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.

[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.

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.

[Rete compensation in agenesis of the internal carotid artery]. / Rete mirabile bei segmentaler Agenesie der A. carotis interna.

The term carotid rete mirabile refers to an anatomic structure common in several lower mammals (e.g., swine). The blood supply for the intracranial arteries originates from branches of the external carotid artery, predominantly the ascending pharyngeal and internal maxillary arteries. In these animals the intracranial internal carotid artery forms from a dense network of numerous converging, small-caliber vessels. An analogous structure is rarely found in humans. Associated with segmental agenesis of the internal carotid artery, so-called carotid rete mirabile can be observed. In it numerous tortuous vessels with a diameter of 1-2 mm are found along the expected course of the internal carotid artery and coming from branches of the external carotid artery. These vessels converge to the intradural paraclinoid segment of the internal carotid artery, which shows a normal diameter. This rare pattern of collateral supply to the brain is illustrated here on the basis of two clinical case histories. Both patients presented with aneurysmal subarachnoid hemorrhage. In one, histological examination of a vessel biopsy revealed medial fibromuscular dysplasia. In both patients the rete mirabile was found in only one carotid system. The affected carotid canal in the skull base was hypoplastic. Human carotid rete mirabile probably has no inherent pathologic significance, but its frequent association with other intra- and extracranial vascular pathologies should be kept in mind.

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.

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.

Endovascular treatment of small intracranial aneurysms: three alternatives to coil occlusion.

INTRODUCTION: Small intracranial aneurysms with a fundus diameter of 2 - 3 mm may rupture and are therefore potential targets for an endovascular approach in treatment. Currently available coil technology is less than optimal for the treatment of aneurysms within this size range. Even the smallest coils are sometimes too large. If such a minute coil can be introduced into a small aneurysm, the hemodynamic effect and the induced thrombosis are frequently inadequate to occlude the aneurysm sufficiently from the parent artery circulation. METHODS: Three technical alternatives for the endovascular treatment of small intracranial aneurysms not suitable for coil occlusion are illustrated with the following three case descriptions. RESULTS: Stent grafts are usable for the intracranial internal carotid artery and for the V4 segment. The stiffness of the stent and the high expansion pressures are the two major drawbacks. Coaxial deployment of two or more self-expanding porous stents can result in sufficient redirection of the blood flow to induce aneurysmal thrombosis. Deployment of multiple stents, however, may require several treatment sessions in order to allow for the integration of the stents into the vessel wall from session to session. A regular microcatheter can block aneurysmal inflow in aneurysms with a very narrow neck. This allows the occlusion of the aneurysm with an appropriate amount of highly concentrated, rapidly polymerizing glue. Polymer emboli may result from excessive or rapid glue injection. CONCLUSION: The available coil technology has inherent limitations in the treatment of very small intracranial aneurysms. Liquid embolic agents and stent-based extrasaccular treatment strategies may provide solutions for these challenging lesions.

Endovascular management of dural carotid-cavernous sinus fistulas in 141 patients.

INTRODUCTION: The purpose of this study was to evaluate the single-centre experience with transvenous coil treatment of dural carotid-cavernous sinus fistulas. METHODS: Between November 1991 and December 2005, a total of 141 patients (112 female) with dural carotid-cavernous sinus fistula underwent 161 transvenous treatment sessions. The patient files and angiograms were analysed retrospectively. Clinical signs and symptoms included chemosis (94%), exophthalmos (87%), cranial nerve palsy (54%), increased intraocular pressure (60%), diplopia (51%), and impaired vision (28%). Angiography revealed in addition cortical drainage in 34% of the patients. Partial arterial embolization was carried out in 23% of the patients. Transvenous treatment comprised in by far the majority of patients complete filling of the cavernous sinus and the adjacent segment of the superior and inferior ophthalmic vein with detachable coils. RESULTS: Complete interruption of the arteriovenous shunt was achieved in 81% of the patients. A minor residual shunt (without cortical or ocular drainage) remained in 13%, a significant residual shunt (with cortical or ocular drainage) remained in 4%, and the attempted treatment failed in 2%. There was a tendency for ocular pressure-related symptoms to resolve rapidly, while cranial nerve palsy and diplopia improved slowly (65%) or did not change (11%). The 39 patients with visual impairment recovered within the first 2 weeks after endovascular treatment. After complete interruption of the arteriovenous shunt, no recurrence was observed. CONCLUSION: The transvenous coil occlusion of the superior and inferior ophthalmic veins and the cavernous sinus of the symptomatic eye is a highly efficient and safe treatment in dural carotid-cavernous sinus fistulas. In the majority of patients a significant and permanent improvement in clinical signs and symptoms can be achieved.

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.

[Endovascular occlusion of the basilar artery for the treatment of dissecting and dysplastic fusiform aneurysms]. / Endovaskulärer Verschluss der A. basilaris zur Behandlung dissektionsbedingter und dysplastischer fusiformer Aneurysmen.

