Impact of anatomical variations of the circle of Willis on the incidence of aneurysms and their recurrence rate following endovascular treatment.

AIM: To analyse the impact of anatomical variations of the parent arteries on the incidence and recurrence rate following coil embolization of aneurysms of the anterior (AcoA), posterior communicating artery (PcoA) and basilar artery (BA) tip. METHODS: Two hundred and two (96 AcoA, 67 PcoA, and 29 BA) aneurysms in 200 patients were treated with coil embolization between January 2000 and April 2008. Parent artery variations at each location were classified as: AcoA: A1 aplasia versus hypoplasia versus symmetrical size; PcoA: foetal origin versus medium versus small size, BA: cranial versus caudal versus asymmetrical fusion. The incidence of aneurysms and difference between recurrence rates for each group were recorded on follow-up. RESULTS: AcoA, PcoA, and BA aneurysms were more often associated with embryonically earlier vessel wall dispositions (A1 aplasia, foetal PcoA, asymmetrical fusion). Two of these variations were also associated with aneurysm recurrence following coil embolization: asymmetrical A1 segment (p=0.01), and asymmetrical BA tip (p=0.02). CONCLUSIONS: AcoA, PcoA, and BA tip aneurysms tend to occur more often in anatomically variant parent artery dispositions, some of which are related to aneurysm recurrence following coil embolization. This may relate to a more fragile vessel disposition as it is not fully matured or to altered haemodynamics secondary to the anatomical variations.

Spontaneous Intracranial Hypotension: A Systematic Imaging Approach for CSF Leak Localization and Management Based on MRI and Digital Subtraction Myelography.

BACKGROUND AND PURPOSE: Localization of the culprit CSF leak in patients with spontaneous intracranial hypotension can be difficult and is inconsistently achieved. We present a high yield systematic imaging strategy using brain and spine MRI combined with digital subtraction myelography for CSF leak localization. MATERIALS AND METHODS: During a 2-year period, patients with spontaneous intracranial hypotension at our institution underwent MR imaging to determine the presence or absence of a spinal longitudinal extradural collection. Digital subtraction myelography was then performed in patients positive for spinal longitudinal extradural CSF collection primarily in the prone position and in patients negative for spinal longitudinal extradural CSF collection in the lateral decubitus positions. RESULTS: Thirty-one consecutive patients with spontaneous intracranial hypotension were included. The site of CSF leakage was definitively located in 27 (87%). Of these, 21 were positive for spinal longitudinal extradural CSF collection and categorized as having a ventral (type 1, fifteen [48%]) or lateral dural tear (type 2; four [13%]). Ten patients were negative for spinal longitudinal extradural CSF collection and were categorized as having a CSF-venous fistula (type 3, seven [23%]) or distal nerve root sleeve leak (type 4, one [3%]). The locations of leakage of 2 patients positive for spinal longitudinal extradural CSF collection remain undefined due to resolution of spontaneous intracranial hypotension before repeat digital subtraction myelography. In 2 (7%) patients negative for spinal longitudinal extradural CSF collection, the site of leakage could not be localized. Nine of 21 (43%) patients positive for spinal longitudinal extradural CSF collection were treated successfully with an epidural blood patch, and 12 required an operation. Of the 10 patients negative for spinal longitudinal extradural CSF collection (8 localized), none were effectively treated with an epidural blood patch, and all have undergone (n = 7) or are awaiting (n = 1) an operation. CONCLUSIONS: Patients positive for spinal longitudinal extradural CSF collection are best positioned prone for digital subtraction myelography and may warrant additional attempts at a directed epidural blood patch. Patients negative for spinal longitudinal extradural CSF collection are best evaluated in the decubitus positions to reveal a CSF-venous fistula, common in this population. Patients with CSF-venous fistula may forgo further epidural blood patch treatment and go on to surgical repair.

Segmental artery exchange technique for stable 4F guiding-catheter positioning in embolization of spinal vascular malformations.

