HYDROCEPHALUS, a dropsical effu sion of fluids into the interior of the skull, occupying one or more of the ventricles of the brain or the submeningeal space, or both. The symptoms of acute meningitis are such that the older authors called this disease acute hydro cephalus, but there may be very little fluid exudation in meningitis, and when present it is not often clear and watery. The causes of chronic hydrocephalus are various. A low grade inflammation may give rise to chronic hydrocephalus, just as chronic peritonitis is ac companied by fluid in the belly, but the usual cause of chronic hydrocephalus is some ob struction to the venous circulation. It is re garded as certain that arrest of development of the brain-substance, pressure upon the veins of Galen by masses of tubercle or cancer, and in fact any condition which obstructs the venous circulation in the brain, may lead to hydro cephalic effusion, just as pressure on the veins of flue leg may produce dropsy of the feet. It is probable also that in arrest of brain develop ment the increase of the normal subarachnoid fluid is a conservative process, serving to keep full the space between the brain and the cranium. The large majority of cases are con genital, and hydrocephalus must be set down as a disease (or symptom) belonging to infantile life; but cases occasionally occur in mature life or in old age. Dean Swift, after three years
of illness, died with hydrocephalus, the result, doubtless, of organic brain disease. The prog nosis of chronic hydrocephalus is very grave. The child may live for many years, but, with rare exceptions, becomes idiotic, and in some cases is epileptic. The head becomes distended, the fontanels remain open, supernumary bones form in the courses of the cranial sutures, and in some cases quarts of fluid are effused, con sisting of water, with earthy salts and a little albumin; while in acute hydrocephalus there is sometimes much albumin present, with some pus-corpuscles or a little blood. When the dis ease is detected early, mercurial inunctions, with the administration of the iodides, may possibly afford benefit. Treatment by systematic com pression or by tapping the skull has been tried in many cases, hut the most common result has been the speedy death of the patient, although in a few instances it would appear that more or less advantage has been obtained by these means. The term spurious hydrocephalus is sometimes applied to cholera infantum, infantile typhoid or other enteric disease, the general symptoms of which may simulate those of acute meningitis.