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)

Coexisting filum terminale arteriovenous fistula and filum terminale lipoma treated with single-stage surgery: illustrative case

BACKGROUND

Both filum terminale arteriovenous fistulas (FTAVFs) and filum terminale lipomas (FTLs) are rare. Because of this rarity, there is a paucity of data regarding concomitant FTAVF and FTL, and the optimal treatment remains to be defined. The authors describe a patient with coexisting FTAVF and FTL treated with single-stage surgery.

OBSERVATIONS

A man in his 70s was referred to the authors' department because of a suspected spinal vascular malformation seen on magnetic resonance imaging that was performed to investigate lower limb weakness, intermittent claudication, and urinary incontinence. Previous imaging had shown a terminal lipoma with an internal flow void. Computed tomography angiography and digital subtraction angiography revealed an FTAVF, the feeder being a lateral sacral artery. The patient was treated surgically with curative intent. The FTL and tethered cord that had been identified by imaging were treated in the same procedure. Postoperative digital subtraction angiography showed absence of the abnormal vessels. The patient was discharged home on the 19th postoperative day.

LESSONS

When considering treatment, it is important to determine whether symptoms are attributable mainly to FTL, tethered cord, or FTAVF. One-stage treatment is useful because it eliminates both the FTAVF and the factors that led to its development.

Filar arteriovenous fistula mimicking upper motor neuron palsy: A case report with review of the literature

Background:

Filar A-V fistula is a rare entity. It requires a high degree of suspicion to diagnose. Magnetic resonance imaging (MRI) findings are often nonspecific and spinal angiogram is required to diagnose it.

Case Description:

A 63-year-old male patient presented with Grade 4 spastic paraplegia and significant sensory disturbance below D8 level along with severe vesicorectal dysfunction. On imaging flow voids were present at lower dorsal and lumbar level in MRI (T2 sequence). Patient underwent spinal digital substraction angiography (DSA) which was suggestive of filar fistula at L4-L5 level. Patient underwent surgical exploration with L4-5 laminectomy. Feeding artery was identified using indigocyanine green (ICG) dye and excised along with filum and dilated vessels. Patient recovered symptomatically in postoperative period.

Conclusion:

Filar fistula is a rare lesion and it presents with long standing progressive congestive myelopathy. It requires a high degree of suspicion to diagnose it. DSA is the gold standard for diagnosis and management planning. Surgical approach utilizing the ICG dye is best treatment options in such cases.

Arteriovenous malformations of the filum terminale: clinical characteristics, angioarchitecture, and management of a rare spinal vascular pathology

OBJECTIVE

The goal of this study was to describe clinical and neuroradiological features of arteriovenous malformations of the filum terminale (FT AVMs) and to present the authors’ diagnostic and therapeutic management in this rare disease.

METHODS

The presented cases were retrieved from a retrospectively collected database of all spinal vascular malformations treated between June 1992 and December 2021 at the Rheinisch-Westfälische Technische Hochschule (RWTH) University Hospital Aachen. Pretreatment and follow-up clinical and neuroradiological data were analyzed for this study.

RESULTS

Data in 15 patients with FT AVM with a mean age of 60 years were included, with an overall incidence of FT AVM of 19% among all spinal AVMs in our cohort. Twelve of 15 (80%) patients were men. Nonspecific but typical clinical and MR findings of thoracolumbar congestive myelopathy were found in all patients. Spinal MR angiography, performed in 10 patients, identified in all cases the arterialized FT vein as well as a lumbar/lumbosacral location of an AV shunt. Digital subtraction angiography (DSA) showed an arterial supply solely via the FT artery in 12/15 (80%) patients and via an additional feeder from the lumbosacral region in the other 3/15 (20%) patients. All patients were treated surgically. During 1-year follow-up, 2 patients presented with recurrent FT AVM due to further arterial supply from the lumbosacral region, and were treated surgically. Neurological status was improved in all patients within the 1-year follow-up, with marginal further changes during long-term follow-up.

