Background: Arachnoid cysts are benign intracranial collections formed by the accumulation of cerebrospinal fluid between the arachnoid membranes. Cerebral shunt implantation is usually reserved for selected symptomatic cases. Shunt dependency syndrome is a relatively rare and underdiagnosed complication of cerebral shunt implantation that has been described almost exclusively in children.

CASE REPORT: A 50-year-old man with a history of cystoperitoneal shunting for a temporal lobe arachnoid cyst at age 34 presented with recurrent episodes of severe headache, nausea, vomiting, and unilateral amaurosis over the preceding 10 years. Brain imaging showed normal-sized ventricles, with no changes in the size of the arachnoid cyst or the position of the cystoperitoneal shunt. Shunt dependency syndrome was suspected, and replacement of the cystoperitoneal shunt system eventually led to resolution of symptoms.

CONCLUSIONS: This case highlights the importance of recognizing shunt dependency syndrome, even in adult patients, to prevent long-term neurological complications.

KEYWORDS: Headache; slit ventricle syndrome; ventriculoperitoneal shunt; intracranial hypertension; arachnoid cysts