Extravasation and arteriovenous shunting after epidural bleeding -- a radiological study.

Eighteen patients with epidural bleeding had preoperative angiography with visualization of the meningeal arteries. Thirteen of these had extravasation of contrast medium from meningeal arteries and eleven also had shunting of contrast medium from meningeal arteries to meningeal or diploic veins. For easier demonstration of these findings, selective external carotid angiography and the use of larger amounts of contrast medium are recommended. Our results support the theory that the arteriovenous shunting has important implications on the pathophysiology of epidural bleeding. Failure to demonstrate extravasation and arteriovenous shunting may be explained in three ways: (1) inadequate angiographic technique; (2) arterial bleeding has stopped; (3) epidural bleeding is not arterial.