Thrombus Attenuation Gradient Can Predict Successful First-Pass Recanalization Following Stentriever Thrombectomy.

OBJECTIVE: Computed tomography angiography (CTA) derived thrombus enhancement characteristics can predict first-pass recanalization. We studied whether dynamic contrast kinetics within the clot in multiphase CTA can predict first-pass recanalization following stentriever thrombectomy. METHODS: Patients with acute large vessel occlusive stroke evaluated with multiphasic CTA who underwent stentriever thrombectomy were selected. Thrombus perviousness on various phases including arterial, venous, and delayed phases was calculated. Thrombus attenuation gradient (TAG), defined as average attenuation difference between adjacent phases, was also evaluated and correlated with successful first-pass outcome (modified Treatment in Cerebral Ischemia score ≥2b). RESULTS: Of 69 patients, 32 (47%) had successful first-pass recanalization (group 1), and 37 (53%) required >1 attempt (group 2). TAG showed significant differences in arterial-plain and venous-arterial phases. The early increase in TAG was seen in group 1 in the arterial-plain phase, as opposed to group 2 (12.6 vs. 9, P = 0.01), which plateaued in the venous-arterial phase for group 1 and showed a further increase in group 2 (2.1 vs. 5.1, P = 0.02). A cutoff value of 9.2 HU for arterial-plain phase (P = 0.001) and 4.2 HU (P = 0.001) for venous-arterial phase was predictive of first-pass effect. Combining 2 metrics had an odds ratio of 2.8 for first-pass recanalization (P = 0.035). Accuracy evaluated in a validation cohort yielded 74%. Other features including histology were not significant. CONCLUSIONS: TAG evaluated from multiphase CTA can predict first-pass effect in stentriever thrombectomy.

Shunt Site Localization of Direct Carotid-Cavernous Fistula Using 3D Rotational Angiography-Utility of Broken-Rim Sign.

BACKGROUND: Direct carotid-cavernous fistulas (DCCF) develop due to breach in the integrity of the wall of the internal carotid artery, and its localization can sometimes be difficult due to rapid high flow shunts. We hypothesized that 3D rotational angiography could locate the fistula site accurately, where an interrupted rim of the carotid wall would be silhouetted against opacified vascular structures. This finding was described as a broken-rim sign, and in this study, we assessed the utility of this sign in the localization of the shunt point of DCCF. METHODS: Retrospective analysis of 15 cases of DCCF was performed, and the rent was characterized based on the broken-rim sign. Two observers independently evaluated the results and compared them against the intraoperative observations. RESULTS: The broken-rim sign was identified and correlated with the actual fistula site in 86.6% and 100% of patients by observers 1 and 2, respectively. The inter-rater agreement was 0.87 (P < 0.001). Misinterpretation was made in 2 patients by 1 observer, due to poor contrast opacification of the vascular structures secondary to very rapid shunting and mild movement artifacts. CONCLUSIONS: Our study highlights the role of 3D rotational angiogram and analysis of the carotid wall in the localization of the shunt site in DCCF. The broken-rim sign accurately points to the location of the fistula.

Volumetric T2-weighted MRI improves the diagnostic accuracy of spinal vascular malformations: comparative analysis with a conventional MR study.

BACKGROUND: To date, very little study of the importance of a volumetric T2-weighted MR sequence in the evaluation of spinal vascular malformations (SVMs) has been carried out. OBJECTIVE: To determine the utility and accuracy of a volumetric T2 MR sequence compared with conventional T2 in the diagnosis of SVMs. METHODS: Retrospective analysis of all patients who underwent spinal DSA for suspected SVMs was conducted. Conventional T2 and volumetric T2 MR images were analysed for the presence of flow voids and parenchymal changes, and SVMs were characterized. The sensitivity, specificity, and overall diagnostic accuracy of these MRI diagnoses were calculated. RESULTS: Of 89 subjects included in the final analysis, 70 patients had angiographically proved SVMs (38 patients with spinal cord arteriovenous malformations [SCAVM-intramedullary or perimedullary] and 32 cases of spinal dural arteriovenous fistula (SDAVF)) and the remaining 19 subjects were normal. The sensitivity and specificity for identification of SVMs were 98.1% and 90% for volumetric T2 sequences, compared with 82.8% and 89.4% for conventional T2 MRI, respectively. For characterization of spinal vascular lesions, volumetric MRI showed high sensitivity, specificity, and accuracy for SDAVF (100%, 90%, 97%, respectively) compared with conventional T2 MRI (71.8%, 89%, 79%, respectively). The positive likelihood ratio was high and negative likelihood ratio was zero for volumetric MRI evaluation of SDAVF, while these ratios were comparable between the two sequences for SCAVM. CONCLUSION: Volumetric T2 MRI is highly sensitive for the detection of SVMs, especially for SDAVF. Volumetric T2 MRI could be introduced into routine clinical practice in the screening of suspected SVMs.

