Local thrombolytic therapy for thrombembolic 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.

Sticky Platelet Syndrome: A Cause of Neurovascular Thrombosis and Thrombo-Embolism

Increased platelet aggregation induced by adenosine diphosphate and epinephrine and enhanced platelet activation response to surface contact are the key features of the “sticky platelet syndrome”, in which the phenotype is transmitted with an autosomal dominant pattern. Two thirds of the patients with this syndrome have a positive family history of thrombo-embolic disease, which may be triggered by stress. We have seen two patients suffering from intracranial arterial and venous sinus thrombosis due to sticky platelet syndrome. Hyperaggregability of the platelets after stimulation with adenosine diphosphate and epinephrine was found in both.

Case 1: A 43 year old man with a superior sagittal and right transverse venous sinus thrombosis developed subdural hygromas and a venous infarct of the parietal lobe. After burr hole evacuation of the hygromas, aspirin and phenoprocumone were prescribed. The patient made a good neurological recovery.

Case 2: A 52 year old woman experienced spontaneous occlusion of a right MCA branch. The work-up revealed bilateral MCA and a basilar tip aneurysm. During the attempt to treat the basilar tip aneurysm by endovascular means, a thrombus formed within the left vertebral artery and was dislodged to both posterior cerebral arteries (PCAs). Local intra-arterial fibrinolysis yielded good recanalization of both PCAs. No new neurological deficit occurred. Continuous prophylaxis with aspirin was started.

In sticky platelet syndrome stress and adrenaline release can trigger the thrombosis of intracranial arterial or venous vessels in otherwise healthy subjects. This is a potential cause of thromboembolic complications during endovascular procedures. Low-dose aspirin normalizes platelet hyperaggregability.

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]

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]

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.

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.

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.

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.

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.

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.

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.

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.

Fibered electrolytically detachable platinum coils used for the endovascular treatment of intracranial aneurysms. Initial experiences and mid-term results in 474 aneurysms

SUMMARY

Between 1992 and 2003, a total of 2029 aneurysms in 1748 patients were treated by endovascular occlusion with electrolytically detachable coils. In this series, electrolytically detachable platinum coils with Nylon fibers (Sapphire Detachable Coil System, MTI, Irvine, CA, USA) were used in 474 aneurysms solely or in combination with bare coils from various manufacturers. To determine the safety and clinical efficacy of Nylon fibered coils for the endovascular treatment of intracranial aneurysms in comparison to bare platinum coils a thorough retrospective statistical analysis by means of logistic regression and matched pairs analysis was performed. Only treatments with data for all matching variables were used, resulting in 421 matched pairs. The analysis was performed with respect to clinical status and numerous parameters concerning individual aneurysm characteristics (e.g., location, neck width, fundus diameter). Treatment-related parameters included the use and percentage of fibered coils, occlusion rate, procedural complications, early clinical outcome and Glasgow Outcome Scale (GOS) scores. Finally, long-term follow-up results (particularly recurrence, cause of recurrence and post treatment haemorrhage) were evaluated. Both logistic regression and matched pairs analysis showed a statistically improved occlusion rate if fibered coils had been used (96% largely occluded with the use of fibered coils vs. 84-85% with the exclusive use of bare coils). However, the amount of fibered coils calculated as percentage of coil length did not seem to have significant impact. Procedures with fibered coils did not lead to a higher rate of thromboembolic events (8.0% for fibered vs. 10.5% for bare coils).The apparently better clinical outcome in the group treated with fibered coils determined by both postprocedural outcome and GOS, did not reach statistical significance. Analysis of the anatomical properties showed no differences between the groups treated with bare and fibered coils in terms of neck width, fundus diameter, and anatomic location. As expected, a higher occlusion rate was achieved in aneurysms with smaller neck and fundus independent from the type of coil used. On follow up angiography, there was an apparently lower rate of recurrence secondary to coil compaction in the group treated with fibered coils, but these data were compromised by the fact that up to date only about one third of 474 aneurysms treated with fibered coils had undergone angiographic follow-up and this did not reach statistical significance. From our experiences, we conclude that the use of fibered electrolytically detachable platinum coils in aneurysm treatment leads to significantly improved occlusion rates compared to the sole use of bare platinum coils. We hope that with increasing follow-up data we will be able to confirm that the apparently reduced recurrence rates for aneurysms treated with fibered coils can be proven with statistical significance.