CONCLUSIONS

Congestive myelopathy is the major pathological mechanism of symptoms in these patients, with no evidence for intradural bleeding. Missing the presence of possible multiple arterial supply of FT AVM during DSA may result in misdiagnosis and/or insufficient treatment. Due to the frequently prolonged course of FT artery, resection of the FT AVM may be a favorable treatment modality in comparison with endovascular treatment. Follow-up examinations are obligatory within the first 3 years after treatment, and further MR angiography and DSA examinations are indicated if congestive myelopathy persists.

Spinal arteriovenous fistula in the lipoma of the filum terminale: A report of two cases and literature review

Background

Filum terminale arteriovenous fistulas (FTAVFs) are rare and their pathogenesis remains unknown. The authors report two cases of FTAVF that arose in the lipoma of the filum terminale.

Case Description

The two patients were 72 and 76 years of age, and both presented with a progressive paraparesis. The first patient had an arteriovenous fistula (AVF) located at L5 that was supplied by the anterior spinal artery originating from the left T10 intercostal artery. The second patient's AVF at L3-4 was fed by the anterior spinal artery originating from the left T8 intercostal artery. Both patients underwent partial resection of the filum terminale at the location of the shunts. The pathological examinations revealed that both the AVFs were embedded in the adipose tissue of the filum terminale, revealing the fatty fila that were not visible in preoperative magnetic resonance images.

Conclusion

Two cases of FTAVF were successfully treated by obliterating the fistulas through partial resection of the affected fatty filum terminale. The literature review revealed 13 cases of FTAVF concomitant with the lipomas of the filum terminale. Resection and histological evaluation of the filum terminale should be performed to treat and elucidate the pathogenesis of FTAVF.

Arteriovenous fistula of the filum terminale masqueraded as a failed back surgery syndrome - A case report and review of literature

BACKGROUND

The filum terminale arteriovenous fistulas (FTAVFs) are a very rare type of spinal vascular malformation. Clinically, these lesions could present with a progressive ascending myelopathy also called FoixAlajouanine syndrome. Due to the rarity of these vascular malformation, some can be misdiagnosed, submitted to unnecessary spinal surgery, and even masqueraded as a failed back surgery syndrome. Based on the present case and related literature, we review all the cases with similar history and describe factors that should raise awareness for diagnosis of this spinal vascular malformation.

CASE DESCRIPTION

We present a case of a patient with a FTAVF at the level of L5-S1 that presented with a FoixAlajouanine syndrome. He had been previously submitted to a lumbar decompressive laminectomy without sustained improvement. After the identification and surgical treatment of the vascular malformation, he had progressive neurological improvement.

CONCLUSION

FTAVF is a very rare spinal intradural spinal vascular malformation that can be masqueraded as a failed back surgery syndrome. In these cases, signs of ascending myelopathy should prompt awareness and vascular voids must be carefully evaluated in MRI.

Cauda Equina and Filum Terminale Arteriovenous Fistulas: Anatomic and Radiographic Features

Intradural AVF below the conus medullaris may develop either on the filum terminale or the cauda equina (lumbosacral and coccygeal radicular nerves). Although not a few filum terminale AVFs are found in the literature, only 3 detailed cauda equina AVFs have been reported. Here, we analyze the angiographic and MR imaging findings of our cauda equina and filum terminale AVF cases, supplemented with literature research to characterize the radiologic features of the 2 entities. On angiography, filum terminale AVFs were invariably supplied by the extension of the anterior spinal artery accompanied by a closely paralleling filum terminale vein. Cauda equina AVFs were fed by either a radicular or a spinal artery or both arteries, often with a characteristic wavy radicular-perimedullary draining vein. On thin-section axial MR imaging, the filum terminale AVF draining vein joined the spinal cord at the conus medullaris apex, but that of the cauda equina AVF joined above the conus medullaris apex.

