I. HYDROCEPHALUS.
Under the term hydrocephalus are included all exudations of serum in the cavities of the brain and in its envelopes. We thus exclude the so called external hydrocephalus, which consists in the collection of fluid between the skin and the cranial bones, and which is purely the result of the uterine contractions, of pressure, or of traction made by the ac coucheur. " Under these influences, " says Herrgott, " internal hydro cephalus existing before labor, a small amount of the fluid contained with in the cranium escapes through one of the sutures and spreads over the external surface of the skull, so as to form a tumor added to the head. This pouch or tumor is simply a diverticulum, so to speak." Hydrocephalus, then, as we understand it, is purely dropsy of the cere bral ventricles, a dropsy which may spread into the substance of the brain, in the pia mater, into the sub-arachnoidean spaces, and finally between the cavity formed by the reflexion of the arachnoid on to the diva mater.
Frequency.—Hydrocephalus is infrequent. Thus: The above figures seem to us too low, for in our two years' service at the Clinique, in 2000 labors we saw three cases, and we have since seen four more in private practice. We believe that Merriman's figures, 1 out of 900, is near the truth.
Causes.—The following causes, more or less hypothetical, have been invoked: Advanced age of the parents, alcoholism, excess in coitus, syph ilis, chronic inflammations of the arachnoid and of the internal lining of the ventricle, interference with the venous circulation (Barrier), heredi tary cretinism (Ilengott); of all these causes syphilis alone would seem to have a real influence, as proved by the cases of Osiander, Haase, Bayer, Gros, Lanceraux. Against these, however, we can oppose the numerous cases of syphilis without hydrocephalus. In certain women there seems to be a habit of giving birth to hydrocephalic infants, as noted by Franck, Underwood, Gelis, Castelli, Armstrong. Bouchacourt finally insists on the influence of consanguineous marriages.
Pathological Anatomy.—The quantity of fluid in the cranial cavity may
vary from a few spoonfuls to a number of quarts. The fluid is like that of dropsy elsewhere, clear, light yellow, containing .246 per cent. of albumin (Hilger), soda salts, and extractives. Where hydrocephalus is complicated by anencephalus, the amount of albumin is greatly increased.
This liquid, distending the cerebral ventricles, pushes the cerebral matter aside, and this atrophies, and tends to disappear with increase in the amount of fluid. In certain cases the brain is converted into a cyst with thin walls. It is apparent that the head may assume enormous propor tions. Wrisberg has reported a case where the greatest diameter of the head was 9j inches, and the circumference 31 inches; Meckel a case where the bi-parietal diameter was 161 inches, and Verdu (1846) a case where the head was 10 inches long and 30 in circumference.
The bones are thinned out in accordance with the amount of distension, and sometimes they lose their consistency, and become as parchment. The fontanelles and the sutures, greatly enlarged, fluctuate, and through the intervals project pouches forming encephaloceles. Further, hydro cephalus may be complicated by hydrorachis and other malformations.
The physiognomy of hydrocephalus is always about the same. The face is small compared with the exaggerated development of the skull (Fig. 169), and the skull may be asymmetrical according as the distension affects one ventricle more than another. Poullet insists on the persist ence of the accessory sagittal suture.
We are more particularly concerned with the affection in its relations to pregnancy and labor.
Hydrocephalus during Pregnancy.—Ordinarily the affection is not recognized before the advent of labor. The symptoms during pregnancy are very vague. The size of the abdomen may be normal or increased; and sometimes, by conjoining the signs furnished by palpation, the touch, and auscultation, we may assume the presence of the affection. In the majority of cases, however, diagnosis during pregnancy is not possible.