For anatomic and technical reasons, it is often difficult to achieve guiding-catheter stability in the segmental arteries during embolization of spinal vascular lesions. We have developed a segmental artery exchange technique using a thin-walled 4F nontapered catheter that is safe and achieves a stable guiding-catheter position. This catheter accommodates both the flow-guided and variable-stiffness microcatheters, allowing selective catheterization and treatment of spinal vascular lesions.

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.

Neurovascular manifestations in hereditary hemorrhagic telangiectasia: imaging features and genotype-phenotype correlations.

BACKGROUND AND PURPOSE: Hereditary hemorrhagic telangiectasia is an autosomal dominant disease that presents in 10%-20% of patients with various brain vascular malformations. We aimed to report the radiologic features (phenotype) and the genotype-phenotype correlations of brain vascular malformations in hereditary hemorrhagic telangiectasia. MATERIALS AND METHODS: Demographic, clinical, genotypic, and imaging information of 75 patients with hereditary hemorrhagic telangiectasia with brain arteriovenous malformations enrolled in the Brain Vascular Malformation Consortium from 2010 to 2012 were reviewed. RESULTS: Nonshunting, small, superficially located conglomerates of enhancing vessels without enlarged feeding arteries or draining veins called "capillary vascular malformations" were the most commonly observed lesion (46 of 75 patients; 61%), followed by shunting "nidus-type" brain AVMs that were typically located superficially with a low Spetzler-Martin Grade and a small size (32 of 75 patients; 43%). Direct high-flow fistulous arteriovenous shunts were present in 9 patients (12%). Other types of vascular malformations (dural AVF and developmental venous anomalies) were present in 1 patient each. Multiplicity of vascular malformations was seen in 33 cases (44%). No statistically significant correlation was observed between hereditary hemorrhagic telangiectasia gene mutation and lesion type or lesion multiplicity. CONCLUSIONS: Depending on their imaging features, brain vascular malformations in hereditary hemorrhagic telangiectasia can be subdivided into brain AVF, nidus-type AVM, and capillary vascular malformations, with the latter being the most common phenotype in hereditary hemorrhagic telangiectasia. No genotype-phenotype correlation was observed among patients with this condition.

Analysis of endoglin expression in normal brain tissue and in cerebral arteriovenous malformations.

BACKGROUND AND PURPOSE: A high incidence of arteriovenous malformations (AVMs) is associated with hereditary hemorrhagic telangiectasia type 1. Endoglin, the gene mutated in this disorder, is expressed at reduced levels on blood vessels of these patients. Since endoglin is a component of the transforming growth factor-beta receptor complex critical for vascular development and homeostasis, we determined its expression in sporadic cerebral AVMs and in normal brain vessels. METHODS: Twenty cerebral AVMs and 10 normal brain samples were analyzed for endoglin, platelet endothelial cell adhesion molecule 1 (PECAM-1), alpha-smooth muscle cell actin, vimentin, and desmin by immunohistochemistry. RESULTS: In normal brain, endoglin was found not only on the endothelium of all vessels but also on the adventitial layer of arteries and arterioles. In cerebral AVMs, the numerous vessels present expressed endoglin on both endothelium and adventitia. Arterialized veins, identified by lack of elastin and uneven thickness of smooth muscle cells, revealed endoglin-positive mesenchymal cells in the adventitia and perivascular connective tissue. These cells were fibroblasts since they expressed vimentin but not actin and/or desmin. CONCLUSIONS: This is the first report of endoglin expression on adventitia of normal brain arteries and on arterialized veins in cerebral AVMs. Increasing numbers of endoglin-positive endothelial and adventitial cells were seen in sporadic cerebral AVMs, but endoglin density was normal. Thus, it is not involved in the generation of these lesions. However, the presence of endoglin on fibroblasts in the perivascular stroma suggests an active role for this protein in vascular remodeling in response to increased blood flow and shear stress.

Histologic long-term follow-up after embolization with polyvinyl alcohol particles.

