This is either a termination or continuation of acute hydrocephalus, especially of the second form of it; or else it is chronic from the first. The symptoms during life in the latter case were not such as to indicate the existence of any acute disease of the brain; they were rather those of a long-continued disease which occasionally underwent exacerbations.

This form of hydrocephalus may occur at any period of life; but it is most frequent in the first years, and then attains its most advanced degree. The quantity of serum accumulated varies considerably, and depends upon the duration of the disease, and especially on the circumstances of the skull being closed, or not, when it commenced, and whether its origin date from early childhood. In the first case it amounts to two or four ounces; while in children, and in adults who have had the disease since childhood, it may be as much as six, eight, or ten ounces, or even more. In children the skull increases in volume in proportion to the quantity of serum and the enlargement of the ventricles, and, at the same time, acquires the well-known hydrocephalic form, which so often continues throughout the remainder of life. This hydrocephalus then precisely resembles the congenital disease, and might in any case be taken for it, were there no certainty that it had come on since birth. The anatomical description of it agrees entirely with that of the congenital disease.

In respect to its causes, and the mode of its development, it essentially corresponds with the second form of acute hydrocephalus; oftentimes it is a primary and substantive disease, but very frequently it is secondary and symptomatic. Thus in the child as well as in the adult it arises as a primary disease from repeated and continued active congestions, such as, in the former, occur during growth, and in the latter, more frequently from excessive exertions of mind, repeated intoxication, etc. As a secondary affection, it is a consequence of different diseases of the brain, particularly of adventitious growths within the cranium; or it comes on in the course of chronic diseases of the lungs, etc. Some growths are so situated that their pressure renders a sinus, particularly the straight sinus, impervious, and thus gives an especial occasion to chronic hydrocephalus (Barrier).

What has been said of the combinations of the second form of acute hydrocephalus applies to the chronic disease also. When thus combined it runs a lingering course, and has the character of a constitutional affection.

Terminations

a. Two circumstances may interfere with a complete cure of the disease by the reabsorption of the fluid, the great quantity accumulated, and the extent to which the skull is correspondingly enlarged. The only real cure is a cessation of the process, and then the quantity of this fluid continues undiminished throughout life, The question, as to a cure being brought about by means of hypertrophy of the brain, has been already met at p. 273.

B. The disease may terminate fatally -

(1.) By pressure, and consequent palsy of the brain, after having reached a certain degree, and having sometimes, in adults, occasioned absorption of the inner table of the skull;

(2.) By the supervention of, or advance of the process to, a considerable acute exudation into the substance of the brain, by oedema of the brain, and hydrocephalic softening;

(3.) By an attack of acute hydrocephalus and meningitis.