Angioarchitecture of Filum Terminale Arteriovenous Fistulas: Relationship with a Tethered Spinal Cord.

Abstract

Spinal arteriovenous fistulas at the filum terminale (filum AVFs) are rare. Treatment strategies have not yet been established, particularly for cases of filum AVF with lipoma. We report 7 cases of filum AVF with (n = 3) or without (n = 4) a tethered spinal cord by sacral terminal lipoma, with a focus on angiographic and operative findings. All 7 patients (median age, 73 years; range, 40-84 years; men: n = 5) presented with slowly progressive paraparesis, lower extremity sensory disturbances, and bladder/bowel disturbances. Filum AVFs were fed by the filum artery, the distal segment of the anterior spinal artery supplied from the artery of Adamkiewicz. The arteriovenous shunt was located at the filum terminale and drained via the ascending filum vein. In 3 patients with filum AVFs without lipoma, the artery of Adamkiewicz originated from the thoracic segmental artery. In contrast, in 3 patients with filum AVFs with lipoma, the artery of Adamkiewicz originated from the lower lumber or sacral artery because of low-lying conus medullaris. In all patients, filum AVFs were completely obliterated by microsurgical resection of the filum terminale including the arteriovenous fistula. Recurrence was not reported in the follow-up period (median, 64 months), except for 1 patient who required additional surgery because of complex neurovascular structures. Caution is needed when identifying the spinal level of occlusion of the fistula, particularly in cases of a tethered spinal cord by lipoma, because the feeding artery is associated with the artery of Adamkiewicz, which supplies the low-lying spinal cord in the sacral region.