Robert A. Willinsky

Clinical Course of Cranial Dural Arteriovenous Fistulas With Long-Term Persistent Cortical Venous Reflux

Background and Purpose— The natural history of aggressive (Borden 2 and 3) cranial dural arteriovenous fistulas (DAVFs) is not well described. Reported annual mortality and hemorrhage rates vary widely and range up to 20% per year. A consecutive single-center cohort of 236 cases that presented with a cranial DAVF between June 1984 and May 2001 was reviewed for the consequences of long-term persistent cortical venous reflux (CVR). Methods— A group of 118 cranial DAVFs was selected for the presence of CVR. All patients were offered treatment aimed at the disconnection of the CVR. Patients who declined or had partial treatment with persistence of the CVR had long-term clinical and angiographic follow-up to study the disease course of this select group. Results— Treatment was instituted in 101 of the 118 patients (85.6%). Three patients were lost to follow-up. The remaining 14 nontreated patients (11.9%) and the partially treated patients (n=6) were assessed clinically and angiographically over time. The mean follow-up in this select group was 4.3 years (86.9 patient-years). During follow-up, 7 patients suffered an intracranial hemorrhage (35%). The incidence of nonhemorrhagic neurological deficit was 30%. Nine patients (45%) died: 6 patients expired after a hemorrhage, and 3 patients died of progressive neurological deterioration. Two patients demonstrated a spontaneous closure of the DAVF (10%). Conclusions— Persistence of the CVR in cranial DAVFs yields an annual mortality rate of 10.4%. Excluding events at presentation, in this series the annual risk for hemorrhage or nonhemorrhagic neurological deficit during follow-up was 8.1% and 6.9%, respectively, resulting in an annual event rate of 15.0%.

Idiopathic intracranial hypertension: The prevalence and morphology of sinovenous stenosis

Objective: To determine the prevalence and nature of sinovenous obstruction in idiopathic intracranial hypertension (IIH) using auto-triggered elliptic-centric-ordered three-dimensional gadolinium-enhanced MR venography (ATECO MRV). Methods: In a prospective controlled study, 29 patients with established IIH as well as 59 control patients underwent ATECO MRV. In a randomized blinded fashion, three readers evaluated the images. Using a novel scoring system, each reader graded the degree of stenosis seen in the transverse and sigmoid sinuses of each patient. Results: There was excellent agreement across the three readers for application of the grading system. Substantial bilateral sinovenous stenoses were seen in 27 of 29 patients with IIH and in only 4 of 59 control patients. Conclusion: Using ATECO MRV and a novel grading system for quantifying sinovenous stenoses, the authors can identify IIH patients with sensitivity and specificity of 93%.

The Natural History and Predictive Features of Hemorrhage From Brain Arteriovenous Malformations

Background and Purpose— Patients harboring brain arteriovenous malformations (bAVMs) are at a lifelong risk for hemorrhagic strokes, but the natural history is poorly understood. We examined the impact of demographic and angiographic features on the likelihood of future hemorrhage. Methods— A prospectively accrued database of bAVM patients maintained at the Toronto Western Hospital was analyzed; 678 consecutive, prospectively enrolled bAVM patients were followed for 1931.7 patient-years. The rate of hemorrhage over long-term follow-up was recorded. The impact of baseline clinical and radiographic features and partial treatment on time to hemorrhage were analyzed using survival analysis. Neurological outcome after hemorrhage was assessed using the Glasgow Outcome Score. Results— Hemorrhage rates were 4.61% per year for the entire cohort (n=678), 7.48% per year for bAVMs with initial hemorrhagic presentation (n=258), 4.16% per year for initial seizure presentation (n=260), 3.99% per year for patients not harboring aneurysms (n=556), 6.93% per year for patients with associated aneurysms (n=122), and 5.42% per year for bAVMs with deep venous drainage (n=365). Hemorrhagic presentation was a significant independent predictor of future hemorrhage (HR, 2.15; P<0.01), whereas associated aneurysms (HR, 1.59; P=0.07) and deep venous drainage (HR, 1.59; P=0.07) showed a trend toward significance. Hemorrhage risk was unchanged in patients who underwent partial arteriovenous malformation embolization (n=211; HR, 0.875; P=0.32). Conclusion— Brain arteriovenous malformations presenting with hemorrhage, with deep venous drainage, or associated aneurysms have ≈2-fold greater likelihood of a future hemorrhage. Partial treatment by embolization does not alter these risks. This natural history should be taken into account in the treatment strategy.

