Visual and Pharmacotherapy Outcomes After Transverse Sinus Stenting for Idiopathic Intracranial Hypertension.

BACKGROUND: Transverse sinus stenting (TSS) is an increasingly common treatment for patients with idiopathic intracranial hypertension (IIH). However, detailed neuro-ophthalmic evidence on visual and pharmacotherapy outcomes after TSS is scarce and heterogeneous. This study aimed to describe the visual outcomes of patients undergoing TSS for IIH and to ascertain the proportion of patients who could be weaned off intracranial pressure (ICP)-lowering medication postoperatively. METHODS: A retrospective chart review of all patients with IIH from 2 tertiary academic neuro-ophthalmology practices who underwent TSS between 2016 and 2022 was performed. Indications for stenting included failure of pharmacotherapy, intolerance of pharmacotherapy, and acute vision loss from severe papilledema. Data on demographics, symptoms, visual function, pharmacotherapy, and TSS were collected. The paired Wilcoxon rank sum test was used to compare changes in visual acuity (VA) and visual field mean deviation (VFMD) between the baseline and most recent visits. RESULTS: Of the 435 patients with IIH, 15 (13 women) met inclusion criteria. After TSS, ICP-lowering pharmacotherapy was discontinued in 10 patients and decreased in 4; 1 patient was not on ICP-lowering medication before TSS. All patients experienced resolution or improvement of symptoms (10 resolution, 4 improved, 1 asymptomatic before TSS) and papilledema (11 resolution, 4 improved) after stenting. Papilledema resolution was confirmed with optical coherence tomography-measured peripapillary nerve fiber layer thickness (median decrease 147 µm, interquartile range 41.8-242.8 µm, P < 0.001). Change in VA between the baseline and most recent visit was not significant, but VFMD improved significantly after stenting (median increase 3.0, IQR 2.0-4.2, P < 0.001). No patient developed transverse sinus restenosis nor in-stent thrombosis postoperatively across a median venogram follow-up of 20.8 (11.3-49.8) weeks. In addition, no patient required subsequent surgical intervention for IIH. CONCLUSIONS: In this cohort of patients with IIH and fulminant presentation, medication resistance, or medication intolerance, TSS was an effective and safe treatment modality. Most patients were able to stop ICP-lowering medications while demonstrating striking improvement in symptomatology and visual function.

Assessment of Reversibility of Transverse Venous Sinus Stenosis in Patients With Papilledema.

BACKGROUND: Bilateral transverse venous sinus stenosis (TVSS) or stenosis of a dominant venous sinus has been found to be very sensitive radiological findings in patients with intracranial hypertension (IH), yet there is still an ongoing debate whether they constitute reversible or permanent phenomena. Thus, the purpose of this study was to investigate the reversibility of TVSS in patients with IH, including conservatively treated patients with signs of IH as defined by the presence of papilledema. METHODS: This was a retrospective chart review of all patients diagnosed with IH between 2016 and 2022, assessed from 2 tertiary university-affiliated neuro-ophthalmology practices. Inclusion criteria were the presence of papilledema, as quantified by optical coherence tomography, and bilateral TVSS, which is considered typical of IH on neuroimaging. During follow-up, included patients must have had confirmation of papilledema resolution as well as subsequent neuroimaging after conservative treatment or cerebrospinal fluid flow diversion. Patients with dural sinus vein thrombosis or intrinsic stenosis from sinus trabeculations or significant arachnoid granulations were excluded from the study. Either CT venography or MRI/MR venography was reviewed by a fellowship-trained neuroradiologist, and the degree of stenosis was scored through the combined conduit score (CCS), as described by Farb et al. The primary outcome was to assess TVSS changes after resolution or improvement of papilledema. RESULTS: From 435 patients, we identified a subset of 10 who satisfied all inclusion criteria. Our cohort comprised entirely women with a median age of 29.5 years and a median BMI of 32.5 kg/m2. Treatment consisted of acetazolamide in 7 patients, of which 1 had additional topiramate and 2 underwent cerebrospinal fluid flow diversion. Furthermore, 6 patients demonstrated significant weight loss during follow-up. For the primary outcome, 5 of 10 patients exhibited no appreciable TVSS change, and 5 patients demonstrated significant improvement in TVSS, of which 4 received conservative treatment only. Papilledema resolution or improvement was statistically significantly associated with increasing average CCS, TVSS diameter, and grade. CONCLUSIONS: We were able to demonstrate that TVSS can be both irreversible and reversible in patients with resolved papilledema. The finding of TVSS reversibility from conservative treatment alone is novel and has important implications to optimize patient care. Future studies should work to identify factors associated with irreversible TVSS for subsequent targeted intervention and prevention.

