Factors Determining the Clinical Complications of Radiosurgery for AVM.

PURPOSE: To identify the predictors of symptomatic post-radiation T2 signal change in patients with arteriovenous malformations (AVM) treated with radiosurgery. MATERIALS AND METHODS: The charts of 211 consecutive patients with arteriovenous malformations treated with either gamma knife radisurgery or linear accelerator radiosurgery between 2000-2009 were retrospectively reviewed. 168 patients had a minimum of 12 months of clinical and radiologic follow-up following the procedure and complete dosage data. Pretreatment characteristics and dosimetric variables were analyzed to identify predictors of adverse radiation effects. RESULTS: 141 patients had no clinical symptomatic complications. 21 patients had global or focal neurological deficits attributed to symptomatic edema. Variables associated with development of symptomatic edema included a non-hemorrhagic symptomatic presentation compared to presentation with hemorrhage, p=0.001; OR (95%CI) = 6.26 (1.99, 19.69); the presence of venous rerouting compared to the lack of venous rerouting, p=0.031; OR (95% CI) = 3.25 (1.20, 8.80); radiosurgery with GKS compared to linear accelerator radiosurgery p = 0.012; OR (95% CI) = 4.58 (1.28, 16.32); and the presence of more than one draining vein compared to a single draining vein p = 0.032; OR (95% CI) = 2.82 (1.06, 7.50). CONCLUSIONS: We postulated that the higher maximal doses used with gamma knife radiosurgery may be responsible for the greater number of adverse radiation effects with this modality compared to linear accelerator radiosurgery. We found that AVMs with greater venous complexity and therefore instability resulted in more adverse treatment outcomes, suggesting that AVM angioarchitecture should be considered when making treatment decisions.Facteurs en cause dans les complications cliniques de la radiochirurgie pour une malformation artérioveineuse.

Alcohol-induced changes in the brain as assessed by MRI and CT.

This review provides an overview of structural magnetic resonance imaging and computed tomography findings of direct and indirect alcohol-related toxic effects on the brain. In addition to ethanol-related changes to the brain, this article will also describe imaging findings in the acute setting of methanol and ethylene glycol poisoning. Alcohol will lead to brain atrophy, osmotic myelinolysis, Marchiafava-Bignami disease and, especially when related to malnutrition, may also cause Wernicke encephalopathy. Brain atrophy can be reversible if alcohol abuse is stopped. If not treated, Wernicke encephalopathy can lead to coma and death and an early diagnosis is important for immediate initiation of thiamine substitution. As clinical symptoms are often unspecific, the radiologist plays an important role in the detection of alcohol abuse and its related clinical conditions.

Partial "targeted" embolisation of brain arteriovenous malformations.

The treatment of pial arteriovenous brain malformations is controversial. Little is yet known about their natural history, their pathomechanisms and the efficacy and risks of respective proposed treatments. It is known that only complete occlusion of the AVM can exclude future risk of haemorrhage and that the rates of curative embolisation of AVMs with an acceptable periprocedural risk are around 20 to 50%. As outlined in the present article, however, partial, targeted embolisation also plays a role. In acutely ruptured AVMs where the source of bleeding can be identified, targeted embolisation of this compartment may be able to secure the AVM prior to definitive treatment. In unruptured symptomatic AVMs targeted treatment may be employed if a defined pathomechanism can be identified that is related to the clinical symptoms and that can be cured with an acceptable risk via an endovascular approach depending on the individual AVM angioarchitecture. This review article gives examples of pathomechanisms and angioarchitectures that are amenable to this kind of treatment strategy.

Radiologic assessment of brain arteriovenous malformations: what clinicians need to know.

Brain arteriovenous malformations (AVMs) are abnormal vascular connections within the brain that are presumably congenital in nature. There are several subgroups, the most common being glomerular type brain AVMs, with fistulous type AVMs being less common. A brain AVM may also be a part of more extensive disease (eg, cerebrofacial arteriovenous metameric syndrome). When intracranial pathologic vessels are encountered at cross-sectional imaging, other diagnoses must also be considered, including large developmental venous anomalies, malignant dural arteriovenous fistulas, and moyamoya disease, since these entities are known to have different natural histories and require different treatment options. Several imaging findings in brain AVMs have an impact on decision making with respect to clinical management; the most important are those known to be associated with risk of future hemorrhage, including evidence of previous hemorrhage, intranidal aneurysms, venous stenosis, deep venous drainage, and deep location of the nidus. Other imaging findings that should be included in the radiology report are secondary effects caused by brain AVMs that may lead to nonhemorrhagic neurologic deficits, such as venous congestion, gliosis, hydrocephalus, or arterial steal.

