Should Magnetic Resonance Venography be Performed Routinely in all Patients Undergoing Evaluation for Idiopathic Intracranial Hypertension?

Idiopathic intracranial hypertension imaging approaches and the implications in patient management

Idiopathic intracranial hypertension (IIH) represents a clinical disease entity without a clear etiology, that if left untreated, can result in severe outcomes, including permanent vision loss. For this reason, early diagnosis and treatment is necessary. Historically, the role of cross-sectional imaging has been to rule out secondary or emergent causes of increased intracranial pressure, including tumor, infection, hydrocephalus, or venous thrombosis. MRI and MRV, however, can serve as valuable imaging tools to not only rule out causes for secondary intracranial hypertension but can also detect indirect signs of IIH resultant from increased intracranial pressure, and demonstrate potentially treatable sinus venous stenosis. Digital subtraction venographic imaging also plays a central role in both diagnosis and treatment, providing enhanced anatomic delineation and temporal flow evaluation, quantitative assessment of the pressure gradient across a venous stenosis, treatment guidance, and immediate opportunity for endovascular therapy. In this review, we discuss the multiple modalities for imaging IIH, their limitations, and their contributions to the management of IIH.

Papilledema: A Review of the Pathophysiology, Imaging Findings, and Mimics

Increased intracranial pressure is the most common cause of papilledema. Multiple etiologies such as cerebral edema, hydrocephalus, space occupying lesions, infection, and idiopathic intracranial hypertension among others should be considered. Imaging plays a critical role in the detection of pathologies that can cause papilledema. MRI with contrast and CE-MRV, in particular, are key for the diagnosis of idiopathic intracranial hypertension. This review will focus in common and infrequent causes of papilledema, the role of imaging in patients with papilledema as well as its potential mimickers.

MRI findings as markers of idiopathic intracranial hypertension

PURPOSE OF REVIEW

Negative findings on neuroimaging are part of the diagnostic criteria for idiopathic intracranial hypertension (IIH), a syndrome characterized by increased intracranial pressure (ICP). Some positive neuroimaging findings are associated with increased ICP, but their role in diagnosis of IIH has not been established. We provide an overview of these findings and their relevance for diagnosis of raised intracranial pressure.

RECENT FINDINGS

MRI acquisition techniques have significantly improved in the last few decades leading to better characterization of the intracranial changes associated with IIH, including empty sella turcica, optic nerve tortuosity, distension of the optic nerve sheath, posterior globe flattening, slit-like ventricles, and venous sinus stenosis. These may be MRI biomarkers of increased ICP. Prevalence difference between people with and without increased ICP, and reversibility of these MRI findings following treatment of increased ICP inform evaluation of their diagnostic potential.

SUMMARY

MRI and magnetic resonance venography findings are important tools in the diagnosis of IIH. Empty sella turcica, optic nerve protrusion, distension of the optic nerve sheath, optic nerve tortuosity, posterior globe flattening, and transverse sinus stenosis have been found to be the most promising diagnostic markers for IIH, although absence of these findings does not rule out the diagnosis.

Magnetic resonance or computed tomography venography in the evaluation of young overweight women with papilledema

BACKGROUND/OBJECTIVES

To compare the yield of magnetic resonance venography (MRV)/computed tomography venography (CTV) in a group of overweight women with incidentally-discovered papilledema and symptomatic intracranial hypertension (IC-HTN) patients without risk factors for dural venous sinus thrombosis (DVST).

DESIGN

Retrospective cohort study.

METHODS

Retrospective cohort study of female patients between ages 16 and 50 with papilledema, body mass index >25 kg/m² and MRV/CTV imaging. Patients were excluded if they had risk factors for DVST. The incidence of DVST and clinical features were retrieved. Patients were divided into those with incidentally-discovered papilledema (Group-1) and those who presented due to symptoms of IC-HTN (Group-2).

RESULTS

One hundred three patients (45 Group-1, 58 Group-2) were included in the study. Group-2 patients were more likely to have pulsatile tinnitus (p = 0.017), transient visual obscurations, and showed a trend towards increased headache (p = 0.058). Group-2 was also more likely to have been treated with acetazolamide (p < 0.01) and undergo lumbar puncture (p = 0.02). DVST was initially reported in four patients (one in Group-1, three in Group-2), but after further review, two cases (one from Group-1, one from Group-2) were found to be false positives. The final two DVST diagnoses were in Group-2 and presented with significant neurological symptoms.

CONCLUSIONS

DVST was not found among a group of 45 young, overweight women with incidentally-discovered papilledema and without DVST risk factors. We therefore believe it is reasonable practice to perform MRI alone, without dedicated MRV/CTV, in the investigation of young, overweight women with incidentally-discovered papilledema without risk factors for DVST.

Update on the Diagnosis and Treatment of Idiopathic Intracranial Hypertension

Advances in ophthalmic diagnostics and results of interventional clinical trials are shifting diagnosis and management of idiopathic intracranial hypertension (IIH) to be more technology- and evidence-based. In this article, the evidence supporting current diagnostic criteria, evaluation, and medical and surgical management of IIH are reviewed.