PMC3115162_01
X-rays of L4-S1 instrumentation and fusion
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F1
He underwent an L4-S1 postero-lateral fusion 2 years prior, without getting any relief from the symptoms [Figure 1].
(a) Early phase spinal angiogram of the left T-10 intercostal artery injection, showing filling of the anterior spinal artery and the site of the filum terminale arteriovenous fistulas. (b) Later phase spinal angiogram showing initial fistulization. (c) Venous phase of spinal angiogram showing dilated and tortuous draining veins of the malformation
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F2
Digital subtraction angiography demonstrated filling of the anterior spinal artery (ASA) extending past the conus and appearing to fistulize directly into a spinal vein in the region of the patient's previous surgery [Figure 2].
PMC3115162_02
DynaCT demonstrating serpentine vessel opacification, unable to localize exact fistula site from this study. Lumbar fusion instrumentation (pedicle screws) is visible
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F3
However, the precise location of artery-vein transition was not apparent despite sophisticated neurovascular imaging [Figure 3].
Intraoperative photograph showing the enlarged filum terminale artery connected to the arterialized dilated venous plexus
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F4
Once the thecal sac was opened and the arachnoid adhesions were taken down, it was noted in each case that the filum terminale harbored several enlarged blood vessels carrying arterialized blood [Figure 4].
Indocyanine green videography showing enhancement with progressive filling of the fistula and draining vein with intermittent release of the feeding artery
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F5
Visualizing the filum with ICG videoangiography - and with the filum pinched with a bipolar forceps above the presumed fistulization site - intermittent brief release of the forceps pressure caused progressive opacification of distal artery, fistula, and eventually the draining veins [Figure 5].
Intraoperative photograph showing ligated filum terminale fistula
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F6
Repeat ICG videoangiograms showed that pressure directly on the identified fistula sites (as opposed to above them) completely eliminated the opacification of the draining veins. 3-0 silk was used to doubly ligate the filum a few millimeters above and below these sites, and then the filum was coagulated and divided [Figure 6].
Artery and vein penetrating the thick, fibrous dura at the filum terminale with fibrofatty changes (bold arrow). Abrupt transition occurs between the feeding arterial vessel and venous vessel. Filum terminale vein at the center of the image is enlarged and filum terminale artery is distorted (black arrow)
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F7
The resected AVF was sent for pathology [Figure 7].