dency to such pain, which may justly be allowed considerable weight in the absence of signs of an organic lesion. This character is frequently of very great practical value, especially in cases of neuralgic pain of unusual seat. Another similar indication is the fact that the neuralgia replaces some other functional disease, as, for instance, migraine. Special Diagnosis.-Their are certain affections with which the several varieties of neuralgia are liable to be confounded. Almost any form of neuralgia may be simulated by the pains of tabes, and the possibility of this cause should always be thought of, especially in the case of migratory pain. In some situations the risk of error is greater than in others, and these will be especially mentioned. In neuralgias in the branches which are distributed over the skull (fifth and great occipital) it is often doubtful whether the affection should be called headache or neuralgia. The distinction in some cases is one of name rather than of real difference. Either term is employed, according as the pain. seems superficial or deeply seated. But the fifth nerve gives fibres to the dura mater, and it is probable that some of the deeply-seated unilateral headaches are really allied to neuralgia, although it is customary, on account of their special association, to describe them separately. The fifth nerve is often damaged by organic intracranial disease, and nerve pain, thus produced, is sometimes mistaken for simple neuralgia. Besides the indications already described, organic disease often causes deeply-seated headache and other symptoms, especially in the functions of other nerves, optic neuritis, and paralysis or convulsion in the limbs. A history of recent syphilis increases the probability of organic disease, but does not render it certain. The occurrence of herpes in the course of a supposed neuralgia is also probable evidence, here as elsewhere, of organic changes in the nerves. It must not be forgotten that neuralgic pains are sometimes the first symptom of morbid growths in the upper jaw and parotid region. The diagnosis of the cervico-occipital form rarely presents any difficulty. The neuralgic pain usually courses along the nerve trunk, but it must be remembered that occipital neuralgia is occasionally bilateral. In caries of the cervical vertebræ pain may be an early symptom, but it scarcely ever spreads to the occiput, and the early interference with movement is usually characteristic. The neuralgias of the arm have to be distinguished chiefly from neuritis, by the indications already mentioned. The diagnosis is seldom difficult, because neuritis usually causes trophic changes in the muscles and skin, and the nerves are accessible in a large part of their course. A more difficult problem is presented by the trunk neuralgias, which have to be distinguished from disease of the internal viscera, and from organic spinal disease. Unilateral pain is a frequent accompaniment of disease of the organs in the thorax and abdomen, and it is hardly necessary to point out that, in every case, a careful examination should be made of the organs adjacent to the seat of pain. The greatest difficulty arises in the case of deeply-seated tumors which cause pain by nerve compression, especially when, as is sometimes the case, the pains are "reflected" and do not precisely correspond in position to their cause. Aneurism of the aorta, for example, often gives rise to such pain, especially when seated in the descending part; pain in the course of the nerves may be the only symptom until sudden death occurs. The pain is usually very severe, and often burning in character, and has not the same foci of intensity and tender points as in ordinary neuralgia. In severe unilateral (and even bilateral) pain, persistent in occurrence, whether uniform in seat or not, this cause should always be suspected. One of the most severe cases of neuralgic pain I have ever seen-darting, stabbing, burning, migratory pains in legs, abdomen, thorax, and left arm-was due to an undiscovered abdominal aneurism. Aneurism of the ascending part of the arch is now and then accompanied by pain passing to the arm, apparently of reflex character. Intercosto-humeral neuralgia may simulate angina pectoris, of which indeed, such neuralgia may be said to form part. The severity of the paroxysms of angina, and the other distressing sensations which accompany the pain, usually render the nature of the attacks sufficiently clear. The parietal pains which accompany disease of the spinal cord rarely have the acute lancinating character of neuralgia; they are sensations of tightness or constriction, and the obtrusive symptoms in the legs indicate the nature of the disease. To this, however, morbid growths of the cord offer an exception, especially in the early stage. The pains may be very severe and of various character, but they are constant in seat, are increased by any movement, and, before long, indications of compression of the cord are added to them. The "lightning pains" of tabes are sometimes felt in the trunk, and have often been mistaken for neuralgia. They are distinguished by their changing seat and momentary duration, by the similar pains in the legs, and especially by diminished sensibility over extensive areas. In most cases there are some pains in the legs and the knee jerk is lost, but I have seen one case in which the changes were confined to the dorsal region of the cord and the knee jerk was normal, but in this, as in other cases of the kind, the light reflex of the iris was lost, a symptom of great indirect diagnostic importance. More constant in seat and neuralgic in character are the pains of pachymeningitis, which are caused by the compression of the nerve roots by the thickened membranes. They are distinguished from neuralgia by the wide extent of the pains, their bilateral situation, by the presence of areas of anesthesia due to still greater damage to the nerves, by muscular wasting in the limbs, and by the symptoms of compression of the cord. The terrible nerve pain which is sometimes produced