Endovascular management of spinal dural arteriovenous fistulas in 78 patients.

INTRODUCTION: The purpose of this study was the evaluation of the safety and efficiency of the endovascular treatment of spinal dural arteriovenous fistulas (SDAVFs). METHODS: Between May 1992 and August 2012, 78 patients (59 men) with an angiographically proven SDAVF with pial venous drainage were treated by endovascular embolization (n = 61) and/or surgery (n = 31) at three German hospitals by a single team of physicians and according to a uniform therapeutic concept. RESULTS: Endovascular treatment resulted in a complete occlusion of the fistula in 47 cases (77 %). After failed embolization with residual shunt, 14 DAVFs were surgically cured (23 % failure rate). We had one permanent and two minor complications after endovascular therapy. Within a postoperative period of 2 weeks, 73.6 % of patients improved in gait disability, 51.1 % in micturition function, and 70.5 % in paresthesia of the lower extremities. Long-term follow-up data showed further improvement of clinical symptoms confirmed by normalization or resolution of spinal changes on MRI. CONCLUSIONS: An interdisciplinary approach to the management of SDAVFs is mandatory. Patients without a common origin of arteries supplying the spinal cord and the dural fistula, and without a stenosis or occlusion of the concerning segmental artery are potential candidates for endovascular treatment (diluted n-butyl-2-cyanoacrylate). Only occlusion of the "nidus" and the proximal segment of the draining vein can lead to clinical improvement.

Tunable quantum dot arrays formed from self-assembled metal-organic networks.

The confinement of Ag(111) surface-state electrons by self-assembled, nanoporous metal-organic networks is studied using low-temperature scanning tunneling microscopy and spectroscopy as well as electronic structure calculations. The honeycomb networks of Co metal centers and dicarbonitrile-oligophenyl linkers induce surface resonance states confined in the cavities with a tunable energy level alignment. We find that electron scattering is repulsive on the molecules and weakly attractive on Co. The tailored networks represent periodic arrays of uniform and coupled quantum dots.

Endovascular management of dural arteriovenous fistulas of the transverse and sigmoid sinus in 150 patients.

INTRODUCTION: This study aimed to evaluate the safety and efficiency of the endovascular treatment of transverse-sigmoid sinus dural arteriovenous fistulas (TS_dAVF). METHODS: A total of 150 consecutive patients and 348 procedures were evaluated. RESULTS: Pulsatile tinnitus (81%), headache (15%), and intracranial hemorrhage (10%) were the most frequent manifestations of the TS_dAVFs. More than half of the affected sinuses were partially or completely thrombosed. Access-wise treatment was performed transarterial (n = 33), transvenous (n = 21), or a combination thereof (n = 96). A mean of 2.4 procedures per patient was required. Immediate postprocedural occlusion rate after transarterial embolization was 30% only. Transvenous treatment alone resulted in an early occlusion rate of 81%, with delayed complete obliteration of half of the remaining fistulas. After combined transarterial/transvenous treatment, the angiographic cure rate was 54%. At follow-up, 88% of patients with residual shunt after the treatment showed complete occlusion. The cumulative complication rate was 9% (n = 13), with minor adverse events in ten patients (7%) and major complications in three patients (2%). CONCLUSION: Transvenous coil occlusion of the sinus segment with the adjacent dAVF site, eventually combined with transarterial occlusion of supplying arteries, is a very effective and well-tolerated treatment method. In selected patients, variations of these methods (e.g., sinus stenting, compartmental sinus occlusion) can be useful.

[Gastroenterology in Germany: results of a survey in hospitals and practices]. / Status quo Gastroenterologie.

In future, the profile of gastroenterology in Germany - as in other countries - will change. New achievements such as capsule endoscopy, aero-scopes and advanced CT and MRI technology and others will become alternatives to conventional endoscopy. Additional emphasis in clinical and outpatient gastroenterology is shifted towards gastrointestinal oncology, dietetics, nutrition and metabolism and in the clinical setting onto infectious diseases, endocrinology/diabetology, intensive care medicine, emergency service and geriatric medicine. The German Confederation of Gastroenterology (BVGD) initiated two Germany-wide surveys on the current diagnostic and therapeutic spectrum in hospitals and out-patient facilities to achieve a base for future discussions regarding the development of gastroenterology. The number of gastroenterologists working in hospitals and in out-patient facilities has been analysed as well as the number of examinations passed successfully during the last few years in the speciality "gastroenterology". The results of this survey offer a valid basis for continuing discussions as to how gastroenterology should develop in Germany.