Endovascular coil occlusion of intracranial aneurysms assisted by a novel self-expandable nitinol microstent (neuroform)

SUMMARY

Endovascular treatment of wide neck intracranial aneurysms is technically difficult and leads to less favorable treatment results and long term outcome. We participated in a multicenter prospective study to evaluate the safety and performance of a new self-expandable nitinol micro stent (Neuroform) in stent assisted coil occlusion of wide neck intracranial aneurysms. Eighteen patients were enrolled in the study in a single center. The anatomy of the target aneurysm and the parent vessel, technical details of the procedure, device functionality, anatomic and clinical results were evaluated. All enrolled aneurysms were either wide necked or showed an unfavorable neck-to-fundus ratio. In 16 out of 18 patients the Neuroform device allowed stent assisted coil occlusion of the aneurysm. The occlusion rate was 95% in eight patients and 100% in eight patients. The two failures were both due to anatomic reasons. Flexibility of the stent, behavior during deployment and subsequent ability to retain coils within the aneurysmal sac were considered as good as or better than the properties of previous balloon expandable stents. No device-related adverse events were encountered. Procedure-related clinical complications occurred in seven patients but caused no severe permanent neurological deficit. The Neuroform neurovascular stenting system is a safe and effective adjunct for the stent-assisted coil occlusion of wide necked intracranial aneurysms. The major advantages of this device are its self-expanding property and very high flexibility which allows safe navigation, easy sizing, as well as accurate positioning of the stent while providing sufficient bridging of the aneurysm neck for subsequent coil placement.

Technical Note on VDS. A System for the Endovascular Electrolytical Detachment of Platinum Coils at Variable Length

SUMMARY

A new system was deviced that allows the electrolytical detachment of platinum microcoils at variable lengths for the endovascular treatment of intracranial aneurysms. The detachment element consists of two short platinum coil segments, which are connected by a threat of stainless steel. The steel threat is interrupted by electrolysis, using a continuous current with 1-2 mA at a voltage of 4-8 Volt. The average detachment time in heparinized blood is about 30-40 sec. The detachment elements can be used to connect either an insertion wire with a platinum coil or to connect several segments of platinum coils with variable helices and lengths. If several detachment elements are integrated in a coil, electrolysis interrupts only the element, which is next beyond the distal tip of the catheter. The electrolytical process does not affect the detachment elements proximal and distal to the element adjacent to the tip of the catheter. Single or several coil segments can be pulled back into the microcatheter if necessary. The system is expected to allow a faster and more complete endovascular coil occlusion of intracranial aneurysms. The principles described in this paper are claimed by the German pending patent DE 100 10840 A1.

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.

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.

The Underlying Mechanisms of Endovascular Exclusion of Intracranial Aneurysms by Coils. How Important is Electrothrombosis?

SUMMARY

Endovascular coil treatment of intracranial aneurysms is now widely accepted. We discuss some of the arguments for the relative roles of electrothrombosis, spontaneous thrombosis, mechanical filling, haemodynamic effects and surface properties in successful coil treatment. Despite an enormous body of literature, with many theories and much data, there is limited evidence for, or understanding of, the mechanisms by which coil treatment protects against aneurysm rupture. It seems likely that electrothrombosis plays no part.Dense packing is probably important in preventing recurrence. New technologies aiming to encourage endothelialisation and increased connective tissue formation appear promising.

Endovascular Treatment of a Dural Arteriovenous Fistula of the Transverse Sinus by Recanalisation, Angioplasty and Stent Deployment. A Case Report and Follow-up

SUMMARY

We report the endovascular treatment of a 40- year-old woman with bilaterally thrombosed transverse sinuses and a dural arteriovenous fistula (DAVF) causing cortical venous reflux by recanalization, angioplasty and stent deployment of the occluded sinus segment followed by occlusion of the DAVF by stent deployment in the fistulous segment. By recanalization of the occluded sinus we re-established normal anterograde venous drainage and eliminated the venous hypertension and cortical venous reflux. After the procedure, the patient was treated with aspirin and clopidogrel for three months. A follow- up examination showed total occlusion of the DAVF, patency of the sinus and a complete resolution of the clinical symptoms.