Results of Endovascular-First Approach for Treatment of Scalp Arteriovenous Malformations and the Effect of Simplified Angiographic Classification in Therapeutic Decision-Making and Outcomes.

BACKGROUND: Scalp arteriovenous malformation (SAVM) is primarily treated by surgery and reports on endovascular treatment are scarce. We report the results of an endovascular-first approach in the treatment of SAVM. We also have proposed a simple dichotomized classification using the angiographically determined morphology findings and discussed its effect on therapeutic decision-making and outcomes. METHODS: A consecutive series of 25 patients with SAVM treated by initial or endovascular-only methods were included in the final analysis. The SAVM was categorized as a plexiform or fistulous type according to the angiographic morphology. The demographic data, treatment variables, and final clinical outcomes were analyzed and correlated with the proposed classification. RESULTS: Of the 25 patients, 21 were treated with n-butyl cyanoacrylate (n-BCA) and 3 with liquid ethylene vinyl alcohol. One patient had been treated initially with polyvinyl alcohol particles and later with n-BCA. Overall, complete or near complete obliteration (>90%) was achieved in 72%. Surgical excision was performed in 76%, most often after n-BCA embolization. Fistulous-type SAVMs required greater n-BCA concentrations (median, 33% vs. 20%; P = 0.024) and achieved greater rates of complete or near-complete obliteration (90% vs. 63%). Two patients with fistulous-type SAVMs treated with liquid ethylene vinyl alcohol showed complete resolution, and further treatment was not necessary. Overall, regardless of the embolic material used, the fistulous type demonstrated a significantly greater rate of complete obliteration (75% vs. 33%; P = 0.041) compared with plexiform type. CONCLUSION: High rates of complete and durable obliteration of SAVM are achievable with endovascular embolization. The proposed simplified classification is easy to implement and can aid in choosing the appropriate embolic agent and predicting the therapeutic outcome.

Extending Endovascular Embolization to Type A Spinal Perimedullary Arteriovenous Fistula Using Liquid Embolic Agent: Technical Nuances, Challenges and Initial Outcome.

BACKGROUND: The definitive treatment of perimedullary arteriovenous fistulas (PMAVFs) is warranted in view of the progressive neurologic decline noted with the conservative mode of management. The treatment options include microsurgical excision, endovascular embolization, or a multimodal approach. Because of the relatively larger size of the feeding arteries in type B and C PMAVFs, an endovascular approach is usually feasible. However, the endovascular treatment for type A lesions is technically challenging in view of near normal sized arterial feeders. Endovascular embolization using n-butyl cyanoacrylate is described; however, successful use of liquid embolic agents such as onyx or squid is not previously documented. CASE DESCRIPTION: The described 3 cases initially presented with insidious onset and gradually progressive paraparesis, paresthesia, and urinary symptoms. The imaging (magnetic resonance and digital subtraction angiography) revealed type A PMAVFs. The microcatheter could be successfully navigated close to the fistulous site, and complete obliteration of the fistula was achieved using ethylene vinyl alcohol copolymer (EVOH)-based liquid embolic agent, squid in all of our cases. The occlusion remained durable, and patients showed steady neurologic improvement in the follow-up period. CONCLUSIONS: Endovascular embolization of type A PMAVF using EVOH-based liquid embolic agent is feasible and could be considered as an effective alternative to surgery.

Recurring Thalamic Symptoms Due to Intracranial Dural Arteriovenous Fistula: Report of Unusual Case and Treatment Outcome.

