MRI Indicators of Papilledema in Brain Tumors.

Background: Intraventricular blockage of cerebrospinal drainage by brain tumors has been proposed as a more powerful mechanism of producing high intracranial pressure (ICP) than tumor size. We tested that hypothesis by investigating the MRI signs closely associated with high ICP in brain tumors.

Methods: We conducted a single-institution retrospective chart review of patients with brain tumors between 1990 and 2023. We selected 100 cases from a larger eligible cohort without regard to clinical or imaging features. Based on ophthalmologic examination, 57 patients had papilledema and 43 patients did not. The study neuroradiologist, masked as to the presence of papilledema, noted relevant MRI brain and eye signs. Associations between these MRI signs and papilledema were analyzed statistically.

Results: The median age of patients with papilledema was significantly younger than that of patients without papilledema. Among the MRI brain signs, the degree of ventriculomegaly was most highly associated with papilledema, and a temporal horn size of greater than 10 mm predicted a 100% chance of papilledema in patients aged 20 years or younger. Tumor size was not associated with papilledema. Posterior scleral flattening and optic disc protrusion were also highly associated with papilledema but were often difficult to identify because of their subtlety.

Conclusions: The degree of ventriculomegaly, especially of the temporal horn, was the MRI brain sign most associated with papilledema, whereas tumor size was not associated with papilledema. These findings support the idea that intraventricular obstruction of cerebrospinal fluid flow is more likely than tumor size to elevate ICP. Together with posterior scleral flattening and optic disc protrusion, ventriculomegaly can be used to predict with high probability the presence of elevated ICP and as a substitute for finding papilledema on ophthalmologic examination, a service that may not be available in low resource settings.