Ischemic and hemorrhagic complications after intra-arterial fibrinolysis in vertebrobasilar occlusion.

BACKGROUND AND PURPOSE: To evaluate the incidence and location of hemorrhagic and ischemic lesions after local intra-arterial (IA) fibrinolysis in patients with acute vertebrobasilar occlusion (VBO). METHODS: One hundred forty-three patients with VBO treated with local IA fibrinolysis were retrospectively evaluated. Two different thrombolytic substances, namely urokinase (UK, n = 57 patients) and recombinant tissue plasminogen activator (rtPA, n = 86 patients), were used. Incidence and location of intracranial hemorrhage and ischemic infarction were assessed by means of 403 peri-interventional CT and MR imaging scans. Recanalization success and bleeding rate were correlated with the type and dosage of fibrinolytic agent. Multiple logistic regression was used for statistical analysis. RESULTS: Intracranial hemorrhage was detected in 46 (32%) patients. Bleeding rate was significantly higher for high-dose rtPA than for UK (36% versus 21%, P < .01). Neurologic outcome was worse in patients with postinterventional bleeding (P < .001). Ischemic infarctions were present in 136 (95%) patients. Ischemic lesions of the occipital lobe and thalamus were more frequently seen in the case of successful recanalization than after absent recanalization (P < .005). Occlusion of the postcommunicating segment of the posterior cerebral artery after successful recanalization was seen in 39% of patients. CONCLUSIONS: In acute VBO, bleeding rate after IA rtPA seems to be higher than that using IA UK, especially after high-dose rtPA. Ischemic lesion patterns after successful local IA fibrinolysis are common and correspond to the frequent distal migration of the thrombus. Novel recanalization techniques allowing for endovascular thrombectomy are needed to reduce ischemic and hemorrhagic complications in the treatment of acute VBO.

A new device for endovascular coil retrieval from intracranial vessels: alligator retrieval device.

The clinical use of a new device (Alligator Retrieval Device) designed specifically for endovascular foreign body (eg, coils) retrieval from intracranial vessels is reported. The Alligator has intrinsic advantages compared with microsnares for the endovascular catheter-based removal of coils.

Outcome of acute vertebrobasilar occlusions treated with intra-arterial fibrinolysis in 180 patients.

BACKGROUND AND PURPOSE: To evaluate predictors of recanalization and a favorable neurologic outcome in patients with acute vertebrobasilar occlusion (VBO) treated with local intra-arterial fibrinolysis (LIF). METHODS: The multicentric data of 180 patients with acute VBO treated with LIF were retrospectively evaluated. The modified Rankin scale (mRS) was used to evaluate the neurologic status before LIF and at the time of discharge. Patient's sex, age, etiology of VBO, recanalization, symptom duration before LIF, and pretreatment mRS were correlated with posttreatment mRS. Multiple logistic regression analysis was used to identify independent variables for recanalization and neurologic outcome. RESULTS: The overall mortality was 43%. Complete recanalization was achieved in 99 (55%) patients and a partial recanalization in 35 (19%) patients, respectively. Recanalization was significantly associated with a favorable outcome (P < .001). The success of recanalization was negatively correlated with the volume of the thrombus (P < .001). No correlation was found between site and etiology of VBO and recanalization. Neurologic outcome correlated strongly with the pretreatment mRS (P < .001) and also with age (P < .02). Coma lasting less than 4.5 hours led to a positive trend toward a better outcome after univariate testing (P < .001). CONCLUSIONS: Success of recanalization and neurologic status before treatment predict neurologic outcome in patients with VBO. Thrombus volume has an adverse effect on the recanalization success.

Detection of microemboli distal to cerebral aneurysms before and after therapeutic embolization.

