Congenital Communicating Hydrocephalus

H YDROCEPHALUS, by current definition, means dilatation of the ventricular system, coupled with raised intracranial pressure, present or past2 Dilatation of the ventricular system without increased pressure is ascribed to atrophy. The fundamental problems of hydrocephalus were elucidated further by the investigations of Dandy and Blackfan2 They proved in experiments on the canine that the dilatation of the cerebrospinal-fluid pathways will extend only as far as the site of an experimental occlusion. They divided clinical hydrocephalus into communicating and noncommunicating types, depending on whether or not dye injected intraventricularly appeared in the lumbar subarachnoid fluid. In noncommunicating hydrocephalus there is an obstruction of the intracerebral ccrebrospinal-fluid pathways. In some cases of communicating hydrocephalus a tumor, a midline defect, or a postmeningitic arachnoiditis will explain the disorder. But in most cases of communicating hydrocephalus it has not been possible to demonstrate any occlusion of the pathways with the prevalent technique of examination. This fact has caused much speculation. Communicating hydrocephalus frequently has been characterized as congenital. 19 Anatomical abnormalities in the choroid plexus, 13 hypersecretion of the cerebrospinal fluid, 15 and stenoses or atresias of the intracranial venous sinuses TM all have been described as plausible explanations. Surgeons, e.g. Dandy and Blackfan, 4 Fraser and Dott , s and pathologists, e.g. Russell, 17 and Laurence 11 have described series of patients with communicating hydrocephalus and arachnoiditis, i.e. changes in the subarachnoid space following meningitis