Dissecting aneurysms of the basilar artery trunk frequently affect young adults. Fusiform shape and narrowing of the proximal parent artery are typical features. Changes in aneurysm size and geometry may be observed more rapidly than in atherosclerotic or dysplastic aneurysms. Dissecting aneurysms carry a significant risk of rupture. Thrombotic or embolic occlusion of small pontine branches may cause ischemic symptoms. Sufficiently large aneurysms compress the adjacent brainstem. The operative treatment of these aneurysms is associated with unacceptable risks. At least one posterior communicating artery with normal calibre together with the ipsilateral P1 segment needs to provide adequate collateral flow to the upper basilar artery to allow endovascular coil occlusion of the segment that is affected by the dissection and/or fusiform aneurysmal dilatation. Four illustrative cases of endovascular coil occlusion of the basilar artery for the treatment of fusiform aneurysms are presented and discussed.

Intravascular pressure measurements in feeding pedicles of brain arteriovenous malformations.

Pressure measurements in arterial feeders of arteriovenous malformations (AVMs) can be easily acquired during endovascular treatment procedures. In this study, mean arterial pressure values in arterial feeders (Pfed) of brain AVMs were determined using a pressure measuring system connected to a standard microcatheter. A total of 148 measurements were performed in 139 patients. Mean systemic arterial pressure values were subtracted for correction. The levels of correlation between the pressure values and various clinical parameters (i.e., AVM location, size, previous hemorrhage) and pathoanatomical features of the AVM (e.g., nidus structure, number of draining veins) were determined. Pfed values were 54.5 mmHg on average. Pfed was lower in more distally located AVMs, in larger lesions and in AVMs with multiple drainage veins. Pressure values were significantly higher in patients with previous hemorrhage and in smaller AVMs. Our results support the importance of hemodynamic parameters in determining the presentation of AVMs. More extensive studies using this simple technique may further elucidate these mechanisms and may result in improved criteria for patient selection and reduction of complications.

Preoperative devascularization of a circumferential osteogenic metastasis to the upper cervical spine by direct percutaneous needle puncture: a technical note.

Direct percutaneous needle puncture (DPNP) for presurgical devascularization of head and neck as well as skull base tumours is an established, yet not widespread method. We present a case of a large and highly vascularized metastasis with partial destruction of the first two cervical vertebrae and encasement of the spinal cord that was successfully treated by DPNP for preoperative devascularization after an attempted endovascular embolization had failed. The lesion was safely and effectively devascularized, which facilitated the surgical removal. The case presented illustrates the technique and furthermore demonstrates its value.

Treatment of intracranial atherosclerotic stenoses with balloon dilatation and self-expanding stent deployment (WingSpan).

The endovascular treatment of atherosclerotic intracranial arterial stenoses has previously been based on balloon dilatation or the deployment of a balloon expandable stent. Both methods have advantages (balloon: flexibility; balloon expandable stent: high radial force) and drawbacks (balloon: risk of elastic recoil and dissection; balloon expandable stent: limited flexibility, risk of injury to the vessel due to excessive straightening, overexpansion at ends of stent). A new combination of balloon dilatation, followed by the deployment of a self-expanding microstent has been applied in 15 patients with atherosclerotic arterial stenoses, symptomatic despite medical treatment. An anatomically and clinically adequate result was achieved in all patients. The initial degree of stenosis was 72% (mean). Balloon dilatation resulted in an average residual stenosis of 54% (mean), reduced further to a mean of 38% after stent deployment. Arterial dissection, occlusion of the target artery or symptomatic distal emboli was not encountered. In one patient, a side branch occlusion occurred after dilatation of a M1 stenosis, with complete neurological recovery. All patients were either stable or improved 4 weeks after the treatment. Recurrent TIA did not occur in any patient. Balloon dilatation and subsequent deployment of a self-expandable stent for the treatment of symptomatic intracranial arterial stenoses combines the advantages of both techniques and allows a rapid, clinically effective and technically safe treatment of these frequently challenging lesions.

Reconstructive treatment of dural arteriovenous fistulas of the transverse and sigmoid sinus: transvenous angioplasty and stent deployment.

Various techniques for the endovascular treatment of dural arteriovenous fistulas (dAVFs) of the transverse and sigmoid sinus have recently evolved. Transvenous coil occlusion of the involved segment and transarterial embolization of the feeding arteries with liquid agents are the commonest treatments utilized. However, with respect to venous hypertension as the probable pathogenic cause of this disorder, a nonocclusive or remodeling technique might be preferable. We will present a series involving four patients, treated with transvenous angioplasty and stent deployment as a definitive treatment of dAVFs of the transverse and sigmoid sinus. This method was used as a primary treatment or as an adjunct to previous noncurative transarterial n-butyl cyanoacrylate and particle embolization. In three of the four cases, complete occlusion of the fistula was achieved with confirmation of occlusion seen on follow-up angiographical studies. In one case a negligible and nonsymptomatic remnant of the fistula fed by the tentorial artery was left untreated. From our experience, we conclude that transvenous stent deployment is an alternative to traditional concepts. Additionally, the pathological theory of dAVFs in this region located in venous pouches of the sinus wall is supported by the fact that they can be occluded by mechanical compression during angioplasty and subsequently maintained by a stent.