Pathomechanisms and treatment of pediatric aneurysms.

Pediatric aneurysms are rare diseases distinct from classical adult aneurysms and therefore require different treatment strategies. Apart from saccular aneurysms that are more commonly found in older children, three major pathomechanisms may be encountered: trauma, infection, and dissection. The posterior circulation and more distal locations are more commonly encountered in children compared to adults, and there is an overall male predominance. Clinical findings are not only confined to subarachnoid hemorrhage but may also comprise mass effects, headaches or neurological deficits. In traumatic aneurysms, the skull base and distal anterior communicating artery are commonly affected, and the hemorrhage occurs often delayed (2-4 weeks following the initial trauma). Infectious aneurysms are mostly bacterial in origin, and hemorrhage occurs early after a septic embolic shower. Dissecting aneurysms are the most often encountered aneurysm type in children and can lead to mass effect, hemorrhage, or ischemia depending on the fate of the intramural hematoma. Treatment strategies in pediatric aneurysms include endosaccular coil treatment only for the "classical berry-type" aneurysms; in the other instances, parent vessel occlusion, flow reversal, surgical options, or a combined treatment with bypass and parent vessel occlusion have to be contemplated.

Predicting factors for the follow-up outcome and management decisions in vein of Galen aneurysmal malformations.

PURPOSE: Vein of Galen aneurysmal malformations (VGAMs) are choroidal arteriovenous malformations that develop during an early embryonic stage. Although recent reports have shown improved outcome for these patients, the overall outcome still is poor. In this study, we evaluated the clinical, imaging, and angiographic features that may predict the outcome in VGAM patients. METHODS: Twenty-five patients diagnosed with VGAM were reviewed for clinical symptoms, including neonatal scoring systems, imaging findings, angioarchitecture, treatment decision, initial treatment age, follow-up timing, and follow-up outcome. RESULTS: Factors that were significantly associated with a poor outcome (p < 0.05) included neurological symptoms at presentation, a medium-to-low overall neonatal score (<12/21), a very poor score (<2/5) in one (or more) categories, focal parenchymal changes, calcifications, tonsillar herniation, arterial steal, or more than two groups of multiple arterial feeders. The venous drainage pattern and treatment age were not significantly associated with the overall outcome. CONCLUSIONS: The presence of multiple factors that are related with poor outcome may warrant withholding aggressive treatment, while a small subgroup of carefully selected patients without any of these factors who are clinically asymptomatic may have a good outcome even with conservative management and close follow-up. For all other patients in which treatment is considered, the optimal treatment time is at 4-5 months of age; however, urgent treatment, regardless of age, should be indicated in those that do not have permanent brain damage on imaging with deteriorating congestive heart failure, evidence of arterial steal, or progressive occlusion of the venous outflow.

Endovascular management of spinal vascular malformations.

Spinal vascular malformations are rare diseases with a wide variety of neurological presentations. In this article, arteriovenous malformations (both from the fistulous and glomerular type) and spinal dural arteriovenous fistulae are described and an overview about their imaging features on magnetic resonance imaging (MRI) and digital subtraction angiography is given. Clinical differential diagnoses, the neurological symptomatology and the potential therapeutic approaches of these diseases which vary depending on the underlying pathology are given. Although MRI constitutes the diagnostic modality of first choice in suspected spinal vascular malformation, a definite diagnosis of the disease and therefore the choice of suited therapeutic approach rests on selective spinal angiography. Treatment in symptomatic patients offers an improvement in the prognosis. In most spinal vascular malformations, the endovascular approach is the method of first choice; in selected cases, a combined or surgical therapy may be considered.

Hydrocephalus in unruptured brain arteriovenous malformations: pathomechanical considerations, therapeutic implications, and clinical course.