Intracranial arterial wall imaging using high-resolution 3-tesla contrast-enhanced MRI

Background: Conventional arterial imaging focuses on the vessel lumen but lacks specificity because different pathologies produce similar luminal defects. Wall imaging can characterize extracranial arterial pathology, but imaging intracranial walls has been limited by resolution and signal constraints. Higher-field scanners may improve visualization of these smaller vessels. Methods: Three-tesla contrast-enhanced MRI was used to study the intracranial arteries from a consecutive series of patients at a tertiary stroke center. Results: Multiplanar T2-weighted fast spin echo and multiplanar T1 fluid-attenuated inversion recovery precontrast and postcontrast images were acquired in 37 patients with focal neurologic deficits. Clinical diagnoses included atherosclerotic disease (13), CNS inflammatory disease (3), dissections (3), aneurysms (3), moyamoya syndrome (2), cavernous angioma (1), extracranial source of stroke (5), and no definitive clinical diagnosis (7). Twelve of 13 with atherosclerotic disease had focal, eccentric vessel wall enhancement, 10 of whom had enhancement only in the vessel supplying the area of ischemic injury. Two of 3 with inflammatory diseases had diffuse, concentric vessel wall enhancement. Three of 3 with dissection showed bright signal on T1, and 2 had irregular wall enhancement with a flap and dual lumen. Conclusions: Three-tesla contrast-enhanced MRI can be used to study the wall of intracranial blood vessels. T2 and precontrast and postcontrast T1 fluid-attenuated inversion recovery images at 3 tesla may be able to differentiate enhancement patterns of intracranial atherosclerotic plaques (eccentric), inflammation (concentric), and other wall pathologies. Prospective studies are required to determine the sensitivity and specificity of arterial wall imaging for distinguishing the range of pathologic conditions affecting cerebral vasculature.

Multidisciplinary management of spinal dural arteriovenous fistulas: Clinical presentation and long-term follow-up in 49 patients

Background and Purpose— In the early 1980s, it was demonstrated that surgical intradural division of the shunting vein to the medullary venous plexus cures a spinal dural arteriovenous fistula (DAVF) at low morbidity. There is, however, growing literature to support endovascular therapy. Methods— The clinical features of 49 consecutive patients with a spinal DAVF treated at a single institution between 1986 and 2001 were studied (mean age, 63 years; range, 28 to 78 years; 80% male). When possible, embolization was offered as the initial treatment. Endovascular treatment was considered adequate only if the proximal shunting vein could be occluded with liquid adhesive embolics. Motor and bladder function was evaluated with Aminoff scores an average of 32.3 months after treatment. Results— All but 1 patient presented with myelopathy. At a mean of 2.3 years after symptom onset, 48 DAVFs were angiographically demonstrated. Since 1999, gadolinium-enhanced MR angiography was additionally performed in 7 patients to point out the level of the DAVF. Endovascular embolization could be attempted in 44 of the 48 DAVFs and resulted in a cure in 11 (25%). Thirty-five DAVFs were surgically cured; 2 patients refused surgery after failed embolization. Angiographic confirmation of the treatment result was available in 97.7% of the patients. No permanent complications of either embolization or surgery were noted. Motor and bladder function scores were significantly improved in 35 patients who had long-term follow-up (both P <0.005). Conclusions— Endovascular treatment with liquid adhesive material provided a result equal to surgery in 25% of patients, overall resulting in a significant amelioration in the neurological status of patients with a spinal DAVF.