BACKGROUND: Initial clinical presentation of dural arteriovenous fistula (DAVF) with predominantly thalamic symptoms is rare and has not been reported until now. CASE DESCRIPTION: A young child presenting with complaints of tinnitus and mild right hemiparesis was evaluated with an initial magnetic resonance imaging, which revealed a Borden type 2 DAVF in the right transverse sinus with retrograde venous drainage and cortical venous reflux. Flow-related small aneurysms were also noted in the left basal vein of Rosenthal (BVR). Two days later, his motor power deteriorated and he developed right hemisensory loss and severe thalamic pain. Aphasia was atypical and mimicked the transcortical type. Repeat imaging revealed expanding thrombosed aneurysm of BVR with mass effect and edema on thalamocapsular region. Initial antiedema measures reversed the neurologic deficits; however, they recurred, necessitating an urgent endovascular intervention. Angiogram revealed an extensive high-flow DAVF in the right transverse-sigmoid sinus and torcula with preferential retrograde venous drainage into deep veins and left BVR. He underwent staged embolization of DAVF, resulting in significant obliteration of shunt. Neurologic deficits improved in the postoperative period, and the patient remained clinically asymptomatic at 6 months of follow-up. CONCLUSIONS: DAVF presenting with recurrent predominantly thalamic symptoms is rare. Atypical transcortical aphasia rather than fluent aphasia is an unusual clinical manifestation of thalamic pathology and could result from the involvement of specific thalamic nuclei. Preferential high flow into BVR in the presence of venous anomalies could potentially induce architectural weakness of the venous wall and precipitate aneurysm formation. Embolization of the DAVF can potentially reverse this unusual neurologic condition.

Dwell Time of Stentriever Influences Complete Revascularization and First-Pass TICI 3 Revascularization in Acute Large Vessel Occlusive Stroke.

OBJECTIVE: In acute ischemic stroke with large vessel occlusion, the interaction between the clot retriever and the stent is critical for achieving successful recanalization. The ideal time of stent deployment (dwell time [DT]) to improve revascularization is currently unknown. We systematically analyzed the effect of different DT on final angiographic and clinical outcomes of patients who underwent mechanical thrombectomy. METHODS: The DT was progressively increased from 3 minutes to 5 minutes and then 8 minutes during the study period. The effect of DT on recanalization attempts, successful angiographic outcome (thrombolysis in cerebral ischemia [TICI] 2b or TICI 3), total revascularization time, and immediate and 3-month clinical outcomes were evaluated. The DT of 3 minutes and 5 minutes (DT3-5) was compared against DT of 8 minutes (DT8). RESULTS: Forty patients were included in the analysis. Good angiographic outcome was observed in 94.1% of patients in the DT8 cohort with an average attempt of 1.2 compared with 78.3% with average attempts of 2.0 in other group. Single-pass good recanalization (TICI 2b or 3) and single-pass complete revascularization (TICI3) was significantly higher in the DT group compared with the DT3-5 group (82.4% vs. 43.5% [P = 0.013] and 42.9% vs. 8.7% [P = 0.003], respectively). A favorable trend toward a reduced overall procedural time (34.59 vs. 55.59 minutes) was observed, but was not statistically significant (P = 0.15). CONCLUSIONS: Mild prolongation of DT to 8 minutes improves revascularization outcome with fewer attempts, possibly because of better clot-stent interaction.

Isolated Subcallosal Artery Infarction Secondary to Localized Cerebral Vasospasm of Anterior Communicating Artery Complex Following Subarachnoid Hemorrhage.

BACKGROUND: Subcallosal artery (ScA) infarction is a well-recognized but uncommon complication of surgical treatment of anterior communicating artery aneurysms. CASE DESCRIPTION: An elderly man presented with massive subarachnoid hemorrhage due to left posterior communicating artery aneurysm with thick clots in the anterior interhemispheric fissure. The aneurysm was coiled with balloon protection, and later, on the fifth day of ictus, the patient became acutely confused and developed memory disturbances. Magnetic resonance evaluation revealed typical infarcts in the anterior subcallosal region and fornix, confirming ScA infarction. Retrospective analysis of follow-up angiograms revealed focal isolated spasm of the anterior communicating artery artery and ScA, responding to intra-arterial milrinone infusion that was administered in view of neurologic worsening and clinical suspicion of cerebral vasospasm. CONCLUSION: Our case demonstrates a rare case of isolated ScA infarction induced by a local vasospasm and highlights the importance of its recognition. An early identification and intervention could potentially halt irreparable cerebral injury.

Anatomical localization of the cavernous sinus dural fistula by 3D rotational angiography with emphasis on clinical and therapeutic implications.

