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 Table of Contents  
Year : 2019  |  Volume : 52  |  Issue : 4  |  Page : 151-153

Clipping of spinal arteriovenous fistula of the filum terminale under intraoperative angiography guidance

Department of Neurosurgery, Mackay Memorial Hospital, Taipei, Taiwan

Date of Submission06-May-2019
Date of Decision16-May-2019
Date of Acceptance25-Jun-2019
Date of Web Publication27-Aug-2019

Correspondence Address:
Dr. Hsin-Yao Lin
Department of Neurosurgery, Mackay Memorial Hospital, Taipei
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/fjs.fjs_36_19

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Arteriovenous fistula of the filum terminale (AVFFT) is an uncommon disease. We reported a case of this rare condition and we used intraoperative angiography to identify the completeness of fistula obliteration. A 53-year-old man presented with a history of low back pain and radiating pain of bilateral legs for 2 months. Lumbar spine magnetic resonance imaging revealed edema of conus medullaris at the T10–L1 level; engorged vein was also identified from L1 to L4. Digital subtraction angiography confirmed the diagnosis of AVFFT. Clipping of fistula was successfully performed, and complete obliteration was confirmed by intraoperative angiography. Magnetic resonance imaging follow-up showed no edema postoperatively. The patient's symptoms/signs improved tremendously. Both radiological and clinical outcomes were good after complete occlusion of the fistula was done. Hence, we suggested intraoperative angiography in hybrid OR as a useful tool to identify the fistulous point and confirm complete occlusion the fistula.

Keywords: Anterior spinal artery, arteriovenous fistula of filum terminale, drainage vein, intraoperative angiography

How to cite this article:
Lee YJ, Lin KC, Tsai CC, Lin HY. Clipping of spinal arteriovenous fistula of the filum terminale under intraoperative angiography guidance. Formos J Surg 2019;52:151-3

How to cite this URL:
Lee YJ, Lin KC, Tsai CC, Lin HY. Clipping of spinal arteriovenous fistula of the filum terminale under intraoperative angiography guidance. Formos J Surg [serial online] 2019 [cited 2021 Mar 8];52:151-3. Available from: https://www.e-fjs.org/text.asp?2019/52/4/151/265492

  Introduction Top

Arteriovenous fistula of the filum terminale (AVFFT) is rare, with only 39 cases reported during the year 1977–2017.[1] AVFFT is five times more common in men than in women and account for ~3.2% of all spinal intradural arteriovenous fistulae (AVF).[2] They are believed to have an acquired etiology.[3],[4] AVFFT is often categorized as a type IV spinal AVF; however, it exhibits characteristics of small venous ectasia and typically occurs in middle-aged men, which is different from typical Type IV spinal AVF. The direct communication causes venous hypertension, likely resulting in spinal cord edema. The definitive treatment is complete obliteration. Due to long and tortuous feeding artery, endovascular treatment is technically challenging. Here, we report a case of symptomatic AVFFT treated successfully with surgical clipping of fistula.