[Diagnosis and embryogenesis of partial anomalous pulmonary venous connection]

In Anomalous Pulmonary Venous Drainage one or more pulmonary veins are not connected with left atrium, but drain into systemic circulation or right atrium. The clinical signs of the shunt between pulmonary and systemic circulation increase during lifetime, thus the abnormality gets late or not diagnosed. Partial Anomalous Pulmonary Venous Drainage is a developmental disorder, according to embryogenesis we recommend a classification of this abnormality. Two case reports are given to illustrate difficulties in diagnosis of this relatively common abnormality. A diagnostic standard of assessment of pulmonary venous disorders is discussed. The "Gold Standard" of selective pulmonary Angiography in combination with oxygen measurement is widely used for diagnosis of Partial Anomalous Pulmonary Venous Drainage. In the future improvement and common use of modern cross sectional imaging techniques will redefine the value of conventional Angiography.

Cure of a direct carotid cavernous fistula by endovascular stent deployment

A 53-year-old woman underwent surgical thrombendarterectomy for treatment of artherosclerotic stenoses of her left internal carotid artery (ICA). A Fogarty catheter was used during this operation. The postoperative course was complicated by the development of a sixth cranial nerve palsy, protrusio, chemosis and ciliar injection of both eyes. Digital subtraction angiography showed a direct fistula between the cavernous segment of the left ICA and the cavernous sinus, with early and retrograde opacification of both superior ophthalmic veins. Endovascular occlusion of the fistula was achieved with preservation of the ICA by stent deployment over the rupture site of the ICA, as two detachable balloons could not obliterate the fistula while preserving the ICA patent. Follow-up angiography 7 months after the endovascular treatment confirmed persisting occlusion of the fistula with a patent ICA. Highly flexible porous coronary stents can easily be introduced into tortuous vessels, including the distal ICA. The haemodynamic effects achieved by stent deployment together with two balloons detached in the cavernous sinus may be sufficient to interrupt a direct carotid cavernous fistula.

Noninvasive follow-up of GDC-treated saccular aneurysms by MR angiography

The aim of this study was to determine sensitivity and specificity of magnetic resonance angiography (MRA) for the assessment of durable occlusion of intracranial aneurysms with Guglielmi detachable coils (GDC) and to point out the influence of MRA results in re-intervention strategies. Forty-five patients with 54 aneurysms that were previously treated by endovascular occlusion with GDC were selected for this study. All patients underwent digital subtraction angiography (DSA) and MRA examinations on the same day. The time-of-flight MRA studies were performed on a 1-T scanner. The MRA images were first read by radiologists who were not aware of the DSA results. In a second consensus reading by the neuroradiologists who had performed all interventional procedures of this series, the decision was made as to whether re-treatment was necessary. The distribution of aneurysm sizes, configurations and treatment results were sufficient for an unbiased evaluation. The first blinded evaluation revealed a sensitivity of 71% and a specificity of 95% for MRA assessment of aneurysm reperfusion. In the second consensus reading, the sensitivity increased to 92% and the specificity was 98%. The blinded reading indicates that MRA is a useful adjunct to DSA for the assessment of durable results after endovascular treatment of intracranial aneurysms. In the consensus reading it became obvious that sensitivity and specificity of MRA can be increased to 92 and 98%, respectively, if the results were evaluated by experienced neuroradiologists, including prior knowledge of all other examinations. We have already increased the follow-up intervals for DSA and use MRA intermittently, based on these results.

Mechanical detachable platinum coil: report of the European phase II clinical trial in 60 patients

PURPOSE

To determine the safety and reliability of the mechanical detachment system of a platinum coil (Detach-18) when used for neurovascular embolization.

MATERIALS AND METHODS

Sixty patients (21 men, 39 women; age range, 26-75 years; mean age, 56.2 years) were treated in seven centers. Ease of introduction of the coil to the microcatheter, effect of coil passage on the microcatheter shape and stability during its delivery, retrievability of the coil before and after the transition zone passed beyond the microcatheter, detachment of the coil, and effect of coil rotation on the microcatheter stability were evaluated. The detachment system itself was evaluated for premature detachment, failure of the coil to detach, detachment time, number of turns, visibility of radiopaque markers, number of coils deployed per patient, and percentage of vessel occlusion obtained. A 0.015-inch-diameter regular coil and a 0.014-inch-diameter soft coil were used.