Filum Terminale Arteriovenous Fistula in Association with Degenerative Lumbosacral Spinal Canal Stenosis: Report of 3 Cases and Review of the Literature

BACKGROUND

Filum terminale arteriovenous fistulas (FTAVFs) are rare, and the pathogenesis of these fistulas remains unclear. They may be either congenital or acquired in origin. The authors report 3 cases of FTAVFs in association with severe spinal canal stenosis. The authors also review literature of FTAVFs associated with spinal canal stenosis.

CASE DESCRIPTION

All 3 cases harboring FTAVFs manifested with progressive myelopathy and bowel/bladder dysfunction following long history of back pain, sciatica, and/or intermittent claudication. The fistulas were located around or at the level of spinal canal stenosis and supplied by the anterior spinal and/or lateral sacral arteries with cranial drainage from the dilated vein of the filum terminale to the perimedullary veins. The first and third cases were treated concomitantly by performing instrumented fusion with decompressive laminectomy along with occlusion of the fistula with good results. The second case was unsuccessfully treated by endovascular treatment through the lateral sacral artery and denied further surgical treatment.

CONCLUSIONS

Our 3 case reports may provide additional evidence supporting an acquired etiology of FTAVFs, probably secondary to the severe central canal stenosis. From our review, the level of the fistulas in most patients is correlated with the level of spinal canal stenosis. The authors preferred the concomitant surgical treatment by performing decompressive laminectomy and obliteration of the fistula in the same surgical session.

Spinal Arteriovenous Fistulas of the Filum Terminale: Case Report and Literature Review

Spiinal arteriovenous fistulae (AVF) are an uncommon cause of myelopathy that require a high degree of suspicion to diagnose. Treatment strategies have not yet been established. Only a few cases of AVFs of the filum terminale (FT) have been reported. In this review, we describe clinical presentation, imaging, and treatment options for this rare type of spinal AV shunt. A 43-year-old male patient presented with progressive low back pain and paraparesis with gradually worsening bilateral foot paresthesias and sphincter dysfunction. He underwent magnetic resonance imaging, which revealed a hypersignal in the thoracolumbar cord and angiography diagnosed a microfistula of the FT. Surgery was preferred over endovascular treatment and we realized an L5 laminectomy to open the dura mater and found a hypertrophic FT. After identifying the fistula which was closely related to cauda equina, and dissecting the root from the fistula, a permanent clip was placed on the proximal part of the arterialized vein. Surgery was uneventful, and 6 months postoperatively, the patient has fully recovered. FT AVFs although rare should be considered as a differential diagnosis of progressive paraparesis, and successful surgery through clipping relies on the angioarchitecture of the shunt and the clinical manifestations of the patient.

Arteriovenous fistulae of the filum terminale

Filum terminale arteriovenous fistulae are a rare type of arteriovenous shunt generally characterized by a single direct communication between the artery of the filum terminale and a single draining vein. These intradural arteriovenous shunts are three times more common in men than women (mean age 55 years). Symptoms are related to venous congestion, vascular hypertension, and a putative chronic steal phenomenon which result in spinal cord ischemia and myelopathy. Interestingly, hemorrhage has never been reported as a mode of presentation. MRI demonstrates increased flow voids and T2 changes involving the conus and the lower spinal cord, and these findings are not dissimilar from those seen with the more common type 1 spinal dural arteriovenous fistulae. Thus conventional spinal angiography is necessary for a definitive diagnosis and to localize exactly the site of the fistula. Both surgical interruption of the fistula and endovascular embolization are safe and effective therapeutic modalities. However, because of the very small caliber of the feeding artery, endovascular therapy is often not feasible; and thus, surgery remains the method more commonly utilized for their treatment. Definitive treatment consists of obliteration of the direct arteriovenous shunt. In this review, we describe the anatomy, pathophysiology, clinical presentation, imaging, and treatment options of these less common intradural arteriovenous shunts.

