PART VIII.

DISEASES OF THE NERVOUS SYSTEM.

DISEASES OF THE NERVES.

NEURITIS.

Definition.-Neuritis is an inflammation of a

may be either localized (that is, confined to a single nervetrunk) or multiple (affecting a number of nerves).

LOCALIZED NEURITIS.

Etiology.-Cold is most frequently the cause. The affec tion is sometimes due to trauma, such as contusions, stabs, or cuts, or to stretching or tearing of a nerve, as might result from a fracture or dislocation. Pressure from muscular contraction may also cause this affection. It may result from extension, as from disease of the bone through which the nerve passes. It is often due to toxins and morbid states arising in the course of infectious and constitutional diseases. The mineral poisons are not infrequent causes. Alcohol most commonly produces peripheral neuritis.

Pathology. The inflammation may be confined to the nerve sheath (perineurium), to the interstitial part, or to the axis-cylinder. In the first instance the nerve is particularly swollen, red, and infiltrated with numerous leukocytes; in the last instance degenerative changes of the axis-cylinder are noticed (parenchymatous neuritis). The nuclei of the nervecells may consist of oily looking globules. The degeneration, according to Waller, extends down the nerve, because the fibers are cut off from the trophic cells. The muscles may undergo atrophy. Increased fibrous tissue may form in the nerve if recovery takes place.

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Symptoms. The constitutional disturbance is slight, and fever is rarely a symptom. Pain and tenderness are the principal symptoms, and are usually localized to the nerve-trunk and its distribution. The pain varies in intensity and character, and is described as burning, aching, boring, or shooting. Commonly it is aggravated at night, or in positions in which pressure upon the nerve-trunk may occur. The nerve-trunk may be swollen, and some reddening of the skin occasionally appears. Muscular twitching and contraction sometimes occur along the course of the nerve. If the disease be protracted, such changes as muscular weakness and wasting, slight edema, with a tremor, hyperesthesia, paresthesia, or anesthesia may develop. Acute cases usually end in recovery in about two weeks. Chronic cases may last for months or years, and may then gradually subside. The electric reaction is normal in mild cases; in severe cases the reaction of degeneration may take place.

Diagnosis. The differential diagnosis between neuritis and neuralgia must be made. In neuritis the pain is continuous, and occurs along the course of the nerve. In neuralgia the pain is intermittent in character, and is often relieved by pressure, whereas the pain of neuritis is aggravated by pressure. Altered sensation is in favor of neuritis.

Prognosis. The prognosis is favorable in mild cases. If the disease becomes chronic, it may last for months or years. Cases due to suppuration are less likely to recover.

Treatment. It is important to remove the cause, if possible. Rest is essential. When it is possible to splint the part, this should be done. Applications of cold by means of an ice-bag are useful. In some cases heat is more desirable. The use of a blister along the nerve-trunk in severe cases is of benefit. If the pain is very severe, morphin hypodermically must be resorted to. Salicylate of sodium is of value in the forms due to cold and exposure. In the chronic variety electricity is of use, galvanism being preferable. The weakest current that can be appreciated is most efficient. When wasting takes place, massage should be tried.

BRACHIAL NEURITIS.

Definition. Inflammation of the brachial plexus. Etiology. This occurs particularly in gouty individuals, affecting both sexes equally. The majority of cases arise after

the fiftieth year of life. Exposure to cold is said to be a predisposing factor.

Symptoms. Pain in the course of the distribution of the brachial plexus is the prominent feature. It is frequently encountered in the wrist, in the axilla, above the clavicle, and in the scapular region. At first it is intermittent, and felt only upon certain movements. It is usually severe. As in other forms of neuritis, trophic changes may occur. The disease is

not common.

Prognosis. The disease lasts for months, sometimes for years, recovery rarely being complete. Relapses are extremely

common.

Treatment.—The treatment is the same as in other forms

of neuritis.

SCIATICA.

Definition. Inflammation of the sciatic nerve.

Etiology. The disease is more frequent in males than in females, in about the proportion of four to one. It is rare in children, and is most frequent between the ages of twenty and fifty. The gouty and rheumatic diatheses are predisposing causes. The exciting cause most often is exposure to cold ; wet cold, it is said, being an especially favorable cause. Occasionally sciatica, it has been claimed, may be due to the poison of acute rheumatic fever. Pressure and intrapelvic disease may give rise to the affection.

Pathology. The pathology is the same as that of other forms of neuritis.

Symptoms.-Pain along the course of the sciatic nerve,— which is commonly felt at the back part of the thigh, in the region corresponding to the sciatic notch,-behind the knee, and below the head of the fibula, is the most important symptom. The pain may be diffused and may extend from the sciatic notch to the toes. All muscular movements aggravate the pain. In long-standing cases trophic changes occur.

