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

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.

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.

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.

Microsurgical or endovascular strategy for complete obliteration of spinal arteriovenous shunts in a single-institute 10-year retrospective study

The objective of this retrospective study is to more fully understand the optimal strategy to manage spinal arteriovenous (AV) shunts. This study included a cohort of 35 patients with a diagnosis of spinal AV shunts who were treated over the past 10 years at a single institute. Angiographic diagnosis of intramedullary AV malformations (IM-AVM), perimedullary AV fistulas (PM-AVF), dural AV fistulas (D-AVF), or epidural AV fistulas (ED-AVF) was carefully made, and the microsurgical or endovascular strategy for them was determined at the interdisciplinary meeting consisting of neurospinal surgeons and endovascular specialists. Endovascular surgery was first considered whenever safely possible. Microscopic direct surgery using intraoperative image guidance was considered for cases in which endovascular access was challenging or not safely possible. Combined treatment was another option. The clinical condition was assessed using the modified Rankin scale (mRS). Seventeen of 35 cases were treated with microscopic direct surgery, 13 cases with endovascular surgery, and the remaining five cases with the combination. Complete angiographic obliteration was achieved in 30 of 35 cases (85.7%). Although residual AV shunts was recognized in 3 cases of IM-AVM, 1 case of PM-AVF and 1 case of ED-AVF, no angiographic recurrence was present with an average postoperative follow-up period of 44 months. The average mRS before surgery was 2.37 and significantly improved to 1.94 at the most recent follow-up. Interdisciplinary collaboration between neurospinal surgeons and endovascular specialists should be standard to achieve safe and successful outcomes in treating such rare and difficult spinal disorders.

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.

Quantitative Analysis of Near-Infrared Indocyanine Green Videoangiography for Predicting Functional Outcomes After Spinal Intramedullary Ependymoma Resection

BACKGROUND

One of the most critical steps in surgery for spinal intramedullary ependymomas is the resection of small feeding arteries from the anterior spinal artery with anatomical preservation of the normal circulation of the ventral spinal cord.

OBJECTIVE

To quantitatively analyze the microcirculation of the ventral spinal cord by near-infrared indocyanine green videoangiography (ICG-VA) after the spinal intramedullary ependymoma resection.

METHODS

This retrospective study included 12 patients (7 male and 5 female; average age 55.2 years, range 36-79 years). Patients' neurological conditions were assessed based on the modified McCormick functional schema of grade 1 (neurologically normal) to 5 (severe deficit). Postoperative functional assessment was conducted at least 3 months after surgery. Quantitative analysis of vascular flow dynamics was carried out following spinal intramedullary ependymoma resection. Fluorescence intensities were measured and the indocyanine green (ICG) intensity-time curves were analyzed and compared with the functional outcomes after surgery.

RESULTS

Microscopically total or subtotal resection of the intramedullary ependymoma was achieved in all cases. Average peak time on ICG-VA was significantly shorter in the postoperative functional grade 1 to 2 group than in the postoperative functional grade 3 to 5 group, but there was no significant difference in average peak intensity between the 2 groups. Postoperative functional grade and the peak time of ICG, but not peak intensity, appeared correlated.

CONCLUSION

To the best of our knowledge, this is the first report showing that quantitative analysis of ICG-VA may predict functional outcomes after spinal intramedullary ependymoma resection.

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.

Usefulness of preoperative cone beam computed tomography and intraoperative digital subtraction angiography for dural arteriovenous fistula at craniocervical junction: Technical case report

Background:

Direct surgery is commonly selected for the treatment of cranio-cervical junction dural arteriovenous fistula and its outcome is more satisfactory than that of embolization. Intraoperative treatment evaluation is relatively easy in embolization, whereas in direct surgery it can be difficult.

Case Description:

A 67-year-old male suffered a subarachnoid hemorrhage. On three-dimensional (3D) images of preoperational cone-beam computed tomography (CBCT), the structure of the draining vein was depicted in detail along with the surrounding bone structures. The radial artery penetrated the dura mater, and it was found that there were two veins derived from the radiculospinal vein; one was the anterior radicular vein descending toward the dorsal side (the shallow layer of the surgical field) and the other was the anterior spinal medullary vein ascending toward the ventral side (the deep layer of the surgical field) and flowing out to the anterior spinal vein.

Conclusion:

Without detailed assessments with preoperative CBCT, the surgery might have been done with dissection of only the anterior radicular vein in the shallow layers. For identification of the draining vein located deep in the surgical field, such as the cranio-cervical junction, careful assessments using 3D CBCT images are important.