Study and therapeutic progress on spinal cord perimedullary arteriovenous fistulas

Spinal cord perimedullary arteriovenous fistulas (PMAVFs) are rare and belong to type IV spinal cord arteriovenous malformations (AVMs). Little is known regarding the treatment and prognosis of spinal cord PMAVFs. In the present study the relevant literature from PubMed was reviewed, and it was found that these fistulas can occur at all ages but are more common in children. In children, most spinal cord PMAVFs are large and with high flow, begin with bleeding and are frequently associated with hereditary hemorrhagic telangiectasia. However, in adults, most spinal cord PMAVFs are small and with low flow and begin with progressive spinal cord dysfunction. The early diagnosis of spinal cord PMAVFs is generally difficult, and symptoms can be very severe at the time of diagnosis. Digital subtraction angiography remains the gold standard; however, computed tomography angiography and magnetic resonance angiography are also promising. Spinal cord PMAVFs can be treated by endovascular embolization, surgical removal or a combination of the two methods. Most spinal cord PMAVFs show good outcomes after the appropriate treatment, and the prognosis is primarily associated with the blood flow of the PMAVF. For high-flow spinal cord PMAVFs, endovascular embolization is more effective and can lead to a good outcome; however, for low-flow spinal cord PMAVFs, surgical removal or the combination with endovascular embolization is the optimal choice. The prognosis for low-flow types is slightly worse than for high-flow spinal cord PMAVFs in children, but the outcome is acceptable.

A case of arteriovenous fistula of the cauda equina fed by the proximal radicular artery: anatomical features and treatment precautions

PURPOSE

Arteriovenous fistula (AVF) of the cauda equina (CE) fed by the proximal radicular artery (PRA) is very rare, and the differentiation from that of the filum terminale (FT) is important to avoid treatment-related injury to the CE when endovascular treatment is selected. The authors describe a case of AVF of the CE fed by the PRA, demonstrate the anatomical features and discuss the treatment precautions.

METHODS

A 69-year-old man presented with a transient weakness of lower limbs. Spinal angiography and magnetic resonance (MR) imaging revealed AVF, of which the feeding artery arose from the anterior spinal artery (ASA), forming the fistula at L2 level to be drained into the longitudinal venous trunk. Under a tentative diagnosis of AVF of the FT, endovascular treatment was attempted but failed due to impossible catheterization into the ASA. Therefore, surgery was performed.

RESULTS

Intraoperative finding revealed that the feeding artery and draining vein were not on the FT but on the CE, resulting in the proper diagnosis of AVF of the CE. Surgical clips were applied to the draining vein closest to the fistula, and postoperatively the symptom improved gradually. Although we thoroughly reevaluated spinal angiography and MR images postoperatively, AVF of the CE fed by the PRA and that of the FT were not distinguishable.

CONCLUSIONS

The authors described a case of AVF of the CE fed by the PRA and demonstrated the difficulty of the differentiation from that of the FT. The utmost precautions are necessary when endovascular treatment is selected.

A case of filum terminale arterial venous fistula needed a long arterial access for trans-arterial shunt obliteration

A 78-year-old man was referred to our institution with a predominantly progressive numbness of both legs, and bladder dysfunction with urinary retention. He was diagnosed as the symptomatic arteriovenous fistula of the filum terminale (AVFFT). A trans-arterial embolization (TAE) of the arteriovenous shunt was planned for his symptomatic AVFFT. The long distance between the origin of the radiculo meningeal artery (Th8) and the site of the fistula (S1) resulted in the first TAE having a feeder occlusion. The length of accessible feeder in the first TAE was the longest (about 40 cm) as the past reports of the endovascular therapy. However, complete shunt occlusion was accomplished at a second session two weeks after the initial TAE because a more accessible feeder was developed by the initial feeder occlusion.

Comparison of 3 Different Types of Spinal Arteriovenous Shunts below the Conus in Clinical Presentation, Radiologic Findings, and Outcomes

BACKGROUND AND PURPOSE

Spinal arteriovenous shunts below the conus constitute 3 types of lesions, which have previously been mainly described in case reports, given their rarity, and are sometimes misdiagnosed. The purpose of this study was to describe the features of each type and compare these types as to epidemiologic features, clinical and radiologic presentations, treatment, and outcomes in a consecutive series of 48 cases.

