AKT · Neurology/Headache & facial pain

Idiopathic intracranial hypertension

Raised ICP without a mass or hydrocephalus

Overview

Raised intracranial pressure with no mass lesion, hydrocephalus or venous thrombosis — classically a young obese woman, often on a precipitant drug. The threat is progressive visual loss from papilloedema. A diagnosis of exclusion after venous imaging.

Recognise

Headache (worse lying down/on waking), pulsatile tinnitus, transient visual obscurations
PAPILLOEDEMA; may have a sixth-nerve palsy (false localising sign), enlarged blind spot, visual field loss
Typically young, obese women; drugs: COCP, tetracyclines, retinoids, steroids, lithium

Red flags

Progressive visual field loss / worsening papilloedema → sight-threatening, urgent ophthalmology

Differentials & how to tell them apart

Cerebral venous sinus thrombosismust be excluded by venography — same raised-ICP picture but a thrombus

Space-occupying lesionmass on imaging

Migraineno papilloedema, normal pressure

Malignant hypertensionvery high BP, retinopathy

Investigations

MRI + MR VENOGRAM (exclude mass and CVST) → then LP shows RAISED opening pressure with normal CSF constituents; formal visual fields + fundoscopy.

Management

Weight loss + acetazolamide + stop precipitant drugs; protect vision

1MRI + venogram then LP (raised opening pressure, normal CSF). Weight loss, acetazolamide, and STOP precipitant drugs (tetracyclines, retinoids, COCP).Gate: Worsening papilloedema/visual fields despite medical therapy → surgery (optic nerve sheath fenestration or CSF shunt) to save sight
2Serial visual fields and fundoscopy; repeated/therapeutic LP can temporise; refer ophthalmology + neurology.

Acetazolamide — carbonic anhydrase inhibitor — reduces CSF production (teratogenic)

Weight loss — disease-modifying

Stop precipitant drug — COCP, tetracyclines, retinoids

Key points

Young obese woman + papilloedema + drug trigger = IIH — but venous imaging must exclude CVST first. Acetazolamide is teratogenic; vision is the thing you are protecting.

Monitor & prognosis

Visual fields, fundoscopy, weight, symptoms.

Good with weight loss; permanent visual loss if papilloedema untreated.

Source: NICE CKS; neurology/ophthalmology guidance