Angioarchitectural Factors Present in Brain Arteriovenous Malformations Associated With Hemorrhagic Presentation

Background and Purpose— Associations between clinical presentation of brain arteriovenous malformations (AVMs) and their angioarchitecture have been described. This study aims to identify significant factors related to the initial hemorrhagic event through multivariate statistical methodology. Methods— The authors studied the initial clinical presentation of 390 consecutive patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Angiographic features present at that time, such as location, size, and blood supply, were recorded following a standard protocol and associated, through multivariate analysis techniques, with type of presentation. Results— Patients had hemorrhagic presentation in 146 cases (37.4%). Hemorrhage was the initial presentation in 59.5% of the deep-seated AVMs (odds ratio [OR]=3.26; 95% CI=1.15 to 9.2;P =0.03). A single draining vein was associated with bleeding at presentation in 57.6% AVMs (OR=1.78; 95% CI=1.12 to 2.82;P =0.01), and 72.8% of the patients with venous ectasia had bleeding as initial evidence (OR=3.9; 95% CI=1.63 to 9.28;P =0.002). Hemorrhage was the initial presentation in 47.6% (111/233) of AVMs <3 cm, 22.5% (32/142) in sizes between 3 and 6 cm, and 20% in malformations >6 cm (3/15), but these differences were not significant in multivariate analyses. Conclusions— For initial hemorrhagic presentation, a small number of draining veins, deep location, and the presence of venous ectasias were significant associated factors. In contrast with many previous reports, AVM size was not associated with hemorrhage at presentation in adjusted analyses.

Acute subarachnoid hemorrhage: using 64-slice multidetector CT angiography to "triage" patients' treatment.

IntroductionTo evaluate the clinical role of CT angiography (CTA) in patients with acute subarachnoid hemorrhage (SAH) for treatment decision-making.MethodsConsecutive patients with acute SAH had CTA using a 64-slice scanner for initial clinical decision-making. Image processing included multiplanar volume reformatted (MPVR) maximum intensity projections (MIP) and 3D volume-rendered reconstructions. CTAs were used for (1) evaluating the cause of SAH, and (2) triaging aneurysm-bearing patients to the more appropriate management, either surgical clipping or endovascular coiling. CTA findings were confirmed by neurosurgical exploration or catheter angiography (digital subtraction angiography, DSA). Successful coiling provided evidence that triaging to endovascular treatment was correct.ResultsIncluded in the study were 73 patients. CTA findings were confirmed by DSA or neurosurgical operation in 65 patients, and of these 65, 47 had aneurysmal SAH, 3 had vasculitis, 1 had arterial dissection and 14 had no underlying arterial abnormality. The cause of SAH was detected with CTA in 62 out of the 65 patients (95.4%, sensitivity 94%, specificity 100%). CTA revealed the aneurysm in 46 of 47 patients (98%, sensitivity 98%, specificity 100%, positive predictive value 100%, negative predictive value 82.3%), 1 of 3 vasculitides and 1 of 1 dissection. Of the 46 patients with aneurysm, 44 (95.7%) were referred for treatment based on CTA. In 2 patients (2 of 46, 4.4%) CTA was not informative enough to choose treatment requiring DSA. Of the 44 patients, 27 (61.4%) were referred to endovascular treatment and successful coiling was achieved in 25 (25 of 27, 92.6%).ConclusionCTA using a 64-slice scanner is an accurate tool for detecting and characterizing aneurysms in acute SAH. CTA is useful in the decision process whether to coil or clip an aneurysm.

Large and Deep Brain Arteriovenous Malformations Are Associated With Risk of Future Hemorrhage

Background and Purpose— The correlation between features present in brain arteriovenous malformations (AVMs) such as size, location, and angioarchitecture at presentation with subsequent risk of hemorrhage may be valuable in predicting the behavior of AVMs and therefore guiding management. Methods— We prospectively followed up 390 patients with brain AVMs at the University of Toronto Vascular Malformation Study Group. Location, size, angioarchitecture details, blood supply, and clinical presentation were recorded at baseline. Intracranial hemorrhages during follow-up were recorded. Significant factors from univariate analyses were used to construct a multivariate model relating the above features to the occurrence of hemorrhage. Results— Thirty-eight patients had bleeding caused by the AVM in a follow-up of 1205 patient-years (mean, 3.1 years per patient). In analyses adjusted for multiple AVM characteristics, large AVMs bled more frequently than small lesions (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.41 to 4.35;P <0.0001), and deep-seated AVMs had more bleeding in follow-up than those located at superficial sites (OR, 5.56; 95% CI, 2.63 to 12.5;P <0.0001). Conclusions— Deep-seated and large AVMs were significantly more prone to hemorrhage during prospective follow-up. The distinction between factors associated with hemorrhagic presentation and the natural history risk of hemorrhage will be emphasized.

