Progressive stenosis of the distal ICAs and proximal ACA/MCA with a basal collateral network — ivy sign on FLAIR, watershed infarcts — in a child with TIAs or an adult with haemorrhage.
Orient first
- Moyamoya disease is idiopathic; moyamoya syndrome accompanies sickle cell disease, NF1, Down syndrome and radiotherapy.
- Suzuki stages describe the progression on angiography (verify).
- Children present with ischaemia; adults often with haemorrhage from fragile collaterals.
Acquire the study
- FLAIR, DWI, TOF MRA, post-gadolinium T1, perfusion.
The manoeuvre
- TOF MRA: stenosis or occlusion of the terminal ICAs and M1/A1 segments.
- T2 and FLAIR: multiple flow voids in the basal ganglia (collaterals); ivy sign (sulcal FLAIR hyperintensity).
- DWI: acute watershed infarcts; FLAIR: old infarcts.
- Perfusion: delayed transit in the affected hemisphere.
What confirms it
- Bilateral or unilateral terminal ICA stenosis with basal collaterals on angiography.
What licenses you to exclude it
- Normal terminal ICAs on MRA exclude moyamoya.
The classic misread
- Calling the ivy sign leptomeningitis or subarachnoid blood.