Background and study aims Idiopathic intracranial hypertension (IIH) is a neurological condition characterised by increased pressure inside the skull, called intracranial pressure (ICP). It is more common in women of reproductive age with obesity. Common symptoms of IIH include headaches, blurred vision and ringing in the ears. If left untreated, the disorder may cause blindness. The majority of patients with IIH are managed with weight loss and medications. Fewer than 10% of patients develop progressive visual loss and require urgent intervention to reduce ICP and preserve vision. This trial will compare the two most common interventions performed in the UK and evaluate their clinical and cost-effectiveness. The first is called cerebrospinal fluid (CSF) shunting and involves a procedure where a thin tube called a shunt is implanted in the body to drain brain fluid. The second is called dural venous sinus stenting (DVSS) and involves a procedure where a metallic mesh tube called a stent is implanted inside a brain blood vessel. Both procedures can preserve vision, but there is no strong evidence to support one over the other. Participants will have the same chance to be treated with CSF shunting or DVSS. The aim of the trial is to know which intervention is the most effective to save the vision and the most cost-effective.

Who can participate? Adults with a diagnosis of IIH at risk of permanent sight loss

What does the study involve? The trial will be conducted in NHS hospitals located in England, Wales and Scotland. Participants are randomly allocated to undergo cerebrospinal fluid (CSF) shunting or dural venous sinus stenting (DVSS). Afterwards the participants will be asked to attend 11 hospital appointments and one telephone appointment. This follow-up will take 2 years from start to finish. Participants will be closely monitored for any side effects and potential device failure, and for changes in vision, headaches and quality of life. The researchers will also collect health data from NHS Digital (the national custodian of NHS health and social care data).

What are the possible benefits and risks of participating? There are no direct benefits from taking part in the trial but the information gained from this trial may help improve treatment for adults with IIH in the future. Participants may be seen more often and/or feel more supported as a consequence of their involvement in the trial. As with any intervention, there are risks and complications, but there are no additional disadvantages or risks involved in taking part in this trial. Both CSF shunting and stenting are treatments for IIH (shunting is widely used internationally, and in some hospitals, stenting is used as part of the standard of care). Participants require an intervention to prevent sight loss. None of these treatments is experimental but at present, there is not enough information to determine which treatment is most suitable and provides the higher level of health benefits to the individual.

Where is the study run from? University of Birmingham (UK)

When is the study starting and how long is it expected to run for? The first site opened in July 2023, and the last patient last visit is expected in May 2028

Who is funding the study? National Institute for Health Research (NIHR, grant number: NIHR131211) (UK)

Who is the main contact? IIH Intervention Trial manager, IIHIntervention@trials.bham.ac.uk (UK)

Inclusion Criteria:

1. Diagnosis of IIH by the IIH consensus guidelines with papilloedema and at risk of visual loss.
2. Presence of papilloedema (Frisén grade ≥ 3) in at least one eye
3. Age 18 to < 64 years at the time of consent.
4. Patients must be suitable for and willing to proceed with both CSF shunting (VP or Lumboperitoneal shunts only) and DVSS.
5. Able to provide written informed consent.

Exclusion Criteria:

1. Presence of current venous sinus thrombosis on diagnostic brain imaging by either MRI, MRV or CTV
2. Previous surgery for IIH including, optic nerve sheath fenestration, CSF shunting procedures, sub-temporal decompression and DVSS.
3. Previous bariatric surgery within the last 3 months
4. Patients with a past ophthalmic history, except refraction error, affecting the eligible eyes (study eyes) that could affect the vision.
5. Patient is, at the time of signing the informed consent, a user of recreational or illicit drugs (including marijuana) or has had a recent history (within the last year) of drug or alcohol abuse or dependence, in the opinion of the investigator.
6. History of any clinically significant disease or disorder which, in the opinion of the investigator, may either put the subject at risk because of participation in the study, or influence the results or the subject's ability to participate in the study.
7. Have participated in any other interventional study within 30 days prior to the screening visit (of note participation in the IIH Life database or other observational studies will not prevent enrolment to this study).
8. Previous randomisation for treatment in the present study.
9. Pregnant.
10. Absolute or serious contraindication to standard anti-thrombotic regimen peri and post stenting.
11. Secondary causes of raised intracranial pressure. (Refer to Protocol appendix 3 for additional information.)
12. History of significant documented iodine-based contrast allergy.
13. History of documented allergy to nitinol or nickel.
14. Absolute or serious contraindication for general anaesthesia.
15. Previous diagnosis of a hypercoagulable state (Factor V Leiden, Protein C or S deficiency, Anticardiolipin antibodies, Lupus anticoagulant, B2-glycoprotein-1 antibodies, or Hyperhomocysteinaemia).
16. Currently requiring full anticoagulation for other medical reasons, such as atrial fibrillation, artificial valves, deep vein thrombosis or pulmonary embolism.
17. Documented prior non-traumatic intracranial haemorrhage.
18. History of deep vein thrombosis or pulmonary embolism (within the last 24 months).
19. History of severe carotid atherosclerotic disease.
20. History of heart failure, dilated cardiomyopathy or congenital heart disease, etc. that are assessed as at high thrombotic risk.
21. Presence of intracranial vascular malformation considered clinically symptomatic (current or within 24 months).
22. Anatomical anomaly of the venous sinus which would prevent safe catheterisation and stenting (e.g. multi-channel sinus).