A large facial vascular malformation was embolized with polyvinyl alcohol particles twice in 8 years. Resected tissue enabled long-term examination of this material, confirming its chemical inertness and revealing minimal tissue reaction to it apart from calcification. No particle migration, fragmentation, or absorption occurred. There was some recanalization of occluded vessels. Most vessels containing polyvinyl alcohol particles, and all of the larger vessels, were incompletely occluded, with particles becoming embedded in their walls.

Experimental models in interventional neuroradiology.

Various experimental models have been developed to test interventional neuroradiologic techniques. Most have been used to test various devices and embolic materials, and a small number of models have been designed for teaching or training purposes. Experimental models in endovascular techniques have seldom been used to stimulate disease processes in order to facilitate their understanding.

Rotational angiography assessment of cerebral aneurysms.

PURPOSE: To compare rotational angiography with conventional digital subtraction angiography in the assessment of cerebral aneurysms. METHODS: Conventional digital subtraction angiography and rotational angiography were compared in 57 patients investigated for the preoperative diagnosis of subarachnoid hemorrhage and in 13 patients after surgery. Images were compared for location, visibility of the aneurysmal neck, vascular branch anatomy, projection, size, presence of spasm, and shape of the aneurysm. RESULTS: Rotational angiography was superior to the digital angiogram in assessing aneurysms and vascular anatomy in the following percentage of cases: 12% for location, 46% for the presence of a neck, 32% in the assessment of branch anatomy, 19% for projection, 12% for size, 3.5% for spasm, and 19% for shape. After surgery, rotational angiography more clearly demonstrated the presence or absence of a neck in 69% of the cases. CONCLUSIONS: Rotational angiography often allows better visualization of vascular anatomy and therefore improves the angiographic assessment of aneurysms when compared with conventional digital subtraction angiography, making it an excellent adjunct in the investigation of subarachnoid hemorrhage. The lack of subtraction artifacts from the surgical clips and multiple angles of view also allow better assessment of the presence or absence of a residual neck in postoperative cases.

Posterior fossa surgery: an unusual cause of superficial siderosis.

With the widespread use of magnetic resonance imaging, an increasing number of cases of superficial siderosis are being discovered. However, the cause remains uncertain in almost half the cases. We report a case where previous surgery for a pontine hematoma established a pathway for extravasation of blood into the 4th ventricle, resulting in superficial siderosis that was demonstrated on a follow-up magnetic resonance imaging scan 8 years later. This case presents an unusual iatrogenic cause of superficial siderosis that has not been reported previously.

Embolization with temporary balloon occlusion of the internal carotid artery and in vivo proton spectroscopy improves radical removal of petrous-tentorial meningioma.

A highly vascular petroclival meningioma supplied by tentorial branches of the internal carotid artery was embolized by temporary balloon occlusion of the parent vessel distal to the tumor, followed by obliteration of the tumor vascularity with polyvinyl alcohol particles. Subsequently, in vivo proton spectroscopy showed necrosis of a large portion of the tumor and helped determine the timing of surgery. Both innovative techniques considerably facilitated the subsequent radical excision of the tumor with no neurological morbidity.

An unusual type of hangman's fracture.

An unusual fracture of the axis was best displayed using three-dimensional reconstruction. The fracture was noted to differ significantly from the usual "hangman's fracture" as it involved the body of C2 with subluxation of the anterior part of C2 forward on C3 and without "decompression" of the spinal canal at the C2 level. Better understanding made feasible by three-dimensional reconstruction had important treatment implications in this case.

Thorotrast-induced meningioma. Case report.

The authors report an adult patient with a symptomatic intracranial meningioma that was demonstrated by computerized tomography, angiography, and at surgery. The meningioma had occurred at a site where 19 years previously thorium dioxide had been injected into an abscess cavity. Pathological examination revealed the presence of thorium granules within the meningioma.

Endovascular treatment of intracerebral arteriovenous malformations: experience in 49 cases.

