Idiopathic intracranial hypertension !

Raised pressure of the fluid around the brain with no tumour or other cause, usually in young women with obesity. It causes headache and can damage sight.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

A condition with raised intracranial pressure and papilloedema but normal brain imaging and normal cerebrospinal fluid composition, with no other identifiable cause. Formerly called pseudotumor cerebri or benign intracranial hypertension; it is not benign, because it can cause permanent vision loss.

Who gets it

Typically affects women of childbearing age with obesity; incidence rises with obesity rates, which are high and increasing in Colombia and the rest of Latin America. Uncommon in men and in children before puberty, where secondary causes are more likely.

Causes

Cause unknown; disturbed production or absorption of cerebrospinal fluid is suspected
Narrowing (stenosis) of the transverse venous sinuses, which raises venous pressure and reduces CSF drainage
Secondary intracranial hypertension with the same picture can follow drugs (tetracyclines, excess vitamin A or retinoids, corticosteroid withdrawal) or venous sinus thrombosis, which must be excluded

Risk factors

Female sex, age about 15 to 45 years
Obesity and recent weight gain
Tetracycline-class antibiotics, retinoids and high vitamin A intake
Endocrine conditions (e.g. polycystic ovary syndrome) and obstructive sleep apnoea are associated

Pathophysiology

Cerebrospinal fluid pressure rises without a mass or hydrocephalus. The pressure is transmitted along the optic nerve sheath, blocks axoplasmic flow and swells the optic disc (papilloedema); prolonged swelling kills optic nerve fibres and narrows the visual field. The abducens nerve, with its long intracranial course, can be stretched and cause a false localising sixth-nerve palsy.

Classification

Typical IIH with papilloedema
IIH without papilloedema (IIHWOP), diagnosed with stricter criteria
Fulminant IIH: rapid vision loss within weeks, needing urgent surgery

Symptoms and signs

Daily headache, often worse lying down, on waking, or with coughing and straining
Brief episodes of visual blurring or greying out (transient visual obscurations), often on standing
Pulsatile tinnitus (a whooshing sound in time with the pulse)
Double vision from sixth-nerve palsy
Nausea, neck or back pain; some people have no symptoms and are found on an eye exam

Diagnosis

Clinical: Fundoscopy shows bilateral papilloedema; neurological examination is normal except for a possible sixth-nerve palsy. Formal visual field testing (perimetry) and visual acuity are essential at baseline.
Tests: Lumbar puncture in the lateral decubitus position after imaging shows a raised opening pressure (above about 25 cm H2O in adults) with normal CSF cell count, protein and glucose. Optical coherence tomography measures optic disc swelling.
Imaging: Brain MRI with MR venography (or CT venography) is required first to exclude a mass, hydrocephalus and venous sinus thrombosis. Supportive signs include an empty sella, flattened posterior globes, distended optic nerve sheaths and transverse sinus stenosis.

Differential diagnosis

Cerebral venous sinus thrombosis
Brain tumour or other intracranial mass
Meningitis or other cause of raised CSF pressure
Pseudopapilloedema (e.g. optic disc drusen)
Migraine or medication-overuse headache

Goal of treatment

Protect vision above all, lower intracranial pressure and relieve headache, and treat the underlying driver, mainly weight.

Treatment

Lifestyle: Weight loss (about 5–10% of body weight) can put the disease into remission; stopping any causative drug.
Medical: Carbonic anhydrase inhibitors (acetazolamide) reduce CSF production and are first-line drug treatment; topiramate is an alternative that also helps headache and weight.
Procedure: Lumbar puncture lowers pressure temporarily; venous sinus stenting is an option in selected patients with transverse sinus stenosis.
Surgical: When vision is threatened: CSF shunting (ventriculoperitoneal or lumboperitoneal) or optic nerve sheath fenestration; bariatric surgery for weight in selected people.
Follow-up: Serial visual fields, acuity and fundoscopy or optical coherence tomography; the frequency depends on severity.

Complications

Permanent visual field loss and, in severe cases, blindness from optic atrophy
Chronic disabling headache
Shunt failure or infection after surgery
Recurrence with weight regain or pregnancy

Prognosis

Many patients improve with weight loss and medical treatment, but a significant minority keep some visual field loss. Recurrence is common with weight regain. Prognosis for vision depends on early diagnosis and close follow-up.

Test yourself

Think of the answer, then tap the question to see it.

Who is the typical patient with idiopathic intracranial hypertension?

A woman of childbearing age with obesity, with headache, transient visual obscurations and bilateral papilloedema.

What lumbar puncture findings support IIH?

A raised opening pressure with normal CSF composition (cells, protein and glucose).

Which imaging must be done before diagnosing IIH, and why?

Brain MRI with MR venography, to exclude a mass, hydrocephalus and cerebral venous sinus thrombosis.

Which cranial nerve palsy is a classic false localising sign in IIH?

Sixth nerve (abducens) palsy, causing horizontal double vision.

What is the first-line drug treatment for IIH?

A carbonic anhydrase inhibitor (acetazolamide), together with weight loss.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Idiopathic intracranial hypertension (MedlinePlus (U.S. National Library of Medicine), 2024).

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Representative model, for educational purposes only.

Optic disc highlighted on the Durgical 3D model