PWI-MRI and contrast extravasation in brain AVM help to estimate angiogenic activity.

INTRODUCTION: The aim of this study is to investigate perfusion characteristics of brain arteriovenous malformation (AVM) by means of MRI perfusion-weighted imaging (PWI). METHODS: Forty-three patients with brain AVM were prospectively included and investigated by PWI-MRI. Diagnosis of type of disease was made by angiogram. According to angiographic features, the study group was classified in three groups: two groups of patients with classical AVM (group 1 with few or no angiogenic feature (13 patients) and group 2 with many angiogenic features (18 patients)) and one group (group 3) which included patients with cerebral proliferative angiopathy (CPA; 12 patients). Twenty-one patients had never been treated endovascularly for their AVM and 22 patients received partial treatment by endovascular embolisation. Through PWI, corrected cerebral blood volume (CBVc), mean transit time (MTT), and percentage of microvascular leakage (MVL) as an indirect measure of permeability were assessed. RESULTS: The three patient groups did not differ significantly in baseline and clinical parameters. CBVc, MTT, and MVL differed significantly between the three groups (p = 0.003, p = 0.04, p = 0.01, respectively), with the lowest mean values found in group 1 and the highest in group 3. Mean MVL was 11.4 in group 1, 18.6 in group 2, and 21.9 in group 3. CONCLUSION: MRI can demonstrate differences in PWI parameters among patients with classical AVM and CPA, which are related to angiographic features of these AVMs. Through PWI, the level of angiogenic activity in AVMs may be monitored.

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.

A rare case of cerebral cortical dysplasia with arterial vascular dysplasia.

BACKGROUND: Cortical dysplasias are rarely associated with vascular anomalies. They are usually associated with venous anomalies or in few cases with both arterial and venous anomalies. METHODS: Twenty-six year old female presented with history of headache showed cortical dysplasia associated with pure arterial dysplasia in the absence of any associated venous anomaly. CONCLUSIONS: An abnormal arterial supply to or an abnormal venous drainage from the growing cortex may result in cortical rearrangements that eventually give rise to various neuronal migration anomalies.

Repair process in spontaneous intradural dissecting aneurysms in children: report of eight patients and review of the literature.

OBJECTIVE: The objective of this study is to present a series of eight pediatric patients (less than 16 years old) with complete spontaneous thrombosis of spontaneous intradural dissecting aneurysms. MATERIAL AND METHODS: Since 1989, eight consecutive patients in whom the cerebral aneurysms (four in middle cerebral arteries, one in posterior cerebral artery, three in basilar arteries) were found complete spontaneous thrombosis on follow-up MRI/MRA or conventional angiography. Patient histories and angiographic features were retrospectively reviewed. RESULTS: Complete thrombosis of aneurysms in between first few days to 7 months was found in eight out of 1,587 patients (0.5%) in this recent series. Aneurysm repair was related to multivariate processes. Headache (50%), vomiting, and hemiplegia (37.5%) were common presenting symptoms. Partial or total resolution of the symptoms in a few months was often seen. Associated parent artery occlusions (50%) were also observed. CONCLUSION: Spontaneous resolution of intradural dissecting aneurysm with or without parent artery occlusion is not uncommon even in the pediatric population. Aneurysm repair is a dynamic and multifaceted entity. Mural hematoma appears to be the most important factor promoting thrombosis and healing of the dissecting intracranial aneurysms.

Spinal arteriovenous malformation associated with syringomyelia.

The authors describe 4 cases of syringomyelia-associated spinal cord arteriovenous malformation (AVM). All cases were managed with embolization of the AVM. Treatments were aimed to stabilize the AVM itself and not directed toward the syrinx. In 3 of the 4 cases the syringomyelia resolved after treatment. Reports concerning AVM as a cause of syringomyelia is very scarce and lacks posttreatment clinical information. In light of the clinical course and imaging findings, the authors propose a theory that venous hypertension in the spinal cord is the trigger for the development of syringomyelia, which may reverse after AVM treatment.

Curable cause of paraplegia: spinal dural arteriovenous fistulae.

BACKGROUND AND PURPOSE: The rarity of spinal dural arteriovenous fistulae makes physicians often overlook this potential diagnosis in patients with progressive gait disturbance and paraparesis. Consequently, patients with spinal dural arteriovenous fistulae can gradually become completely paraplegic if the final diagnosis is delayed considerably. The objective of the current study is to demonstrate that, particularly in patients with paraplegia, surgical treatment of fistula is necessary and often has a favorable outcome. METHODS: Of 42 patients with spinal dural arteriovenous fistulae treated in our institution (surgery or endovascular treatment), 6 were paraplegic preoperatively (Grade IV on the McCormick scale and Grade V on the Aminoff scale, Grade 5 of modified Rankin Scale with motor ASIA between 0 and 10 for both lower limbs). Their clinical history revealed that paraplegia appeared progressively within a period of <3 months. All patients were clinically evaluated at 6 weeks, 6 months, and then annually during an average follow-up of 3 years. Patients received at least one spinal angiography and MRI test during the follow-up period. RESULTS: Total exclusion of the fistula was performed surgically in all cases and was confirmed by spinal angiography. No surgical complications were recorded. All patients improved postoperatively. Three patients showed almost normal walking (Grade I on the McCormick scale, I on the Aminoff scale, Grade 1 of modified Rankin Scale) and 3 were able to walk with a cane (Grade II on McCormick, Grade III on Aminoff scale, Grade 2 of modified Rankin Scale). MRI tests were normal in all patients. CONCLUSIONS: Our results indicate that treatment of fistula is a necessary intervention, even in patients with complete paraplegia.

