Increased intracranial pressure caused by non-space-occupying arachnoid cysts: report of two patients.

In this article we report on two patients with arachnoid cysts previously treated by shunt implantation presenting with clinical signs of an increased intracranial pressure i. e., papilledema, headache and nausea. Repeated MRI scans showed no alteration of the cerebrospinal fluid circulation and no space-occupying effect of the cysts. Although neuroimaging showed no signs of increased intracranial pressure, neurosurgical exploration was performed and revealed a distinctly increased pressure in both arachnoid cysts. After replacement of the shunt a prompt reduction of papilledema and relief of symptoms was observed.