The dural shunt syndrome. Pathophysiology and clinical course.

Dural shunts are vascular communications in which blood flows through small meningeal branches of the carotid arteries to enter the venous circulation near the cavernous sinus. The features of 10 patients with dural shunts are described. Most of these patients were postmenopausal women with dilated episcleral vessels, unilateral elevation of intraocular pressure, and exophthalmos. Pain or discomfort was common and ptosis or limited eye movement was usually present. These findings were characteristically more mild than those associated with carotid-cavernous sinus fistulas. CT scans usually showed enlargement of the extraocular muscles and the superior ophthalmic vein. Arteriography visualized partial or complete occlusion of intracranial venous drainage posterior to the cavernous sinus in all patients. Vascular dynamics of dural shunts are reviewed, and it is suggested that many of these communications may be congenital and that the onset of clinical abnormalities may be associated with the occurrence of intracranial venous thrombosis. Most patients eventually had resolution of their clinical abnormalities without treatment, and in some cases this improvement occurred soon after carotid arteriography.