MATERIALS AND METHODS

The prospectively collected data bases of 2 referral centers for spinal vascular lesions were retrospectively reviewed. Spinal arteriovenous shunts below the conus were defined as all dural and intradural shunts below the conus medullaris. Clinical features, radiologic findings, treatment results, and clinical outcomes were assessed.

RESULTS

There were filum terminale arteriovenous fistulas in 11 patients (22.9%), radicular arteriovenous shunts in 7 patients (14.6%), and spinal dural arteriovenous fistulas in 30 patients (62.5%). Radicular arteriovenous shunts presented at a younger age (P = .017) and with a higher incidence of back pain symptoms (P = .037). A tethered spinal cord was found in 54.5% of patients with filum terminale arteriovenous fistulas and 23.3% of patients with spinal dural arteriovenous fistulas. After treatment, the angiographic complete obliteration rate was 89.4% and spinal function was improved significantly (P < .001).

CONCLUSIONS

Three groups of spinal arteriovenous shunts below the conus can be differentiated according to clinical and radiologic features. Filum terminale arteriovenous fistulas are frequently associated with dysraphic malformations, which may suggest a particular embryologic origin.

Indocyanine green videoangiography methodological variations: review

Indocyanine green videoangiography (ICGVA) procedures have become widespread within the spectrum of microsurgical techniques for neurovascular pathologies. We have conducted a review to identify and assess the impact of all of the methodological variations of conventional ICGVA applied in the field of neurovascular pathology that have been published to date in the English literature. A total of 18 studies were included in this review, identifying four primary methodological variants compared to conventional ICGVA: techniques based on the transient occlusion, intra-arterial ICG administration via catheters, use of endoscope system with a filter to collect florescence of ICG, and quantitative fluorescence analysis. These variants offer some possibilities for resolving the limitations of the conventional technique (first, the vascular structure to be analyzed must be exposed and second, vascular filling with ICG follows an additive pattern) and allow qualitatively superior information to be obtained during surgery. Advantages and disadvantages of each procedure are discussed. More case studies with a greater number of patients are needed to compare the different procedures with their gold standard, in order to establish these results consistently.

Arteriovenous fistula of the filum terminale misdiagnosed and previously operated as lower lumbar degenerative disease

Filum terminale arteriovenous fistula (FTAVF) presenting as a cause of failed back surgery syndrome is a rare entity. We report a 48-year-old male patient who presented with clinical features of a conus medullaris/cauda equina lesion. He had upper and lower motor neuron signs in both the lower limbs with autonomic dysfunction. The patient was misdiagnosed and was operated twice earlier for lumbar canal stenosis and disc prolapse. After reviewing his clinical and radiological findings a diagnosis of FTAVF was made. He underwent surgery and there was a significant improvement in his neurological functions. We discuss the case and review the literature on FTAVF's.

Congestive myelopathy (Foix-Alajouanine Syndrome) due to intradural arteriovenous fistula of the filum terminale fed by anterior spinal artery: Case report and review of literature

Spinal arteriovenous fistulas are rare entities. They often present with congestive myelopathy but are infrequently diagnosed as the cause of the patients’ symptoms. Only one such case has been described previously in Indian literature. We describe one such case who presented to us after a gap of 3 years since symptom onset and following a failed laminectomy where the cause was later diagnosed to be an intradural fistula in the filum terminale fed by the anterior spinal artery and review the available literature.

Filum terminale arteriovenous fistulas: the role of endovascular treatment

Object

The authors describe the clinical presentation, imaging features, and management of patients presenting with filum terminale arteriovenous fistulas (FTAVFs) and the role of transarterial treatment in their management.

Methods

The authors retrospectively reviewed data obtained in 10 patients with FTAVFs diagnosed between January 1990 and December 2011.