PURPOSE: Recently developed interventional radiologic techniques, such as embolization with platinum coils, may induce thrombus formation within an aneurysm. The aim of the present study was to investigate the frequency of microemboli distal to untreated and treated cerebral aneurysms. METHODS: Among a total of 110 patients treated with platinum coil embolization, 35 patients (27 women and eight men, aged 50+/-10 years) who were at high risk of ischemic complications underwent emboli detection with a transcranial Doppler sonographic monitoring system. All patients were studied before and after coil embolization. The aneurysms were located at the internal carotid artery (n=14), the basilar artery (n=10), the middle cerebral artery (n=7), or the vertebral artery (n=4). Twenty-nine (85%) of 35 patients were monitored within 6 hours of the completion of treatment. RESULTS: Microemboli distal to the aneurysm were not detected in any of the patients before treatment. Microemboli were detected in 11 patients (31%) after embolization (mean, 16+/-21 per hour; range, 1-74 per hour). Microemboli were detected in five (71%) of seven patients in whom ischemic complications occurred after treatment, but in only six (21%) of 28 asymptomatic patients. This difference was statistically significant. The rate of occurrence of emboli in patients with ischemic complications (23+/-30 emboli per hour) was higher than in asymptomatic patients (10+/-7 emboli per hour), but this difference was not statistically significant. CONCLUSION: Microemboli were detected significantly more often in patients who suffered from cerebral ischemia after coil embolization of an intracranial aneurysm. This observation supports the definition of a high-risk group of patients with incomplete embolization or with a large-diameter, broad-neck aneurysm. The early detection of microemboli after treatment may be an indicator for excessive intraaneurysmal thrombus formation and could influence the decision for prophylactic treatment with heparin or aspirin.

Intracranial vertebrobasilar stenosis: angioplasty and follow-up.

BACKGROUND AND PURPOSE: When medication fails to improve symptoms of atherosclerotic stenosis of the intracranial vertebral and basilar arteries, percutaneous transluminal angioplasty (PTA) is considered. However, because investigators disagree on the usefulness of this procedure, we conducted a retrospective study to evaluate the indications, efficacy, and safety of PTA. METHODS: Twenty patients underwent PTA of the vertebral (n = 14) or basilar (n = 6) artery, 18 for neurologic signs and symptoms of arterial stenosis that recurred or progressed despite pharmacotherapy and two prophylactically. Neurologic examinations were performed before and after the procedure and arterial patency was evaluated at follow-up by digital subtraction angiography and/or MR angiography. Imaging follow-up was available for 14 (70%) of the 20 patients, neurologic follow-up for 15 (75%). RESULTS: The stenosis was successfully dilated in all patients, and on follow-up neuroradiologic examinations, vessel patency could be seen in 12 (86%) of 14 patients. Only one (7%) of 15 patients who returned for a follow-up neurologic examination had new symptoms (caused by occlusion of the vertebral artery 4 months after the procedure). One patient had a reversible neurologic deficit and one had hemiparesis after PTA. No patient died as a result of PTA. CONCLUSION: In our study, PTA of intracranial vertebrobasilar arteries was associated with a low mortality and morbidity rate and with a high degree of patency. This technique may therefore be regarded as an effective means of improving the patency of stenotic arteries. In selective cases, it might be considered for use prophylactically.

A report of the clinical use of the detach-18 mechanical detachable platinum coil in 41 patients.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the safety and reliability of the mechanical detachment system of a new platinum coil, Detach-18, when used as a vascular occlusive device for neurovascular disease. METHODS: Forty-one patients (nine male and 32 female patients; age range, 26-75 years; mean age, 54.4 years) underwent treatment at seven centers. Twenty-two patients had dural arteriovenous fistulae of the transverse sinus treated by a transvenous route. Fourteen patients underwent internal carotid artery occlusion in the treatment of aneurysms, meningioma, facial tumor, or carotid injury. One patient underwent occlusion of the basilar artery and one patient underwent occlusion of the vertebral artery for treatment of aneurysms. In two patients, coils were used as part of the treatment of their arteriovenous malformations. In all cases, the Detach-18 coils were delivered through a microcatheter with two distal markers. Two types of coils, a 0.015-inch-diameter "regular" coil and a 0.014-inch-diameter "soft" coil, were used. RESULTS: A total of 569 coils were used, 541 of which were detached. The number of coils in ranged from four to 53 (average number of coils, 14). The coils passed easily through the microcatheter. The detachment maneuver occurred within 10 to 25 s with 20 turns of the introducing wire. No premature coil detachment occurred. Complete occlusion of the vessel lumen was achieved in 35 cases. In three cases, 80% to 90% occlusion was achieved. In two cases, 70% to 80% occlusion was achieved. There were no device-related complications. CONCLUSION: The detachment system was safe, reliable, consistent, and fast. This is a useful system for coil embolization in neurovascular applications.