Transarterial Embolization of Dural Arteriovenous Fistulas: Conventional, Pressure Cooker, and Microballoon Catheter Embolization Techniques.

BACKGROUND AND OBJECTIVES: Dural fistulas are abnormal connections between dural arteries and intracranial veins treated mainly endovascularly in most settings. The aim was to examine a single-institution experience of microballoon catheter transarterial embolization (TAE) of dural arteriovenous fistulas (dAVFs) and compare it with other TAE techniques. METHODS: We retrospectively identified all dAVFs treated at our institution between 2017 and 2022 with microballoon, conventional, and pressure cooker TAE. We studied occlusion and retreatment rates, treatment-related complications, and radiation doses. RESULTS: During the study period, 66 patients underwent 75 TAE procedures to treat 68 dAVFs: 47 conventional TAE, 14 pressure cooker TAE, and 14 microballoon TAE. Median age of the study population was 63 years with 32% females. The most common dAVF location was the transverse sinus and 20% of dAVFs presented with hemorrhage. At 3-month follow-up, stable complete occlusion of the dAVF was seen in 72% (n = 34) after conventional TAE, 79% (n = 11) after pressure cooker TAE, and 86% (n = 12) after microballoon TAE. Retreatment was required in 19% (n = 9) after conventional TAE, 7% (n = 1) after pressure cooker TAE, and 7% (n = 1) after microballoon TAE. Treatment-related complications occurred in 17% (n =) after conventional TAE, 29% (n = 4) after pressure cooker TAE, and 7% (n = 1) after microballoon TAE. CONCLUSION: In our experience, microballoon TAE of dAVFs resulted in better initial and 3-month angiographic outcomes and required less retreatment than conventional TAE. Microballoon TAE also resulted in fewer treatment-related complications than other techniques. In our experience, microballoon TAE is a reliable and safe endovascular technique to treat dAVFs.

Evaluation of effectiveness and safety of the CorPath GRX robotic system in endovascular embolization procedures of cerebral aneurysms.

BACKGROUND: Robotic-assisted neurointervention was recently introduced, with implications that it could be used to treat neurovascular diseases. OBJECTIVE: To evaluate the effectiveness and safety of the robotic-assisted platform CorPath GRX for treating cerebral aneurysms. METHODS: This prospective, international, multicenter study enrolled patients with brain aneurysms that required endovascular coiling and/or stent-assisted coiling. The primary effectiveness endpoint was defined as successful completion of the robotic-assisted endovascular procedure without any unplanned conversion to manual treatment with guidewire or microcatheter navigation, embolization coil(s) or intracranial stent(s) deployment, or an inability to navigate vessel anatomy. The primary safety endpoint included intraprocedural and periprocedural events. RESULTS: The study enrolled 117 patients (74.4% female) with mean age of 56.6 years from 10 international sites,. Headache was the most common presenting symptom in 40/117 (34.2%) subjects. Internal carotid artery was the most common location (34/122, 27.9%), and the mean aneurysm height and neck width were 5.7±2.6 mm and 3.5±1.4 mm, respectively. The overall procedure time was 117.3±47.3 min with 59.4±32.6 min robotic procedure time. Primary effectiveness was achieved in 110/117 (94%) subjects with seven subjects requiring conversion to manual for procedure completion. Only four primary safety events were recorded with two intraprocedural aneurysm ruptures and two strokes. A Raymond-Roy Classification Scale score of 1 was achieved in 71/110 (64.5%) subjects, and all subjects were discharged with a modified Rankin Scale score of ≤2. CONCLUSIONS: This first-of-its-kind robotic-assisted neurovascular trial demonstrates the effectiveness and safety of the CorPath GRX System for endovascular embolization of cerebral aneurysm procedures. TRIAL REGISTRATION NUMBER: NCT04236856.

