant nerves; sometimes, finally, to a functional disorder of the nervous centres. The arguments in favor of this opinion are that the difference between the symptoms of the different neuralgias as regards their mode of onset and decline, their duration, the persistence of the pain, and the degree to which the attacks are accompanied by organic changes of nutrition in the tissues and in the nerve itself, are so great as to make it appear improbable that we are dealing in every case simply with one or another modification of a single affection.
This is a valid reasoning, and it is certainly proper to exhaust the possibilities of explaining the symptoms that we find in a particular case by referring them to morbid processes which we can see or of which we can fairly infer the presence, before we invoke an influence of the nature of which we understand so little as we do that of the functional neuroses. At the same time, it must be distinctly borne in mind that the symptoms of certain neuralgias, and the relation which the neuralgias in general bear to other neuroses, can only be accounted for on the neurosal theory, and that in a given case we can never be sure that this neurosal tendency is not present and is not acting as at least a predisposing cause. It is especially important to bear this possible influence in mind in deciding upon prognosis and treatment.
We may now review briefly the signs which should lead us to diagnosticate or suspect the presence of the various special causes of neuralgic symptoms.
Neuritis is indicated by the presence of organic disorders of nutrition affecting the skin, hair, or nails, or of well-marked muscular wasting; by pain, not only occurring in paroxysms, but felt also in the intermissions between the paroxysms, or continuous sensations of prickling and numbness, even without pain; by tenderness along the course of the nerve; by anæsthesia, showing itself within the first few days of the outbreak of a neuralgia; by persistent paralysis or paresis of muscles.