Venous Sinus Stenosis with Prominent Emissary Veins: A New Common Cranial MRI Finding of Mucopolysaccharidosis I

A, Axial T1-weighted image with contrast (patient 3) demonstrates prominent bilateral posterior fossa horns (black arrows) with a draining emissary vein from the right sigmoid sinus (white arrow) and a stenotic left sigmoid sinus (black arrowhead). B, Axial T1-weighted images with contrast (patient 10) demonstrate left-greater-than-right bilateral posterior fossa horns (black arrows) with a draining emissary vein from the left sigmoid sinus (white arrow), an emissary venous plexus (white arrow), and a stenotic left sigmoid sinus (black arrowhead). C, MRV (patient 8) shows a hypoplastic right transverse sinus (black arrow) with a large emissary venous plexus from the distal jugular bulb (white arrow).