NEURALGIA, literally nerve pain, is a term which is frequently employed both technically and popularly in a somewhat loose manner, to describe pains the origin of which is not clearly traceable. In its strict sense it denotes the existence of pain in some portion or throughout the whole of the distribution of a nerve without any distinctly recognizable structural change in the nerve or nerve centres. This strict definition, if adhered to, how-ever, would not be applicable to a large number of cases of neuralgia; for it is well known that in not a few instances the pain is connected with some source of irrita-tion, by pressure or otherwise, in the course of the affected nerve ; and hence the word is generally used to indicate pain affecting a particular nerve or its branches from any cause. There are few ailments which give rise to greater human suffering than neuralgia, and some of the chief causes concerned in its production, or the conditions most frequently found associated with it, may be briefly alluded to.
It may be stated generally that neuralgia rarely occurs-in the midst of good health. On the contrary its exist-ence usually betokens a depressed or enfeebled state. Constitutional conditions inherited or acquired are among the most powerful of the predisposing influences in the production of neuralgia. Thus it is often found to affect the hereditarily rheumatic or gouty. In weakened con-ditions of the system from improper or insufficient food, or as a result of any drain upon the body, or in ansemia from any cause, and in certain disease poisons, such as-syphilis or malaria, neuralgia is a frequent concomitant. Further, any strain upon the nervous system, such as mental overwork or anxiety, is a predisposing cause of recognized potency. Among the exciting causes of an attack of neuralgia by far the most common is exposure to-cold and damp, which seems to excite irritation in a nerve already predisposed to suffer. But irritation may be pro-duced by numerous other causes besides this,such as a decayed tooth, diseased bone, local inflammations in which nerves are implicated, by some source of pressure upon a nerve trunk, or by swelling of its sheath in its passage through a bony canal or at its exit upon the surface. Further, there would appear to be causes of a reflex character which are capable of setting up neuralgia at a distance, such as intestinal or uterine derangements. The practical importance of ascertaining the probable nature of the cause is obvious.
The pain of neuralgia is generally localized, but may come to extend beyond the immediate area of its first occurrence. It is usually of paroxysmal character, and not unfrequently periodic, occurring at a certain time of the day or night. It varies in intensity, being often of the most agonizing character, or less severe and more of a tingling kind. Various forms of perverted nerve function may be found co-existing with or following neuralgia. Thus there may be hyperesthesia, anaesthesia, paralysis, or alterations of nutrition, such as wasting of muscles, whitening of the hair, &c. Attacks of neuralgia are liable to recur, particularly when the general health is low, and some persons unhappily continue to suffer from occasional attacks during the greater part of their lifetime.
The nature of the disease and its manifestations will be best understood by a reference to the forms in which neuralgia most commonly shows itself. These are facial neuralgia or tic douloureux, migraine (hemicrania or brow ague), intercostal neuralgia, and sciatica. Other forms, such as those affecting the neck, arm, &c, are described, but they are of less frequent occurrence.
Facial neuralgia, or tic doloureux, is one of the most common forms of neuralgia, and one of the most severe. It affects the great nerve of sensation of the face (fifth nerve), and may occur in one or more of the three divisions in which the nerve is distributed.. It is usually confined to one side. Females suffer, on the whole, more frequently than males, and adults or young persons more than , children or the aged. Among the more prominent conditions associated with it may be mentioned a low state of health as a result of previous disease, any drain upon the system (such as excessive menstruation, over-lactation, &c.), and, very specially, over-exertion of body or mind and mental anxiety. It is occasionally associated with epilepsy (Trousseau). The attack is often precipitated by the irritation of a decayed tooth or by exposure to cold air. When the first or upper division of the nerve is involved, the pain is mostly felt in the forehead and side of the head. It is usually of an in-tensely sharp, cutting, or burning character, either constant or with -exacerbations, and often periodic, returning at a certain hour each day while the attack continues. Occasionally the paroxysms are of extreme violence, and are brought on by the slightest provoca-tion, such as a draught of eool air. The skin over the affected part is often red and swollen, and, even after the attack has abated, feels stiff and tender to the touch. In this, as in all forms of neuralgia, there are certain localities where the pain is more intense, these "painful points," as they are called, being for the most part in those places where the branches of the nerves emerge from bony canals or pierce the fascia to ramify in the skin. Hence, in this form, the greater severity of the pain above the eye-brow and along the side of the nose. There is also pain in the eyelid, redness of the eye, and flow of tears. When the second division of the nerve is affected the pain is chiefly in the cheek and upper jaw, the painful points being immediately below the lower eyelid, over the cheek bone, and about the upper lip. When the third division of the nerve suffers the pain affects the lower jaw, and the chief painful points are in front of the ear and about the chin. As a result of this malady important nutritive disturbances may appear in the affected area, such as thickening of the tissues, falling out or blanching of hair, &c., as well as various alterations of sensibility. Attacks of tic douloureux, extremely distressing .as they are, may recur occasionally for years; and, although, by depriving the sufferer of sleep and interfering with the taking of food, they may in some measure impair the health, they rarely .appear to lead to any serious results.
