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.

Diffusion tensor imaging assessment of the epileptogenic zone in children with localization-related epilepsy

BACKGROUND AND PURPOSE

Patients with MR imaging-negative epilepsy could have subtle FCD. Our aim was to determine if structural changes could be identified by using DTI in children with intractable epilepsy, from MR imaging-visible FCD and MR imaging-negative localization-related epilepsy, that were concordant with the epileptogenic zone as defined by using the MEG dipole cluster.

MATERIALS AND METHODS

Eight children with MR imaging-visible FCD and 16 with MR imaging-negative epilepsy underwent DTI and MEG. Twenty-six age-matched healthy children underwent DTI. Analysis was performed on controls across individual patients. Agreement between the location of DTI abnormalities and FCD and MEG dipole clusters was assessed.

RESULTS

In patients with MR imaging-visible FCD, abnormal FA, MD, λ(1), λ(2), and λ(3) were lobar concordant with the MEG dipole cluster in 4/8 (50.0%), 5/8 (62.5%), 3/8 (37.5%), 6/8 (75.0%), and 5/8 (62.5%), respectively. In patients with MR imaging-visible FCD, abnormal FA, MD, λ(1), λ(2), and λ(3) overlapped the x-, y-, and z-axes of the MEG dipole cluster in 1/8 (12.5%), 4/8 (50%), 4/8 (50%), 6/8 (75%), and 4/8 (50%), respectively, and with FCD in 1/8 (12.5%), 3/8 (37.5%), 0/8 (0%), 3/8 (37.5%), and 1/8 (12.5%), respectively. In patients with MR imaging-negative epilepsy, abnormal FA, MD, λ(1), λ(2), and λ(3) were lobar-concordant with the MEG dipole cluster in 11/16 (68.8%), 11/16 (68.8%), 8/16 (50.0%), 10/16 (62.5%), and 10/16 (62.5%), respectively, and overlapped the x-, y-, and z-axes of the MEG dipole cluster in 9/16 (56.3%), 10/16 (62.5%), 8/16 (50%), 8/16 (50%), and 8/16 (50%), respectively. There was no significant difference between abnormal DTI lobar concordance with the MEG dipole cluster in patients with MR imaging-visible FCD and MR imaging-negative epilepsy.

CONCLUSIONS

White matter changes can be detected with DTI in children with MR imaging-visible FCD and MR imaging-negative epilepsy, which were concordant with the epileptogenic zone in more than half of the patients.

Transvenous embolization of intracranial dural arteriovenous shunts through occluded venous segments: experience in 51 Patients

BACKGROUND AND PURPOSE

DAVFs with cortical venous reflux carry a high risk of morbidity and mortality. Endovascular treatment options include transarterial embolization with a liquid embolic agent or transvenous access with occlusion of the involved venous segment, which may prove difficult if the venous access route is thrombosed. The aim of this article is to describe the technique and results of the transvenous approach via thrombosed venous segments for occlusion of DAVFs.

MATERIALS AND METHODS

Our study was a retrospective analysis of 51 patients treated with a transvenous approach through an occluded sinus that was reopened by gentle rotational advancement of a 0.035-inch guidewire, which opened a path for a subsequently inserted microcatheter.

RESULTS

Of 607 patients with DAVFs, the transvenous reopening technique was attempted in 62 patients in 65 sessions and was successful in 51 patients and 53 sessions. Immediate occlusion was seen in 42 patients; on follow-up, occlusion was seen in 49 patients, whereas 2 patients had reduced flow without cortical venous reflux. No permanent procedure-related morbidity was noted.

CONCLUSIONS

The reopening technique to gain access to isolated venous pouches or the cavernous sinus for the treatment of DAVFs is a safe and effective treatment, which should be considered if transarterial approaches fail or are anticipated to result only in an incomplete anatomic cure.

