Idiopathic intracranial hypertension causes increased intracranial pressure without a mass lesion or hydrocephalus, probably by obstructing venous drainage; cerebrospinal fluid composition is normal.
(See also Approach to the Patient With Headache.)
Idiopathic intracranial hypertension typically occurs in women of childbearing age. Incidence is 1/100,000 in normal-weight women but 20/100,000 in women with obesity. Intracranial pressure (ICP) is elevated (> 250 mm H2O); the cause is unknown but can involve obstruction of cerebral venous outflow, which can result from increased CSF pressure which can result in increased venous obstruction—a vicious circle.
Symptoms and Signs of Idiopathic Intracranial Hypertension
Almost all patients have a daily or near daily generalized headache of fluctuating intensity, at times with nausea. They may also have transient obscuration of vision, diplopia (due to 6th cranial nerve dysfunction), and pulsatile intracranial tinnitus. Vision loss begins peripherally and may not be noticed by patients until late in the course. Permanent vision loss is the most serious consequence. Once vision is lost, it usually does not return, even if ICP is reduced.
Bilateral papilledema is common; a few patients have unilateral or no papilledema. In some asymptomatic patients, papilledema is discovered during routine ophthalmoscopic examination. Neurologic examination may detect partial 6th cranial nerve palsy but is otherwise unremarkable.
Pearls & Pitfalls
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Diagnosis of Idiopathic Intracranial Hypertension
MRI with magnetic resonance venography
Lumbar puncture
If clinical findings suggest idiopathic intracranial hypertension, clinicians should check visual fields and optic fundi, even in patients with no visual symptoms.
Diagnosis of idiopathic intracranial hypertension is suspected clinically and established by brain imaging (preferably MRI with magnetic resonance venography) that has normal results (except for narrowing of the venous transverse sinus). If not contraindicated, lumbar puncture with cerebrospinal fluid (CSF) testing is then done. Elevated opening pressure and normal CSF composition suggests idiopathic intracranial hypertension.
Use of certain medications and certain disorders can produce a clinical picture resembling idiopathic intracranial hypertension and should be excluded (see table Conditions Associated With Papilledema and Resembling Idiopathic Intracranial Hypertension).
Treatment of Idiopathic Intracranial Hypertension
Weight loss if needed
Sometimes surgery
Idiopathic intracranial hypertension occasionally resolves without treatment.
Treatment of idiopathic intracranial hypertension is aimed at the following:
Reducing pressure
Preserving vision
Relieving symptoms
Preventive medications used for migraine may relieve headache. Nonsteroidal anti-inflammatory drugs (NSAIDs) can be used as needed.
Patients with obesity are encouraged to lose weight, which may help reduce intracranial pressure.
Serial lumbar punctures are controversial but are sometimes used, particularly if, while waiting for definitive treatment, vision is threatened. Definitive treatment includes optic nerve sheath fenestration, shunting, and venous sinus stenting.
Any potential causes (disorders, drugs, or medications) are corrected or eliminated if possible.
Frequent ophthalmologic assessment (including quantitative visual fields) is required to monitor response to treatment; testing visual acuity is not sensitive enough to warn of impending vision loss.
If vision deteriorates despite treatment, one of the following may be indicated:
Optic nerve sheath fenestration
Shunting (lumboperitoneal or ventriculoperitoneal)
Endovascular venous stenting
Bariatric surgery with sustained weight loss may cure the disorder in patients who have obesity and were otherwise unable to lose weight.
Key Points
Consider idiopathic intracranial hypertension if patients, particularly women with excess body weight, have a daily generalized headache with or without visual symptoms; check visual fields and optic fundi.
Diagnose based on results of brain imaging (preferably MRI with venography) and, if not contraindicated, lumbar puncture; consider chronic meningitis.
Do frequent ophthalmologic assessments (including quantitative visual fields) to monitor response to treatment.
If vision deteriorates despite treatment, consider optic nerve sheath fenestration, shunting, or endovascular venous stenting.