Utilisation of the Scepter Mini dual-lumen balloon - An illustrative series.

BACKGROUND: Dual-lumen balloon microcatheters can aid in the safety and efficacy of endovascular embolisation of cerebrospinal vascular malformations. The Scepter Mini dual-lumen balloon is a novel device with a smaller profile than previous balloon microcatheters, opening up new indications not only in the treatment of cerebrospinal malformations but in various other neurovascular therapeutic and diagnostic scenarios. METHODS: Following institutional ethics review board approval, a retrospective review of our prospectively maintained database of cases employing the Scepter Mini dual-lumen microballoon catheter was conducted. Five cases in particular were highlighted, demonstrating utilisation of this device, which may be of interest to the Neurointerventionalist. Patient demographics, procedure details, complications and clinical outcome data were reviewed. RESULTS: Five cases employing the Scepter Mini dual-lumen microballoon catheter are presented; trans-arterial embolisation of cerebral AVM, pre-operative tumour embolisation, diagnostic angiography, trans-venous embolisation of cerebral AVM and trans-arterial embolisation of DAVF. No intraprocedural complications were recorded, one patient had a delayed haemorrhage. CONCLUSION: Potential utilisation of the Scepter Mini lies not only in the trans-arterial embolisation of cerebrospinal vascular malformations, but in a range of other diagnostic and therapeutic indications as demonstrated.

Use of the neuroform atlas for stenting of intracranial atherosclerotic disease: Clinical and angiographic outcomes.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) is a potential cause of ischemic stroke. Treatment of ICAD can include intracranial stenting. There are specifically designed stents for this use-case; however, less is known about the off-label use of the Neuroform Atlas stent. In this study, we describe the outcomes of the Neuroform Atlas stent for treatment of ICAD. METHODS: Adult patients with symptomatic ICAD failing best medical treatment undergoing elective intracranial stenting using the Neuroform Atlas stent between November 2018 and March 2021 were included. Patient demographics, procedure-related details and clinical and imaging outcomes were analyzed. RESULTS: Eighteen patients met the inclusion criteria, with a mean follow-up duration of 9.6 ± 6.8 (standard deviation) months. There were two procedure-related mortalities (one massive intracranial hemorrhage and one groin site complication with sepsis). Fifteen patients were alive at the 6-month follow-up, all with satisfactory stent patency on follow-up imaging without any new ischemic events. Modified Rankin Scale at latest follow-up was 1.9 (interquartile range 5). CONCLUSION: In this single-center consecutive series, intracranial stenting with the Neuroform Atlas stent was a safe and effective treatment for symptomatic ICAD patients failing best medical management.

A dual-center validation of the PIRAMD scoring system for assessing the severity of ischemic Moyamoya disease.