Corroboration of normal and abnormal fetal cerebral lamination on postmortem MR imaging with postmortem examination

BACKGROUND AND PURPOSE

The presence of normal fetal cerebral lamination of the germinal matrix, intermediate zone, subplate layer, and cortex can be used as a marker of normal fetal cerebral development. Our aim was to compare postmortem MR imaging assessment of normal and abnormal fetal cerebral lamination on T1- and T2-weighted images with histopathology.

MATERIALS AND METHODS

Fifty-five formalin-fixed brains from postmortem fetuses, ranging from 16 to 30 weeks' gestational age, mean of 23 weeks, underwent T1- and T2- weighted MR imaging and subsequent sectioning and histologic examination. The cerebral lamination was graded as normal or abnormal on T1- and T2-weighted imaging and compared with postmortem findings. The sensitivity, specificity, and positive and negative predictive values of T1 and T2 assessment of cerebral lamination were calculated.

RESULTS

Twenty-six fetuses had abnormal and 29 had normal cerebral lamination on histology. On T1, the overall sensitivity, specificity, and positive and negative predictive values of evaluating cerebral lamination were 96.15%(CI, 78.42%-99.80%), 89.66%(CI, 71.50%-97.29%), 89.29%(CI, 70.63%-97.19%), and 96.29%(CI, 79.11%-99.80%), respectively. On T2, the overall sensitivity, specificity, and positive and negative predictive values of evaluating cerebral lamination were 73.08%(CI, 51.95%-87.65%), 96.55%(CI, 80.37%-99.82%), 95.00%(CI, 73.06%-99.74%), and 80.00%(CI, 62.54%-90.94%), respectively.

CONCLUSIONS

Postmortem MR imaging has high sensitivity, specificity, and positive and negative predictive values in assessing fetal cerebral lamination compared with histology. T1-weighted imaging has a higher sensitivity and negative predictive value, while T2-weighted imaging has a higher specificity and positive predictive value.

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.

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.

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.

Functional MR imaging in patients with carotid artery stenosis before and after revascularization

BACKGROUND AND PURPOSE

Significant extracranial stenosis of the ICA is a known risk factor for future stroke and it has been shown that revascularization reduces the risk of future stroke. We applied BOLD fMRI in patients with carotid artery stenosis before and after CEA. Our purpose was to determine whether fMRI is able to demonstrate impaired CVR and to identify patient parameters that are associated with postoperative changes of cerebral hemodynamics.

MATERIALS AND METHODS

Nineteen consecutive patients with symptomatic (n = 13) and asymptomatic (n = 6) stenosis of the ICA were prospectively recruited (male/female ratio = 16:3; age, 69 ± 8,1 years). fMRI using a simple bilateral motor task was performed immediately before and after CEA.

RESULTS

Mean BOLD MSC was significantly increased postoperatively (MSC, 0.13 ± 0.66; P = 0.0002). Patients with a stenosis of <80% demonstrated an increase in MSC (MSC, 0.32 ± 0.59; P ≤ .0001). Patients with previous ischemic stroke showed a larger MSC than patients with TIAs (stroke: MSC, 0.55 ± 0.65; P ≤ .0001; TIA: MSC, 0.05 ± 0.26; P = 0.054). Patients older than 70 years had a significantly larger MSC following surgery (≤70 years: MSC, -0.01 ± 0.39; P = .429; >70 years: MSC, 0.29 ± 0.48; P ≤ .0001).

CONCLUSIONS

BOLD fMRI can demonstrate changes in cerebral hemodynamics before and after CEA, indicative of an ameliorated CVR. This response is dependent on the age of the patient, the degree of preoperative stenosis, and the patient's symptoms.

