Orbital pseudotumor: association of orbital vein deformities and myositis.

Twenty adult patients with orbital pseudotumor were studied with orbital venography and magnification arteriography. Computed tomography (CT) scans were obtained in 14 patients. Occlusive and constrictive changes of the proximal segments of the superior ophthalmic veins were the most frequent vascular abnormalities. The affected ophthalmic arteries were often attenuated but not occluded. Myositis and surrounding connective tissue inflammatory changes are thought to result in sufficient mass effect to cause the venous stasis with narrowing and subsequent occlusion. Such venographic changes are not distinctive for orbital pseudotumor but may also be seen in cases of thyrotoxicosis, Tolosa-Hunt syndrome, and orbital tumors.