Results

Most patients (70%) were male, and the age of the population ranged from 31 to 72 years (mean 58.2 years). Clinical presentation was progressive paraparesis and sensory loss in the lower extremities in 9 cases, back pain in 7, radicular pain in 3, bowel/bladder disturbance in 5, and impotence in 1. The duration of symptoms varied between 2 and 24 months. Initial MRI studies showed intramedullary increased T2 signal, swollen cord, and dilated perimedullary veins in all patients. One patient had syringomyelia, presumably caused by venous hypertension transmitted by the perimedullary venous system. Embolization was attempted in 7 patients and was curative in 6 patients. Surgery was performed in the other 4 patients in whom embolization was unsuccessful or deemed not feasible. There was no treatment-related complication in either group. Symptoms, venous congestion in the cord, and syringomyelia improved on follow-up in all patients.

Conclusions

Embolization should be considered the treatment of choice for FTAVFs and can effectively treat the majority of patients presenting with an FTAVF. In a smaller group of patients in whom the angioarchitecture is unfavorable, open surgery is recommended.

Direct surgery for spinal arteriovenous fistulas of the filum terminale with intraoperative image guidance

STUDY DESIGN

A technical case report of direct surgery for spinal arteriovenous fistulas of the filum terminale.

OBJECTIVE

We present 2 cases of spinal arteriovenous fistulas of the filum terminale directly fed by the anterior spinal artery that were successfully obliterated with intraoperative image guidance such as digital subtraction angiography, intra-arterial dye injection technique, or indocyanine green video angiography.

SUMMARY OF BACKGROUND DATA

The goal of direct surgery for spinal arteriovenous fistulas is the complete obliteration of shunt vessels while preserving the normal circulation of spinal cord. Safe isolation of feeding arteries, nidus, and draining veins needs to be obtained first. Vascular flow or anatomical orientation of shunt vessels also needs to be ensured with intraoperative image guidance.

METHODS

Two cases are presented. The first patient (case 1) had the lesion with a nidus formation at the L2 spinal level supplied directly by the anterior spinal artery via left L1 segmental artery. The second patient (case 2) had a lesion at the L4-L5 spinal level also supplied directly by the anterior spinal artery via the left T11 intercostal artery. Standard exposure of the lesion followed intraoperative image guidance to achieve the appropriate vascular flow or anatomical orientation of the shunt vessels.

RESULTS

Complete obliteration of shunt vessels was successfully achieved without any complications in both cases.

CONCLUSION

Although intraoperative image guidance is certainly not a prerequisite, the concept of safe and minimally invasive surgery makes it indispensable. It can facilitate identification of crucial or important landmarks where anatomic structures may be distorted.

Selective intraarterial injection of ICG for fluorescence angiography as a guide to extirpate perimedullary arteriovenous fistulas

BACKGROUND

Fluorescence angiography with indocyanine green (ICG) provides real-time information regarding the patency of vessels. To enhance the capability to delineate flow direction, flow velocity and sequence of dye filling in different components of complex spinal vascular lesions such as perimedullary arteriovenous fistulas (AVFs), we tried selective intraarterial injection of ICG with catheterization in the proximity of the AVFs.

METHOD

Prior to taking the position for surgery, a metallic introducer sheath was placed into the femoral artery, and placed over the patient's lateral buttock. After the exposure of the AVFs, a standard angiographic catheter was advanced into the proximal portion of the feeding artery and a small volume of diluted ICG (0.06 mg in 5 ml saline for one examination) injected repeatedly. To avoid the thromboembolism, heparinized saline was perfused continuously thorough the catheter and sheath.

FINDINGS

The small injection volume and the close proximity of the injection site to the lesions resulted in quick rise and fall of the fluorescence without any background. Time and spatial resolution of analysis were enhanced; flow dynamics such as direction, velocity and alteration after temporary occlusion were well visualized. The feeders and drainers were clearly distinguished, and the shunts could be precisely identified.

CONCLUSIONS

Selective intraarterial injection ICG fluorescence angiography was very useful for perimedullary AVFs. Albeit that it requires intraoperative selective catheterization, this repeatable technique has an advantage to improve temporary resolution and provides accurate information of the flow dynamics through the complex anatomy of vascular lesions.