Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) — sometimes called pseudotumour cerebri — is a condition in which the pressure of the cerebrospinal fluid around the brain is elevated without an obvious cause.

The brain and spinal cord float in a thin layer of clear fluid, the cerebrospinal fluidcerebrospinal fluid (CSF)The clear fluid that surrounds and cushions the brain and spinal cord. It is produced inside the brain, circulates around it, and is reabsorbed into the venous system.. That fluid is constantly produced, circulated, and reabsorbed. In IIH, the balance is disturbed — pressure rises — and the consequences fall most heavily on the optic nerves, which are particularly vulnerable to swelling at their entry into the eye (called papilloedema).

The word idiopathic just means “we can’t identify a single triggering cause”. It does not mean untreatable. Modern care focuses on three things, in this order:

• Protecting vision — the most serious potential consequence.
• Controlling the pressure — with medication, and where appropriate, procedures.
• Managing the headache — which often has multiple coexisting drivers (see Section V).

A note on terminology: the older name pseudotumour cerebri is still used. The modern modified Friedman criteriamodified Friedman criteriaThe 2013 international diagnostic framework for IIH (Friedman, Liu, Digre — Neurology 2013). Distinguishes primary (idiopathic) from secondary intracranial hypertension. (2013) distinguish primary (idiopathic) intracranial hypertension from secondary intracranial hypertension — the latter is driven by an identifiable cause (e.g. a venous sinus thrombosis, certain medications, or an endocrine disorder) and is managed differently.

Headache — the most common symptom

Headache affects roughly nine in ten people with IIH and is often the symptom that finally drives the diagnosis. The classic raised-pressure pattern is:

• Worse first thing in the morning or after lying down for a while
• Worse with coughing, sneezing, or straining (Valsalva)
• Often felt as pressure behind the eyes or across the head
• Eased, at least partially, when the pressure is brought down

But not every headache in someone with IIH is a pressure headache — coexisting migraine, occipital and cervicogenic headaches are common, and matter for treatment (see Section V).

Vision symptoms

Around seven in ten patients describe one or more of:

• Transient visual obscurationstransient visual obscurationsBrief greyouts or blackouts of vision in one or both eyes lasting seconds, often triggered by bending or coughing. A warning sign in IIH that vision needs urgent monitoring. — brief greyouts or blackouts lasting seconds, often when bending or standing up. A warning sign worth flagging on referral.
• Blurred or double vision
• Peripheral vision loss — usually only detected on formal visual field testingvisual field testingA test performed by an eye specialist that maps each eye’s visual field and detects the enlarged blind spot, nasal step, and arcuate defects associated with papilloedema. because patients rarely notice it themselves until it is advanced
• Flashing lights or sparkles in the visual field

Pulsatile tinnitus

Many patients describe a whooshing or pulsing sound in one or both ears that matches their heartbeat. It is one of the more characteristic IIH symptoms and is often the clinical clue that prompts MR venography.

Less common but worth noting

• Nausea and vomiting
• Dizziness or balance problems
• Neck and shoulder pain
• Memory and concentration problems
• Persistent fatigue

IIH is, by definition, idiopathic — we cannot point to a single trigger. But the population of people who develop it has consistent features.

Demographic risk

• Female sex and reproductive-age years. IIH is roughly 8–10 times more common in women than in men, and most cases present between 20 and 40 years of age.
• Body weight. Approximately 90% of women diagnosed with IIH are above a healthy BMI (BMI ≥25), with the majority in the obese range. The relationship is real and important, but weight is one factor among several — not a moral category, and not the whole story.
• Recent weight gain can precipitate IIH even in people not classified as obese.

IIH in men

Men account for around 5–10% of IIH cases. Most men with IIH are also above a healthy BMI, but compared with women the condition shows a stronger association with obstructive sleep apnoea and low testosterone, and tends to present with more severe visual loss at diagnosis. For both reasons, a sleep study and morning testosterone are part of the standard CURA workup in any male IIH patient, and we monitor vision more aggressively in the early months.

