The role of CT in evaluation of the effectiveness of embolisation of spinal dural arteriovenous fistulae with N-butyl cyanoacrylate

A failed embolisation of a spinal dural arteriovenous fistula (AVF), because a pedicular injection has not reached the initial venous compartment, must be identified immediately, to allow prompt surgery and thus avoid clinical deterioration. The purpose of our study was to determine the role of CT in confirming a complete cure just after embolisation with N-butyl cyanoacrylate (NBCA). Seven patients embolised for spinal dural AVFs with perimedullary venous drainage had an immediate postembolisation CT scan. In six patients a complete cure was achieved, with a normal postembolisation angiogram in five cases. Just after injection of NBCA, we were unable to determine on plain films whether or not the glue had reached the draining vein in six of seven cases. The postembolisation CT showed various patterns: in two cured patients, the glue was visible in the inner surface of the dura mater and therefore on the venous side. In five cases, the glue was approaching the dura mater around the cord or seemed to reach its surface: in the four patients cured, the glue column was 7-18 mm high, whereas it was less than 2 mm high in the patient with angiographic proof of recurrent fistula. The follow-up angiogram remains the only way to confirm a durable cure. We suggest that immediate postembolisation CT may help in assessing endovascular treatment of spinal dural AVFs.