OBJECT: The goal in this study was to present possible pathological mechanisms, clinical and imaging findings, and to describe the management and outcome in patients with hydrocephalus due to unruptured pial brain arteriovenous malformations (AVMs). METHODS: Medical records and imaging findings in 8 consecutive patients with hydrocephalus caused by AVMs and treated between June 2000 and September 2007 were retrospectively reviewed to determine clinical symptoms, AVM location, venous drainage, level/cause of obstruction, and degree of hydrocephalus. Management of hydrocephalus, AVM treatment, complications, and follow-up results were evaluated. RESULTS: Headaches were the most common clinical symptom (7 of 8 patients). Deep venous drainage was identified in all patients. Mechanical obstruction by the draining vein or the AVM nidus was seen in 6 patients, in whom obstruction occurred at the interventricular foramen (2 patients) or the aqueduct (4 patients). Hydrodynamic disorders following venous outflow obstruction and venous congestion of the posterior fossa led to hydrocephalus in the remaining 2 patients. Ventriculoperitoneal (VP) shunts were placed in 6 of 8 patients with a moderate to severe degree of hydrocephalus. Regression of hydrocephalus was noted in 4 patients, whereas in 2 the imaging findings were stable, 1 of whom had decreased hydrocephalus only after AVM size reduction. In 2 patients with mild hydrocephalus who were not treated with shunt insertion, 1 improved and 1 was clinically stable after AVM treatment. CONCLUSIONS: The most common cause of hydrocephalus in unruptured brain AVMs is mechanical obstruction by the draining vein if it is located in a strategic position. Management should be aimed at treatment of the AVM; however, VP shunts may be necessary in acute and severe cases of hydrocephalus.

Abnormal fetal cerebral laminar organization in cobblestone complex as seen on post-mortem MRI and DTI.

We report a unique case of cobblestone complex using post-mortem MR and diffusion tensor imaging to assess the laminar organization of the fetal cerebrum. The imaging findings were correlated with autopsy findings. Abnormal cortical development in cobblestone complex resulted in disruption of normal laminar organization of the fetal brain, which was seen as interruption and nodularity of the high-signal T1 cortical band with increased anisotropy and medium diffusivity extending beyond the cortical band into the cerebral mantle on post-mortem MR and diffusion tensor imaging.

Dynamic CT angiography and CT perfusion employing a 320-detector row CT: protocol and current clinical applications.

The aim of this study is to report the authors' initial clinical experience of a 320-detector row computed tomography (CT) scanner in cerebrovascular disorders. Volumetric CT using the full 160-mm width of the 320 detector rows enables full brain coverage in a single rotation that allows for combined time-resolved whole-brain perfusion and four-dimensional CT angiography (CTA). The protocol for the combined dynamic CTA and CT perfusion (CTP) is presented, and its potential applications in stroke, stenoocclusive disease, arteriovenous malformations and dural shunts are reviewed based on clinical examples. The combined CTA/CTP data can provide visualization of dynamic flow and perfusion as well as motion of an entire volume at very short time intervals which is of importance in a variety of pathologies with altered cerebral hemodynamics. The broad coverage enabled by 320 detector rows offers z-axis coverage allowing for whole-brain perfusion and subtracted dynamic angiography of the entire intracranial circulation.

Pathomechanisms of symptomatic developmental venous anomalies.

BACKGROUND AND PURPOSE: Although it is generally accepted that developmental venous anomalies (DVAs) are benign vascular malformations, over the past years, we have seen patients with symptomatic DVAs. Therefore, we performed a retrospective study and a literature study to review how, when, and why DVAs can become clinically significant. METHODS: Charts and angiographic films of 17 patients with DVAs whose 18 vascular symptoms could be attributed to a DVA were selected from a neurovascular databank of our hospital. MRI had to be available to rule out any other associated disease. In the literature, 51 cases of well-documented symptomatic DVAs were found. Pathomechanisms were divided into mechanical and flow-related causes. RESULTS: Mechanical (obstructive or compressive) pathomechanisms accounted for 14 of 69 symptomatic patients resulting in hydrocephalus or nerve compression syndromes. Flow-related pathomechanisms (49 of 69 patients) could be subdivided into complications resulting from an increase of flow into the DVA (owing to an arteriovenous shunt using the DVA as the drainage route; n=19) or a decrease of outflow (n=26) or a remote shunt with increased venous pressure (n=4) leading to symptoms of venous congestion. In 6 cases, no specific pathomechanisms were detected. CONCLUSIONS: Although DVAs should be considered benign, under rare circumstances, they can be symptomatic. DVAs, as extreme variations of normal venous drainage, may represent a more fragile venous drainage system that can be more easily affected by in- and outflow alterations. The integrity of the DVA needs to be preserved irrespective of the treatment that should be tailored to the specific pathomechanism.