Medications and substances

Several medications can trigger or worsen IIH. Bring a complete list to your consultation. Common contributors:

• Tetracycline antibiotics — particularly doxycycline and minocycline (often prescribed for acne)
• High-dose vitamin A and retinoid acne medications (isotretinoin)
• Some corticosteroids, particularly on withdrawal
• Lithium (uncommonly)

Coexisting medical conditions

• Obstructive sleep apnoea
• Polycystic ovary syndrome (PCOS)
• Chronic kidney disease
• Some autoimmune conditions, including lupus
• Iron deficiency anaemia (in some series)

IIH is diagnosed using the modified Friedman criteria (Friedman, Liu, Digre, Neurology 2013). All five elements must be present.

What the workup looks like in practice

History and examination. Your neurologist takes a detailed history (headache pattern, vision changes, medications, obstetric history), examines the cranial nerves and the back of each eye with an ophthalmoscope, and reviews any previous optometry or ophthalmology records you bring.

Eye-specialist input. Detailed eye examination is central. We coordinate with optometry and neuro-ophthalmology colleagues for OCTOCT (optical coherence tomography)A non-invasive scan of the back of the eye that gives objective, repeatable measurements of optic-disc swelling and optic-nerve health over time. and visual-field testing — together these are the most sensitive tools for catching early visual change.

MRI brain with MR venography. An MRI is required to exclude a tumour, hydrocephalus, or other structural cause, and to look for the empty-sella sign, optic-nerve-sheath dilatation, and posterior globe flattening that often accompany IIH. The MR venography sequence is essential — it examines the brain’s draining veins and identifies both the venous sinus stenoses commonly seen in IIH and the venous sinus thrombosis that excludes it. If your earlier MRI was done for headache and didn’t include MRV, the scan often needs to be repeated with the right protocol.

Lumbar puncture (LP). The LP confirms the diagnosis by measuring the opening pressure of the CSF and excluding infection or other CSF abnormalities. A thin needle is placed in the lower back under local anaesthetic with the patient lying on their side; the LP itself takes about 10 minutes, and the appointment overall around 1-2 hours including positioning, recovery and observation. The opening pressure is read with a manometer with the patient relaxed and legs extended — tense or seated readings are misleading. A well-recognised side effect is post-LP headache, which is usually self-limiting.

Visual field testing detects the characteristic enlarged blind spot, nasal step, and arcuate defects of papilloedema-related optic neuropathy. Any abnormality on perimetry is a trigger to escalate monitoring or treatment urgently.

Headache is the symptom that most often disrupts daily life with IIH — and it is almost never just one kind of headache. Pressure-related headache is the starting point, but coexisting patterns matter for treatment.

Pressure-related headaches

Caused directly by the raised intracranial pressure. Worse on lying down or bending over, eased by standing, often felt as pressure behind the eyes. These tend to improve when the pressure comes down — with acetazolamide, weight loss, or stenting.

Coexisting headache types

• Migraine — can be triggered or worsened by IIH and may persist even after pressure normalises. Modern preventives include the CGRP-pathway therapies — the anti-CGRP-receptor and anti-CGRP-ligand monoclonal antibodies (erenumab, galcanezumab, fremanezumab, eptinezumab) and the oral gepants (atogepant, rimegepant). Triptans and gepants are used for acute attacks where not contraindicated. PBS authority criteria apply to several of these and are reviewed at consultation.
• Occipital and cervicogenic — arising from tension and altered posture in the muscles at the base of the skull and neck. Greater occipital nerve blocks can give rapid relief.
• Medication-overuse headache — analgesics taken on more than 10–15 days a month can themselves drive a chronic daily headache pattern. This is one of the things we look for at the first consult.

Why this matters

Reducing intracranial pressure helps many of these headaches, but rarely resolves all of them on its own. Effective IIH headache management almost always involves layered treatment — pressure control plus targeted therapy for the headache phenotype that remains. This is one of the reasons IIH benefits from a headache-specialist neurologist and an interventional neurologist on the same team, which is exactly the structure at CURA.