  Case Report Top

A 53-year-old male presented with a history of progressive low back pain and radiating pain of the bilateral lower leg lasted for 2 months. Urine retention was noticed. There was no history of trauma or cancer. Physical examination revealed a spastic gait. Muscle power of the bilateral lower limbs was slightly decreased along with enhanced deep tendon reflexes. The numbness was mainly in the S1, S2 dermatome but did not involve the perianal area. Radiography of the lumbar spine revealed no signs of bony destruction or spondylolisthesis. Magnetic resonance imaging (MRI T2-weighted image) showed no obvious disk herniation; however, an abnormal vascular lesion with flow void was observed along with cord edema in the thoracolumbar area [Figure 1]a and [Figure 1]b. Digital subtraction angiography (DSA) confirmed the diagnosis of Type IV AVFFT region; the top of the arterial feeder was around L1 and the fistulous point was around L3 [Figure 2]a and [Figure 2]b, the engorged vein was raising from L3 [Figure 2]b. The surgery was planned in our hybrid operation room (equipped with Artis zeego ecosystem, a Multi-axis system), which has the facility for intraoperative DSA. Under intraoperative neuromonitoring, we performed laminectomy over L3, where the fistulous point was discovered [Figure 3]. Clipping was performed under intraoperative neuromonitoring of electromyography (EMG). Rootlet compression was detected during the first clipping. After adjustment of the clip position, the EMG returned to its baseline; intraoperative DSA revealed successful obliteration of the fistulous point [Figure 2]c. The postoperative period was uneventful, and the patient could walk with no obvious neurological deficit. Follow-up MRI after 10 months showed disappearance of abnormal vascular lesion and cord edema [Figure 1]c.
Figure 1: Magnetic resonance imaging T2-weighted image of lumbar spine (a) abnormal vascular lesion and flow void are seen (dotted circle) (b) edema of the thoracic spinal cord (arrow) (c) no abnormal vascular lesion or flow void is seen post clipping

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Figure 2: (a) The artery of filum terminale is the continuation of the anterior spinal artery (arrow head) and the  Artery of Adamkiewicz More Details (arrow). (b) Engorged vein (arrow head) ending at the fistulous point (arrow) (c) the fistula point disappeared after clipping (arrow head)

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Figure 3: Intraoperative photograph showing the fistula point (arrow head)

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  Discussion Top

The filum terminale is a delicate fibrovascular end structure of the spinal cord. It has an intradural component of the filum terminale and an extradural component of the filum terminale externum. The filum terminale internum is ~15-cm long; it extends from the conus medullaris at L1-2 to the end of the dural tube (S2 level). All types of ganglion cells and medullated fibers are present in the central canal in the upper one-half of the filum.[5] The filum terminale artery typically arises from the termination of the anterior spinal axis as the caudal continuation of the anterior spinal artery (ASA); it traverses in front of the filum terminale, gradually reduces in diameter and supplies the filum and coccygeal nerve root. Djindjian et al.[6] also described the filum terminale artery as a part of the continuation of the artery of Adamkiewicz, connecting to the spinal artery at the conus level and continuing as a longitudinal artery on the ventral surface of filum terminale. Apparently, no other arteries support the filum terminale; however, Lim et al.[7] reported that branches from the lateral and middle sacral arteries may supply the filum terminale. The vein of the filum is a single structure lying on the dorsal surface of the filum from its sacral end to the tip of the conus medullaris behind the artery;[6],[7] it continues to the extradural venous plexus of sacrum to the ventral vein of the spinal cord. The venous flow could be cephalad or caudad. AVFFT terminale is initially mentioned in the literature as the intradural extramedullary spinal AV fistulas, mostly congenital, as well as acquired in nature, characterized by a direct AVF located on the ventral surface of the filum fed by the ASA and are typically drained by a single filum terminale vein to the venous plexus of sacurm.

The typical clinical presentation is slowly progressive myelopathy, which most commonly manifests as motor weakness, sensory disturbances, back pain, bladder and bowel dysfunction, and sexual dysfunction. Therefore, the condition may be misdiagnosed as degenerative disc disease.

MRI is recommended as the initial diagnostic tool; however, it may be difficult to differentiate AVFFT from perimedullary AVF, dural AVF, or epidural AVF. Prominent vascular flow voids (46%) and vascular enhancement (67%) are common.[8] Computed tomography angiography/magnetic resonance angiography may be required to confirm fistula location. However, DSA remains the gold standard for accurate delineation of the lesion. Overall, 8% fistulas are located at the L3–L5 level and have one longitudinal arterial feeder from ASA. Most case reports showed a small caliber arterial feeder and long distance from the segmental artery of the fistula; therefore, it is safer to perform surgical clipping (success rate, nearly 100%; complication rate, <5%).[9],[10] However, the choice between surgical clipping and endovascular treatment is largely based on the size of the feeding artery and the distance of feeding pedicle from the fistulous point.

