Normal Venous Phase Documented during Angiography in Patients with Spinal Vascular Malformations: Incidence and...

A key angiographic sign observed in patients with spinal vascular malformations is the absence of a normal venous phase. While this finding alone is often believed to rule out a lesion impacting the perimedullary venous drainage, the observation of a venous phase in several patients with vascular malformations led us to reconsider the validity of that sign.

Eighty-one patients with 6 spinal arteriovenous malformations, 16 perimedullary arteriovenous fistulas, 61 spinal epidural or dural AVFs, and 1 paravertebral AVF (2 patients had multiple lesions) were reviewed. The venous phase was defined as normal, absent, or indeterminate. The venous phase timing was analyzed in patients with spinal dural or epidural AVFs.

The existence of a venous phase could not be determined for technical reasons in 23 patients. A venous phase was documented in 25 of 58 patients (43%), including 16 of 49 vascular malformations (40.0%) with perimedullary venous drainage. Twelve of the 30 patients (40.0%) with dural or epidural AVFs had a normal venous phase, appearing, on average, 10.1 seconds and best visualized 15.0 seconds after opacification of the artery of Adamkiewicz.

A normal venous phase was observed in 43% of patients with spinal vascular malformations, and within an acceptable delay (<18 seconds) in 40% of slow-flow AVFs. While it remains an important angiographic sign, the observation of a normal venous phase cannot be used to exclude the presence of a vascular malformation or justify interrupting a diagnostic spinal angiogram.