The authors report the results of treatment in 49 consecutive patients with brain arteriovenous malformations (AVM's) who underwent therapeutic embolization with liquid adhesive agents between 1984 and 1988 at the Toronto Western Hospital. Thirty-three patients had no other treatment and were followed up with angiography at 2 years and clinically from 2 to 6 years. Of the other 16 patients, 10 had adjunctive radiosurgery and six underwent surgical resection following embolization. Seven (14%) of the 49 patients had a morphological cure effected by embolization as evidenced on their 2-year follow-up angiograms: these have remained clinically stable. Twelve patients developed neurological deficits after embolization; eight (16% of the series) were transient and four (8%) were permanent. Two patients (4%) had a delayed hemorrhage after incomplete obliteration of their malformations. Endovascular treatment resulted in clinical improvement in 15 (33%) of the other 46 patients. None of the patients who initially presented with hemorrhage had a rebleed following embolization. It is concluded that endovascular treatment with liquid embolic material can be an integral part of the multidisciplinary treatment protocol for patients with brain AVM's.

A simple relationship between radiological arteriovenous malformation hemodynamics and clinical presentation: a prospective, blinded analysis of 31 cases.

OBJECT: The authors sought to establish prospectively whether there is a simple relationship between radiological features of brain arteriovenous malformation (AVM) hemodynamics and a patient's clinical presentation. METHODS: Thirty-one consecutive patients with AVMs underwent cerebral angiography at 3.8 frames/second during each standardized injection of contrast material. Contrast dilution curves were derived from the image sequences by using regions of interest (ROIs) traced on arteries feeding and veins draining the AVM nidus. Angiographic parameters were then analyzed in a blinded fashion. These parameters included the times required to reach the peak contrast density, the contrast decay time, and fractions thereof, in the ROI for each vessel. The authors determined whether these parameters, the arteriovenous transit time, and/or AVM size were related to patients' presentation with hemorrhage (11 patients), seizure (11 patients), or other clinical symptoms (nine patients). Statistically significant results were found only in analyses of arterial phase times to reach peak contrast density. Analyses of venous parameters, AVM size, and nidus transit time showed trends but no statistical significance. Arterial filling with contrast material was significantly slower in patients presenting with hemorrhage (mean 50%, 80%, and 100% of time to peak +/- standard error [SE] = 1.19+/-0.13, 1.97+/-0.18, and 3.04+/-0.34 seconds, respectively) compared with patients presenting with seizures (mean 50%, 80%, and 100% of time to peak +/- SE = 0.80+/-0.12, 1.32+/-0.18, and 1.95+/-0.29 seconds, respectively) according to analysis of variance (p<0.05) and post-hoc t-tests (p<0.05) for each parameter. Patients who presented with other symptoms had intermediate arterial filling times. CONCLUSIONS: These simple hemodynamic parameters, which can be obtained without added risk to the patient, may help identify a subset of individuals in whom AVMs pose a higher risk of future hemorrhage and who may therefore warrant more expeditious treatment.

The role of angiography in the evaluation of vascular and neoplastic disease in the external carotid artery circulation.

Angiography has a defined role in the management of vascular or neurologic diseases with less emphasis on screening and diagnosis and greater emphasis on pretherapeutic evaluation and endovascular treatment. This is especially true in diseases in the external carotid circulation. Advances in catheter technology and super-selectivity have improved our understanding of the anatomy and hemodynamics in normal and pathologic states. The functional neurovascular anatomy of the external carotid artery and diseases in which angiography has a role are reviewed.

Long-term clinical and imaging follow-up of complex intracranial aneurysms treated by endovascular parent vessel occlusion.