In our patient, there was a longitudinal, tiny filum terminale artery (~10 cm) extending from the confluence of ASA and the artery of Adamkiewicz at T10; it was connected with a single drainage vein at L3. Based on the fistulous connection between the single feeding artery and an enlarged venous channel in the subarachnoid space, the lesion was classified as Type IV AVF. Owing to the tiny feeding artery, we opted for surgical clipping and decompression by laminectomy. However, the treatment decision-making should be guided by patient's preoperative condition, neurological status, surgeon's expertise, and AVF characteristics.

Accurate delineation of the feeding artery and precise localization of the fistulous point are extremely important for AVFFT management. The artery and vein might adhere tightly with a much longer segment than fistula; therefore, separating the tight adherence and identifying the fistulous point in that area is crucial. The use of hybrid OR allows for intraoperative confirmation of fistula location and complete obliteration. In addition, intraoperative electrophysiological parameters helped us monitor the neurological status. The amplitude of potential wave once decreased during the first attempt at clipping, and a rootlet attached to the vessel was compressed by the clip. After adjustment, the potential wave was restored to its original amplitude, and the patient showed no deterioration of neurological function postoperatively.

  Conclusion Top

AVFFT is extremely rare entities that may be misdiagnosed in the absence of definitive investigations. The goal of the treatment is complete obliteration, necessitating accurate intraoperative characterization of all the feeding arteries and exact localization of the fistula. Owing to the nature of the feeding artery, open surgery is the preferred approach for most AVFFTs, once the complete obliteration is done, improvement of the neurological deficits could be expected. In our case experience, we suggested that intraoperative angiography in hybrid OR as a useful tool to identify the fistulous point and confirm complete occlusion the fistula.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Giordan E, Brinjikji W, Ciceri E, Lanzino G. Arteriovenous fistulae of the filum terminale. J Neurointerv Surg 2018;10:191-7.  Back to cited text no. 1
Rodesch G, Hurth M, Alvarez H, Tadié M, Lasjaunias P. Classification of spinal cord arteriovenous shunts: Proposal for a reappraisal – The bicêtre experience with 155 consecutive patients treated between 1981 and 1999. Neurosurgery 2002;51:374-9.  Back to cited text no. 2
Trinh VT, Duckworth EA. Surgical excision of filum terminale arteriovenous fistulae after lumbar fusion: Value of indocyanine green and theory on origins (a technical note and report of two cases). Surg Neurol Int 2011;2:63.  Back to cited text no. 3
[PUBMED]  [Full text]  
Oldfield EH, Doppman JL. Spinal arteriovenous malformations. Clin Neurosurg 1988;34:161-83.  Back to cited text no. 4
Harmeier J. The normal histology of the intradural filum terminale. Arch Neurol Psychiatry 1933;29:308-16.  Back to cited text no. 5
Djindjian M, Ayache P, Brugieres P, Poirier J. Sacral lipoma of the filum terminale with dural arteriovenous fistula. Case report. J Neurosurg 1989;71:768-71.  Back to cited text no. 6
Lim SM, Choi IS, David CA. Spinal arteriovenous fistulas of the filum terminale. AJNR Am J Neuroradiol 2011;32:1846-50.  Back to cited text no. 7
Chanthanaphak E, Pongpech S, Jiarakongmun P, Kobkitsuksakul C, Chi CT, Terbrugge KG. Filum terminale arteriovenous fistulas: The role of endovascular treatment. J Neurosurg Spine 2013;19:49-56.  Back to cited text no. 8
Takami T, Yamagata T, Mitsuhashi Y, Hayasaki K, Ohata K. Direct surgery for spinal arteriovenous fistulas of the filum terminale with intraoperative image guidance. Spine (Phila Pa 1976) 2012;37:E1524-8.  Back to cited text no. 9
Djindjian M, Ribeiro A, Ortega E, Gaston A, Poirier J. The normal vascularization of the intradural filum terminale in man. Surg Radiol Anat 1988;10:201-9.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3]

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