Definition.—Neuralgia is a term used to express a pain of varying character in the course of a nerve or its branches, in which there is no structural change. The pain is intermittent or remittent in character, and tends to shift from place to place. There are frequently painful points (points douloureux) in the course of the nerve.

Etiology.—Predisposing Causes.—Neuralgia is a disease of middle life, being very rare in children or persons of extreme age, and occurs in men more frequently than in women, though females of a neurotic temperament are quite often affected. Heredity seems to have some influence in giving rise to neuralgia, it frequently occurring in hysterical and epileptic families; in fact, the general physical condition predisposes to neuralgia, and persons reduced by sickness, severe physical or mental exertion, anemia, and mal-nutrition, are prone to this affection. Workers in paints and metal-workers are also quite likely to attacks of neuralgia, while rheumatism, gout, chronic nephritis, diabetes, and the infectious fevers favor neuralgia. Exposure to cold and wet is a frequent exciting cause, while pressure from morbid growths or inflammation of near-by tissues are not to be overlooked as causal factors.

Reflex conditions must not be overlooked, for some of the most severe forms of neuralgia are due to wrongs of the uterus, ovaries, rectum, or urethra, or to disease of the teeth, nose, middle ear, sinuses, or antrum and to eyestrain.

Symptoms.—Pain is the most characteristic symptom, and is usually located in the course of a nerve. The attack may come on abruptly or be preceded by prodromal symptoms, such as chilly sensations, mental depression, uneasiness in the part, or a stinging, tingling, or burning sensation. When fully ushered in, the attack seems unbearable; the pain is lancinating, stabbing, burning, or boring in character, localized or darting to neighboring nerves.

The skin of the affected part may be quite sensitive, and painful spots can be detected., especially where the nerve becomes superficial. Sometimes the skin of the affected area becomes anesthetic, and may remain so for some little time after the attack ceases. Twitching or spasms of the muscles may occur during a paroxysm. Herpes often follows an attack.

Neuralgic paroxysms exhibit a marked tendency to periodicity. A paroxysm may last for a few minutes or for several hours.

Clinical Varieties.—Trifacial neuralgia (tic douloureux). In this form the pain is felt in one or more branches of the fifth nerve, more frequently the ophthalmic division.

The symptoms vary, from an occasional paroxysm of a mild type, to paroxysms of such excruciating intensity, and occurring so frequently, as to cause the patient to take his own life. Hyperesthesia of the skin of the affected part is common, and vaso-motor phenomena frequently are present, such as flushing, sweating, increased lachrymation, and nasal secretion and salivation.

The pain is of a rending or boring character, and may be so severe as to cause great prostration. Spasms of the muscles may occur. The painful points are: the supraorbital foramen, when the first branch is involved; the infraorbital foramen, when the second branch is affected; and when the third branch is the seat of the lesion, the mental foramen will be the painful spot.

When the pain is long continued, trophic changes, such as erythema, formation of ulcers, induration or drying of the skin, loss of hair or local grayness take place.

Neuralgia of the Neck and Trunk.—Cervico-occipital Neuralgia.—Exposure to cold, or cervical caries, is the most frequent cause of this form of neuralgia. The pain is localized over the occipital and posterior parietal regions, the most painful spot being located between the mastoid process and the upper cervical nerve, where the great occipital nerve becomes superficial. Hypresthesia of the scalp frequently occurs, and loss of hair is not uncommon.

Phrenic Neuralgia.—The pain is in the lower anterior thoracic region, at or near the insertion of the diaphragm. It is a rare condition.

Intercostal Neuralgia.—This is a common form ofi neuralgia, especially in anemic and hysterical women, the middle intercostal nerves of the left side suffering more frequently than the right. There is commonly a dull pain, with paroxysms of a stabbing character at intervals. Painful points are located under the angle of the scapula, beside the vertebra, and at the middle of the ribs.

Expansion of the chest increases the pain; hence respiration is shallow. Where the attack is severe and persistent, herpes zoster may appear, though this is usually associated with neuritis.