Background: Prior Infarcts, Reactivity, and Angiography in Moyamoya Disease (PIRAMD) is a recently proposed imaging-based scoring system that incorporates the severity of disease and its impact on parenchymal hemodynamics in order to better support clinical management and evaluate response to intervention. In particular, PIRAMD may have merit in identifying symptomatic patients that may benefit most from revascularization. Our aim was to validate the PIRAMD scoring system. Methods: Patients with ischemic Moyamoya disease, who underwent catheter angiographic [modified Suzuki Score (mSS) and collateralization status], morphological MRI and a parenchymal hemodynamic evaluation with blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) at two transatlantic centers, were retrospectively included. The primary outcome was the presence of neurological symptoms. The diagnostic capacity of each PIRAMD feature alone was evaluated, as well as combined and the inter-institutional differences of each parameter were evaluated. Results: Seventy-two hemispheres of 38 patients were considered for analysis, of which 39 (54%) were classified as symptomatic. The presence of a prior infarct had the highest odds ratio [odds ratio (OR) =24; 95% CI: 6.7-87.2] for having neurological symptoms, followed by impaired CVR (OR =17; 95% CI: 5-62). No inter-institutional differences in the odds ratios or area under the curve (AUC) were found for any study parameter. The PIRAMD score had an AUC of 0.88 (95% CI: 0.80-0.96) with a similar AUC for the PIRAMD grading score. Conclusions: Our multicentric validation of the recently published PIRAMD scoring system was highly effective in rating the severity of ischemic Moyamoya disease with excellent inter-institutional agreement. Future studies should investigate the prognostic value of this novel imaging-based score in symptomatic patients with Moyamoya disease.

Spontaneous intracranial hypotension due to CSF-venous fistula: Evaluation of renal accumulation of contrast following decubitus myelography and maintained decubitus CT to improve fistula localization.

PURPOSE: Presented here is a strategy of sequential lateral decubitus digital subtraction myelography (LDDSM) followed closely by lateral decubitus CT (LDCT) to facilitate cerebrospinal fluid (CSF)-venous fistula (CVF) localization. MATERIALS AND METHODS: This is a retrospective analysis of patients referred to our institution for evaluation of CSF leak. Patients with Type 1 and Type 2 leaks, and those not displaying MR brain stigmata of intracranial hypotension were excluded. All patients underwent consecutive LDDSM and LDCT. If the CVF was not localized on the first LDDSM-LDCT pair the patient returned for contralateral examinations. Images were reviewed for CVF and for accumulation of contrast within the renal pelvises expressed as a renal pelvis contrast score (RPCS) in Hounsfield units (HU). RESULTS: Twenty-two patients were included in this study. In 21 of 22 patients (95%) a CVF was identified yielding an RPCS for the LDDSM-LDCT pair ipsilateral to the CVF ranging from 71 to 423 with an average of 146 HU. An RPCS of the negative side LDDSM-LDCT pair contralateral to a CVF was available in 8 patients and averaged 51 HU. In 4 patients the initial bilateral LDDSM-LDCT pairs did not reveal the location of the CVF however in 3 of these 4 cases the CVF was revealed on a third LDDSM repeated ipsilateral to the higher RPCS. CONCLUSION: The strategy of sequential LDDSM-LDCT coupled with evaluation of renal accumulation of contrast agent appears to improve the rate of CVF localization and warrants further evaluation.

Periventricular nodular heterotopia associated with a "transmantle band sign" in patients with epilepsy.

OBJECTIVE: Previous studies using advanced magnetic resonance imaging (MRI) techniques have documented abnormal transmantle bands connecting ectopic nodules to overlying cortex in patients with periventricular nodular heterotopia (PNH). We describe a similar finding using conventional MRI techniques. METHODS: Patients were identified by means of a full-text search of radiological reports. All scanning was performed using conventional sequences at 3 Tesla (3T). Scans were reviewed by three neuroradiologists, and we characterized imaging features based on type of PNH and cortical irregularities associated with the transmantle band. RESULTS: A total 57 PNH patients were reviewed, of whom 41 demonstrated a "transmantle band" connecting the nodule to the overlying cortex. One or more periventricular heterotopic nodules was present in all 41 patients-this was bilateral in 29 of 41 (71%) and unilateral in the remaining 29%. In many cases there was more than one such band, and in some cases this band was nodular. In 19 of the cases, the cortex to which the band connected was abnormal, showing thinning in 4 cases, thickening in 5 cases, and polymicrogyria in another 10. SIGNIFICANCE: The transmantle band can be seen frequently in both unilateral and bilateral cases of PNH and can be visualized with conventional 3T MRI sequences. The band highlights the underlying neuronal migration issues at play in the pathogenesis of this disorder, but its underlying role in the complex, patient-specific epileptogenic networks in this cohort has yet to be determined and warrants further investigation.

