1. INTRODUCTION
The term "hydrocephalus" is merely a symptomatic designation for an idiopathic disease. The subdivisions into acute and chronic, internal and external, congenital and acquired, are made according to no one standard, but according to several—pathological, clinical and embryological. Such subdivisions do not clarify the pathogenesis, but serve to obscure it. Chronic internal hydrocephalus, whether congenital or acquired, is the most important and frequent form encountered.Internal hydrocephalus is characterized by a progressive accumulation of cerebrospinal fluid in the ventricles, causing their dilatation and a consequent cortical atrophy and, when possible, enlargement of the head. The disease is usually fatal; spontaneous recovery, however, does occur in a small percentage of cases.Numerous forms of treatment have been suggested and tried, but, as the number of methods indicates, they have been almost uniformly unsuccessful. The etiology being so obscure, any treatment is necessarily empirical and