Treatment has three goals, in priority order: protect vision, control pressure, and relieve headache. The right combination depends on how threatening the disease is to the eyes, how disabling the headache is, the presence or absence of a venous sinus stenosis on imaging, and personal factors like pregnancy plans.

Lifestyle and weight

For overweight and obese patients, sustained 5–10% body-weight loss reduces intracranial pressure and improves symptoms in most cases. The IIH:WT trial (Mollan et al., JAMA Neurology 2021) showed bariatric surgery was more effective than community weight management for sustained pressure reduction in patients with severe obesity.

A 2023 randomised trial of exenatide in IIH (Mitchell, Sinclair et al., Brain 2023) reported a reduction in intracranial pressure that appeared at least partly independent of weight loss. The newer weight-loss agents — semaglutide (a GLP-1 receptor agonist) and tirzepatide (a dual GIP/GLP-1 agonist) — are subsequently thought to be of some benefit in IIH on a similar basis, although direct trial-level evidence in IIH is not yet established for these agents. In current Australian practice they are used as part of weight-directed therapy. Salt and fluid moderation, and dietetic support, remain part of the plan when relevant.

Medications

• Acetazolamide is first-line. It reduces CSF production. The NORDIC IIH Treatment Trial established the modern evidence base. Acetazolamide is used in IIH on a private script in Australia; cost varies by pharmacy and is reviewed at consultation. Dosing is titrated to tolerance — common dose-limiting side effects are paraesthesiae (tingling in the fingers and toes), dysgeusia (the metallic taste, often described as flat fizzy drinks), fatigue, and, less commonly, kidney stones.
• Topiramate is a second-line option, with mild carbonic-anhydrase activity and the side benefit of weight loss. It is teratogenic: first-trimester exposure roughly doubles the rate of oral clefts and is associated with an increased risk of neurodevelopmental disorders — including intellectual disability and autism spectrum disorder — in exposed children. In line with current Australian and European regulatory guidance, topiramate use in anyone who could become pregnant requires a documented Pregnancy Prevention Programme: a negative pregnancy test before initiation, highly effective contraception (intrauterine device or contraceptive implant preferred — the combined oral contraceptive pill alone is no longer considered sufficient under this framework), and at least annual re-counselling. A particularly important caveat given that IIH predominantly affects women aged 20–40.
• Furosemide is occasionally added to acetazolamide where the response is partial. It is not used as a substitute.

Procedures — in priority order of how often we use them

Therapeutic lumbar puncture. Repeated LPs can give temporary relief while medical therapy takes effect, and occasionally to bridge to a definitive procedure. Used sparingly because of the discomfort and modest durability.

Transverse sinus stenting — an endovascular procedure performed personally by Dr Hugh Stephen Winters at CURA. See the next section for detail.

Optic nerve sheath fenestration (ONSF). A microsurgical procedure performed by neuro-ophthalmology colleagues that creates small openings in the sheath around the optic nerve to relieve local pressure. ONSF is generally used as a surgical adjunct alongside other treatments when vision is acutely threatened — not as an isolated solution — and is less effective for headache.

CSF shunting. A neurosurgical procedure that places a tube to drain excess CSF from the brain to the abdomen (ventriculoperitoneal) or from the lower back (lumboperitoneal). Generally reserved for severe disease that has not responded to medication or stenting. Shunts have the highest revision and complication rates of the IIH procedures, and most patients require one or more revision surgeries over time.

How we choose between them

The choice depends on whether vision is acutely threatened, whether headache is the dominant problem, whether MRV shows a treatable venous sinus stenosis, and the patient’s anatomy and preferences. ONSF is added as a vision-protection adjunct; stenting addresses both pressure and headache when there is a venous stenosis; shunting is the fallback when neither is appropriate.

Transverse sinus stenting is performed on-site at CURA by Dr Hugh Stephen Winters — you are not referred elsewhere for the procedure.

