Rheumatic Neuralgia.-In a loose way, all neuralgias produced by cold are sometimes styled "rheumatic," but the mere causal relation scarcely warrants the epithet. The peculiar affection termed "muscular rheumatism" is also sometimes called a rheumatic neuralgia, but this is to extend the use of the term in a manner that is scarcely justified or needed. Pain that occurs only on movement should never be called neuralgia. Acute articular rheumatism is rarely associated with true neuralgia, but some forms of spontaneous pain are frequently produced by cold in those who present what is termed the "rheumatic diathesis," who perspire easily, are liable to catarrh, and whose urine readily becomes loaded with lithates after a chill. Such pains may correspond to a certain nerve, or may occupy some part of a limb, without any definite relation to nerves, and are often migratory. Their exact pathology is uncertain. Gouty Neuralgia.—The subjects of gout not unfrequently suffer from nerve pains, apparently idiopathic in character, coming and going, and sometimes very severe. The pain may disappear when an attack of acute gout is developed. The fifth nerve, the intercostals, and the sciatic are those most frequently affected. Severe sciatica sometimes occurs in the gouty, but is certainly due to neuritis. One visceral neuralgia is also sometimes due to gout, gastralgia. Diabetic Neuralgia.-Patients with diabetes may suffer from neuralgic pains that have no special characters, but Worms has called attention to the symmetry of the pains, which occupy the same nerve on both sides, as a characteristic of diabetic neuralgia. The pain has hitherto been observed chiefly in the third division of the fifth nerves and the sciatics. It must be remembered, however, that ordinary neuralgia is occasionally symmetrical. The nerve pains met with in diabetes are often severe and obstinate until the cause is removed by dietetic treatment. They have been observed to increase and decrease with the amount of sugar in the urine. Ziemssen has suggested that they may be sometimes the result of a peripheral neuritis analogous to that which is met with in alcoholism. While there is some evidence that such neuritis may occur in diabetes, it seems improbable that it is the cause of the pains commonly met with. Anamic Neuralgia.-Anæmia is one of the most powerful women. causes of neuralgia in all its forms, but certain varieties are more frequent than others in this condition, especially in young One of these is situated in the fifth nerve, either in the first division or in the auriculo-temporal branch. It is generally intermittent and is increased by movement, while it is lessened by the recumbent posture. Another, still more frequent and more continuous, is that which is felt in the thorax, in the fifth and sixth interspaces on the left side, the well-known infra-mammary pain. Gastralgia is also common apart from ulcer. Headaches that have no true neuralgic character are also very common. Neuralgia of the cerebro-spinal nerves sometimes occurs in lead poisoning, but it is uncertain whether it is the result of the toxic influence or of the anæmia which this causes. The knowledge of their cause, however, is very important. According to Briquet, lead colic is in part a neuralgia of the abdominal wall, but the evidence of this is scarcely satisfactory. Malarial neuralgias are not very common even where ague is frequent. They present nothing characteristic in seat, although the supra-orbital and intercostal forms are the most frequent; nor is there anything special in the character of the pain. Their chief feature is regular periodicity, the intervals between the attacks being from one to four days. The periodicity is less characteristic when the attacks are diurnal than when three or four days intervene. Occasionally the paroxysms are attended with slight symptoms of an ague fit, a trifling cold and hot stage (Anstie). They must not be confounded with the vaso-motor phenomena met with in cases of the ordinary form. It is very doubtful whether the neuralgia is, in most cases, a direct effect of the malarial poison, in the sense in which ague is. It is probably an indirect effect, the result of the anæmic and depressed state of the nervous system induced by malarial influences, even in those who do not suffer from intermittent fever. Neuralgia, apparently due to malarial causes, does not always yield to quinine, even when given in the most approved manner. It is probable that the exact periodicity of many malarial neuralgias is the result of the state of the nervous system produced by the poison, and it does not prove the neuralgia to be truly malarial. In some cases of supra-orbital neuralgia with exact periodicity coming from malarial districts (recorded by Seeligmüller), quinine failed entirely while other treatment was quickly successful. Syphilitic Neuralgia.-The pains of syphilis constitute a prominent symptom of that disease, but, for the most part, have no correspondence with nerve distribution, and can therefore be scarcely regarded as neuralgic. Symptomatic neuralgic pains occur in many syphilitic affections of the nervous system which cause irritation of the nerves or their roots, in chronic meningitis, neuritis, and pressure from growths. One of the most severe and obstinate cases of pain in the region of the fifth nerve I have seen, was due to chronic syphilitic meningitis at the origin of the nerve. In such cases the nature of the lesion is usually clear from the evidence of structural damage to the nerve fibres. In the case just mentioned, for instance, there was anæsthesia and paralysis of the masseter. Whether idiopathic neuralgia results from the influence of the syphilitic poison is uncertain. Fournier believes that such neuralgia is common during the secondary stage, but very few conclusive cases have been recorded. It must be remembered that in the early stage of neuritis, etc., pain may be the only symptom, and, on the other hand, the anæmia which results from syphilis may be the real cause of the neuralgia. Anstie believed that syphilis does not cause true neuralgia, although it may recall a neuralgia which had long ceased. A peculiarly distressing post-sternal pain, apparently neuralgic in character, has been occasionally observed in constitutional syphilis (Eccheverria, Buzzard). Degenerative Neuralgia.