Filum Terminale Arteriovenous Fistulas with Multiple Shunt Points: A Report of Two Exceptional Cases

Treatment of filum terminale pial arteriovenous fistulas in the sacral region: A case report and systematic review

Spinal filum terminale pial arteriovenous fistulas (FT PAVFs) are uncommon. Most FT PAVFs are located in the lumbar region; far fewer are located in the sacral region. Due to the rarity of sacral FT PAVFs, the precise surgical dissection and removal of these lesions are challenging. Here, we report an FT PAVF in the sacral region. The patient was a 45-year-old male who suffered from progressive weakness and numbness of the bilateral lower limbs; his symptoms gradually worsened. Digital subtraction angiography (DSA) showed an AVF at the sacral canal at the S3-4 level. Microsurgical treatment with intraoperative DSA was performed, and the FT PAVF was resected. After the operation, the patient gradually recovered. Follow-up magnetic resonance imaging revealed a recession in the dilation of the spinal cord venous plexuses. A literature review was also performed, and a total of 14 FT PAVFs of the sacral region were identified. The patients identified in the literature review had an average age of 58.9 ± 12.9 years, and 92.9% of the patients were male. Spinal cord edema was present in 85.7% of the FT PAVF patients. Regarding treatment, 64.3% of the FT PAVF patients underwent microsurgical resection, 28.6% patients underwent endovascular treatment, and 7.1% patients underwent a hybrid operation; good outcomes were achieved with all three methods. Therefore, FT PAVF of the sacral region is a unique lesion whose angioarchitecture needs to be identified carefully; prompt treatment is necessary, and microsurgery can yield good outcomes.

Filum terminale arteriovenous shunt with nidus structure: a report of rare condition and treatment consideration

BACKGROUND

 In the literature, filum terminale arteriovenous shunts (FTAVSs) always feature a single shunt point. Nidus-type FTAVSs have rarely been reported, and the best treatment strategy is unclear. This is a report of one exceptional case of a nidus-type FTAVS and surgical treatment of the lesion.

CASE DESCRIPTION

The patient suffered from cauda equina syndrome for 9 months. Magnetic resonance imaging and spinal angiography revealed a nidus-type FTAVF at the L2 level. Surgical resection was performed in the hybrid operating room, and the nidus was completely resected with the assistance of intraoperative methylene blue angiography and neurophysiological monitoring. The postoperative neurological function was stable.

CONCLUSIONS

A nidus-type arteriovenous shunt could originate from the FT, and in such cases, complete surgical resection with intraoperative neurophysiological monitoring in a hybrid operating room should be suggested.

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.

The efficacy and deficiency of contemporary treatment for spinal cord arteriovenous shunts

Contemporary treatments for spinal cord arteriovenous shunts are only based on clinicians' treatment experiences and expertise due to its rarity. We reviewed the clinical course of the largest multi-cantered cohort to evaluate the efficacy and deficiency of contemporary interventional treatments for spinal cord arteriovenous shunts. The clinical features, treatment results and clinical outcomes of 463 spinal cord arteriovenous shunts patients were retrospectively assessed. The main outcome was the neurological deterioration that was evaluated based on the modified Aminoff and Logue scale. According to post-treatment DSA, complete obliteration was defined as disappearance of the intradural lesion, whereas partial obliteration was defined as any residual intradural lesion remaining visible and was further categorized as shunt-reduction obliteration (the nidus or shunt points was reduced) or palliative obliteration (only obliterated aneurysms or feeders). Cure rate was 40.6% for whole cohort, 58.5% after microsurgery, and 26.4% after embolization. The curative resection was associated with non-metameric lesions, lesions with a maximum diameter < 3 cm and lesions without anterior sulcal artery supply. The curative embolization was associated with fistula-type lesions, non-metameric lesions, and main drainage diameter < 1.5 mm. Permanent treatment-related neurological deficits rate was 11.2% for the whole cohort, 16.1% after microsurgery, and 5.6% after embolization. The pre-treatment clinical deterioration rate was 32.5%/year, which decreased to 9.3%/year after clinical interventions. After partial treatment, the long-term acute and gradual deterioration rate were 5.3%/year and 3.6%/year, respectively. The acute deteriorations were associated with metameric lesions, craniocervical lesions, lesions with a maximum diameter ≥2 cm and residual aneurysm. Residual aneurysm was the only predictor of acute deterioration for non-metameric spinal cord arteriovenous shunts. The gradual deteriorations were associated with palliative obliteration, absence of pre-treatment acute deterioration and intact main drainage. Although clinical risks of spinal cord arteriovenous shunts were reduced after clinical interventions, contemporary treatments for spinal cord arteriovenous shunt remains associated with considerable risks and incomplete efficacy. Individualized treatment plans should be adopted according to the angioarchitectural features and major clinical risks of specific lesions. There is a higher opportunity for complete obliteration for lesions with simple angioarchitecture. However, regarding most of spinal cord arteriovenous shunts with complex vascular anatomy, partial treatment is the only choice. For these patients, palliative obliteration targeting the aneurysms is recommended for reducing hemorrhagic risk, whereas shunt-reduction obliteration is necessary for non-haemorrhagic myelopathy. Contemporary treatment is ineffective in reducing hemorrhagic risk of incurable metameric spinal cord arteriovenous shunts.

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.

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.