RESULTS

A total of 1,061 coils were used; 1,009 were detached. The number of coils deployed ranged from four to 104 (mean, 17 coils). The coils passed easily through the microcatheter. The detachment maneuver occurred within 5-25 seconds, with five to 60 turns of the introducing wire. One premature coil detachment occurred without clinical sequela; 100% occlusion of the vessel lumen was achieved in 53 patients; 80%-90%, in four; and 70%-80%, in two. There were no device-related complications.

CONCLUSION

The detachment system was safe and reliable. This is a useful system for coil embolization in neurovascular diseases.

Bypass-surgery and coil-embolisation in the treatment of cerebral giant aneurysms

OBJECTIVE

Operative clipping is the most effective method in the treatment of cerebral giant aneurysms. But about 50% of all giant aneurysms are treatable this way. We want to report about eight patients with giant cerebral aneurysms, which were in our opinion "unclippable" without causing ischaemia in depending brain areas.

METHODS

We describe eight cases of giant aneurysms of the pericallosal artery (n = 1) the middle cerebral artery (n = 3), the basilar tip (n = 3) and of the upper part of the basilar artery (n = 1). One patient with an aneurysm of the pericallosal artery was treated with an extra-intracranial saphenous vein bypass saphenous bypass, in three cases of middle cerebral artery aneurysms an extra-intracranial bypass was also done combined with a resection of the aneurysm. The four patients suffering from an aneurysm of the basilar artery got an extra intracranial bypass too followed by an occlusion of the aneurysm with GD-Coils.

RESULTS

There was no peri-operative mortality and no severe peri- or postoperative complication. The neurological symptoms of all patients were unchanged after the operation. An angiographic control showed a complete obliteration of the aneurysm and a free running bypass in all cases.

CONCLUSION

Bypass surgery and combined bypass surgery and coil embolisation are effective methods in the treatment of giant cerebral aneurysms, which can not be treated by clipping alone.

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.

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.

Haemangiopericytoma of the nasal cavity

Haemangiopericytomas (HPC) are rare vascular tumours originating from a pericytes, a term coined by Zimmermann to refer to the main location of this cell line in the pericapillary connective tissue. HPC may arise in any part of the body. We report a 29-year-old man with a histologically proven nasal haemangiopericytoma-like tumour. The lesion was embolised through the ophthalmic artery before it was removed surgically. The main symptoms of nasal HPC are epistaxis and obstruction of the nose. Malignant and benign clinical courses have been described. Local recurrence and metastases may be observed years after initial diagnosis.

[Chronic encapsulated intracerebral hematoma]]

The purpose of this case report is to describe chronic encapsulated intracerebral hematoma (CEIH), a rare and not fully understood brain lesion. The differentiation from chronic cerebral hematoma, cerebral abscess, and intra-axial tumor is based on clinical and imaging criteria. The diagnosis is confirmed by histological analysis. In the English medical literature, we found 39 patients reported with this lesion. The key feature is the formation of a capsule between a hematoma and cerebral parenchyma. The reasons for this formation are not known. In our patient, an arteriovenous malformation was located outside but adjacent to the CEIH.

[Clinical aspects and diagnostic imaging in sarcoidosis of the nervous system]

The central nervous system is frequently affected during the course of sarcoidosis. Many of these lesions remain without clinical correlates. Unenhanced and contrast enhanced CT and MRI play an important role during the diagnostic work-up of patients with sarcoidosis and suspected or proved CNS involvement. This article summarizes the most frequent manifestations of neurosarcoidosis and provides illustrative examples of MRI findings.