Neuralgia of the Extremities; Cervico-brachial Neuralgia.—In this form the sensory nerves of the brachial plexes are involved, the radial and ulnar nerves being affected more frequently than the median.

The pain is most often located in the axilla, along the course of the ulnar nerve, and when the circumflex nerve is involved, in the deltoid muscle. Tender points are found in the axilla, in the posterior border of the deltoid, the superior ulnar behind the elbow, the inferior ulnar in front of wrist, and the musculo-spiral nerve at the bend of the elbow.

Obturator neuralgia is frequent in women suffering with uterine or ovarian lesions, the pain extending along the inner side of the thigh as low as the knee.

Lumbar neuralgia gives rise to pain in the lumbar region, along the crest of the ilium, in the inguinal and femoral regions, and in the spermatic cord, scrotum, or vulva. If severe and located in the testicles, it may be attended by syncope.

Sciatica.—Next to facial neuralgia, sciatica is the most common, and affects males more than females. The pain may be uniformly distributed along the entire length of the nerve, though more frequently the paroxysm is most severe in the gluteal and popliteal regions; other painful spots are the middle of the thigh, below the head of the fibula, behind the external malleolus and the back of the foot.

The pain may be constant, though, usually paroxysms of intense pain, of a shooting, stabbing, or boring character, occur at irregular intervals. Damp weather seems to aggravate the attacks.

The pain is increased by walking or motions of the limb. In walking the knee is flexed and the patient throws his weight upon his toes, to diminish the tension on the nerve. Tremors or spasm of the muscles may be present, and when the disease is long continued there may be atrophy, of the muscles.

Neuralgia of the Genitalia and Rectum.—Of all neuralgias, none are more severe or harder to bear than neuralgia of the rectum and genitals. Coccygodynia is a common affection in women, and is usually associated with other nervous affections. It is aggravated by the sitting posture. This form is often very intractable, resection of the coccyx having been resorted to in some very severe cases, though, unfortunately, not always attended by relief.

Visceral Neuralgia.—In persons of nervous habits, and subject to neuralgias, it is not uncommon to find a sudden attack of severe pain in certain of the viscera, such as kidney, liver, stomach, bowel, and spleen, and is referred to as neuralgia of the kidney, liver, etc.

Treatment.—In the treatment of neuralgia, much depends upon our ability to remove the underlying cause, which may be local, general, or reflex. Thus when it is local, such as a neuroma, caries, aneurism, or cicatrix, we would not expect much benefit from medication, but surgical measures would effect a cure. Where the cause is general, our attention would be directed toward improving the general health by correcting septic processes, establishing the secretions, and improving nutrition. When due to reflex causes, a careful search must be instituted for the irritant part, a correction of which is followed by relief. It may be due to uterine, ovarian, rectal, or urethral lesions, and until this is overcome, but little relief can be obtained by the administration of medicines.

An illustration of this may be seen in one of the most intractable facial neuralgias I ever encountered. The patient, aged about seventy years, had suffered for eighteen months with the most intense pain, the paroxysms occurring every few minutes day and night. He had had heroic dosing and infinitesimal medication, but, worn in body and mind, was growing worse. My first examination of the patient revealed hemorrhoids, pockets, and redundant tissue of the rectum, and a bad stricture of the urethra; the correction of which gave the patient the first relief in eighteen months.

In the most severe paroxysms, the physician may have to resort to morphia hypodermically, though it should be used at long intervals, lest the morphine habit be established.

Remedies that influence neuralgic conditions are the following:

Facial Neuralgia.—Aconite, gelsemium, plantago, passiflora, piper methysticum, and chamomilla.

Cervico-occipital and Cervico-brachial.—Aconite, macrotys, rhamnus Californica, gelsemium, and sticta pulmonaria.

Intercostal.—Bryonia, asclepias, lobelia, and macrotys.

Lumbar and Sciatic.—Macrotys, rhamnus Californica, bryonia, collinsonia, sticta, apocynum, aesculus, quebracho, and the salicylates. Antikamnia, phenacetin, and like remedies, should be used with care. Where the neuralgia shows periodicity, quinine should be administered. Counter-irritants will be found useful in many cases.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.