HY'DROCEPH'ALUS (Neo-Lat., from Gk. hydrokrphalon, water in the head, from i hydor, water + imDaAh.
head). A collection of serous fluid in the cra nium. If it is within the 1.entrieles of the brain, the condition is knom.n as internal hydrocephalus. If beneath the arachnoid membrane, ,xternal hydrocephalus. The disease may be primary, being then usually tuberculous in origin, or it may follow some other disease, iu which case it is termed sccondary. 'Three types, the acute, the chronic, and the congenital, are described. Hydro cephalus may occur in children or in adults as a secondary lesion resulting from meningitis. Iu such cases, the bones of the skull having milted, there is much less opportunity for distention.
Act•IT: Ilvintocr:PnAixs. This is usually a sudden disease, marked by an acute collection of fluid within the skull, internal or external to the brain ventricles. It may be primary or secondary to such diseases as whooping cough, heart disease, rachitis, tumors within the skull cavity, or acute fevers, such as pneumonia or typhoid. The symptoms are various, much de pending on its cause. The most characteristic
symptoms are those due to the pressure on the brain. In addition to the enlargement of the head, there may he much restICSSIIPSS• inability to sleep, miusea and vomiting, paralysis or con vulsions. The pupils are apt to be unequal and sluggish. In the severer cases pressure upon the brain causes death.
Cunoxia• YDRoCENIALUS. 'This may follow an acute attack. or the disease may begin very insidiously. The symptoms again are those due to pressure. The fontanelles in the skull are apt lo bulge, the eyeballs protrude somewhat, the blood-vessels on the outside of the head are apt to be swollen and Headache is com mon. A peculiar sidewise shifting movement of the eye, termed is very constant, and crossed eyes are not uneommon. There is usually notch restlessness, and if the patients live they arc apt to he dull mentally or idiotic. Some of these patients live to middle age, but most of them die young. The treatment requires the greatest medical and surgical skill.