Fig 5.

Representative examples of targets for blood patching. A, CT myelogram demonstrates extravasation of contrast from a nerve root sleeve (white arrow) due to a high-flow leak. Note the presence of an extradural collection surrounding the thecal sac (black arrow). B, CT myelogram in a different patient demonstrates an enlarged diverticulum of the nerve root sleeve (arrowhead). Although no direct myelographic evidence of leak is seen, this site was chosen for empiric blood patching on the basis of the potential for an intermittent or low-flow leak.