Bare, bio-active and hydrogel-coated coils for endovascular treatment of experimentally induced aneurysms. Long-term histological and scanning electron microscopy results

Endovascular treatments of cerebral aneurysms with bare platinum coils have a higher rate of recurrence compared to surgical clipping. This may be related to failed vessel wall reconstruction since histological and scanning electron microscopy results following embolization failed to demonstrate neoendothelialization over the aneurysm neck. The present study tried to elucidate whether the use of modified coils resulted in a better rate of reconstructing the vessel wall over the aneurysm neck in experimental aneurysms. Aneurysms were created in 20 rabbits by intraluminal elastase incubation of the common carotid artery. Five animals each were assigned to the following groups: untreated, bare platinum coils, bioactive coils with polyglycolic/polylactic acid coating, and hydrogel-coated platinum coils. After 12 months, angiography, histology and scanning electron microscopy was performed. No neoendothelial layer was visualized in the bioactive and bare coil groups with a tendency to an increased layering of fibroblasts along the bioactive coils at the aneurysm fundus. However, at the aneurysm neck perfused clefts were present and although a thin fibrinous layer was present over some coils, no bridging neointimal or neoendothial layer was noted over different coils. Following loose Hydrogel coiling, a complete obliteration of the aneurysm was present with neoendothelialization present over different coil loops. The study demonstrates that with surface coil modifications complete and stable aneurysm obliteration may become possible. A smooth and dense surface over the aneurysm neck may be necessary for endothelial cells to bridge the aneurysm neck and to lead to vessel wall reconstruction.

Subarachnoid hemorrhage following posterior spinal artery aneurysm. A case report and review of the literature

Isolated posterior spinal artery aneurysms are rare vascular lesions. We describe the case of a 43-year-old man presenting with spinal subarachnoid hemorrhage after a minor trauma who was found to have a dissecting aneurysm of a posterior spinal artery originating from the right T4 level. Endovascular treatment was not contemplated because of the small size of the feeding artery, whereas surgical resection was deemed more appropriate because of the posterolateral perimedullary location that was well appreciated on CT angiography. After surgical resection of the aneurysm the patient had a complete neurological recovery. In comparison to anterior spinal artery aneurysms whose pathogenesis is diverse, posterior spinal aneurysms are most often secondary to a dissection and represent false or spurious aneurysms. Although the definite diagnosis still requires spinal angiography, MRI and CT may better delineate the relationship of the aneurysm to the spinal cord in order to determine the best treatment method. Prompt treatment is recommended as they have high rebleeding and mortality rates.

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.

Angiographic characteristics and treatment of cervical spinal dural arteriovenous shunts

Spinal DAVSs of the cervical level are rare lesions. The purpose of this study is to describe the clinical and angiographic characteristics of cervical spinal DAVSs. From a prospectively collected database including 449 cases of brain and spinal DAVSs, lesions located at the cervical level were selected. The clinical presentation, angiographic characteristics, and treatment outcome were assessed. Twelve cases of spinal DAVSs were identified at the level of the cervical spinal canal (male to female ratio = 8:4; mean age = 56.5 years). Five patients (41.7%) presented with hemorrhage including SAH (n = 4) and cerebellar hemorrhage (n = 1). Coincidental spinal DAVSs with cranial DAVSs or brain AVMs were noted in 5 cases (41.7%). The spinal DAVS was the symptomatic lesion in 10 cases and was incidentally discovered during evaluation for SAH from a coincidental lesion in 2 cases. Combined endovascular and surgical resection resulted in symptomatic improvement in 10 patients. In conclusion, DAVSs of the cervical spine are rare lesions which often present with hemorrhage and are frequently associated with complex coincidental vascular lesions. Combined endovascular and surgical treatment will result in good outcome.

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.

Alteration of human fetal subplate layer and intermediate zone during normal development on MR and diffusion tensor imaging

BACKGROUND AND PURPOSE

The subplate layer and intermediate zone are the precursors for neonatal white matter. The aims of this study were to evaluate 1) T1 and T2 signal intensity, and 2) FA of subplate and intermediate zone in postmortem fetuses and correlate with histology, and 3) T2 signal intensity of subplate and intermediate zone on antenatal MR imaging.

