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Objective:
Urgent head MRI or CT is recommended for papilledema and new onset headache, as these may indicate raised intracranial pressure and neurologic emergencies. Patients are increasingly presenting to the emergency department (ED) with these symptoms, however, due to idiopathic intracranial hypertension (IIH). Some may also share risk factors for cerebral venous sinus thrombosis (CVST). Although MRI is recommended over CT imaging in patients with suspected IIH, head CT and venography is often requested in the ED due to increased availability. The utility of CT and MRI in this cohort and the incidence of CVST is unknown. We hypothesize that the diagnostic yield of MRI and venography is noninferior to CT imaging and venography unless red flags are present.

Materials and Methods:
We conducted a retrospective review of head CT and venogram imaging performed at a single center from January 2018 to September 2021 in patients who presented to the ED with papilledema and clinically suspected raised intracranial pressure. Subsequent MRI was also reviewed. The diagnostic outcomes and management were recorded and analyzed.

Results:
A total of 358 patients (286 women, 72 men; mean age 32.4 (SD = 13) years) were included. The diagnostic yield of CT imaging and venography for papilledema and suspected raised intracranial pressure was low for significant pathology (5.9%); CVST (1.4%) and moderate or major neurosurgical findings, including intracranial mass and hydrocephalus (4.5%). 1.7% had equivocal findings with no significant management impact. 33% had features suggestive of IIH on CT imaging. The diagnostic yield for CVST (100%) and moderate or major neurosurgical findings (88%) increased when there were red flag symptoms. 146 patients had subsequent MR head imaging. MR imaging findings were concordant with CT imaging, with 1.1% additional diagnostic yield of demyelination. 51% had raised opening CSF pressures in keeping with IIH on subsequent lumbar puncture.

Conclusion:
The diagnostic yield of head CT and venography in ED patients for papilledema and suspected raised intracranial pressure is very low, unless there are red flag symptoms. Most patients are young women without significant acute intracranial pathology. A large proportion have underlying IIH. This trend is expected to increase given the increased prevalence and incidence of IIH. MRI and venography has higher diagnostic yield compared with CT imaging and venography, and does not involve the risks of ionizing radiation and iodinated contrast (5). We propose urgent head CT and venogram in ED patients with papilledema and symptoms of raised intracranial pressure with red flags. Without red flags, nonemergent head MRI and venography is advised as the first-line investigation.