BACKGROUND AND PURPOSE: Flow-diverting stents are increasingly being used for the treatment of complex intracranial aneurysms, but the indications for their use in lieu of traditional endovascular PVO have yet to be precisely defined. The purpose of this study was to review the clinical and imaging outcomes of patients with intracranial aneurysms treated by PVO. MATERIALS AND METHODS: A total of 28 patients with intracranial aneurysms, treated by PVO between July 1992 and December 2009, were reviewed. Aneurysms arising from peripheral arteries were excluded. Clinical and imaging data were retrospectively analyzed from a prospectively maintained data base. RESULTS: There were 28 patients with 28 aneurysms treated by PVO. Aneurysms of the anterior circulation presenting with mass effect (n = 11) or discovered incidentally (n = 1), and dissecting-type VB aneurysms presenting with subarachnoid hemorrhage (n = 6) faired the best with high obliteration rates (83.3% and 83.6%, respectively) and no permanent major ischemic complications. In contrast, VB aneurysms presenting with mass effect (n = 7) demonstrated the lowest obliteration rate (57.1%), the highest rate of permanent major ischemic complications (28.6%), and a high mortality rate (28.6%). CONCLUSIONS: PVO is a safe and effective treatment for complex intracranial aneurysms of the carotid artery and dissecting-type VB aneurysms presenting with SAH. In contrast, PVO for aneurysms of the VB circulation presenting with mass effect is less efficacious and associated with significant morbidity and mortality. It is hoped that flow diverters may represent a better treatment technique for these most difficult-to-treat lesions.

Osteogenesis imperfecta, multiple intra-abdominal arterial dissections and a ruptured dissecting-type intracranial aneurysm.

We describe an adult patient with a ruptured dissecting-type superior cerebellar artery aneurysm and known osteogenesis imperfecta. He was successfully treated with coil embolization and intentional parent vessel sacrifice. During his hospital admission, he also suffered from abdominal distension. An incidental note was made of multiple intra-abdominal arterial dissections. These were managed conservatively. We review the rare association of osteogenesis imperfecta and intracranial aneurysms, as well as discuss management implications.

Detection and classification of cranial dural arteriovenous fistulas using 4D-CT angiography: initial experience.

BACKGROUND AND PURPOSE: The criterion standard to diagnose and classify cranial DAVFs is DSA. Since this is invasive, relatively expensive and time-consuming, a noninvasive alternative is of interest. We aimed to evaluate the capabilities and pitfalls of 4D-CTA in a consecutive series of patients who presented with a newly diagnosed cranial DAVF, as demonstrated by conventional DSA. MATERIALS AND METHODS: Eleven patients were included in this study after biplane DSA demonstrated a cranial DAVF. They subsequently underwent 4D-CTA imaging by using a 320-detector CT scanner. DSA and 4D-CTA studies were independently read by 2 blinded observers, by using a standardized scoring sheet. 4D-CTA results were analyzed with DSA as the criterion standard. RESULTS: In 10 cases, there was full agreement between DSA and 4D-CTA regarding the Borden classification. However, in the remaining patient, a slow-filling DAVF with a low shunt volume was missed by both readers on 4D-CTA. In all 10 detected cases, ≥ 1 of the major contributing arteries could be identified with 4D-CTA. Although, by using DSA, the 2 observers identified additional arterial feeders in 7 and 8 cases, respectively, these discrepancies did not influence clinical decision making. CONCLUSIONS: Although novel 4D-CTA imaging may not rule out a small slow-flow DAVF, it appears to be a valuable new adjunct in the noninvasive diagnostic work-up, treatment planning, and follow-up of patients with cranial DAVFs.

Hydrocephalus secondary to hydrodynamic disequilibrium in an adult patient with a choroidal-type arteriovenous malformation.

We describe an adult patient with an unruptured choroidal-type arteriovenous malformation (AVM) associated with progressive hydrocephalus. There was no evidence of mechanical obstruction of the ventricular system by the AVM nidus itself or a draining vein. However significant reflux into periventricular and transmedullary veins was demonstrated. Following partial targeted embolization of the AVM, no further reflux was observed, the patient's clinical deficits resolved, and the hydrocephalus improved. We suggest a hydrodynamic disorder as a potential pathomechanism of hydrocephalus in this adult patient with an unruptured AVM.