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Idiopathic intracranial hypertension (IIH)
Idiopathic intracranial hypertension is raised CSF pressure without a tumour or thrombosis, mainly in young women with excess weight, and its main danger is vision loss from papilloedema — so you monitor visual fields, not just the headache.
Why it matters in the exam
The classic scenario is a young woman with obesity, daily headache, pulsatile tinnitus, brief visual blurring with posture changes and horizontal double vision from a 6th nerve palsy. The tests check the order of work-up (MRI and MRV before lumbar puncture, to exclude a tumour and venous thrombosis), the value of the opening pressure, the first treatment (weight loss and acetazolamide), and when urgent surgery is needed to save vision. Common distractors are calling the headache migraine and skipping fundoscopy, or choosing repeated punctures as long-term treatment. Look for trigger drugs such as tetracyclines and vitamin A derivatives. The neurological exam shows nothing except papilloedema and sometimes a 6th nerve palsy; any other finding means another diagnosis. Even modest weight loss improves pressure and symptoms.
Key points
- IIH occurs mainly in young women with excess weight and with exposure to trigger drugs.
- Headache, pulsatile tinnitus and papilloedema, sometimes with a 6th nerve palsy.
- MRI and MRV come before the puncture; opening pressure 25 cm water or more with normal fluid.
- Treatment: weight loss and acetazolamide, with visual field follow-up.
- A threat to vision requires urgent surgery.
Summary table
| Aspect | Finding or rule | Note |
|---|---|---|
| Who gets it | Women of childbearing age with excess weight; drugs: tetracyclines, vitamin A and isotretinoin, steroid withdrawal | In a man or without obesity, search harder for a secondary cause |
| Symptoms | Headache, pulsatile tinnitus, transient visual obscurations, double vision from a 6th nerve palsy | On exam: bilateral papilloedema; the rest of the neurological exam is normal |
| Imaging | MRI and MRV free of tumour and thrombosis; supportive signs: empty sella, flattened posterior globe, transverse sinus narrowing | MRV is mandatory to exclude cerebral venous thrombosis |
| Lumbar puncture | Opening pressure 25 cm water or more in adults, lying on the side; normal fluid composition | Normal protein and cells are part of the definition |
| Treatment | Weight loss and acetazolamide (alternative: topiramate); visual field follow-up | Threat to vision: optic nerve sheath fenestration, CSF shunt or venous sinus stenting |
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Sources
- Revised Diagnostic Criteria for the Pseudotumor Cerebri Syndrome (Friedman et al., Neurology), 2013 — Diagnostic criteria
- IIH Consensus Guidance (Mollan et al., J Neurol Neurosurg Psychiatry), 2018 — Investigation and management
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.