Transvenous Treatment of a Dural Arteriovenous Fistula of the Transverse Sinus by Embolization with Platinum Coils and Onyx HD 500+.

SUMMARY: We report the endovascular treatment of a symptomatic dural arteriovenous fistula in a 61- year-old male patient. The medial portion of the fistula was occluded with detachable platinum coils during an initial intervention using a transvenous approach. Due to persistence of the symptoms in a second intervention eight months later the fistula was completely occluded by the transvenous introduction of a liquid embolic agent (Onyx 500+). The liquid embolic agent was introduced under protection by the temporary balloon occlusion of the fistula's venous drainage. After the procedure, the patient was treated for three months with 75 mg clopidogrel (Plavix(R)) and with 100 mg acetylsalicylic acid (ASS(R)). A few days after the intervention, the patient was discharged without any neurological deficit and in good clinical condition. The follow- up examination six months later neither detected a recurrence of the dural arteriovenous fistula in the angiogram nor any neurological symptoms.

Coil treatment of a fusiform upper basilar trunk aneurysm with a combination of "kissing" neuroform stents, TriSpan-, 3D- and fibered coils, and permanent implantation of the microguidewires.

Endovascular coil occlusion of fusiform intracranial aneurysms without sacrifice of the parent artery can be technically challenging. Bridging of wide aneurysm necks with stents is common practice for side-wall aneurysms but is less frequently used for bifurcation aneurysms. We describe the technical aspects of the successful coil occlusion of a fusiform aneurysm of the upper basilar trunk, with preservation of the parent vessel. The procedure comprised the following steps: (a) stenting of the left V1- and proximal V2 segments; (b) simultaneous deployment of two Neuroform stents from both P1 segments down to the basilar artery ("kissing" stents) (c) using a TriSpan device to hold (d) three-dimensional electrolytically detachable coils in place and (e) filling the aneurysmal lumen mainly with fibered electrolytically detachable coils; and finally (f) cutting the extracorporeal part of both microguidewires below the skin level in both groins, leaving the microguidewires as they were used for the deployment of the stents in place, thus reaching from both P2 segments down to the basilar artery and further proximally.

In vitro and in vivo Studies of the Extent of Electrothrombotic Deposition of Blood Elements on the Surface of Electrolytically Detachable Coils.

SUMMARY: Endovascular treatment of intracranial aneurysms with electrolytically detachable coils is often claimed to be based on electrothrombosis, i.e. intra-aneurysmal thrombus formation through applied direct current. Despite the fact that this concept was described more than a century ago, the significance of electrothrombosis in the endovascular treatment of aneurysms remains debatable. Apart from electrothrombosis, mechanical obliteration of the aneurysmal lumen might be one of the many possible mechanisms to explain why and how detachable coils are effective in preventing aneurysms from (re-)rupture. The purpose of this experimental study was to investigate to what extent direct current comparable to that used for coil detachment would influence the adhesion of cellular and liquid blood components to the surface of electrolytically detachable platinum coils. For the in vitro study, electrolytically detachable platinum coils of various types were exposed to stagnant heparinised blood for a total of 16 h, without or with applied direct current for 30 or 90 s (1 mA, 4-6 V, coil as anode). For the in vivo study, electrolytically detachable platinum coils were exposed to flowing blood for 180 s, without or with applied direct current (2 mA, 4-6 V, coil as either anode or cathode), without anti-coagulation and after intravenous administration of 5000 U Heparin and again after the intravenous administration of 500 mg Aspisol in addition to Heparin. After exposure to blood according to these different experimental protocols, the coils were fixed in formalin solution, gold coated and examined by scanning electron microscopy. Thrombus formation on the surface of all unfibred coils was thin and highly variable both from coil to coil, and on different areas of any given coil. The application of direct current minimally enhanced thrombus formation in stagnant blood in vitro, but not in vivo. The cellular and fibrin adhesions on the coil surfaces without and with applied current did not effectively increase the diameter or volume of unfibred coils. Coils with attached nylon fibres, however, proved to be highly thrombogenic without or with application of current. In fibred coils, surface adhesions without and with applied current were voluminous enough to effectively increase the diameter of the coil, potentially important for the process of endosaccular aneurysm occlusion. Electrothrombosis plays no role in the endovascular treatment of intracranial aneurysms with electrolytically detachable coils. This explains why platinum coils with non-electrolytic detachment mechanisms show a similar efficiency and recurrence rate.