The presence of pachymeningeal hyperintensity on non-contrast flair imaging in patients with spontaneous intracranial hypotension.

PURPOSE: Traditionally, in the work-up of patients for spontaneous intracranial hypotension, T1 post-contrast imaging is performed in order to assess for pachymeningeal enhancement. The aim of this study is to assess whether pachymeningeal hyperintensity can be identified on a non-contrast FLAIR sequence in these patients as a surrogate sign for pachymeningeal enhancement. METHODS: The patient cohort was identified from a prospectively maintained database of patients with a clinical diagnosis of intracranial hypotension. Patients who had both a post-contrast T1 sequence brain as well as non-contrast FLAR sequence of the brain were reviewed. Imaging was retrospectively reviewed by three independent neuroradiologists. Each study was assessed for the presence or absence of pachymeningeal hyperintensity on the FLAIR sequence. RESULTS: From January 2010 to July 2022, 177 patients were diagnosed with spontaneous intracranial hypotension. In total, 121 were excluded as post-contrast imaging was not performed during their work-up. Twenty-four were excluded as the FLAIR sequence was performed after administration of contrast. Six were excluded as there was no pachymeningeal thickening present on T1 post-contrast imaging, although there were other signs of intracranial hypotension. The study group therefore consisted of 26 patients. Pachymeningeal thickening was correctly identified on the non-contrast FLAIR sequence in all patients (100%). CONCLUSION: Where present, diffuse pachymeningeal hyperintensity can be accurately identified on a non-contrast FLAIR sequence in patients with spontaneous intracranial hypotension. This potentially obviates the need for gadolinium base contrast agents in the work-up of these patients.

Thoracolumbar spinal dural arteriovenous fistulae present with longer arteriovenous transit compared to cranial and cervical dural fistulae.

BACKGROUND: Thoraco-lumbar spinal dural arteriovenous fistulae represent a rare subset of central nervous system vascular malformations. One of the unique features of spinal dural arteriovenous fistulae is their extremely low propensity to cause hemorrhage (either parenchymal or subarachnoid), with a distinct clinical presentation of myelopathy secondary to spinal venous congestion. The exact mechanism for this unique presentation is still unclear. METHODS: Following institutional review board approval, we retrospectively analyzed our prospectively maintained database of spinal dural arteriovenous fistulae and cranial (cr) DAVF cases presenting between 2008 and 2021. For all cases, angiograms were reviewed and arteriovenous transit times were calculated. Patient demographics, angiographic features, and clinical and radiological outcomes were assessed. RESULTS: In total, 66 patients presenting with confirmed thoracolumbar spinal dural arteriovenous fistulaes were identified and compared to patients presenting with cervical spinal dural arteriovenous fistulaes (n = 10), ruptured crDAVFs (n = 32) and unruptured crDAVFs (n = 20). Mean age in the target group was 66 ± 13 versus 57-62 in the other groups, p < 0.05 on one-way analysis of variance; with 80% males versus 50%-65% in other groups. Mean arteriovenous transit time in the thoracolumbar group measured 1.98 s ± 0.96 versus 0.25-0.5 s range in other groups (p < 0.0001 on one-way analysis of variance). CONCLUSION: Prolonged arteriovenous transit times may represent a distinct feature of thoracolumbar spinal dural arteriovenous fistulaes. This may, amongst other factors, play a role in the observed lesser likelihood of hemorrhagic complications compared to other dural arteriovenous shunts.

Visual Recovery in 2 Cases of Central Retinal Artery Occlusion Treated With Prompt Intra-ophthalmic Artery Fibrinolysis.