Dural arteriovenous shunts: a new classification of craniospinal epidural venous anatomical bases and clinical correlations.

BACKGROUND AND PURPOSE: The craniospinal epidural spaces can be categorized into 3 different compartments related to their specific drainage role of the bone and central nervous system, the ventral epidural, dorsal epidural, and lateral epidural groups. We propose this new classification system for dural arteriovenous shunts and compare demographic, angiographic, and clinical characteristics of dural arteriovenous shunts that develop in these 3 different locations. METHODS: Three hundred consecutive cases (159 females, 141 males; mean age: 47 years; range, 0 to 87 years) were reviewed for patient demographics, clinical presentation, multiplicity, presence of cortical and spinal venous reflux, and outflow restrictions and classified into the 3 mentioned groups. RESULTS: The ventral epidural group (n=150) showed a female predominance, more benign clinical presentations, lower rate of cortical and spinal venous reflux, and no cortical and spinal venous reflux without restriction of the venous outflow. The dorsal epidural group (n=67) had a lower mean age and a higher rate of multiplicity. The lateral epidural group (n=63) presented later in life with a male predominance, more aggressive clinical presentations, and cortical and spinal venous reflux without evidence of venous outflow restriction. All differences were statistically significant (P<0.001). CONCLUSIONS: Dural arteriovenous shunts predictably drain either in pial veins or craniofugally depending on the compartment involved by the dural arteriovenous shunt. Associated conditions (outflow restrictions, high-flow shunts) may change that draining pattern. The significant differences between the groups of the new classification support the hypothesis of biological and/or developmental differences in each epidural region and suggest that dural arteriovenous shunts are a heterogeneous group of diseases.

Cerebral proliferative angiopathy: clinical and angiographic description of an entity different from cerebral AVMs.

BACKGROUND AND PURPOSE: The purpose of this article is to describe "cerebral proliferative angiopathy" (CPA) as a clinical entity, which may be regarded as separate from "classical" brain AVMs in angioarchitecture, natural history, clinical presentation, and, therefore, treatment and which can be discerned from other cerebral AVMs by characteristic imaging features. METHODS: In a prospectively entered databank encompassing 1434 patients with brain AVMs, a subgroup of 49 patients harboring specific angiographic characteristics were identified. Their charts and imaging films were retrospectively reviewed. RESULTS: We found a preponderance of CPA in young (mean age: 22) females (67%). Clinical symptoms were seizures, disabling headaches, and stroke-like symptoms; hemorrhagic presentations were exceptional. On cross-sectional imaging, CPA demonstrated as a diffuse network of densely enhancing vascular spaces with intermingled normal brain parenchyma. The discrepancy between the large size of the nidus and the small shunting volume, the absence of flow-related aneurysms, the presence of diffuse angiogenesis (eg, transdural supply, progressive arterial occlusion), and the small calibre of a multitude of feeding arteries and draining veins were the angiographic hallmarks of this disease. CONCLUSIONS: The diffuse angiogenetic activity is presumably related to reduced perinidal perfusion and subsequent chronic cortical ischemia. Natural history demonstrates a low risk of hemorrhage. CPA may be regarded as a separate clinical entity different to "classical" cerebral AVMs, because normal brain is interspersed with the abnormal vascular channels increasing the risk of neurological deficit in aggressive treatments, which in the light of the natural history does not seem to be indicated.

Angioarchitecture determines obliteration rate after radiosurgery in brain arteriovenous malformations.

