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 Limay and receives the overflow from two smaller neighbouring lakes. The temperature of the Andean region is cold even in summer, but on the lower plains it is hot in summer, and only moderately cold in winter. The principal industry is the raising of stock for the Chilean markets, as there is little cultivation. Cereals, forage crops, vegetables and fruits of the cold temperate zone can be produced easily, but distance from markets and lack of transport have restricted their production to local needs. The territory is reached by a light-draft river steamer which ascends the Rio Negro to Fort Roca at the confluence of the Limay and Neuquen, and by a branch of the Great Southern railway from Bahia Blanca to the same point. The population is concentrated in a few small towns on the rivers and in some colonies, established by the national government to check Chilean invasions, in the fertile districts of the Andes. A majority of the population, however, is of Chilean origin. The capital is Chos Malal, a small town on the upper Neuquen, in the mountainous district in the northern part of the territory.

NEURALGIA (Gr. , nerve, and  , pain), a term denoting strictly 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, however, would not be applicable to a large number of cases of neuralgia; for in not a few instances the pain is connected with some source of irritation, 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. The existence of neuralgia usually betokens a depressed or enfeebled state of health. It is often found to affect the hereditarily rheumatic or gouty. In weakened conditions of the system from improper or insufficient food, or as a result of any drain upon the body, or in anaemia from any cause, and in such diseases as syphilis or malaria, neuralgia is a frequent concomitant. Any strain upon the nervous system, such as mental overwork or anxiety, is a potent cause; or exposure to cold and damp, which seems to excite irritation in a nerve already predisposed to suffer. But irritation may be produced 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.

The pain 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 hyperaesthesia, anaesthesia, paralysis, or alterations of nutrition, such as wasting of muscles, whitening of the hair, &c.

The forms in which neuralgia most commonly shows itself are facial neuralgia or tic douloureux, migraine (hemicrania or brow ague), intercostal neuralgia and sciatica.

Facial neuralgia, or tic douloureux, 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. 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 intensely sharp, cutting or burning character, either constant or with exacerbations, and often periodic, returning at a certain hour each day while the attack continues. 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 eyebrow 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.

Hemicrania, migraine, brow-ague and sick headache are various terms employed to describe what by some is considered to be another form of neuralgia. 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. Gout, eyestrain and intestinal toxaemia have been put forward as causes of migraine, and Sir W. Gowers regards it as the equivalent of a true epileptic attack.

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. 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 constitution. 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 be 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 constitutional morbid condition is associated with the malady. 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 prevent the paroxysm. Many topical applications are of great efficacy. Liniments containing opium, belladonna or aconite rubbed into the affected part will often soothe the most severe local pain. And antipyrin, phenacetin, aspirin and similar analgetics are commonly taken. The plan at one time resorted to of dividing or excising a portion of the affected nerve is now seldom employed, but the operation