MATERIALS AND METHODS

Fourteen immersion-fixed normal brains from 18 to 25 gestational weeks underwent 1.5T MR imaging, including DTI and histologic examination. The subplate and intermediate zone were graded on a scale of 1-5 on T1 and T2, and FAs were evaluated and then correlated with age. Seventeen antenatal MR images from 20 to 26 gestational weeks with normal brain were evaluated by using the same grading.

RESULTS

On T1 postmortem MR imaging, subplate has lower signal intensity compared with intermediate zone; subplate signal intensity correlated positively (r = 0.66, P = .012) with age, and intermediate zone signal intensity correlated negatively (r = -0.78, P = .001) with age. On T2 postmortem MR imaging, subplate has higher signal intensity compared with intermediate zone and remained persistently high in signal intensity; intermediate zone signal intensity showed moderate correlation (r = 0.48, P = .086) with age. FA of subplate correlated positively (r = 0.55, P < .001) with age; FA of intermediate zone correlated negatively (r = -0.64, P < .0001) with age. On histology, extracellular matrix decreased and cellularity increased in subplate layer, tangentially organized cellularity decreased, and projecting fibers became thicker in intermediate zone with increasing gestation. The findings on T2-weighted antenatal MR imaging were similar to T2-weighted postmortem MR imaging.

CONCLUSIONS

The changes in signal intensity and FA of subplate and intermediate zone in the second trimester reflect microstructural changes on histology.

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.

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.

Clinical characteristics of dural arteriovenous shunts in 446 patients of three different ethnicities

SUMMARY

Dural arteriovenous shunts (DAVSs) developing in either the ventral, dorsal or lateral epidural spaces (VE, DE and LE-shunts) predictably drain in either cranio/spino-fugal or -petal directions. Associated conditions like venous outflow restrictions (VOR) may be responsible for changes in this drainage pattern. The goal of this study was to compare demographic, angiographic and clinical characteristics of different types of DAVS in Europe, South America, and Asia to find out whether the same clinical profile is present in different ethnicities. Charts and angiographic films of 446 patients with DAVS from three hospitals in Europe, Asia and South America were retrospectively evaluated. Clinical symptoms were separated into benign and aggressive and the presence or absence of cortical venous reflux (CVR) and VOR was noted. LE-shunts were present in elderly men and were always associated with CVR resulting in aggressive symptoms. VE-shunts were present in females and almost always had benign symptoms. There were no differences among the three populations for these shunts. DE-shunts in the Asian population were more aggressive secondary to a higher rate of VOR with associated CVR. VE-shunts rarely lead to CVR even in the presence of VOR, whereas LE-shunts invariably lead to CVR, irrespective of the population investigated. CVR in DE-shunts is not related to the primary disease (i.e. the shunt itself) but to associated factors that led to VOR. Since the occurrence of these varied between different ethnicities, DE-shunts were aggressive in the Asian population and benign in the European and South American populations.

Dural arteriovenous fistulas draining into the petrosal vein or bridging vein of the medulla: possible homologs of spinal dural arteriovenous fistulas. Clinical article

OBJECT

Dural arteriovenous fistulas (DAVFs) with leptomeningeal venous reflux generally pose a high risk of aggressive manifestations including hemorrhage. Among DAVFs, there is a peculiar type that demonstrates direct drainage into the bridging vein rather than the dural venous sinus. The purpose of this study was to investigate the characteristics of DAVFs that drain directly into the petrosal vein or the bridging vein of the medulla oblongata.

METHODS

Eleven consecutive cases of DAVFs that drained directly into the petrosal vein and 6 that drained directly into the bridging vein of the medulla were retrospectively reviewed. These cases were evaluated and/or treated at Hospital de Bicêtre in Paris, France, over a 27-year period. A review of previously reported cases was also performed.

RESULTS

Both of these "extrasinusal"-type DAVFs demonstrated very similar characteristics. There was a significant male predominance (p < 0.001) for this lesion, and a significantly higher incidence of aggressive neurological manifestations including hemorrhage or venous hypertension than in DAVFs of the transverse-sigmoid or cavernous sinus (p < 0.001). This finding was considered to be attributable to leptomeningeal venous reflux. Regarding treatment, endovascular embolization (either transarterial or transvenous) is frequently difficult, and surgery may be an effective therapeutic choice in many instances.