Hemicrania, migraine, brow-ague, and sick headache are various terms employed to describe what appears to be another form of neuralgia, notwithstanding the opinion of some that it is a different kind of disease. The causes giving rise to it appear to be similar to those which bring about any of the forms of neuralgia. In some instances it would seem to be hereditary. It most frequently affects females, and generally occurs in early life, tending to disappear as age advances. An attack may come on suddenly, but, in general, begins by a dull aching pain in the brow or temple, which steadily increases in severity and extent, but remains usually limited to one side of the head. It attains at times an extreme degree of violence, and is apt to be aggravated by movement, loud noises, or bright light. Accompanying the pain there is more or less of nausea, and when the attack reaches its height vomiting may occur, after which relief comes, especially if sleep supervene. An attack of this kind may last for a few hours or for a whole day, .and after it is over the patient feels comparatively well. It may recur periodically, or, as is more common, at irregular intervals. During the paroxysms, or even preceding them, certain sensory disturbances may be experienced, more especially affections of vision, such as ocular spectra, hemiopia, diplopia, &c.; and there is also apt to be considerable mental depression.
Intercostal neuralgia is pain affecting the nerves which emerge from the spinal cord and run along the spaces between the ribs to the front of the body. This form of neuralgia affects the left side more than the right, is much more common in women than in men, and occurs generally in enfeebled states of health. It might "be mistaken for pleurisy or some inflammatory affection of the lungs; but the absence of any chest symptoms, its occurrence independently of the acts of respiration, and other considerations well establish the distinction. The specially painful points are _chiefly at the commencement of the nerve as it issues from the spinal canal, and at the extremities towards the front of the body, where it breaks up into filaments which ramify in the skin. This form of neuralgia is occasionally the precursor of an attack of shingles (Herpes zoster) as well as a result of it.
Sciatica is another of the more common forms of neuralgia. It affects the great sciatic nerve which emerges from the pelvis and runs down the leg to the foot. It is in most instances traceable to exposure to cold or damp, to overuse of the limbs in walking, &c.; but there are many other possible causes. Any source of pressure upon the nerve within the pelvis, such as may be produced by a tumour or even by constipation of the bowels, may excite an attack of sciatica. It is often connected with a rheumatic or gouty con-stitution. In general the nerve of one side only is affected. The pain which is felt at first a little behind the hip-joint steadily Increases in severity and extends along the course of the nerve and its branches in many instances as far as the toes. The specially painfuL points are about the knee and ankle joints ; besides which a feeling of numbness is experienced throughout the whole limb. In severe cases all movement of the limb aggravates the pain, and the patient is obliged to remain in bed. In prolonged attacks the limb may waste and he drawn up and fixed in one position. Attacks of sciatica are often attended with great suffering, and are apt to be very intractable to treatment.
In the treatment of all forms of neuralgia it is of first importance to ascertain if possible whether any constitu-tional morbid condition is associated with the malady, for otherwise the most powerful and approved remedies will often fail. Thus, if evidence of rheumatism, gout, anaemia, &c, be present, treatment appropriate to these conditions must be employed.
Of means available for the relief of the pain the number is so great that any detailed statement would be impossible in a general notice like the present. Only the more approved and potent remedial measures can be alluded to. The internal administration of narcotics and sedatives often succeeds in quelling the attack and procuring sleep. Among these the various preparations of opium, belladonna, henbane, chloral, croton-chloral, bromide of potassium, the bromide and chloride of ammonium, aconite, gelsemium, &c, are most commonly employed; but to many of them, such as opium and chloral, there exists the serious objec-tion of the risk of the acquisition of the habit of indulgence in them.
When the attack is periodic the administration of a large dose of quinine two or three hours previous to the usual time of the seizure will often mitigate, and may even pre-vent, the paroxysm. In migraine, caffein and its prepara-tions are recommended. Many topical applications are of great efficacy. The various liniments or ointments con-taining the preparations of opium, belladonna, or aconite rubbed into the affected part will often soothe the most severe local pain. An excellent sedative application is a lotion composed of equal parts of camphor and chloral painted or gently rubbed over the painful area. In many cases relief may be obtained by the hypodermic injection of morphia or atropia, by acupuncture, by blisters, or by counter-irritation with the button cautery.
The plan at one time resorted to of dividing or excising a portion of the affected nerve is now seldom employed, but the operation of nerve-stretching has been recently introduced, and in some forms of neuralgia, notably sciatica, is sometimes successful. It consists in cutting down upon and exposing the nerve, and in seizing hold and drawing upon it so as to stretch it. Such an operation is obviously justifiable only in cases where other less severe measures have failed to give relief. The employment of electricity, either in the form of faradization or galvanism, has much to recommend it, and in long continued and intractable forms of neuralgia proves in many instances
eminently serviceable. (J. O. A.)
The above article was written by: Dr. J. O. Affleck.