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Microsurgical Management of L1 Arteriovenous Fistula

December 02, 2015


Microsurgical clip ligation or disconnection of spinal arteriovenous fistula is quite effective. This procedure remains quite popular despite the use of endovascular techniques as the surgical disconnection of the fistula is quite low risk. Let's go ahead and discuss the technical nuances in this case. This is a 57-year-old male who presented with sudden onset of bilateral lower extremity weakness, which resolved spontaneously by the time the patient arrived to the emergency room. The spinal MRI in this case did not demonstrate any evidence of stenosis or compression. However, careful inspection revealed evidence of hypervascularity and numerous number of vessels along the posterior aspect of conus medullaris. The next imaging modality, a thoracic MRI, also confirmed hypervascularity of the area within the posterior aspect of the spinal cord. An arteriovenous fistula was suspected and a spinal angiogram was completed, which demonstrated a pedicular or radicular artery at the level of the L1 connecting to a large draining vein, an early draining vein along the posterior aspect of the spinal cord. Therefore, this is an arteriovenous fistula at the level of the L1 on the left side. The patient subsequently underwent a lumbar laminectomy at the level of L1 and L2. You can see the traditional positioning in L1 and L2 laminectomy. The dura is open in the level of the midline and the arachnoid layers are also tacked up using Weck clips. Without any significant dissection, I was able to immediately identify the arterialized vein at the level of the L1 nerve roots. I continued to inspect around the fistula to assure that I am not necessarily overlooking any smaller fistulas. The arteriovenous fistulas are typically along the posteriolateral aspect of the nerve root as demonstrated here. You can see the nerve root of L1. No other abnormality is obvious. Obviously, the arterial disconnections are within the dura, and this is a single draining vein of the fistula and disconnecting the vein is quite effective. You can see the pathology clearly here, which is a great demonstration of arteriovenous fistulas at the level of the spinal cord. I'm going to place a straight clip across the fistula right at the level of the dura and disconnect the fistula next. The intraoperative indocyanine green angiography again reveals the early draining vein before any of the arteries along the cauda equina are visible. This again confirms that the correct pathology has been identified. Here is the straight clip that has been placed right at the level of the dura. The vein is coagulated and cut. Intraoperative fluorescein angiography confirms complete disconnection of the fistula without a need for intraoperative angiogram. The clip was removed so watertight dural closure is possible. After dura was closed in a watertight fashion, the fascia was also closed in a watertight fashion to prevent or minimize the risk of CSF leakage. This is a postoperative angiogram which was performed two days later which demonstrates complete disconnection of the arteriovenous fistula at the level of L1. This patient recovered from his surgery without any untoward effects and has since done very well. Thank you.

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