Headache: A Merck Manual of Patient Symptoms podcast

Idiopathic intracranial hypertension causes increased intracranial pressure without a mass lesion or hydrocephalus, probably by obstructing venous drainage; CSF composition is normal.

Idiopathic intracranial hypertension typically occurs in women of childbearing age. Incidence is 1/100,000 in normal-weight women but 20/100,000 in obese women. Intracranial pressure is elevated (> 250 mm H₂O); the cause is unknown but probably involves obstruction of cerebral venous outflow.

Symptoms and Signs

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.

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.

Diagnosis

• MRI with magnetic resonance venography
• Lumbar puncture

Diagnosis is suspected clinically and established by brain imaging (preferably MRI with magnetic resonance venography) that shows normal results, followed by lumbar puncture showing elevated opening pressure and normal CSF composition. Use of certain drugs and certain disorders can produce a clinical picture resembling idiopathic intracranial hypertension (see Table 5: Headache: Conditions Associated With Papilledema and Resembling Idiopathic Intracranial Hypertension).

Table 5
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Conditions Associated With Papilledema and Resembling Idiopathic Intracranial Hypertension Condition Examples Obstruction of cerebral venous drainage Cerebral venous sinus thrombosis Jugular vein thrombosis Disorders Addison disease COPD Hypoparathyroidism Iron deficiency anemia if severe Obesity (usually in young women) Polycystic ovary syndrome Renal failure Right ventricular heart failure with pulmonary hypertension Sleep apnea Drugs Anabolic steroids Corticosteroid withdrawal after prolonged use Growth hormone in patients with a deficiency Nalidixic acid Nitrofurantoin Tetracycline and its derivatives Vitamin A toxicity

Treatment

• Acetazolamide
• Weight loss
• Drugs used for migraine, especially topiramate

Treatment is aimed at reducing pressure and relieving symptoms. The carbonic anhydrase inhibitor acetazolamide (250 mg po qid) is used as a diuretic. Obese patients 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. Any potential causes (disorders or drugs) are corrected or eliminated if possible. Drugs used for migraine (particularly topiramate, which also inhibits carbonic anhydrase) may relieve headache. NSAIDs can be used as needed.

If vision deteriorates despite treatment, optic nerve sheath fenestration, shunting (lumboperitoneal or ventriculoperitoneal), or endovascular venous stenting may be indicated. Bariatric surgery with sustained weight loss may cure the disorder in obese patients who were otherwise unable to lose weight.

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.

Last full review/revision November 2012 by Stephen D. Silberstein, MD