BACKGROUND: Central retinal artery occlusion (CRAO) rapidly produces inner retinal ischemia and irreversible vision loss. Although many therapeutic interventions have been proposed, no interventions have proven effective in restoring vision in large randomized controlled trials and final visual outcome in most patients is very poor. METHODS: Retrospective case series. RESULTS: We describe 2 cases of CRAO occurring after uncomplicated cataract surgery under topical anesthesia and rapidly diagnosed. Both had very severe vision loss at presentation with dramatic improvement after intra-ophthalmic artery fibrinolysis administered 2.75 and 5.5 hours after symptom onset. CONCLUSIONS: Sudden monocular vision loss is an ophthalmologic emergency as CRAO must be ruled out and if diagnosed, rapid intervention should be performed. Devastating vision loss can be prevented if interventional neuroradiology is trained and available on a 24-hour basis for administration of local intra-arterial thrombolysis.

Motion artifact correction for cone beam CT stroke imaging: a prospective series.

BACKGROUND: Imaging assessment for acute ischemic stroke (AIS) patients in the angiosuite using cone beam CT (CBCT) has created increased interest since endovascular treatment became the first line therapy for proximal vessel occlusions. One of the main challenges of CBCT imaging in AIS patients is degraded image quality due to motion artifacts. This study aims to evaluate the prevalence of motion artifacts in CBCT stroke imaging and the effectiveness of a novel motion artifact correction algorithm for image quality improvement. METHODS: Patients presenting with acute stroke symptoms and considered for endovascular treatment were included in the study. CBCT scans were performed using the angiosuite X-ray system. All CBCT scans were post-processed using a motion artifact correction algorithm. Motion artifacts were scored before and after processing using a 4-point scale. RESULTS: We prospectively included 310 CBCT scans from acute stroke patients. 51% (n=159/310) of scans had motion artifacts, with 24% being moderate to severe. The post-processing algorithm improved motion artifacts in 91% of scans with motion (n=144/159), restoring clinical diagnostic capability in 34%. Overall, 76% of the scans were sufficient for clinical decision-making before correction, which improved to 93% (n=289/310) after post-processing with our algorithm. CONCLUSIONS: Our results demonstrate that CBCT motion artifacts are significantly reduced using a novel post-processing algorithm, which improved brain CBCT image quality and diagnostic assessment for stroke. This is an important step on the road towards a direct-to-angio approach for endovascular thrombectomy (EVT) treatment.

The butterfly effect: improving brain cone-beam CT image artifacts for stroke assessment using a novel dual-axis trajectory.

BACKGROUND: Cone-beam computed tomography (CBCT) imaging of the brain can be performed in the angiography suite to support various neurovascular procedures. Relying on CBCT brain imaging solely, however, still lacks full diagnostic confidence due to the inferior image quality compared with CT and various imaging artifacts that persist even with modern CBCT. OBJECTIVE: To perform a detailed evaluation of image artifact improvement using a new CBCT protocol which implements a novel dual-axis 'butterfly' trajectory. METHODS: Our study included 94 scans from 47 patients who received CBCT imaging for assessment of either ischemia or hemorrhage during a neurovascular procedure. Both a traditional uni-axis 'circular' and novel dual-axis 'butterfly' protocol were performed on each patient (same-patient control). Each brain scan was divided into six regions and scored out of 3 based on six artifacts originating from various physics-based and patient-based sources. RESULTS: The dual-axis trajectory produces CBCT images with significantly fewer image artifacts than the traditional circular scan (whole brain average artifact score, AS: 0.20 vs 0.33), with the greatest improvement in bone beam hardening (AS: 0.13 vs 0.78) and cone-beam artifacts (AS: 0.04 vs 0.55). CONCLUSIONS: Recent developments in CBCT imaging protocols have significantly improved image artifacts, which has improved diagnostic confidence for stroke and supports a direct-to-angiography suite transfer approach for patients with acute ischemic stroke.