A meaningful proportion of patients with IIH have narrowing (stenosis) of one or both transverse venous sinuses on MR venography. In selected patients, this stenosis contributes mechanically to the raised pressure: blood backs up, drainage falls, intracranial pressure rises. Restoring venous outflow with a stent can reverse the cycle.

Who is a candidate

• MR venography evidence of significant transverse or sigmoid sinus stenosis — typically bilateral, sometimes dominant-side unilateral.
• Persistent or progressive symptoms despite medical therapy, or intolerance of medication.
• A pressure gradient across the stenosis confirmed at catheter venography — the procedure that also places the stent. The pressure gradient, not the imaging appearance alone, is the procedural threshold; some MRV-apparent stenoses are non-physiological and do not warrant intervention.

What the procedure involves

Catheter venography and stenting is performed under general anaesthesia at an affiliated Sydney hospital. A catheter is passed from a small puncture in the groin to the brain’s draining veins. Pressures are measured on either side of the stenosis. If a treatable gradient is confirmed, a self-expanding stent is deployed across the narrowing. Hospital stay is typically 1–2 nights.

Patients are placed on dual antiplatelet therapy (aspirin plus clopidogrel or ticagrelor) commencing before the procedure and continuing for several months afterwards, with a long-term aspirin tail. Where appropriate, pre-procedure platelet-function testing is used to confirm responsiveness to clopidogrel and switch the regimen if indicated.

Outcomes and risks

In appropriately selected patients, around 75–85% see meaningful headache improvement and papilloedema resolution in published systematic reviews (e.g. Saber et al., 2018; Nicholson et al., 2019). Serious peri-procedural complications (intracranial bleeding, stent thrombosis) occur in roughly 1–2% of cases in the same series; minor complications such as a temporary headache on the side of the stent are more common. The long-term effects of having a permanent intracranial stent — particularly in young patients — are still being studied, and this is part of the consultation conversation.

IIH most commonly affects women aged 20–40. Pregnancy planning, contraception, and the risk profile of the medications used in IIH all need to be on the table from the first consultation — not when a positive pregnancy test arrives.

Pregnancy

Pregnancy in IIH is co-managed with obstetrics and (where needed) obstetric medicine. Key principles:

• Acetazolamide in pregnancy is increasingly individualised. Earlier guidance favoured avoiding it in the first trimester, and that remains the conservative default; current obstetric-medicine practice supports continued use through pregnancy where vision is at stake, with informed consent and joint maternal-fetal medicine review. If acetazolamide cannot be used and pressure is threatening vision, the threshold to consider stenting may be lower.
• Topiramate is teratogenic — first-trimester exposure roughly doubles the rate of oral clefts and is associated with an increased risk of neurodevelopmental disorders, including intellectual disability and autism spectrum disorder, in exposed children. Use in anyone who could become pregnant requires a documented Pregnancy Prevention Programme: a negative pregnancy test before initiation, highly effective contraception (an intrauterine device or implant is preferred; the combined oral contraceptive pill alone is not considered sufficient under this framework), and at least annual re-counselling. If you are on topiramate and pregnancy is a possibility, raise this at consultation immediately so we can sequence a switch under contraceptive cover.
• OCT and visual-field monitoring are safe in pregnancy and become more important.
• IIH does not in itself mandate caesarean delivery. Mode of delivery is decided jointly with obstetrics; epidural anaesthesia is generally not contraindicated.
• Active weight-loss programs are deferred until after delivery and postpartum recovery.

Contraception

The combined oral contraceptive pill has historically been listed as a possible association with IIH onset, but a causal role is not established and modern reviews do not treat it as a meaningful trigger. The contraceptive question that does matter is topiramate: where topiramate is used, the Pregnancy Prevention Programme above applies, and a long-acting reversible contraceptive (intrauterine device or implant) is preferred over the combined oral contraceptive pill alone.

IIH is a chronic condition rather than a one-time illness, and monitoring intensity is matched to disease activity, not the calendar.

