Pitfalls in the diagnosis of arrested hydrocephalus.

Arrested hydrocephalus probably results from improvement of CSF circulation during growth. Although a generally accepted condition, its mode of onset, its presence in a given patient, and time required to establish the absence of progressive hydrocephalus have not been defined. Five patients are presented with ostensibly arrested hydrocephalus due to: aqueductal stenosis, communicating hydrocephalus, and Dandy-Walker malformation. In a period ranging from 4 to 13 years, they presented clinical signs of decompensation with intracranial hypertension. One had never had a shunt procedure. Another two were performing well in school until they suddenly deteriorated. The diagnosis of arrested hydrocephalus requires close follow-up well into adolescence, with periodical neurological and psychomotor evaluations. Sequential observation of the ventricular size with computed tomography (CT) is recommended.