case_images: PMC8053458_01
case_images: Filum terminale arteriovenous fistula at L5 (Case 1). (a) Sagittal T2-weighted magnetic resonance image (MRI) shows the swollen spinal cord surrounded by flow voids. It also shows redundant cauda equina and spinal canal stenosis from L3 to L5. (b) Sagittal T1-weighted MRI does not show high signal intensity in the filum terminale. (c and d) Axial T1- and T2-weighted MRIs at L5 indicate thickened filum terminale due to edema, although the fatty component is not evident. (e) Selective catheter angiography from left T10 intercostal artery shows an arteriovenous fistula located at L5 that is fed by a caudally running artery in the filum terminale. The drainer is a vein in the filum terminale with an ascending flow.
case_images: SNI-12-103-g001.jpg
case_images: PMC8053458_01_SNI-12-103-g001.jpg
case_images: F1
case_images: The preoperative T2-weighted magnetic resonance imaging (MRI) revealed edema plus flow voids in the lower spinal cord including the conus medullaris accompanying lumbar canal stenosis from L3 to L5 [Figure 1]. In addition, the preoperative T1-weighted MRIs did not show any high signal intensity suggestive of the fat tissue along the filum terminale [Figure 1]. Spinal digital subtraction angiography (DSA) of the left T10 intercostal artery revealed AVF at L5 [Figure 1].
case_images: Case 1 continued. (a) Intraoperative findings show edematous filum terminale with dilated arteries and veins, (b) Intravenous indocyanine green (ICG) video angiogram shows the artery of the filum terminale (AFT) with a caudal inflow (arrow), connecting directly with the vein in the filum terminale drained rostrally (arrowhead), The transitional point from the artery to the vein was considered as the arteriovenous fistula (AVF) (asterisk), (c) A temporary aneurysm clip is applied on the AFT immediately proximal to the shunting point, (d) intravenous ICG angiogram shows another minor feeding artery (arrow) joining the AVF with a caudal inflow, (e) one more temporary aneurysm clip is applied to the minor feeding artery, (f) the pathological finding of resected filum terminale shows an arterialized vein embedded in the adipose tissue (hematoxylin and eosin stain, x50).
case_images: SNI-12-103-g002.jpg
case_images: PMC8053458_01_SNI-12-103-g002.jpg
case_images: F2
case_images: AVF. At surgery, we found dilated arteries and veins running over the edematous filum terminale at L5 level [Figure 2]. Intravenous indocyanine green (ICG) showed that the AFT had a caudal inflow, and directly connected to the dilated veins of the filum terminale draining rostrally [Figure 2]. The transitional point from the caudally running artery to the cranially running vein was considered a shunting point; and a temporary aneurysm clip was applied on the arterial side immediately proximal to the shunting point [Figure 2]. Intravenous ICG revealed that another minor feeding artery with a rostral inflow was connected to the AVF, and another temporary aneurysm clip was applied to the minor feeder near the shunting point [Figure 2].
case_images: PMC8053458_02
case_images: Filum terminale arteriovenous fistula at L3-4 (case 2). (a) Sagittal T2-weighted magnetic resonance image (MRI) shows edematous spinal cord and perimedullary flow voids, (b) spinal lipoma is not recognized on sagittal T1-weighted MRI, (c) selective catheter angiography from left T8 intercostal artery shows an arteriovenous fistula located at the L5 level supplied by an artery that originated from the anterior spinal artery.
case_images: SNI-12-103-g003.jpg
case_images: PMC8053458_02_SNI-12-103-g003.jpg
case_images: F3
case_images: T2-weighted MRI of the thoracic and lumbar spine revealed edema of the spinal cord with flow voids around it [Figure 3]. The T1-weighted MRIs did not indicate any evidence of fat deposition in the filum terminale [Figure 3]. L3-4 level [Figure 3]. L3-4 laminectomy was performed and revealed dilated abnormal vessels running over a swollen filum terminale [Figure 4].
case_images: Case 2 continued. (a) Intraoperative finding shows edematous filum terminale with dilated arteries and veins. (b) The filum terminale is resected with the arteriovenous fistula (arrow). (c) The histopathological study of the resected filum terminale shows an arterialized vein surrounded by the adipose tissue.
case_images: SNI-12-103-g004.jpg
case_images: PMC8053458_02_SNI-12-103-g004.jpg
case_images: F4
case_images: L3-4 level [Figure 3]. L3-4 laminectomy was performed and revealed dilated abnormal vessels running over a swollen filum terminale [Figure 4]. Part of the filum terminale and the AVF was resected along with the feeding/ draining vessels [Figure 4]. The postoperative histological study confirmed that the arterialized vein was embedded in the adipose tissue [Figure 4].