BACKGROUND AND PURPOSE: Carotid cavernous sinus dural arteriovenous fistulas (CSDAVFs) are presumed to be located within the walls of the cavernous sinus, however the exact fistulous site has not yet been studied by angiographic or anatomical methods. The present study aimed to localize CSDAVFs with the help of 3D rotational angiography (RA) and correlated the observations with clinical and angiographic findings. MATERIALS AND METHODS: The CSDAVFs were categorized as dural, extradural or osseous based on the site of convergence of feeders into the venous sac. Extradural CSDAVFs were further subcategorized into posteromedial, posterolateral and anterior subtypes, depending on proximity to a possible venous plexus. This classification was correlated with various clinical presentations and angiographic subtypes. RESULTS: Thirty-seven patients were included in the final analysis. The sac was identified in all the patients and the mean sac size of the fistula was small (<4mm). Dural type was associated with exclusive cortical venous drainage. Extradural anterior CSDAVF showed tendency towards younger age predilection. Extradural posterolateral CSDAVF was more often associated with initial oculomotor nerve palsy and this observation was statistically significant. Discordancy between the location of the fistula and the side of clinical affection was observed in midline fistulas such as osseous CSDAVF and posteromedial type of extradural CSDAVF. CONCLUSIONS: CSDAVF is a heterogeneous vascular disorder involving the sphenoclival bone, extradural space and dura, homologous to the epidural-dural shunts of vertebra with a common clinical presentation of orbital manifestations. Preoperative localization of the fistula could explain enigmatic observations and potentially simplify its interventional management.

Factors Predicting Spontaneous Thrombosis of Aggressive Cranial Dural Arteriovenous Fistulas.

BACKGROUND: Dural arteriovenous fistula (DAVF) with cortical venous drainage is known to be aggressive in clinical course and is usually managed promptly. Spontaneous resolution of DAVF is a rare phenomenon and usually occurs in benign fistulas. Spontaneous thrombosis of aggressive DAVF is an extremely rare occurrence. The present study aimed to identify the incidence and factors determining spontaneous resolution of aggressive DAVF. METHODS: All patients presenting to our institution with suspected DAVF during the study period (July 2013 to December 2015) were prospectively enrolled into a database. Different clinical, demographic, and angiographic factors were compared between the control cohort who showed spontaneous resolution and the interventional cohort who underwent endovascular intervention for definite cure. The potential determinants reported in the literature were also included in this detailed analysis. RESULTS: Thirty-two patients were included in the final analysis. Five patients (15.7%) showed spontaneous resolution in the follow-up period while awaiting definitive treatment. Univariate analysis showed 3 variables (DAVF architecture, thrombosis of draining vein, and transit time) to be statistically significant (P < 0.05). However, multivariate logistic regression analysis showed that only sparse fistulous network was significantly associated with acceptable outcome of spontaneous disappearance of DAVF. CONCLUSIONS: Spontaneous thrombosis of aggressive DAVF is a known phenomenon in the natural evolution of cerebral dural arteriovenous malformation. DAVF architecture could categorize this particular subset of DAVF, which had an overall good prognosis. Further observations in large multi-institutional cohorts are needed to validate this finding and to ascertain other factors precipitating this outcome.

The Lurking Catastrophic Complication of an Equally Catastrophic Disease: The Lesson Learned.

BACKGROUND: Medullary-bridging vein dural arteriovenous fistula (DAVF) is an uncommon type of DAVF with an aggressive clinical course due to direct fistulous shunting into medullary and brainstem veins. Important considerations need to be given to retrograde embolic migration or perforator involvement while treating these fistulas endovascularly with a liquid embolic agent. We report a lateral spinal artery feeding the DAVF, the recognition of which is important to avoid potential catastrophic complications during definitive therapy, and which has not been described before. OBJECTIVE: To discuss the anatomy of the lateral spinal artery (LSA) and its communications with pial arteries such as the posterior inferior cerebellar artery (PICA) that may have important implications in the management of neurovascular diseases in and around the foramen magnum. METHODS: A retrospective analysis of cerebral angiograms and 3-dimensional rotational angiograms of a patient with medullary-bridging vein DAVF treated by transarterial embolization under balloon protection was performed after the patient developed lateral medullary syndrome in the postoperative period. RESULTS: Detailed analysis revealed a dural branch from the LSA feeding the DAVF which anastomosed with rudimentary PICA. CONCLUSION: LSA has important anastomoses with perforating arteries of the medulla and cervical cord and, hence, it is important to recognize and identify LSA prospectively in the vascular pathologies of the foramen magnum to avoid fatal neurological complications during endovascular therapy. This is especially important while treating neurovascular pathologies using liquid embolic agents such as Onyx or SQUID, because they can percolate retrogradely through the anastomoses into PICA or other vertebrobasilar perforators.