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

BACKGROUND

Filum terminale arteriovenous fistula (FTAVF) with multiple shunt points has not been reported in the literature. In previous studies, the angioarchitecture of FTAVFs was always featured with only one single shunt point, and such a uniformity had established the preconceived and conventional understanding of FTAVFs for clinicians.

CASE DESCRIPTION

The authors describe 2 exceptional cases of FTAVFs with multiple shunt points confirmed by open surgery, which means that the above understanding may lead to misdiagnosis and incomplete treatment in future. The surgery of both cases was performed in a hybrid operating room, and all of shunt points were obliterated with the help of intraoperative digital subtraction angiography.

CONCLUSIONS

The exceptional finding of these 2 cases is a renewal of the conventional understanding of FTAVFs, not only for the angioarchitecture of the lesions but also for the treatment strategy.

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.

Surgical Outcomes of Posterolateral Sulcus Approach for Spinal Intramedullary Tumors: Tumor Resection and Functional Preservation

BACKGROUND

Selection of the access myelotomy is a key issue in surgery for spinal intramedullary tumors. This study focused on surgical outcomes with the posterolateral sulcus (PLS) approach, equivalent to dorsal root entry zone myelotomy.

METHODS

This retrospective study of the 10-year period from 2007 to 2016 included 90 cases of spinal intramedullary lesions (99 operations). A PLS approach was indicated for intramedullary lesions situated laterally in the spinal cord showing no contact with the spinal cord surface. Neurological conditions before and after surgery were carefully assessed objectively.

RESULTS

A PLS approach was applied in 34 of the 99 operations (34.3%). Among 70 cases involving astrocytic tumor, ependymal tumor, cavernous malformation or hemangioblastoma, 23 cases (32.9%) were operated on using a PLS approach. Microscopically gross total or subtotal removal of the tumor was achieved in 18 of 23 cases (78.3%). These 18 cases demonstrated mild deterioration of motor function on the approach side early after surgery, but usually resolving within several months postoperatively. Average grade of the modified McCormick functional schema before surgery was maintained 6 months postoperatively. Average grade of the sensory pain scale before surgery was significantly improved by 6 months postoperatively. Segmental dysesthesia on the approach side unexpectedly remained in 2 of 18 cases (11.1%) even late after surgery.

CONCLUSIONS

These findings suggest that the PLS approach can provide direct access to tumors with minimal tissue damage, when applied appropriately after careful case selection.

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.

Benefits and Limitations of Indocyanine Green Fluorescent Image-Guided Surgery for Spinal Intramedullary Tumors

BACKGROUND

Intraoperative image guidance using near-infrared indocyanine green videoangiography (ICG-VA) has been used to provide real-time angiographic images during vascular or brain tumor surgery, and it is also being used for spine surgery.

OBJECTIVE

To further investigate the benefits and limitations of ICG-VA image-guided surgery for spinal intramedullary tumors through retrospective study.

METHODS

ICG-VA was used in 48 cases that were treated surgically over the past 5 yr. The pathological diagnoses of the tumors included astrocytic tumor, ependymal tumor, cavernous malformation, and hemangioblastoma.

RESULTS

Localization of normal spinal arteries and veins on the dorsal surface of the spinal cord helped the surgeons determine the length or point of myelotomy. Well-demarcated tumor stain was recognized in limited cases of anaplastic or highly vascularized tumors, whereas the location of cavernous malformation was recognized as an avascular area on the dorsal surface of the spinal cord. Feeding arteries and tumor stain were well differentiated from draining veins in dorsal hemangioblastomas, but not in intramedullary deep-seated or ventral tumors. The preservation of small perforating branches of the anterior spinal artery after successful resection of the tumor could be well visualized.

CONCLUSION

ICG-VA can provide real-time information about vascular flow dynamics during the surgery of spinal intramedullary tumors, and it may help surgeons localize the normal circulation of the spinal cord, as well as the feeding arteries and draining veins, especially in highly vascular tumors. However, the benefits of intraoperative ICG-VA might be limited for intramedullary deep-seated or ventral tumors.

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.

Posterolateral approach for spinal intradural meningioma with ventral attachment

Background:

Spinal meningioma with ventral attachment is a challenging pathology. Several technical modifications have been proposed to secure safe and precise resection of these tumors.