Prognosis. The disease is liable to be obstinate, usually lasting for months.

tant.

Treatment. Rest by means of splinting the limb is imporAttention should be directed to the cause of the disease. If of rheumatic origin, the salicylates are useful. The use of mercury has been advised by some authorities, notably Gowers. Phenacetin, antipyrin, and other members of the coal-tar group are useful; however, in severe cases morphin

is necessary. Injections of chloroform or sterile water into the tissues along the course of the sciatic nerve may give relief in severe cases. Surgical interference by nerve-stretching should be resorted to only when other methods have failed to give relief.

MULTIPLE NEURITIS.

Definition. An inflammation involving many nerves, often by a symmetric change. These may be affected simultaneously or in rapid succession.

Synonyms.-Peripheral neuritis; polyneuritis.

Etiology. Multiple neuritis is almost invariably caused by some toxic agent, the most frequent, with the exception of lead and diphtheria, being alcohol. It occurs most often in persons who use strong liquors, but malt liquors also give rise to the condition. The disease is said to be more prevalent in females than in males. Scarce and improper food and exposure to cold are asserted to be predisposing factors. The fumes of some gases, such as carbon monoxid from charcoal stoves, and the fumes of anilin and bisulphid of carbon, are said to cause multiple neuritis through inhalation. The condition is frequently a sequel of infectious diseases; however, it more frequently follows diphtheria than any of the others. It takes place as a sequel in enteric fever, and more rarely from measles, pneumonia, influenza, scarlet fever, variola, varicella, and erysipelas. It is exceedingly uncommon after septic infection and syphilis. Neuritis occasionally occurs in the course of tuberculosis, but is very frequent in the course of leprosy. Of the metallic poisons, lead is the most frequent cause, but arsenic and mercury are also occasional factors. It occurs in the cachexias, such as malignant disease and anemia, and the affection has been noticed in the puerperal state. is sometimes met with in the aged, arterial sclerosis probably being the exciting cause. Perforating ulcer and Raynaud's rheumatoid arthritis have been attributed to peripheral neuritis.

It

Pathology. The pathology of multiple neuritis is practically the same as that of neuritis occurring in isolated nerves. The secondary changes which occur in the muscles are quite pronounced. Changes in the spinal cord, such as meningitis or chronic myelitis, may be encountered. Vacuolation of the ganglion cells and atrophy of the gray matter sometimes accompany multiple neuritis.

Symptoms. The symptoms vary. According to Gowers, three distinct varieties must be differentiated as to the prominence of certain symptoms, such as the motor and sensory phenomena, or those of incoordination. Pure types of each class may exist, but it is much more usual to find them combined. The disease mostly begins abruptly, but prodromes may exist, and may extend from a period of weeks to months, characterized by numbness and tingling in the hands and feet and by muscular cramps. In the acute cases the onset resembles the beginning of the acute infectious diseases. The temperature rises abruptly to 102° F. or 104° F., often with splenic enlargement, slight albuminuria, and even jaundice. Active pain in the limbs, with slight swellings at the articulations, is sometimes present, so that the attack may resemble acute rheumatic fever. Numbness and tingling, some pain, and muscular cramp, which occurs in the extremities, precede or accompany loss of power in certain muscle groups. This is an early phenomenon. The extensors of the hands and the anterior tibial group are the muscles chiefly involved; wristand foot-drop, as a result, are quite characteristic. Tenderness in the muscles, especially in alcoholic cases, aggravated by the least change of posture or by the slightest pressure, is a symptom of great importance. Paralysis may develop rapidly, and be complete in a few days. Occasionally the onset is more gradual, the paralysis requiring several weeks before it occurs. Either the arms or the legs may be involved, but the paralysis is always symmetric. It is most common for both arms and both legs to be affected, the lower extremity being more frequently involved than the upper. The muscles primarily involved are those at the periphery of the part, as below the elbow and knee, principally the groups supplied by the musculospiral and popliteal nerves. From a loss of

power in the muscles of the anterior surface of the leg the "steppage" gait, in which the thighs are unduly flexed, results. The muscles of the neck, back, chest, and abdomen are rarely involved, save in the severest cases. When paralysis of the muscles of respiration or of the diaphragm takes place, the attack is liable to terminate fatally. Increased cardiac action and paralysis of the larynx occur from involvement of the pneumogastric nerve. Unless the spinal cord is affected the sphincters are not involved. Only in neuritis due to diphtheria have the cranial nerves been found affected; however, in rare instances there may be paralysis of the