NEURITIS (Gr. νεῦρον, nerve), a term applied to the inflammation of one or more bundles of nerve fibres. Two varieties are known, the localized and the multiple. The localized form frequently follows on exposure to cold and may attack a single nerve. Facial paralysis (Bell's palsy) is commonly seen following a neuritis of the facial nerve. Neuritis may follow blows and wounds of a nerve, injuries involving stretching of a nerve or long continued pressure such as may occur in a dislocation of the elbow joint, or the nerve may share in the extension of a neighbouring inflammation. The first symptom of a localized neuritis is pain of a boring character along the course of a nerve and its distribution, the part being sensitive to pressure. There may be slight redness and oedema along the course of the nerve, movement becomes painful in the muscles to which the nerve is distributed, numbness may follow and the tactile sense be impaired, finally the muscles atrophy, and degenerative changes may take place in the nerve or nerve sheath. Slight cases following cold or injury may pass off in a few days, while severe cases such as those following the pressure of an unreduced dislocation may last for months.
Multiple neuritis or polyneuritis is a disease which may affect many of the peripheral nerves symmetrically and at the same time. For the pathological changes see Neuropathology. Th e difference in these changes is due mostly to the difference in the aetiology of the neuritis. The causes may be divided as follows: (1) The toxins of acute infective diseases, such as diphtheria, influenza, typhoid fever, malaria, scarlet fever and septicaemia. (2) Acute or chronic poisoning by lead, arsenic, mercury, copper and phosphorus. (3) General disorders: gout, rheumatism, tubercle, carcinoma. (4) The local action of leprosy and syphilis. (5) Endemic disease: beri-beri. (6). Alcohol, the most common.
Alcoholic neuritis occurs as a result of constant steady drinking, particularly in those who drink beer rather than spirit. The earliest symptom is numbness of the feet and later of the hands, then painful cramps in the legs appear and there is pain on moving the limbs, or the patient complains of deadness, tingling and burning in the hands and feet, and superficial tenderness is occasionally present. In other varieties of the disease the earliest symptoms are weakness of the legs and extreme fatigue, leading to a characteristic "steppage gait," or marked inco-ordination of movement may occur and the gait become ataxic. Trophic changes soon appear, in some cases early and rapid muscular wasting occurs, the skin becomes dry and glossy, the nails brittle and the hair thin. In time actual contractures takes place, the hip and knee-joints become flexed and the foot dropped at the ankle. In cases that recover there may be permanent deformity. Should the case progress the patient may become bedridden and powerless, and degenerative mental changes may take place, loss of memory, irritability of temper and emotional instability. Various complications such as bronchitis, fatty changes in the heart, albuminuria and a liability to pulmonary tuberculosis, tend to carry off the victim of chronic alcoholic neuritis. Cases seen early in the progress of the disease, who can be placed under supervision, may recover under treatment, but those in whom the attacks have recurred several times and in whom there is much mental impairment rarely make a complete recovery. The treatment consists in putting the patient to bed, with the administration of strychnine hypodermically, and attention should be paid to the position of the limbs so as to avoid the development of contractures, cradles being used, the limbs kept in the correct positions by sandbags, and gentle massage being employed as soon as possible. Should contractures have already formed some mechanical device adapted to stretch the contracted muscle must be resorted to. Biers' hyperaemic suction apparatus is very useful in the painless stretching of contracted joints, or old-standing adhesions may have to be broken down under an anaesthetic, extension apparatus being afterwards worn. In the later treatment the galvanic and faradaic currents combined with massage are useful in helping to restore the wasted muscles, and hot-air baths and warm applications are appreciated.
Arsenical neuritis mostly affects the lower extremities, as contrasted with lead, which mainly paralyses the fingers and wrists; recovery is even slower than in alcoholic neuritis, the treatment being on the same lines, with the removal of the cause of the disease. In the neuritis of chronic lead poisoning a fine tremor of the hands is an early symptom and sensory symptoms are usually absent; the muscles affected are the extensors of the wrists, thumb and fingers (see Lead Poisoning
). The course of the disease is long, and an attempt should be made to eliminate the lead from the system by purgatives and the administration of potassium iodide.
The diabetic neuritis paraesthesia is slight, and the legs are chiefly affected; weakness and ataxia may be present. Trophic sores on the feet are of frequent occurrence in this variety. The treatment is that of the disease.
Post-diphtheritic neuritis occurs in about 10% of all cases of diphtheria. In this form paralysis of the soft palate is the earliest symptom, and this may be the only one, or the pharynx may be affected. The limbs are affected much later, usually about the 5th or 6th week. Atrophy of the muscles is frequently rapid. If the respiratory muscles are unaffected the prognosis is good, but the paralysis of the limbs may last for several months. The treatment is complete rest, good food and the administration of strychnine.
Acute polyneuritis with numbness and motor weakness has been noted after influenza, together with slight muscular wasting and electrical degeneration. Later, loss of sensation in the peripheral portion of the limbs is complained of, and the motor weakness may affect the muscles of the trunk and face. Such cases tend towards complete recovery.