Imaging of Idiopathic Intracranial Hypertension

Abstract

Idiopathic intracranial hypertension (IIH) is a syndrome due to increased intracranial pressure without any evident cause, previously known as pseudotumor cerebri. We discuss the etiology, epidemiology, clinical symptoms, treatment options, and radiological findings of IIH, a rare condition with a predominance in obese women of reproductive age but also seen in men and children. The pathophysiology of IIH is not well understood, and several mechanisms are suggested to play a role such as excessive cerebrospinal fluid (CSF) production, impaired CSF absorption, increased intravascular volume, or increased intracranial venous pressure. Known risk factors are certain medications, hormonal alterations, infections, as well as autoimmune disorders. Main clinical symptoms of IIH are headache and vision loss, less frequently pulsatile tinnitus, diplopia, photopsia, eye pain, or cranial nerve palsies. Ophthalmological evaluation usually reveals papilledema. Lumbar puncture demonstrates elevated opening CSF pressure. The role of clinical neuroradiology is firstly to exclude causes of secondary intracranial hypertension due to space-occupying masses, hydrocephalus, infection, or vascular pathologies including venous sinus thrombosis. Secondly, imaging can show findings that support the diagnosis of IIH such as enlargement of the perioptic CSF spaces, tortuosity of the optic nerves, flattening of the posterior aspect of sclera, intraocular protrusions of optic nerve heads and their contrast enhancement, partially empty sella, enlarged Meckel’s cave, small meningoceles within the skull base, slit-like ventricles, acquired tonsillar ectopia, and transverse sinus narrowing. Recommended radiological protocol includes contrast-enhanced MR examination of the brain and orbits followed by MR venography.

This publication is endorsed by: European Society of Neuroradiology (www.esnr.org).