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.

Intradural saccular aneurysms treated by Guglielmi detachable bare coils at a single institution between 1993 and 2005: clinical long-term follow-up for a total of 1810 patient-years in relation to morphological treatment results.

BACKGROUND AND PURPOSE: The aim of this study was to analyze the clinical results of Guglielmi detachable bare coil (GDC) embolization of intradural saccular aneurysms (AAs) at a single center and to relate the morphological results at various time points to the clinical situation. METHODS: All intradural saccular AAs treated with GDCs between 1993 and April 2005 were prospectively entered into a database completed by retrospective analysis of charts and images and a long-term clinical outcome questionnaire. In 413 consecutive patients, there were 466 treated AAs, of which 68.7% were ruptured and 31.1% were unruptured. RESULTS: The periprocedural thromboembolic event rate, retreatment procedures included, was 5.4%, causing permanent neurologic deficits in 2.2% of patients. One patient (0.2%) bled during a mean+/-SD clinical follow-up of 64.3+/-39.9 months (93 AAs were followed up for >8 years and 45 AAs were followed up for >10 years) for a total of 1810 patient-years. The modified Rankin Scale score was 0 in 54.7%, 1 in 21.0%, 2 in 12.1%, 3 in 7.1%, 4 in 2.1%, 5 in 0.3%, and 6 (death from unrelated causes) in 2.7% of patients. If an aneurysm, with or without a remnant, was unchanged for 12 months, then the risk for future morphological loss was 4.8%, whereas if an aneurysm showed a morphological loss during the earlier 12-month interval, the risk for additional late loss was 38.3% (P<0.001, odds ratio=12.4). CONCLUSIONS: Embolization of saccular AAs entails a prolonged management period. A stable angiographic result during a 12-month interval predicts a low risk for morphological deterioration. This regimen, aiming for a stable angiographic result rather than complete aneurysm occlusion, gives a low rebleed rate and excellent clinical long-term results.

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.

Arterial vascularization of the cranial nerves.

We discuss the arterial supply of the cranial nerves from their exit out of the brain stem to their exit from the skull base. Four distinct groups can be differentiated from an embryologic and phylogenetic standpoint. Understanding the arterial supply to the cranial nerves and the potential anastomoses is paramount in the endovascular treatment of dural AV shunts and highly vascularized tumors of the skull base to avoid neurologic deficits.

Diagnosis and endovascular treatment of pediatric spinal arteriovenous shunts.

Spinal arteriovenous shunts (SAVSs) are rarely diagnosed in infants and children, but they are important clinically because morbidity can be significant. Although these lesions do not form a distinct pathologic group separate from the SAVSs seen in older patients, experience with these malformations in the pediatric population has led to the identification of several important features that are characteristic of this group of SAVSs. Association with genetic abnormalities, heritable (hereditary hemorrhagic telangiectasia) and nonheritable somatic (spinal arteriovenous metameric syndrome or Cobb syndrome), is relatively common and likely underrecognized. Male predominance is more pronounced than in the adult population. Hemorrhagic presentation is more frequent than in adults, except in extremely young children. The natural history seems to be better than previously thought, with early rehemorrhage uncommon. Despite early presentation and severe symptoms, these lesions are frequently amenable to endovascular treatment, often with anatomic cure achieved and with improvement or stabilization of symptoms after partial targeted treatment.

Vein of galen aneurysmal malformations.

Different types of malformations share a dilated vein of Galen, but only one of them is a true vein of Galen aneurysmal malformation (VGAM). The optimal window of opportunity for treatment is between 4 and 5 years of months [corrected], because this allows the child to grow and mature. Heart failure and hydrocephalus respond favorably to embolization. Cerebrospinal fluid ventricular shunting, if needed, should be performed after the embolization. The transvenous approach carries significantly elevated morbidity and mortality and is rarely indicated. Anatomic cure of the VGAM is not the main goal of treatment; the ultimate goal is control of the malformation to allow the brain to mature and develop normally.

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.

Diffusion tensor magnetic resonance imaging and fiber tracking in spinal cord lesions: current and future indications.

Diffusion-weighted imaging and fractional anisotropy may be more sensitive than other conventional magnetic resonance imaging techniques to detect, characterize, and map the extent of spinal cord lesions. Fiber tracking offers the possibility of visualizing the integrity of white matter tracts surrounding some lesions, and this information may help in formulating a differential diagnosis and in planning biopsies or resection. Fractional anisotropy measurements may also play a role in predicting the outcome of patients who have spinal cord lesions. In this article, we address several conditions in which diffusion-weighted imaging and fiber tracking is known to be useful and speculate on others in which we believe these techniques will be useful in the near future.

