Pyrexia From Lesions Of The Central Nervous System

There are many cases on record in which injuries or diseases of the brain have led to elevation of temperature, sometimes to a high degree. These clinical observations have been confirmed by physiological experiment. The clinical cases consist of various lesions of the brain and cord, such as tumours, injuries, haemorrhages, etc. The experiments were generally such as separate the medulla oblongata from the pons.

Dr. Hale White has made a very admirable collection of cases of pyrexia from disease of the nerve centres. He classifies the cases in twelve groups, which include tumours of the brain and cord, haemorrhages, especially of the pons, embolism, ill-defined degenerations, insular sclerosis, locomotor ataxia, obscure nervous cases (including hysterical pyrexia), mental disease, injuries to the spine and brain. He endeavours to give unity to the cases on the ground that in all of them there is interruption of nerve-fibres passing from a supposed centre in the motor region of the cortex of the brain.

The experiments of Wood of Philadelphia are most important in regard to the production of pyrexia from injury to the brain and cord. A section at the junction of the pons and medulla, if made in such a way as not to injure the vasomotor centres in the medulla oblongata, causes a rise in the temperature of the animal.

Both Hale White and Wood found that injuries or diseases of the central nervous system sometimes lead to a fall of temperature. Such a result seems always referable to a vaso-motor paralysis of the vessels of the skin, the congestion of these vessels causing an undue cooling of the body.

From these observations an endeavour has been made to establish the existence of a calorific or thermic centre in the brain, that is to say, of a centre which, by its own action, is capable of producing heat. We have seen that the nervous system has arrangements for the regulation of the temperature, but there is not sufficient evidence that there is any single centre having a direct control of the process of heat production. The lesions which lead to elevation of temperature are such as to produce complex derangement of the vaso-motor and muscular functions, and it cannot be said that these have been sufficiently eliminated to prove the existence of a centre which produces its effects apart from the,ordinary processes in the muscles, blood-vessels, etc.

According to the views of Wood, which are partly adopted by Hale White, the heat-producing tissues have a continual tendency to produce too much heat, and the thermal centre is chiefly exercised in controlling or inhibiting the process. As the nervous lesions which cause a rise in temperature are chiefly such as paralyze or divide the nervous connections, it is supposed that they act by removing the inhibition of the thermic centre.

Pyrexia From Contamination Of The Blood. Fever Proper

In the great majority of cases pyrexia is produced by the existence in the blood of abnormal matters. These are most commonly the products of the action of microbes, but the microbes themselves need not enter the blood; it is sufficient that their toxines be present there. Thus putrid matter injected into the blood gives rise to fever, but it does so when all solid particles have been removed, and only the dissolved products used. In the case of putrid wounds or inflammations, we commonly have fever, but there is not usually any actual propagation of bacteria in the blood. In tuberculosis also, fever is usually present, but it seems doubtful whether the tubercle bacillus is at all capable of multiplication in the blood.

But fever may be produced without the agency of microbes. It has been induced by the injection of small quantities of water containing granules of starch or charcoal. These particles having caused obstruction of the pulmonary capillaries, the blood shut off from the circulation undergoes metamorphosis, and its products, being absorbed, cause pyrexia. The products of metamorphosis of the blood, produced in other ways, may lead to fever. Thus the injection of large quantities of pure water, apparently by causing solution of the red corpuscles, leads to elevation of temperature (Billroth and others). Even an extravasation of blood in the tissues and the absorption of its products may lead to pyrexia. Thus Volkmann found that in 14 cases of simple fracture of the femur, fever was present in 11 cases, in 5 it lasted for several days, in one as long as ten.

Fevers have been divided into three stages, namely, rigor or cold stage, fastigium or acme, and crisis.

During the Cold stage there is a marked feeling of cold, and the skin is cold to the touch, and pale or livid in appearance. The feeling of cold is actually due to a reduction in the temperature of the skin, and the shivering which is often pronounced in this stage is a reflex phenomenon, just like ordinary shivering from cold. The coldness of the surface is due to a general spasm of the cutaneous arteries.

While the surface is cold there is a great rise in the internal temperature. This rise may be partly the result of the diminished loss of heat from the surface, but is not entirely so. The rise is too great to be accounted for in this way. For instance, Liebermeister found that in the cold stage of intermittent fever the temperature in the rectum rose in thirty minutes as much as 2.31° C. (4° F.). This author also determined that in the cold stage there is a great increase in the process of combustion, as evidenced by the elimination of carbonic acid. The very rapid rise in temperature is therefore due to increased production, with diminished discharge, of heat.

The Fastigium is characterized by a more or less continued elevation of temperature, which may last for days and weeks and keep near that attained at the end of the cold stage. There is a great increase both in the production and discharge of heat. The former is evidenced by an increased absorption of oxygen and discharge of carbonic acid, and the latter has been determined by actual observation. The hot skin of the fever patient is generally a sufficient indication of excessive discharge of heat, but Leyden has demonstrated it by experiment, in which the leg was put into a bath, and the loss of heat measured by the rise in temperature in the water.