Flattened posterior globes, distended optic nerve sheaths, a partially empty sella and transverse sinus stenosis support raised pressure; MR venography excludes the sinus thrombosis that mimics it.
Orient first
- A diagnosis of exclusion: normal brain parenchyma, no mass, no hydrocephalus, no venous sinus thrombosis.
- The signs are supportive, not diagnostic — they are frequent in IIH but can occur in healthy people.
- Bilateral transverse sinus stenosis is common and is a target for venous stenting.
Acquire the study
- MRI brain with thin axial and coronal T2 through the orbits, sagittal T1 of the sella, post-gadolinium 3D T1, and MR venography (contrast-enhanced or phase-contrast).
The manoeuvre
- Axial T2 through the orbits: posterior globe flattening, optic nerve sheath distension (diameter in mm), tortuous optic nerves, optic papilla protrusion.
- Sagittal T1: partially empty sella — pituitary height in mm.
- Coronal T2: widened Meckel caves; tonsillar position.
- MR venography: each transverse sinus — smooth stenosis at the transverse-sigmoid junction vs a filling defect of thrombus.
- Parenchyma: no mass, no hydrocephalus (ventricles normal or small).
What confirms it
- Clinical diagnosis (papilloedema, raised opening pressure) with normal parenchyma, no thrombosis, and supportive MRI signs.
What licenses you to exclude it
- Imaging cannot exclude IIH; it excludes its mimics — mass, hydrocephalus, venous sinus thrombosis.
The classic misread
- Reporting "empty sella" as the diagnosis — it is a supporting sign only.
- Missing venous sinus thrombosis by relying on flow gaps of non-contrast MR venography (arachnoid granulations and hypoplasia mimic it).