CONCLUSIONS

Embryologically, both the petrosal vein and the bridging vein of the medulla are cranial homologs of the spinal cord emissary bridging veins that drain the pial venous network. The authors believe that DAVFs in these locations may be included in a single category with spinal DAVFs because of their similar clinical characteristics.

Addictive illegal drugs: structural neuroimaging

Illegal addictive drugs can lead to functional or structural impairment of the central nervous system. This review provides an overview of the structural imaging findings on CT, MR imaging, and conventional angiography related to chronic and acute abuse of the most commonly abused illegal drugs, including cannabis, organic solvents, and amphetamines and opioids and their respective derivatives. Pathomechanisms include excitotoxicity, which may lead to an acute or subacute leukoencephalopathy, and vascular complications, including vasoconstriction, vasculitis, or hypertension, which may lead to intracranial hemorrhage or ischemia. Because clinical findings alone are often nonspecific, and afflicted patients are unlikely to admit to the substance abuse, the neuroradiologist may play an important role in establishing the diagnosis and, thereby, initiating treatment.

Classification of Spinal Vascular Malformations

Spinal vascular malformations are rare diseases with a wide variety of neurological presentations. Their classification depends on the differentiation of shunting versus non-shunting lesions, the latter being the spinal cord cavernomas. In the shunting lesions, the next step in the proposed classification scheme is related to the feeding artery which can subdivide the dural vascular shunts from the pial vascular malformations: while those shunts that are fed by radiculomeningeal arteries (i.e. the counterparts of meningeal arteries in the brain) constitute the dural arteriovenous fistulas, the shunts that are fed by arteries that would normally supply the spinal cord (i.e. the radiculomedullary and radiculopial arteries) are the pial cord arteriovenous malformations (whose cranial counterparts are the brain AVMs). Depending on the type of transition between artery and vein the latter pial AVMs can be further subdivided into glomerular (plexiforme or nidus-type) AVMs with a network of intervening vessels in between the artery and vein and the fistulous pial AVMs. The last step in the classification then describes whether the type of fistula has a high or a low shunting volume which will differentiate the “Macro-” from the “Micro-”fistulae. The proposed classification is therefore based on a stepwise analysis of the shunt including its arterial anatomy, its nidus-architecture and its flow-volume evaluation. The major advantage of this approach is that it leads to a subclassification with direct implications on the choice of treatment, thereby constituting a simple and practical approach to evaluate these rare diseases.

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.

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.

Dangerous extracranial-intracranial anastomoses and supply to the cranial nerves: vessels the neurointerventionalist needs to know

Transarterial embolization in the external carotid artery (ECA) territory has a major role in the endovascular management of epistaxis, skull base tumors, and dural arteriovenous fistulas. Knowledge of the potential anastomotic routes, identification of the cranial nerve supply from the ECA, and the proper choice of embolic material are crucial to help the interventionalist avoid neurologic complications during the procedure. Three regions along the skull base constitute potential anastomotic routes between the extracranial and intracranial arteries: the orbital, the petrocavernous, and the upper cervical regions. Branches of the internal maxillary artery have anastomoses with the ophthalmic artery and petrocavernous internal carotid artery (ICA), whereas the branches of the ascending pharyngeal artery are connected to the petrocavernous ICA. Branches of both the ascending pharyngeal artery and the occipital artery have anastomoses with the vertebral artery. To avoid cranial nerve palsy, one must have knowledge of the supply to the lower cranial nerves: The petrous branch of the middle meningeal artery and the stylomastoid branch of the posterior auricular artery form the facial arcade as the major supply to the facial nerve, and the neuromeningeal trunk of the ascending pharyngeal artery supplies the lower cranial nerves (CN IX-XII).