-In advanced life, and sometimes before the senile period is reached, neuralgia is occasionally met with, of extreme obstinacy, and associated with other signs of degeneration of the central nervous system, such as failure of memory or persistent mental depression. The neuralgia is apparently one effect of a degenerative tendency. The affection has all the characters of a central neuralgia. The fifth nerve is by far the most common seat, but the pain sometimes occurs in other situations. Diagnosis.--The diagnosis of neuralgia rests on the unilateral situation of the pain, on its correspondence to the distribution of certain nerves, its intermitting or remitting character (i.e., the occurrence of paroxysmal exacerbations), on the fact that the patient has suffered from similar pains elsewhere, on the variations in the seat of the pain, and on the absence of any indications of actual damage to the nerve fibres. The variability is a symptom of great importance. If the pain shifts about, now in one spot and now in another, it is not likely to be due to an organic cause. For instance, a man with fronto-occipital neuralgia had foci of pain in the forehead, temple, and occiput, but he never had pain at the same time at more than one of these places. The last of the above indications, however, is the most important element in the distinction of neuralgia from the similar pains which result from organic disease of the nerves due to external pressure or neuritis. It is in the case of the fixed neuralgias (as distinguished from the migratory forms) that the distinction is of chief importance. The diagnosis is more difficult in the case of neuritis than of external pressure (tumor, etc.), because, in the latter case, the cause of the pressure usually produces other symptoms, and the effect of the pressure is progressive, so that gradually increasing signs of a structural lesion are added to the pain. But from neuritis the distinction may be much less easy. The difficulty is the greater, the slighter the degree of neuritis. Severe inflammation causes severe constant pain, at first more intense at its seat than in the distribution of the nerve, because the inflammation is most intense in the nerve sheath, and the sheath nerves suffer first. In severe forms, however, the proper fibres of the nerve are soon impli cated to a degree that interferes with their conducting functions, so as to cause at first persistent hyperæsthesia, and then areas of anesthesia, while if the nerve is "mixed," the muscles supplied become weak, flabby, and rapidly waste, with changes in electrical irritability. In slight cases, on the other hand, the sheath chiefly suffers; there may be no interference with conduction, and the pain resembles neuralgia more closely, although, as a rule, it is more continuous than in true neuralgia. The diagnosis is also difficult when the seat of the neuritis is such as to render the nerve inaccessible to direct examination. If it can be reached, there will be found from the first local tenderness of the nerve. In idiopathic neuralgia tenderness of the trunk in the intervals is only developed after the neuralgia has existed for some weeks. Moreover, in neuritis distinct swelling of the nerve can sometimes be felt. Local tenderness is thus chiefly of significance in the early stage of the affection, or when it occupies a considerable area of the nerve trunk, and is not confined to certain points. If, therefore, the pain is migratory, if it is completely intermittent, especially if the intermissions are of long duration, if the attacks are induced by psychical influences, the suspicion of an organic cause will scarcely arise. If, on the other hand, there is continuous pain, rapidly developing to a considerable degree, organic disease should be suspected, and the suspicion will be confirmed if there is persistent alteration of sensibility, muscular wasting or altered irritability, or trophic changes in the skin. Great care is necessary, however, in testing the muscles, because a strong electrical, stimulus may greatly increase the pain. The isolated faradic shocks should be employed rather than the current, because they cause much less pain, and because they detect most readily the earliest change produced by neuritis, a slight increase of irritability; an altered reaction to voltaism will also often be found. Early tenderness of the nerve, not merely during but between the paroxysms, extending some distance, and distinct swelling of the nerve, indicate neuritis. The absence of these does not exclude neuritis, because it may occupy an inaccessible portion of the nerve. If the symptoms of structural damage gradually increase and progress, and especially if they involve the whole region of the distribution of the nerve, compression may be suspected, and is confirmed by the discovery of any other symptoms indicating organic disease in the vicinity of the nerve trunk, such as, in the case of the fifth, damage to other nerves which arise or pass near it. It must be remembered that in some cases the differential diagnosis of slight inaccessible neuritis from neuralgia may be impossible, because, on the one hand, the irritation of neuritis may cause neuralgic changes in the nerve centre, and, on the other, a primary functional neuralgia may cause, by reflex vaso-motor disturbance, secondary changes in the sheath, so that in each case a mixed affection, partly functional, partly organic, is the result; or, in current terms, a neuralgia which is at first either symptomatic or idiopathic, may ultimately be both. In all forms of neuralgia, the circumstance that the patient has previously had attacks of pain in other situation is a very important help in diagnosis. It does not, of course, prove that a given pain is of functional origin, but it is proof of a ten |