Christopher Wallace

Analysis of Endoglin Expression in Normal Brain Tissue and in Cerebral Arteriovenous Malformations

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

Venous Thromboembolism after Brain Tumor Surgery: A Retrospective Review

We retrospectively reviewed the incidence rate of clinical postoperative deep vein thrombosis and/or pulmonary embolism in 1703 patients undergoing initial craniotomy for meningioma, glioma, or cerebral metastasis. The incidence rate of clinical thromboembolic complications was 1.59% for all tumor groups within the first 4 weeks of surgery. Patients undergoing surgery for meningiomas had a statistically significant increased risk of thromboembolism despite fewer overall perioperative risk factors, when compared with the other tumor groups. The tumor-specific incidence rates of deep vein thrombosis and/or pulmonary embolism for meningioma, glioma, and metastasis were 3.09%, 0.97%, and 1.03%, respectively. Whether this difference was a result of increased surgical time or an inherent property of meningiomas could not be ascertained.

Spontaneous angiographic conversion of intracranial dural arteriovenous shunt: long-term follow-up in nontreated patients.

Background and Purpose— Dural arteriovenous shunt (DAVS) is a disease in which abnormal arteriovenous communications develop within the dura. Some case series have suggested DAVS may evolve over time, but the natural history is poorly understood. In this study, we aimed to define the incidence and clinical characteristics of patients with DAVS showing spontaneous angiographic pattern conversion. Methods— We assessed clinical and angiographic features of patients with angiographic conversion without any treatment from a single center database consisting of 335 DAVS cases. Spontaneous angiographic conversion was defined as complete occlusion of a pre-existing DAVS or conversion of a benign into an aggressive lesion on follow-up diagnostic subtraction angiography. Results— One hundred twelve patients were followed without treatment after the initial diagnosis of DAVS. Overall, we saw pattern conversion on angiography in 18 of the 112 cases (16.1%). Fourteen patients showed spontaneous occlusion of the shunt (12.5%); the most common locations of spontaneous obliteration were the transverse and cavernous sinuses. Four patients showed conversion to an aggressive lesion from benign DAVS (4.0%); all of these cases were associated with occlusion of the ipsilateral draining vein. Conclusions— DAVS is a dynamic disorder, which will show chronological progression. Spontaneous angiographic obliteration or conversion into an aggressive type may occur on follow-up of untreated DAVSs.

Angiographic Characteristics and Treatment of Cervical Spinal Dural Arteriovenous Shunts

SUMMARY: 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.

Direct imaging of the distal dural ring and paraclinoid internal carotid artery aneurysms with high-resolution T2 turbo-spin echo technique at 3-T magnetic resonance imaging.

OBJECTIVETo evaluate the feasibility of the direct visualization of the distal dural ring (DDR) and adjacent anatomic structures in patients with paraclinoid internal carotid artery aneurysms at 3-T magnetic resonance imaging (MRI). METHODSSix consecutive patients (1 man, 5 women; mean age, 45.5 years; age range, 34–51 years) who underwent a 3-T MRI examination for the evaluation of 7 paraclinoid carotid artery aneurysms were reviewed retrospectively. MRI scans were acquired using a T2 turbo-spin echo sequence with 2-mm thickness without gap on the coronal plane perpendicular to the diaphragma sellae. Identifications of the DDR, adjacent regional anatomic landmarks, and paraclinoid aneurysms were analyzed. The locations of the paraclinoid aneurysms were categorized into intradural (aneurysm neck and sac located above the DDR), transdural (aneurysm neck or sac were straddling the DDR), and extradural (aneurysm neck and sac located below the DDR). Interstudy agreement between computed tomographic angiography and 3-T MRI for the anatomic location of the paraclinoid aneurysms was assessed in 6 patients who underwent both examinations. RESULTSIn all cases, the DDR was clearly identified and the relationship between the DDR and the paraclinoid aneurysm was successfully determined on 3-T MRI. The aneurysm locations determined with 3-T MRI were 4 intradural and 3 extradural. A comparison between computed tomographic angiography and 3-T MRI revealed discordant anatomic locations in 3 aneurysms (3 of 6, 50%). CONCLUSIONDirect visualization of the DDR as well as precise evaluation of paraclinoid aneurysm location with high-resolution 3-T MRI is possible. This study shows that high-resolution 3-T MRI is an important means to determine the appropriate management for patients with paraclinoid aneurysms.