Progressive spontaneous herniation of the thoracic spinal cord: case report.

OBJECTIVE AND IMPORTANCE: We report one case of spontaneous thoracic spinal cord herniation. To our knowledge, this is the first case involving radiological documentation of the development of herniation. Clinical features and surgical techniques are also presented. CLINICAL PRESENTATION: We describe the case of a 51-year-old female patient who experienced progressive Brown-Sequard syndrome for 2 years. Three magnetic resonance imaging examinations were performed; they revealed the progressive development of anterolateral spinal cord herniation at the level of T6 during those 2 years. INTERVENTION: After laminectomy at T6, the herniated myelon was microsurgically removed and the neurological symptoms improved. CONCLUSION: We present the possible causes, the proposed pathophysiological mechanisms, and the clinical and radiological development of this rare entity, with a review of the literature published to date. We propose that a preexisting weakness of the ventral dural fibers, combined with abnormal adhesion of the spinal cord to the anterior dural sleeve, leads to progressive herniation throughout life. Microsurgical treatment may halt the exacerbation of the neurological symptoms.

Local thrombolytic therapy for thromboembolic occlusion of the middle cerebral artery.

We report on 10 patients with thromboembolic occlusion of the middle cerebral artery (MCA) who underwent local thrombolytic therapy. Six patients developed a MCA occlusion during long-standing interventional neuroradiological procedures, while four had a proven or suspected cardio-embolic stroke. Streptokinase or urokinase was applied by a microcatheter placed into the thrombus within six hours of clinical onset. Complete or partial revascularization was achieved in all patients. Recovery was complete in seven and partial in three of the patients. In two patients, minor haemorrhagic transformation of the infarct occurred, which did not lead to neurological deterioration. It is concluded that in a selected group of patients with MCA occlusion, local thrombolytic therapy represents a safe and effective therapy.

Endovascular therapy of brain AVMs prior to radiosurgery.

The purposes of this study were to determine the safety and efficacy of embolization of brain AVMs prior to radiosurgery and to evaluate the total obliteration rate achieved. The brain AVMs of 64 patients were subselectively embolized mainly with NBCA, platinum microcoils and/or PVA. The aim of embolization was the reduction of the target volume and/or the elimination of vascular structures bearing an increased risk of hemorrhage. Presenting symptoms were intracranial hemorrhage in 33 patients, a seizure disorder in 21 patients, and headache in 6 patients. Four AVMs had been detected as an incidental finding. The initial AVM volume was in the range of 0.5 to 84 cc (mean 17 cc). Grading of the AVMs according to the Spetzler-Martin scale showed the following distribution: grade I, 3x; II, 13x; III, 11x; IV, 17x; V, 4x; VI, 16x. A total of 300 endovascular procedures including 47 subselective catheterizations without and 253 with embolization were performed. A size reduction of the AVMs between 10% and 95% (mean 63%, median 70%) was achieved. Neurological symptoms due to treatment complications were transient in 12 patients, of minor clinical significance but permanent in 4 patients. Following radiosurgery, one patient died due to recurrent intracerebral hemorrhage. Three patients are doing well but refused final follow-up angiography. A total of 30 patients is currently within the latency interval after radiosurgery. Radiosurgery failed to obliterate the embolized AVMs in 16 patients. Angiography confirmed complete nidus obliteration in 14 patients. The endovascular treatment of brain AVMs prior to radiosurgery proved safe and effective and may be considered in either high grade or incidental AVMs. AVM obliteration after embolization and radiosurgery is less frequently achieved than after stereotactic irradiation of primarily small AVMs.