Minimally invasive surgery for spinal cerebrospinal fluid-venous fistula ligation: patient series.

BACKGROUND: Cerebrospinal fluid-venous fistulas (CVFs) may cause cerebrospinal fluid leaks resulting in spontaneous intracranial hypotension (SIH). Surgical treatment of CVFs aims to eliminate abnormal fistulous connections between the subarachnoid space and the epidural venous plexus at the level of the nerve root sleeve. The authors propose a percutaneous minimally invasive technique for surgical ligation of CVF as an alternative to the traditional open approach using a tubular retractor system. OBSERVATIONS: Minimally invasive surgical (MIS) ligation of spinal CVF was performed in 5 patients for 6 CVFs. The definite disconnection of the CVF was achieved in all patients by clipping and additional silk tie ligation of the fistula. None of the patients experienced surgical complications or required transition to an open procedure. One patient underwent 2 MIS procedures for 2 separate CVFs. Postoperative clinical follow-up and cranial magnetic resonance imaging confirmed resolution of symptoms and radiographic SIH stigmata. LESSONS: MIS ligation of CVFs is safe and efficient. It represents an elegant and less invasive procedure, reducing the risk of wound infections and time to recovery. However, preparedness for open ligation is warranted within the same surgical setting in cases of complications and difficult accessibility.

Severe papilledema and multiple hypercoagulability abnormalities in patient with dural arterio-venous fistulas.

A 54-year-old man noticed right-sided pulsatile tinnitus for the past six months and recently started experiencing transient visual obscurations when standing up. MRI demonstrated two separate brain dural arteriovenous fistulas (bdAVF) in sagittal and right sigmoid dural sinuses. Neuro-ophthalmological exam demonstrated severe bilateral optic disc edema with preserved visual acuity but early nerve fiber bundle defects on visual field testing. Hypercoagulable profile testing revealed very elevated D-dimer, significantly decreased protein S level and elevated homocysteine levels. This case highlights importance of referring all patients with bdAVFs for neuro-ophthalmological consultation as venous hypertension can cause increased intracranial pressure and resultant papilledema. Papilledema does not affect central vision until late stages when visual loss is irreversible thus screening for its presence and pre-treatment extent of peripheral visual loss is paramount. It also demonstrates that hypercoagulable workup should be initiated in all patients with bdAVF in order to prevent future thromboembolic events.

Recognition of the variant type of spinal dural arteriovenous fistula: a rare but important consideration.

OBJECTIVE: Spinal dural arteriovenous fistulas (SDAVFs) typically represent abnormal shunts between a radiculomeningeal artery and radicular vein, with the point of fistulization classically directly underneath the pedicle of the vertebral body, at the dural sleeve of the nerve root. However, SDAVFs can also develop in atypical locations or have more than one arterial feeder, which is a variant of SDAVF. The aim of this study was to describe the incidence and multidisciplinary treatment of variant SDAVFs in a single-center case series. METHODS: Following institutional review board approval, the authors retrospectively analyzed their prospectively maintained database of patients with SDAVFs who presented between 2008 and 2020. For all patients, spinal digital subtraction angiograms were reviewed and variant SDAVFs were identified. Variant types of SDAVFs were defined as cases in which the fistulous point was not located underneath the pedicle. Patient demographics, angiographic features, clinical outcomes, and treatment modalities were assessed. RESULTS: Of 59 patients with SDAVFs treated at the authors' institution, 4 patients (6.8%) were identified as having a variant location of the shunt zone, pinpointed on the dura mater at the intervertebral level, further posteriorly within the spinal canal. In 3 cases (75%), a so-called bimetameric arterial supply was demonstrated. CONCLUSIONS: Recognition of the variant type of SDAVF is crucial for management, as correct localization of the fistulous point and bimetameric supply are critical for successful surgical disconnection, preventing delay in achieving definitive treatment.