Teaching Neuro Images : Cortical blindness following acute obstructive hydrocephalus by a colloid cyst

Abstract

A 46-year-old woman was admitted for acute headache, postseizure confusion, and visual loss. Urgent head CT scan showed obstructive hydrocephalus due to a colloid cyst (figure 1). External ventricular drains inserted emergently demonstrated CSF under pressure, above 40 mm H2O. MRI confirmed the suspected diagnosis of a colloid cyst and highlighted bilateral occipital lobe infarcts (figure 2). CT angiography showed no thrombosis of the posterior cerebral arteries (PCAs). After neurosurgical excision of the colloid cyst, the patient remained blind. The presumed mechanism of infarction was acute compression of the PCAs against the edge of the tentorium cerebelli.