Endovascular laser detachment of platinum alloy microcoils: principle and initial experimental experience.

The aim of the investigation was the technical realization and approval of a new method for insertion and detachment of platinum alloy microcoils and other vascular implants via standard microcatheters. Flexible lightconducting fibers, 105 microns in diameter were connected to platinum alloy microcoils. It was examined whether an insertion wire, a lightconducting fiber and a platinum alloy microcoil could be advanced through a Tracker-18 (Target) microcatheter. The detachment of the attached coil from the lightconducting fiber was investigated. Platinum alloy microcoils can be attached to available lightconducting fibers in a reliable and reproduceable manner. Together with the fiber they can be advanced via a Tracker-18 microcatheter. Only extremely tortuous vessels may increase the friction to critical values. A Ho-YAG laser source was used. This allowed the instantaneous detachment of microcoils from laser fibers. In contrast to electrolytical detachment, no foreign substances are released to the blood stream. The detachment does not require waiting time and does not activate thrombus formation. Due to specific technical features, injuries of the vessel wall are avoided. After further miniaturization and adaption of the lightconducting fibers to the required characteristics, laster detachment may have the potential to replace current methods such as electrolytical and mechanical coil detachment.

Accuracy of intravascular microcatheter pressure measurements: an experimental study.

Intravascular pressure measurements are considered useful for the monitoring and assessment of endovascular treatment effects in intracranial vascular malformations. Experimental data on the accuracy of these measurements are limited. A flow phantom with defined intraluminal pressures and pulsatility flow waveforms was used in this study. Microcatheters commercially available for neuroendovascular procedures (length 140-155 cm), with different outer (0.5-0.83 mm) and inner (0.3-0.53 mm) diameters, were introduced into the phantom in the direction of flow. In a static experiment, pressure values from 0 to 75 mmHg were applied, and in the dynamic part of the experiment mean pressure values from 25 to 65 mmHg, with a pulsatile amplitude from 70 to 170 mmHg were employed. In the static experiment, there was a linear relationship between the pressure values obtained through the microcatheters and the local transducer of the flow phantom. The pulsatile experiments showed increased damping of the pressure waveforms with decreasing inner diameter of the microcatheters. However, the mean pressure values remained accurate. This experimental study has shown that mean pressure values can be accurately measured through microcatheters from 0.3-0.5 mm inner diameter and more than 140 cm in length. In vivo pressure measurements during interventional procedures are therefore reproducible and can be used for monitoring of embolization effects in patients.

[Meningioma of the tentorium cerebelli: computer tomographic and angiographic aspects (author's transl)]. / Memingeome mit Beziehung zum Tentorium cerebelli: computertomographische und angiographische Aspekte.

The relationship of a meningioma to the tentorium is of great significance for the choice of treatment. In order to evaluate the role of computer tomography and angiography for elucidating this problem, 21 cases were examined (all had angiograms, 13 had computer tomography). In most cases the tumour was attached to the tentorium. In 18 patients it was possible to compare the results of radiology with operative findings. It was found that computer tomography and angiography are complementary; indirect involvement of the tentorium by tumour passing through the tentorial hiatus can nearly always be demonstrated by computer tomography, whereas demonstration of direct involvement is best achieved by selective or super selective angiography. Extension of tumour to both sides of the tentorium is accomplished most easily by computer tomography or angiography, if the meningioma is in the mid-line.

[Occlusion of the basilar artery (author's transl)]. / Zum Verschluss der A. basilaris

Occlusion of the basilar artery was demonstrated arteriographically in two cases. The symptomatology is described. Due to effective collateral circulation the patients survived and recovered from severe neurological deficits. One of the patients, clincally in a state resembling akinetic mutism for several weeks, not only survived but regained speech. To our knowledge this has not been reported in the literature previously. Our cases as well as similar ones of others showed, that for development of effective intrcranial collaterals the time, during which occlusion occurs, is clearly of importance. Development of collateral circulation also depends on the anatomy of the circle of Willis and a sufficient extracranial circulation.