Materials and Methods:

This retrospective study focused on the precise and safe surgery of spinal meningiomas with strictly ventral attachment of cervical or thoracic spine. The surgical technique included a lateral oblique position for the patient, laminectomy with unilateral medial facetectomy on the tumor side, and spinal cord rotation with the dentate ligament. The neurological status of patients was assessed using the modified McCormick functional schema (mMFS) and sensory pain scale (SPS) before and at least 3 months after surgery. Patients were followed-up for a mean of 23.7 months. Tumor removal was graded using the Simpson grade for removal of meningiomas, and the extent of excision was confirmed using early postoperative magnetic resonance imaging.

Results:

Simpson grade 1 or 2 resections were achieved in all cases. No major surgery-related complications were encountered, postoperatively. The mean mMFS score before surgery was 3.1, improving significantly to 1.7 after surgery (P < 0.05). The mean SPS score before surgery was 2.4, improving significantly to 1.6 after surgery (P < 0.05).

Conclusions:

This surgical technique offers a posterolateral surgical corridor to the ventral canal of both cervical and thoracic spine. The present preliminary analysis suggests that functional outcomes were satisfactory with minimal surgery-related complications, although considerable surgical experience is needed to achieve a high level of surgical confidence.

Surgical management of solitary nerve sheath tumors of the cervical spine: a retrospective case analysis based on tumor location and extension

Complete resection of spinal nerve sheath tumors (NSTs) does not always result in significant neurological deficit. The purpose of this retrospective case analysis was to discuss the optimal surgical strategy for spinal NST of the cervical spine. Twenty-four patients who underwent surgery for solitary cervical NST over the past decade were included in this retrospective study. Patients with neurofibromatosis or schwannomatosis were excluded. Seventeen of the 24 cases (70.8%) showed extradural dumbbell extension, most frequently at the C1 or C2 vertebral level. Neurological condition was assessed using the modified McCormick functional schema and sensory pain scale. Total removal of the tumor was achieved in 20 of 24 cases (83.3%). Staged surgery using combined anterior and posterior approaches was applied for 2 of 17 cases with extradural dumbbell extension. Tumor involvement with nerve root fibers critical for upper extremity function (C5–C8) was recognized in 6 of 24 cases (25.0%), with complete resection in all 6 cases. Final assessment of neurological function revealed satisfactory or acceptable recovery in all 6 patients. Spinal NSTs with extradural dumbbell extension are a common condition in the cervical spine. Complete removal of spinal NST of the cervical spine may carry a risk of permanent neurological deficit, but such sequelae appeared to be the exception in the present case analysis. A radical and safe surgical strategy, including staged surgery combining anterior and posterior approaches, should be tailored to the individual case.

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.

Surgical management of spinal meningiomas: A retrospective case analysis based on preoperative surgical grade

Background:

Although spinal meningiomas respond favorably to surgical excision, their surgical management is impacted by several factors. This study utilized a surgery-based grading system to discuss the optimal surgical strategy.

Methods:

Twenty-three consecutive patients who underwent surgery for spinal meningiomas were included in this retrospective study. The patients’ neurological condition was assessed using the modified McCormick functional schema (mMFS) and sensory pain scale (SPS), and tumor removal was assessed using Simpson grade. Major factors contributing to surgical difficulty included; tumor size, extent/severity of cord compression, location of tumor attachment, spinal level, and anatomical relationships plus tumor extending in a dumbbell shape and local postoperative recurrence.

Results:

Fifteen cases were classified as ventral attachment (65.2%). There were two dumbbell-shaped tumors and three local recurrences at the primary site. Simpson grade 1 or 2 resections were performed in 18 of 20 cases (90%) with preoperative surgical grades 0 to 3. Simpson grade 4 resections were achieved in all three cases with preoperative surgical grades 4 to 5. Overall neurological assessment after surgery revealed the satisfactory or acceptable recovery on mMFS and SPS analysis.

Conclusions:

Lower preoperative grade yielded better results, while the higher the preoperative grade, the more likely tumor was insufficiently removed. A preoperative surgical grading system appeared to be helpful when considering the surgical strategy. Ventral meningiomas could be safely resected via the posterolateral or lateral approach using technical modifications. Recurrent tumors, especially with ventral attachment, were hard to resolve, and primary surgery appears to be important.

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.

Pathomorphological description of the shunted portion of a filum terminale arteriovenous fistula

BACKGROUND CONTEXT

The clinical morphology of a filum terminale arteriovenous fistula (f-AVF) is well known; however, pathological details of the fistulized portion are unknown. Herein, we report the pathological findings of the f-AVF.

STUDY DESIGN

Case report and literature review.