Canadian Experience with the Pipeline Embolization Device for Repair of Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE: Flow-diverting stents, such as the PED, have emerged as a novel means of treating complex intracranial aneurysms. This retrospective analysis of the initial Canadian experience provides insight into technical challenges, clinical and radiographic outcomes, and complication rates after the use of flow-diverting stents for unruptured aneurysms. MATERIALS AND METHODS: Cases were compiled from 7 Canadian centers between July 2008 and December 2010. Each center prospectively tracked their initial experience; these data were retrospectively updated and pooled for analysis. RESULTS: During the defined study period, 97 cases of unruptured aneurysm were treated with the PED, with successful stent deployment in 94 cases. The overall complete or near-complete occlusion rate was 83%, with a median follow-up at 1.25 years (range 0.25–2.5 years). Progressive occlusion was witnessed over time, with complete or near-complete occlusion in 65% of aneurysms followed through 6 months, and 90% of aneurysms followed through 1 year. Multivariate analysis found previous aneurysm treatment and female sex predictive of persistent aneurysm filling. Most patients were stable or improved (88%), with the most favorable outcomes observed in patients with cavernous carotid aneurysms. The overall mortality rate was 6%. Postprocedural aneurysm hemorrhage occurred in 3 patients (3%), while ipsilateral distal territory hemorrhage was observed in 4 patients (3.4%). CONCLUSIONS: Flow-diverting stents represent an important tool in the treatment of complex intracranial aneurysms. The relative efficacy and morbidity of this treatment must be considered in the context of available alternate interventions.

The natural history and management of intracranial dural arteriovenous fistulae. Part 1: benign lesions.

The recently proposed classification scheme of Borden, Wu, and Shucart (Borden*) should have the ability to identify those intracranial dural arteriovenous fistulae (ICDAVF) which will continue to behave in a benign fashion. We examine for the first time the natural history of benign ICDAVF, including the predictive ability of this grading scale, and the implications for lesion management. A cohort of 55 Borden* grade I lesions was selected from a heterogeneous series of 102 consecutive ICDAVF seen at one institution between 1984 and 1995. Data were collected prospectively from 1991. Grade I lesions were those whose nidus drained directly into a dural venous sinus (DVS) or meningeal vein. The absence of retrograde leptomeningeal venous drainage (RLVD) was an important feature. Intracranial haemorrhage (ICH), non haemorrhagic neurological deficit (NHND), and death were considered aggressive features. There were 23 cavernous sinus, 2 foramen magnum, 1 middle cranial fossa, and 29 transverse sinus lesions. One patient received obliterative surgical treatment. Thirty-two lesions were observed only, and 22 patients developed symptoms or signs requiring palliative embolisation. Two minor complications occurred following embolisation: transient pulmonary aedema (1), and an asymptomatic pericallosal artery embolus (1). Follow-up was available on 48 (89%) patients for a total of 133 patient years (mean 33 months). This included 26 of the 32 patients observed and all 22 of the patients embolised. Aggressive interval behavior was seen in only one patient. Symptom improvement or resolution was observed in the majority of patients, whether observed only [21/26 (81%)], or whether they required embolisation for symptom palliation [19/22 (86%)]. Overall, 53 of the 54 (98%) of ICDAVF behaved in a benign fashion in the follow-up period. The predictable benign natural history of patients identified as Borden* grade I at presentation mandates a conservative approach to these ICDAVF. In some patients, when symptom severity demands, palliative embolisation is an effective and safe therapy.