Idiopathic Intracranial Hypertension (IIH)

Typically presents in an overweight young woman (can occur in men), often after recent weight gain.

Presentation

Headache with raised-ICP features: worse in the morning and lying down, improved by upright posture, aggravated by cough/straining/Valsalva. May feature transient visual obscuration, pulsatile tinnitus and papilloedema. Visual field loss and permanent damage can follow initial transient visual symptoms.

Exclude a space-occupying lesion, venous sinus thrombosis/obstruction, and causative drugs (COCP, tetracyclines, vitamin A analogues — isotretinoin, acitretin).

Refer to an expert to confirm the diagnosis — untreated IIH can cause permanent visual loss.

Investigations

MRI + MR venography (or CT venography) to exclude venous obstruction/ space-occupying lesion, then lumbar puncture to confirm raised opening pressure.

Management

• Weight loss is the most effective treatment — consider bariatric surgery if lifestyle change is insufficient; GLP-1 receptor agonists are increasingly used off-label given the mechanistic link to obesity, though not yet a formal first-line recommendation.
• Acetazolamide is the preferred pressure-lowering drug: 250mg PO BD, increasing gradually to 500mg QID as tolerated.
• Monitor vision closely — visual fields, acuity and colour vision (Ishihara chart).
• Urgent referral for expert advice and possible surgery (ventriculoperitoneal shunt, optic nerve fenestration) if visual symptoms worsen, especially with deteriorating acuity, colour vision or fields.