Spinal dural arteriovenous fistulas

Spinal dural arteriovenous (AV) fistulas are the most commonly encountered vascular malformation of the spinal cord and a treatable cause for progressive para- or tetraplegia. They most commonly affect elderly men and are classically found in the thoracolumbar region. The AV shunt is located inside the dura mater close to the spinal nerve root where the arterial blood from a radiculomeningeal artery enters a radicular vein. The increase in spinal venous pressure leads to decreased drainage of normal spinal veins, venous congestion, and the clinical findings of progressive myelopathy. On MR imaging, the combination of cord edema, perimedullary dilated vessels, and cord enhancement is characteristic. Therapy has to be aimed at occluding the shunting zone, either by superselective embolization with a liquid embolic agent or by a neurosurgical approach. Following occlusion of the fistula, the progression of the disease can be stopped and improvement of symptoms is typically observed.

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.

The aneurysmal wall. The key to a subclassification of intracranial arterial aneurysm vasculopathies?

SUMMARY

The pathogenesis of intracranial arterial aneurysms (AA) has been debated for many years and still remains unclear, although these entities might pose life-threatening risks to the patient and understanding the disease is of utmost importance for choosing treatment concepts. Apart from the "classical" berry-type aneurysm, there are different other types of intracranial AA such as infectious, dissecting or giant, partially thrombosed aneurysms. From the clinician's perspective, the hypothesis that some of these intracranial aneurysms might be due to abluminal factors has been put forward for many years. Alterations of the vessel wall, either due to luminal or abluminal factors may be employed for an etiological classification of aneurysmal vasculopathies as will be discussed in this article. Moreover, regarding certain aneurysmal vasculopathies as an abluminal disease might alter current therapeutic strategies since therapy should not only aim at the intraluminal repair of the artery but may also target the vessel wall.

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.

Trigeminal fistula treated by combined transvenous and transarterial embolisation

Trigeminal cavernous fistulae are rare, compared to other types of carotid-cavernous fistulae with only about 17 examples previously reported in English literature. The aetiology can be either post-traumatic or spontaneous, and in the latter group either due to a ruptured trigeminal aneurysm or postulated intrinsic weakness of the artery itself. The treatment goal is to close the fistula while preserving the parent artery and this can be done either by surgical or endovascular methods. We present a 35-year-old woman with a spontaneous trigeminal fistula treated by combined trans-venous and trans-arterial embolisation.

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.

Infantile dural arteriovenous shunt draining into a developmental venous anomaly

SUMMARY

A three-year-old girl with an incidentally discovered infantile type of dural arteriovenous shunts (DAVs) along the superior sagittal sinus during investigation of a minor head trauma is presented. The DAVs drained into a developmental venous anomaly of the right cerebral hemisphere. In addition, there was a small cavernoma within the territory drained by the DVA. The patient underwent multiple transarterial embolizations to decrease the shunt flow and thus the constrained venous drainage of the DVA and right cerebral hemisphere. Pediatric dural arteriovenous shunts are a different entity from the adult type DAVs and should be managed according to the growth and development of the child. DVAs are extreme variations of the venous system with reduced flexibility to increased venous drainage. Regardless of the type of treatment employed, the DVA and its drainage pathway must be preserved.

Segmental Neurovascular Syndromes in Children

The concept of segmental vascular syndromes with different, seemingly unrelated, diseases is based on the embryology of the neural crest and the mesoderm migration of cells that share the same metameric origin. Migrating patterns of these cells link the brain, the cranial bones, and the face on the same side. A somatic mutation developing in the region of the neural crest or the adjacent cephalic mesoderm before migration can, therefore, be postulated to produce arterial or venous metameric syndromes, including PHACES, CAMS, Cobb syndrome, and Sturge-Weber syndrome. Although these diseases may be rare, their relationships among each other and their postulated linkage with the development of the neural crest and the cephalic mesoderm may shed light on the complex pathology and etiology of various cerebral vascular disorders.