In active disease — close monitoring

• For active papilloedema or any visual-field abnormality: weekly to fortnightly review until stable, then monthly, with frequency stepped down only as OCT and perimetry confirm sustained improvement.
• Fulminant or rapidly worsening cases may require daily review until stabilised.

In stable disease — surveillance

• Eye examinations every 6–12 months once papilloedema has resolved and visual fields are stable.
• Neurology review every 6–12 months.
• Repeat MRI/MRV if symptoms change, the headache pattern shifts, or a new finding appears.

What OCT shows

OCT gives objective, repeatable measurements of the optic disc and surrounding retina. In IIH, it is used to quantify the swelling of the optic nerve head over time and to detect any thinning of the nerve’s structural layers — an early signal that pressure is doing damage and treatment needs to escalate. Your eye specialist will interpret the trend on each scan rather than any single number.

A first IIH consultation usually takes 45–60 minutes. The consultation itself is the first appointment; imaging, eye-specialist tests and lumbar puncture are organised as separate bookings — either ahead of the consult (so we can review the results with you) or shortly after, depending on what’s needed.

Bring

• Your GP referral letter
• All imaging on USB or via secure link — CTs, MRIs (especially anything with MR venography), plus the radiology reports
• Any optometry or ophthalmology records: fundus photos, OCT scans, visual field reports
• A current medication list including the contraceptive pill, any acne treatments, tetracycline antibiotics, vitamin A supplements, and any over-the-counter medicines
• Recent blood pressure readings if you have them
• Medicare card and any private health insurance details
• A family member or friend — a second pair of ears is invaluable when there’s a lot of new information

What the consult typically covers

Specifics depend on your presentation and what’s already been done. Where appropriate, we’ll:

• Review your history, examine you, and review your imaging
• Arrange or coordinate any further tests still needed — OCT, visual-field testing, MRI/MR venography, lumbar puncture — as separate bookings
• Confirm or rule out the diagnosis against the modified Friedman criteria
• Start or adjust medication, set the eye-monitoring cadence, and discuss the trigger points that would move us toward stenting or surgery
• Send a written letter to your GP with a clear shared-care plan

Fees and wait time

Consultation fees and out-of-pocket gaps depend on consultation type and your Medicare and private-health eligibility. Lumbar puncture, MRI/MR venography, OCT, and visual-field testing are Medicare-rebatable when ordered for a clinical indication. Wait times depend on triage urgency — symptomatic IIH with vision change is triaged urgently. For current fees and availability, please call our reception or use the online booking page.

• IIH UK — iih.org.uk. The largest English-language IIH-specific patient charity, with up-to-date plain-English explainers, treatment guides, and a patient community.
• Brain Foundation Australia — brainfoundation.org.au
• Healthdirect Australia — healthdirect.gov.au (Healthdirect helpline 1800 022 222)
• NORDIC IIHTT trial summary — Wall et al., JAMA 2014; the trial that anchors first-line acetazolamide therapy.
• NSW Ambulance — 000 for any emergency

References cited in this guide

• Friedman DI, Liu GT, Digre KB. Revised diagnostic criteria for the pseudotumor cerebri syndrome in adults and children. Neurology. 2013;81(13):1159–1165.
• Wall M, McDermott MP, Kieburtz KD, et al. (NORDIC IIHTT Study Group). Effect of acetazolamide on visual function in patients with idiopathic intracranial hypertension and mild visual loss: the IIH treatment trial. JAMA. 2014;311(16):1641–1651.
• Markey KA, Mollan SP, Jensen RH, Sinclair AJ. Understanding idiopathic intracranial hypertension: mechanisms, management, and future directions. Lancet Neurology. 2016;15(1):78–91.
• Mollan SP, Davies B, Silver NC, et al. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurol Neurosurg Psychiatry. 2018;89(10):1088–1100.
• Mollan SP, Mitchell JL, Ottridge RS, et al. Effectiveness of bariatric surgery vs community weight management intervention for the treatment of idiopathic intracranial hypertension: a randomized clinical trial. JAMA Neurology. 2021;78(6):678–686.