by organic disease of the bone of the spinal column closely resembles neuralgia in its fixity of site and unilateral situation, but is distinguished by its peculiar dependence on movement of the trunk. Leg symptoms are usually soon associated with it. The lumbo-abdominal neuralgia may be confounded with renal colic. The distinction rests chiefly on the urinary symptoms that accompany the latter. The sharp pains of tabes are more frequently felt in the legs than in the trunk, and these also are often mistaken for neuralgia, but the indications already mentioned suffice to distinguish them. The distinction of sciatic neuralgia from neuritis must be made by the indications. Of still greater practical importance is the distinction of crural and sciatic neuralgia from the pains due to pressure on the lumbar and sacral plexus by tumors in the pelvis and abdomen. Such pains are felt along the course of the nerves, and are almost invariably thought at first to be neuralgic. Pains in the front of the thigh are rare except as the result of extension of neuritis from the sciatic nerve to the lumbar plexus, or as the result of pressure. In each case there is generally muscular wasting, which shows organic damage. The diagnosis be tween neuralgia in the front of the thigh and pain due to a lesion of the nerves, is also aided by the state of the knee jerk, which is generally early lost in organic disease, but remains intact in neuralgia. In every case of neuralgic pain in this situation, the abdomen should be carefully examined, and whenever pain in the sciatic is of a progressive character, and apparently due to mischief above the accessible part of the nerve, a rectal examination should be made, by which the source of pressure, if there be any, will readily be felt. It must also be remembered that pain felt in the knee may be a reflex effect of the irritation of the branches of the obturator nerve in hip-joint disease, and that obscure pains in the groin and thighs are sometimes the result of disease of the femur. (In one case of intense stabbing pains in the groin, closely resembling neuralgia, the cause was ultimately found to be necrosis of the great trochanter.) The diagnosis of the spinal forms of neuralgia need not detain us long. In the reflex or sympathetic variety the cause of the pain will usually be discovered, if it is remembered that it may be outside the area in which pain is felt. It is rarely far distant; often in another branch of the same nerve. Pain in any part of the fifth nerve, for instance, may be due to the irritation of a carious tooth. It is possible to confound epileptiform neuralgia with the form of true epilepsy in which the aura is a sudden pain. I have known, for example, slight attacks of minor epilepsy to be preceded by a most severe momentary pain in one fifth nerve. The occurrence of distinct loss of consciousness, and still more of convulsion, sufficiently indicate the epileptic nature of the case. A painful epileptic aura in a limb, followed by local convulsion, could only be mistaken for neuralgia with reflex spasm, in a patient who had never had a severe fit. But the course of such an aura is usually centripetal and deliberate, and the spasm has also a deliberate march. Prognosis. The prognosis in neuralgia is influenced by the age of the patient, by the duration of the affection, its situation, severity, and cause. It is far better when the disease is due to any constitutional condition than when no general cause can be discovered, since, as a rule, the constitutional states that cause neuralgia are amenable to treatment, at any rate in such a degree as to influence the pain. In hysteria, however, some neuralgias are readily removed; others, especially when there is no anæmia, are most obstinate. The prognosis is better when there is no hereditary tendency than when this is marked. We do not yet know whether the prognosis is influenced by the fact that the heredity is general or special. The more severe the pain, and the longer the disease has lasted, the more difficult is its treatment. It is generally believed that neuralgias of the fifth nerve are more intractable than others. During the decline of life, neuralgias of all kinds, especially those of the degenerative form, are peculiarly obstinate, and in old age they sometimes cannot be relieved by any treatment whatever. However severe the pain may be, neuralgia involves little danger to life; as Buzzard has well said, "the disease does not seem, of itself, to shorten the duration of the life which it fills with suffering." Epileptiform neuralgia is, of all forms, the most obstinate; Trousseau, in his large experience, never knew a case to be cured. When neuralgia has once ceased it is extremely prone to recur, and this fact, which is true of all varieties, must be remembered in giving an opinion regarding the future. Treatment.-The treatment of neuralgia consists, first, in the relief of the symptom, pain, and, secondly, in the removal of its cause, i.e., in the restoration of normal conditions of function in the sensory apparatus. The means by which these ends are to be secured are threefold-by hygiene, by drugs, given internally and applied externally, and by certain surgical operations on the nerves. It is evident that the treatment to be adopted must be influenced, to some extent, by the nature of the case. When there is distinct evidence of neuritis, the treatment for this, already described, must be adopted. The treatment now to be considered is that of the "idiopathic form, but the means for the alleviation of all forms is nearly the same. Although the relief of pain has usually to be the first actual step in treatment, the first in importance is the removal of the causes of the disease. Any discoverable condition on which the neuralgia may depend must be treated. The detailed measures that are necessary need not here be indicated, since they are sufficiently suggested by the enumeration of the causes and causal varieties already given. Especially should any source of nerve irritation be removed, whether in the |