BACKGROUND: Radiosurgery as a potential treatment modality for brain arteriovenous malformations (AVM) has 60% to 90% obliteration rates. OBJECTIVE: To test whether AVM angioarchitecture determines obliteration rate after radiosurgery. METHODS: This study was a retrospective analysis of 139 patients with AVM who underwent radiosurgery. Multiple angioarchitectural characteristics were reviewed on conventional angiogram on the day of radiosurgery: enlargement of feeding arteries, flow-related or intranidal aneurysms, perinidal angiogenesis, arteriovenous transit time, nidus type, venous ectasia, focal pouches, venous rerouting, and presence of a pseudophlebitic pattern. The radiation plan was reviewed for nidus volume and eloquence of AVM location. A chart review was performed to determine clinical presentation and previous treatment. Outcome was dichotomized into complete/incomplete obliteration, and various statistics were performed, examining whether outcome status was associated with the investigated factors. RESULTS: Marginal dose ranged from 15 to 25 Gy (mean, 18.8 Gy), with lower doses prescribed in eloquent locations. Sizes of AVMs ranged from 0.08 to 21 cm (mean, 3.78 ± 4.19 cm). Complete AVM obliteration was achieved in 92 patients (66%) and was related to these independent factors: noneloquent location (odds ratio [OR], 3.20), size (OR, 0.88), low flow (OR, 3.47), no or mild arterial enlargement (OR, 3.32), and absence of perinidal angiogenesis (OR, 2.61). Concerning the 3 last angioarchitectural characteristics, if no or only a single factor was present in an individual patient (n = 92 patients), obliteration was observed in 74 (80%); if 2 or 3 factors were present (n = 47), obliteration was observed in 18 patients (38%; OR, 6.62). CONCLUSION: Angioarchitectural factors that indicate high flow are associated with a lower rate of AVM obliteration after radiosurgery.

Impact of individual intracranial arterial aneurysm morphology on initial obliteration and recurrence rates of endovascular treatments: a multivariate analysis.

OBJECT: The goal was to investigate whether morphological features of aneurysms can be identified that determine initial success and recurrence rates of coiled aneurysms of the basilar artery tip, the posterior communicating artery (PCoA), and the anterior communicating artery. METHODS: The authors evaluated 202 aneurysms in connection with their pretreatment morphological features including size, neck-to-dome ratio, angulation of the aneurysm in relation to the parent artery, orientation of the aneurysm dome, and associated anatomical variations. The mean follow-up was 19 months (range 6-96 months) after endovascular coil occlusion. Using multivariate logistic regression, probabilities for initial complete occlusion and long-term stability of the treatment were calculated. RESULTS: Recanalization occurred in 49 of 202 cases. Favorable factors for long-term stability included small aneurysms with small necks. However, additional factors related to local hemodynamic forces could be identified for the different aneurysm locations, which may influence initial success rates and long-term stability of aneurysm treatment with endovascular coiling. These factors were a medial dome orientation and a symmetrical disposition of both A(1) segments (for the anterior communicating artery), a posteroinferior dome orientation and a small-size PCoA (for the PCoA), and a cranial symmetrical fusion (for the basilar artery tip). CONCLUSIONS: A detailed pretreatment analysis of morphological features of aneurysms may help to determine those aneurysms that are more prone to recurrence, which could add to the treatment decision and the follow-up algorithm.

Intracranial aneurysms: from vessel wall pathology to therapeutic approach.

An aneurysm is a focal dilatation of an arterial blood vessel. Luminal forces, such as high blood flow, shear stress and turbulence, are implicated in the pathogenesis of intracranial aneurysms, and luminal characteristics, such as sac size and morphology, are usually essential to the clinical decision-making process. Despite frequent clinical emphasis on the vessel lumen, however, the pathology underlying the formation, growth and rupture of an aneurysm mainly resides in the vessel wall. Research on the morphology and histopathology of the vessel wall reveals that intracranial aneurysms do not constitute a single disease, but are a shared manifestation of a wide range of diseases, each of which has a unique natural history and optimum therapy. This Review classifies intracranial aneurysms by vessel wall pathology, and demonstrates that understanding the morphology and pathology of this structure is important in determining the therapeutic approach. The article concludes that aneurysms represent a symptom of an underlying vascular disease rather than constituting a disease on their own.

Classification and endovascular management of pediatric cerebral vascular malformations.

Pediatric vascular malformations of the central nervous system differ from those seen in adults. Their classification may be based on symptoms, pathomechanics, patient's age, morphologic features, or presumed etiology. This review describes the different classification schemes and the endovascular management options of these rare and challenging diseases. The proposed etiologic classification of pediatric vascular malformations may add to our understanding of these diseases in general because the phenotypic expression of a given vascular malformation can shed light on the nature and timing of the causative agent, thereby potentially opening up treatment modalities in the future that are directed against the triggering event rather than against the clinical manifestations or the morphologic appearance. With current endovascular methods, most vascular diseases can be approached safely and with good clinical results.