PURPOSE

To present a detailed pathological examination of the fistulized portion of the f-AVF.

METHODS

A 71-year-old man presented with gradually worsening bilateral foot paresthesias and anal dysesthesia. T2-weighted magnetic resonance imaging showed flow voids surrounding an edematous conus medullaris and cauda equina with spinal stenosis at L3-L4 and L4-L5. Spinal digital subtraction angiography demonstrated an f-AVF fed by the left T9 intercostal artery.

RESULTS

We performed laminotomies of L3 and L4 to open the dura mater and found a hypertrophic filum terminale. It was resected, leaving a length of 2 cm between the abnormal proximal end and normal distal end. The f-AVF completely disappeared after the surgery. On pathological examination, the filum terminale included two vessels at the proximal end and one at the distal end. At the proximal end, immunostaining showed one vessel that was definitively an artery with both an internal elastic membrane (IEM) and smooth muscle. The other was a vein and lacked an IEM. On the distal side, the collagen fibers gradually increased, the IEM partially disappeared from the arterial wall, and the vein became arterialized with a thin IEM. At the distal end the two vessels joined. Therefore, we speculated that the fistulized portion of the f-AVF was not a fistula point but had some lengths where the artery had characteristics of a vein and there was venous arterialization.

CONCLUSIONS

The filum arteriovenous shunting occurred at the portion where there was venous arterialization and the artery had the characteristics of a vein. Therefore, resecting the filum terminale requires more proximal from the normal distal end.

Posterolateral sulcus approach for spinal intramedullary tumor of lateral location: technical note

Posterolateral sulcus (PLS) approach of the spinal cord, being equivalent to the dorsal root entry zone myelotomy, may offer the satisfactory exposure of the spinal intramedullary tumor if applied appropriately. Eight consecutive patients with spinal intramedullary tumors of lateral location underwent the surgery of PLS approach in our institute. There were 6 male and 2 female patients, ranging in age from 34 to 72 years (mean, 57 years). PLS approach was indicated for the intramedullary tumor situated laterally in the spinal cord and that do not contact the posterior or lateral surfaces on magnetic resonance (MR) images before surgery. Total removal of the tumor was achieved in 6 cases except of 2 cases of anaplastic astrocytoma. All 6 patients with total removal of the tumor demonstrated the modest or mild deterioration of motor function on the approach side early after surgery, which resolved within 1 month after surgery. Average grade of the modified McCormick functional schema was 3.5 before surgery and improved to 3.0 at 3 months after surgery. These 6 patients demonstrated satisfactory pain relief early after surgery. Average grade of the sensory pain scale was 2.7 before surgery and improved to 1.7 at 3 months after surgery. PLS approach can be one of the surgical choices to the spinal intramedullary tumors, if applied appropriately. Better indication for PLS approach may be the tumors of the uneven location within the spinal cord associated with moderate or severe local pain.

Intraoperative assessment of spinal vascular flow in the surgery of spinal intramedullary tumors using indocyanine green videoangiography

Background:

The authors demonstrate the utility of indocyanine green videoangiography (ICG-VA) for intraoperative vascular flow assessment in the surgery of a variety of spinal intramedullary tumors to achieve an additional level of safety as well as precision with the surgical procedure.

Methods:

Fourteen patients with spinal intramedullary tumors (nine cervical and five thoracic) operated on between August 2011 and April 2013 were included in the present study. A fluorescence surgical microscope was used to perform ICG-VA after standard exposure of the lesion to assess the dynamic flow of the spinal microvasculature.

Results:

Twenty-seven ICG-VA injections were performed in 14 cases. Pathological diagnosis of the tumors included ependymoa, astrocytoma, cavernous malformation, or hemagioblastoma. There were no complications or side-effects related to ICG-VA. Intraoperative ICG-VA provided dynamic flow images of the spinal microvasculature in accordance with the progress of surgical procedures. Angiographic images could be divided into arterial, capillary, and venous phases. All angiographic images were well integrated into the microscopic view. The utility of ICG-VA could be summarized into three categories: (1) Localization of normal spinal arteries and veins, (2) assessment of posterior spinal venous circulation, and (3) differentiation of feeding arteries, tumor, and draining veins.

Conclusions:

Intraoperative vascular flow assessment using ICG-VA was easy, repeatable, and practical without any significant procedure-related risks. ICG-VA can be used for careful analysis of spinal microvascular flow or anatomical orientation, which is necessary to ensure safe and precise resection of spinal intramedullary tumors.