[Computer tomography in malformations, inflammatory and degenerative changes in the spine]. / Die Computertomographie bei Fehlbildungen, entzündlichen und degenerativen Veränderungen der Wirbelsäule.

Technical improvements and the use of intrathecal Metrizamide have made computer tomography of the spine a valuable diagnostic method. The value of CT in demonstrating morphological changes in the spine was investigated in 77 examinations of congenital malformation or inflammatory and degenerative disease. Measurements of the spinal canal provide more accurate information than conventional radiology and these are discussed. Intradural injection of contrast medium makes it possible to diagnose abnormalities of the cord by means of CT. Inflammatory changes in the spine and in the paraspinal soft tissues are shown at an early stage. A diagnosis of tumour can be confirmed by CT-controlled needle biopsy. It is usually possible to demonstrate disc prolapse without the use of contrast medium. On the other hand, the investigation of pain following disc operations remains a difficult problem.

Percutaneous transluminal angioplasty of intracranial artery stenosis: clinical results in 24 patients.

Circumscribed stenotic lesions of the intracranial arteries can cause cerebral ischemia by hemodynamic and/or thromboembolic mechanisms. Anticoagulation therapy, antiplatelet therapy, and bypass surgery are treatment strategies that have no direct impact on the underlying lesion. This study summarizes the experience of a single institution at which percutaneous transluminal angioplasty (PTA) of intracranial atherosclerotic stenoses was performed. The authors performed a retrospective analysis of 24 consecutive patients. Their medical histories (cardiovascular risk factors, current clinical signs and symptoms and their duration, previous stroke[s], and medical treatment) were evaluated together with findings from previous imaging studies. The site and degree of the stenoses to be treated (target lesion) were identified with the use of ultrasound and angiography studies. Additional vascular stenoses were noted. Percutaneous transluminal angioplasty was performed using single-lumen balloon microcatheters with appropriate diameters. The results of PTA were correlated with angiographic and ultrasound findings and the clinical outcome. Significant cardiovascular risk factors and clinical signs and symptoms related to the target lesion that persisted despite medical treatment were identified in all patients except one. The duration of symptoms varied from several days to 8 months. Previous stroke had occurred in four patients. The degree of stenosis was classified as "high grade" in 10 patients and as "subtotal" in 14. The target lesion (stenosis) was located in the anterior circulation in eight patients (four in the internal carotid and four in the middle cerebral arteries). Stenoses of posterior circulation vessels were treated in 16 patients (nine vertebral, six basilar, and one posterior cerebral arteries). Recanalization was rated "complete" in 15 patients and sufficient in six patients. In three patients residual stenosis remained. Complications were encountered in seven patients: two asymptomatic dissections, one transient vessel occlusion, one vessel occlusion with subsequent stroke, and three ischemic lesions likely due to thromboembolism, two of which caused only transient neurological symptoms. Percutaneous balloon dilation proved effective in the treatment of intracranial atherosclerotic stenosis. There are, however, potential complications and experience with this procedure is only limited. Long-term results need to be determined. The authors conclude from their preliminary results that PTA may be an alternative to bypass surgery and conservative management and may be considered for patients in whom ischemic neurological symptoms persist despite medical treatment.

Torquability of microcatheter guidewires: the resulting torsional moment.

Guidewires for microcatheters used for the subselective catheterization of small vessels must meet high quality requirements in regard to handling, steerability, radiopacity and physical properties. The aim of this paper is to classify one of the factors that determine the physical and mechanical parameters of a number of existing microcatheter guidewires. A torsion-testing equipment for guidewires was devised. Nitinol wires were tested and compared with the austenitic stainless steel variants. 13 different commercial wires were tested. Tensile strength, shear modulus and wire diameter are the determining factors of the torsional rigidity of guidewires. By interpreting the measured torsional momentums various statements concerning the torsional rigidity of different wires can be made. The properties of guidewires are characteristic features of a system and friction and flexible strength examinations have to be carried out to design new variants of wires to meet the requirements of interventional physicians.