Symptomatic spontaneous vertebrobasilar dissections in children: review of 29 consecutive cases.

OBJECT: The purpose of this study is to analyze the clinical presentation, morphological characteristics, angio-architecture, and outcome of vertebrobasilar dissection (VBD) in the pediatric population. METHODS: The authors retrospectively reviewed 29 consecutive cases involving children younger than 16 years of age who were diagnosed with symptomatic VBDs. Data were gathered with respect to the patient's age, sex, clinical history, associated underlying disease, and symptoms (headache, vertigo) as well as the location of the dissection and the imaging appearance. RESULTS: The patients' mean age was 8.24 years (range 2 months-15 years). There was an overall 3:1 male predominance, although among children older than 8 years, girls and boys were similarly affected. Hemorrhagic dissections occurred in 10 of 29 cases. In nonhemorrhagic dissections, stroke occurred in 16 cases, with the most common presenting symptoms being headaches and vertigo; in the other 3 cases, mass effect due to a chronic dissecting aneurysm was present. In 7 children an underlying vessel wall disease was found. The location of the dissection was extradural in 11 cases and intradural in the remainder. There was no preference with respect to side. The basilar artery was affected in 9 patients. CONCLUSIONS: The imaging appearance and clinical presentation of symptomatic VBDs in the pediatric population differs from that in adults. Boys are more often affected, especially at younger ages, and hemorrhagic presentation is more common, presumably owing to the fact that the basilar artery is more commonly involved. Depending on the pathogenetic mechanism underlying the dissection, different clinical symptoms will evolve, necessitating individually tailored treatment.

Longitudinal brain volumes in children with intractable partial seizures.

Cross sectional studies in children with epilepsy have reported variable changes in brain volume. The study hypothesis was that seizures result in injury to the developing brain, which is manifested as a reduction in brain volume. The aim was to evaluate the gray and white matter volumes longitudinally in children with partial epilepsy. All patients had two magnetic resonance scans, 1-7 years apart. The total, cerebral, and hemispheric gray and white matter volumes of 20 children with intractable partial epilepsy were measured. The correlation between change in volume and age at epilepsy onset and duration of epilepsy were assessed. There were no significant differences in total, cerebral, or hemispheric gray and white matter volumes with time. Up to six patients exhibited greater than 10% volume loss in total, cerebral, or hemispheric gray or white matter. There were no significant correlations between change in volume and age or duration of epilepsy. The findings suggest that volume loss does not occur in the shorter-term monitoring of children with partial seizures. It is possible that volume loss could become evident with long-term monitoring of children with epilepsy. Alternatively, brain volume may be an insensitive measure of alteration in brain structure secondary to epilepsy, and that other imaging techniques, such as diffusion tensor imaging, may be more sensitive for detecting microstructural changes induced by recurrent seizures.

Cervical spine dural arteriovenous fistula presenting with congestive myelopathy of the conus.

Spinal dural arteriovenous fistulas (DAVFs) are the spinal vascular malformations that are encountered most often, and they are usually encountered in the lower thoracic region. Cervical spine DAVFs are exceedingly rare and may be difficult to differentiate from radicular arteriovenous malformations, epidural arteriovenous shunts, or perimedullary AVFs. Typical angiographic findings in spinal DAVFs include a slow-flow shunt with converging feeding vessels from radiculomeningeal arteries draining via a radicular vein centripetally into perimedullary veins. The MR imaging findings such as spinal cord edema and perimedullary dilated vessels may be used to direct the spinal angiography that is needed to localize and classify the shunt. When the shunt is distant from the pathological imaging findings, the diagnosis may be difficult to establish, especially when the shunt is present at an atypical location such as the cervical spine. The authors present the case of a 51-year-old man presenting with lower thoracic and conus medullaris congestive edema due to a cervical spine DAVF that was located at the C-5 level. Transarterial embolization with N-butyl cyanoacrylate closed the proximal vein and completely obliterated the fistula. Clinical and imaging follow-up confirmed occlusion of the fistula, with improvement in clinical symptoms.