Magnetic resonance imaging in pseudotumor cerebri.

OBJECTIVE To determine whether magnetic resonance (MR) imaging can be used to predict the presence of elevated intracranial pressure. DESIGN Retrospective case series. PARTICIPANTS Twenty patients with pseudotumor cerebri and 20 control subjects. INTERVENTION Magnetic resonance imaging. MAIN OUTCOME MEASURES The presence or absence of the following six neuroimaging signs was measured: (1) flattening of the posterior sclera; (2) enhancement of the prelaminar optic nerve; (3) distension of the perioptic subarachnoid space; (4) intraocular protrusion of the prelaminar optic nerve; (5) vertical tortuosity of the orbital optic nerve; and (6) empty sella. RESULTS The MR imaging disclosed flattening of the posterior sclera in 80% of patients with pseudotumor cerebri, empty sella in 70%, distension of the perioptic subarachnoid space in 45%, enhancement of the prelaminar optic nerve in 50%, vertical tortuosity of the orbital optic nerve in 40%, and intraocular protrusion of the prelaminar optic nerve in 30%. Each neuroimaging sign was detected in 5% of control subjects, except for enhancement of the prelaminar optic nerve, which was not detected in control subjects. Based on these MR imaging signs, the examiner was able to predict the presence of elevated intracranial pressure in 90% of cases with pseudotumor cerebri and the absence of elevated intracranial pressure in all control subjects. CONCLUSIONS Elevated intracranial pressure produces a constellation of MR imaging signs that can assist in establishing the diagnosis of pseudotumor cerebri.