Even in cases where the cerebral congestion has preceded the convul sion, it seems probable that something besides mere distention of ves sels, unless this be extreme, is necessary to give rise to the eclamptic seizure. Some time ago I was asked to see a little child, aged. six months, who had impetigo of the head. The cervical glands of both sides were enlarged and had set up considerable pressure upon the veins of the neck —enough, indeed, to induce great cedema of the head and face. In this case, where there must have been serious impediment to the return of blood from the brain, there were no signs of nervous disturbance. So in cases of enlarged bronchial glands with pressure upon the vascular trunks in the chest, oedema of the head and neck is sometimes produced, and some heaviness may be complained of ; but convulsions are not a symptom of the disease.
It appears probable that in many cases, in addition to the engorged state of the blood-vessels, small embolisms or thromboses in the minute arteries and capillaries of the brain may be agents in the production of nervous symptoms. Dr. Bastian found this condition of the brain in per sons who had died whilst suffering from delirium and coma in the course of acute specific diseases, and has recorded his belief that minute and widespread congestions are often a consequence of these obstructions. There is no reason to suppose that young children differ in this respect from older persons ; and probably the convulsive seizures which often oc cur towards the close of measles, scarlatina, and other infectious fevers, may owe their origin not to the accompanying congestion, but to minute plugging of the cerebral capillaries. Such vascular obliterations, if widely distributed, must produce, as Dr. Bastian remarks, " total disturbance in the incidence of blood-pressure, and in the conditions of nutritive supply in the convolutional gray matter of the brain." Besides the eruptive fevers and convulsive attacks, exposure to extreme heat and cold, or direct violence applied to the head, may be, directly or indirectly, determining causes of acute hypermmia of the brain. A passive congestion may be induced in the child during a difficult labour ; it is sometimes the consequence of energetic expiratory effort in whooping cough ; it may be set up by diseases of the heart and lungs, or by other causes which interfere with the return of blood from the head ; and it may be induced by the pressure of intracranial growths upon the cerebral sinuses and veins.
Morbid Anatomny.—A congested brain has a swollen appearance. The dura mater is tightly stretched; and if slits are inadvertently made in the membrane in the process of removal of the calvarium, the organ bulges through the artificial opening. The convolutions look broad. They are flattened by pressure against the bones of the skull, and their sulci are nar rowed. The veins of the pia mater are engorged, tortuous, or even vari cose ; and the small vessels are filled to their minnte ramifications. The
cranial sinuses are distended with thick, dark, partially coagulated blood, and the choroid plexuses are also congested. The gray matter of the brain is also darker than natural, and its section shows fine dots from the in jected vessels. The white substance also contains numerous red points, and sometimes the :cerebral tissue is oedematous, with excess of fluid in the ventricles. In cases where the congestion has existed for some time, little masses of blood pigment may be found lying outside the vessels within the lymphatic sheath. These are described by Bastian as molecular grains of a dark olive or amber colour.
Symptoms.—Signs of general irritability of the nervous system, such as heat of head, fretfulness, dislike to light and noise, disturbed sleep, starlings and have been said to constitute an early stage of cere bral congestion. Such symptoms in impressionable infants frequently ac company digestive disturbance and teething, but are more probably due to reflex irritation of the nervous centres than to engorgement of the cere bral capillaiieg and veins. They are often, perhaps, accompanied by in creased activity of the cerebral circulation, but are not necessarily induced by it. The so-called " irritative stage " of cerebral congestion, then ap pears to me to be one which cannot be clinically recognised, at least I know of no evidence to show that the symptoms said to be characteristic of this stage have any necessary relation to an engorged state of the cere bral circulation.
The common form in which congestion of the brain is met with in practice is that in which an infant who has been taken with violent convul sions from teething, or other form of reflex irritation, is left drowsy and stupid after the fits have subsided. Instead of clearing quickly away the heaviness continues. The child lies with his head retracted on his shoulders, sometimes he vomits, and he may even squint. In these cases congestion with effusion of serosity into the lateral ventricles, and perhaps the substance of the brain, appears to be an important agent in the pro duction of the symptoms. In cases of death we find excess of fluid in the ventricles ; the volume of the brain, is increased, the convolutions are flattened, and the vessels of the brain and the pia mater are engorged with blood. Such a case has already been narrated in the chapter on convul sions. Another, which seems to have been of a similar kind, although it ended differently, is the following : A little boy, seven months old, a strong, healthy-looking child, who was being brought up at the breast, and had cut four of his teeth, was suddenly attacked with vomiting and purging. The symptoms appear to have been severe, for after a few hours the child fell into a lethargic state in which he lay for four days. At the end of this time he had a fit which lasted six hours. For the next ten days he was drowsy and half stupefied. His bowels were confined and once or twice he vom ited.