Synopsis
Confirm raised intracranial pressure safely after excluding secondary causes, protect vision through structured ophthalmic monitoring, and use weight, medicine or surgery according to visual risk.
- Idiopathic intracranial hypertension is raised intracranial pressure with normal cerebrospinal-fluid composition and no mass, hydrocephalus, venous thrombosis or other secondary cause on appropriate investigation.
- Headache is common but non-specific; papilloedema, transient visual obscurations, pulsatile tinnitus and sixth-nerve palsy provide more diagnostic and risk information.
- Confirm suspected papilloedema with competent ophthalmic assessment, documenting visual acuity, pupils, formal visual fields and optic-disc appearance or imaging.
- Urgent MRI or CT must exclude structural disease, and CT or MR venography is required to exclude cerebral venous sinus thrombosis before the condition is called idiopathic.
- After safe normal imaging, perform lumbar puncture in the lateral decubitus position with a relaxed patient, measure opening pressure correctly and analyse normal CSF constituents.
- An adult opening pressure above 25 cm CSF supports diagnosis, but a single measurement must be interpreted with the complete phenotype, technique and imaging.
- Weight loss is the only established disease-modifying therapy in patients with obesity; frame support respectfully and offer access to structured weight-management services.
- Acetazolamide can be used to protect visual function in selected patients, but it is not established as a treatment for headache alone and adverse effects often limit dosing.
- Serial therapeutic lumbar punctures are not recommended for routine management because benefit is short-lived; deteriorating vision needs definitive specialist escalation.
Key red flags
Bilateral optic-disc swelling with transient visual obscurations, headache or pulsatile tinnitus raises intracranial-pressure concern and needs urgent competent visual assessment.
Horizontal diplopia from an abduction deficit can occur as a false localising sign; other cranial or limb deficits should prompt a search for an alternative lesion.
Rapid visual-acuity or field decline over days to weeks represents sight-threatening disease and requires immediate surgical-level escalation rather than routine medication titration.
Brief binocular dimming with postural change, enlarging blind spot or progressive peripheral field loss can signal optic-nerve compromise even when central acuity remains good.
Pregnancy or puerperium, thrombosis risk, anaemia, tetracycline or vitamin-A exposure, steroid withdrawal, endocrine disease or systemic symptoms demands an active search for secondary intracranial hypertension.
Investigation priorities
Confirm papilloedema and establish visual acuity, pupils, colour, perimetry, fundus grade and optic-nerve imaging baseline.
Management branches
Disc swelling or pressure-related visual symptoms are identified.
- Measure blood pressure, acuity, pupils and fields urgently, obtain experienced confirmation of papilloedema and identify rapidly changing vision.
- Arrange urgent brain imaging with venography to exclude mass, hydrocephalus and cerebral venous sinus thrombosis before lumbar puncture.
- When safe, perform a technically correct lateral-decubitus lumbar puncture with opening pressure and normal-composition studies.
- Coordinate neurology and ophthalmology so diagnosis, visual-risk grade and ownership of follow-up are explicit from the outset.
IIH is confirmed without rapidly deteriorating visual function.
- Explain the diagnosis and visual risk, review secondary associations and provide a respectful supported weight-management referral where obesity is present.
- Consider acetazolamide for visual protection, titrating through specialist or local protocol while monitoring tolerability, renal risk and acid-base effects.
- Treat migraine-like headache with an appropriate acute and preventive plan, limiting rescue days and avoiding routine repeated lumbar puncture.