Chronological changes in MRI findings of spinal dural arteriovenous fistula

BACKGROUND Intramedullary high-intensity changes on T2-weighted magnetic resonance images (MRI) occur in patients with spinal dural arteriovenous fistulas (AVF). Reduction of the high-intensity area after treatment has been noted; however, there are still questions about whether the change is related to preoperative clinical grade, postoperative improvement, or efficacy of treatment. This study tried to clarify the relationship between chronological changes in the high intensity area with the treatment and clinical course. METHODS Chronological changes in an intramedullary high-intensity area after surgery were retrospectively analyzed in recent 13 patients with spinal dural AVFs who were treated and followed by MRI. RESULTS Preoperative intramedullary high-intensity areas were observed on T2-weighted images in all cases. The extent of the high-intensity area correlated with preoperative neurological deficits. The intramedullary high-intensity area was reduced or diminished after successful interruption of AVFs. The high-intensity area started to decrease within 1 to 4 months after treatment in ail patients, and disappeared at 2 weeks to 23 months in seven patients. The reduction may suggest interruption of the fistula and improvement of venous circulation, but was not always correlated to clinical improvement. The intramedullary high-intensity areas rag idly disappeared in two patients, but did not clearly correspond to the clinical improvement. CONCLUSIONS The time course of postoperative MRI changes is helpful for evaluating the efficacy of treatment after surgery for spinal dural AVFs. (C) 2000 by Elsevier Science Inc.