Imaging in spinal vascular disease.

Spinal vascular diseases are rare and constitute only 1% to 2% of all vascular neurologic pathologies. In this article, the following vascular pathologies of the spine are described: spinal arterial infarcts, spinal cavernomas, and arteriovenous malformations (including perimedullary fistulae and glomerular arterivenous malformations), and spinal dural arteriovenous fistulae. This article gives an overview about their imaging features on MRI, MR angiography, and digital subtraction angiography. Clinical differential diagnoses, the neurologic symptomatology, and the potential therapeutic approaches of these diseases, which might vary depending on the underlying pathologic condition, are given.

Craniofacial vascular malformations in Wyburn-Mason syndrome.

BACKGROUND: Wyburn-Mason syndrome (WMS) is a rare syndrome associated with multiple arteriovenous malformations (AVMs) involving the orbit, brain and/or face. The purpose of this study was to analyze the imaging spectrums of craniofacial vascular malformations in 14 patients with WMS. METHODS: The medical records of 14 patients with the diagnosis of WMS who underwent neuroimaging studies (computed tomography [CT], 8; magnetic resonance imaging [MRI], 12; conventional angiography, 14) were reviewed, emphasizing the location, extension and type of facial, orbital and brain vascular malformations. Complete WMS was defined as vascular malformations involving all the 3 zones of the face, orbit and brain, while partial WMS was considered as vascular malformation distributed in 2 zones. RESULTS: The craniofacial vascular malformations were confined on the left side in 7 patients, 2 were found on the right side, while the remaining other 5 patients had midline brain AVMs involving both sides. All but 1 of these 14 patients had orbital and/or brain AVMs; facial vascular malformations were documented in 5 patients. The most common site of involvement was the optic nerve (n = 12), followed by the retina (n = 10), optic chiasma/hypothalamus (n = 9), thalamus (n = 7), basal ganglion (n = 5), midbrain (n = 2), occipital lobe (n = 1), temporo-occipital lobe (n = 1) and fronto-temporo-parieto-occipital lobe (n = 1). The complete form of WMS was found in 2 patients and the partial form in 12. CT, MRI and conventional angiography have the capacity to demonstrate the extent of intracranial AVMs. However, MRI is superior to both CT and angiography for detecting the size, extent of AVMs and the effects of AVMs on adjacent brain. Conventional angiography is superior to both CT and MRI in determining the detailed angioarchitecture of AVMs. CONCLUSION: WMS has a wide spectrum of multiple AVMs involving unilateral or bilateral craniofacial regions. The most common involved site is the orbit, followed by the brain. WMS should be considered in patients with ocular AVMs associated with brain AVMs.

MR diffusion tensor imaging, fiber tracking, and single-voxel spectroscopy findings in an unusual MELAS case.

A 23-year-old man was admitted to the intensive care unit for respiratory failure, global lower and upper limb palsy, and higher cognitive function deterioration. Imaging, performed with a combination of the MR diffusion tensor imaging, fiber tracking, and MR spectroscopy, suggested the diagnosis of an acute severe unusual mitochondrial encephalopathy, lactic acidosis, and strokelike event, which was confirmed by muscle biopsy, but fiber tracking showed unexpected unaltered white matter tracts.

Foramen tympanicum, or foramen of Huschke: pathologic cases and anatomic CT study.

BACKGROUND AND PURPOSE: A persistent foramen tympanicum, or foramen of Huschke, is an anatomic variation of the tympanic portion of the temporal bone due to a defect in normal ossification in the first 5 years of life. The foramen is located at the anteroinferior aspect of the external auditory canal (EAC), posteromedial to the temporomandibular joint (TMJ). We sought to define its prevalence, location, and size on high-resolution spiral CT (HRCT). METHODS: We prospectively examined 102 consecutive HRCT studies of the temporal bone (204 ears). HRCT was performed by using 120 kV, 400 mAs, an ultra-high-resolution filter, 0.6-mm section thickness, 0.3-mm section increment, 728 x 728 matrix, and 160-mm field of view. We noted the size and location of the foramen tympanicum relative to the tympanic membrane and calculated its prevalence. Patients with focally decreased tympanic bone thickness of <1 mm at the anteroinferior EAC (between the 3- and 6-o'clock positions) were considered separately. RESULTS: We found a foramen tympanicum was found in six (4.6%) of 130 ears. Mean axial diameter was 4.2 mm, and mean sagittal diameter was 3.6 mm. Focally reduced bone thickness in the same location was found in 45 (35%) ears, with a female preponderance (P = .003). CONCLUSION: HRCT is sensitive for detection of the foramen tympanicum because of its thin sections, high spatial resolution, and multiplanar capabilities. Awareness of this anatomic entity may be useful in evaluating patients with transient otorrhea in whom no otologic cause (e.g., ear infection, TMJ disease) is identified.