[Septic-embolic and septic metastatic brain abscess]

The hematogenous spread of bacteria, fungi and protozoa may also reach the brain vessels, which happens mostly through septic emboli. From such an embolus a metastatic focal encephalitis and later a septic-embolic brain abscess may arise. The most frequently underlying infections that may cause septic emboli are bacterial endocarditis as well as bacterial infections of artificial heart valve prostheses. Congenital heart malformations with a right-to-left shunt also play here a certain role. Basically, however, all septic conditions and bacteriemias may cause septic-embolic brain abscesses. They occur frequently as multiple lesions. MRI is superior to CT in depicting the different stages of evolution from focal encephalitis, through the hardly encapsulated early abscess, to the formation of a membrane and later a dense fibrous capsule. The medical treatment of a brain abscess requires properly performed CT or MRI follow-up examinations in order to realize early enough a possible growing of such a lesion.

[Diagnostic imaging in viral encephalitis]

The diagnostic procedure in viral encephalitis is based on the synopsis of clinical signs and symptoms, serological data, CSF analysis and diagnostic imaging findings. This article summarizes the findings of those viral encephalitides most frequently encountered in Western Europe. MRI is more sensitive than CT for the detection of inflammatory brain lesions due to the higher contrast resolution. The pattern of parenchymal damage is highly specific in only some viral encephalitides (e.g., the frequently hemorrhagic lesions of structures of the limbic system in herpes simplex virus type I encephalitis; the symmetric and confluent lesions of the frontal white matter of progressive diffuse leukoencephalopathy in AIDS). In the majority of viral encephalitides MRI demonstrates the location and extension of parenchymal damage. The specific diagnosis in terms of the causative agent is based on serological studies.

[Stent implantation into the basilar artery for supporting endovascular aneurysm treatment]

In aneurysms with a neck:dome ratio of 1:2 or more or with a wide neck, endovascular treatment is less effective. In this situation, the rate of thrombotic and thromboembolic complications is increased. Recently available highly flexible balloon expandable coronary stents improved the technique of endovascular aneurysm treatment. Two patients with wide neck midbasilar aneurysms were successfully treated endovascularly using a combination of stent deployment into the basilar artery and coil occlusion of the aneurysm. The creation of an artificial boundary between a side wall aneurysm and the parent artery by stent deployment improves the conditions for subsequent coil occlusion of the aneurysm. If, after detachment, coils protrude from the lumen of a side wall aneurysm into the parent vessel, stenting of this vessel can prevent thrombotic and thromboembolic complications.

Practicality and accuracy of prehospital rapid venous blood glucose determination

Blood glucose testing plays an important role in emergency medicine. Although the use of visual reagent test strips is widely established in this setting, the accuracy of reflectometric blood glucose determinations under emergency conditions has rarely been investigated. In a prospective study, 522 of a total of 3,217 patients undergoing emergency blood glucose testing had parallel blood glucose measurements performed using a specific enzymatic method. These 522 patients (aged 61.4 years, 54% men, 90 cases of severe hypoglycemia) had an intravenous access placed at the scene of the emergency. Venous whole blood from the introducer needle of the access was applied to the test strip and the glucose measured with a GlucoTouch reflectometer (LifeScan, Inc.). A blood sample from the intravenous access was then immediately collected in a monovette for subsequent glucose determination in a chemical laboratory (hexokinase method) within 20 to 40 minutes. The emergency glucose measurements (mean: 7.3 mmol/L [95% confidence interval [CI] 6.9 to 7.7]; range: 0.55 to 27.7) correlated well with the reference laboratory results (Pearson's r = .98; linear regression analysis: slope 1.0, axial intercept 1.74). Error grid analysis also showed good agreement between corresponding measurements: zone A 96.7%, B 2.5%, C 0% and D 0.8%. The mean difference using the Bland-Altman method was 0.14 mmoVL; 2 SD 1.8 mmol/L; minimum -7.0 mmol/L; maximum 4.4 mmol/L. The accuracy of the rapid venous blood glucose determination by constantly changing emergency teams was high. Especially in 90 hypoglycemic patients, there were no deviations from the reference method that could have led to clinically relevant wrong decisions. The method of collecting whole blood directly from the venous access is simple and robust, and is independent of the hemodynamic status of the patient.

Combined endovascular-microsurgical treatment of tentorial-incisural dural arteriovenous malformations. Report of five cases

Dural arteriovenous malformations of the tentorial edge are rare lesions with an unfavorable clinical course if left untreated. As yet no optimum treatment has been established. We retrospectively evaluated the results of our therapy concept, which consists of endovascular embolization followed by microsurgical obliteration, and compared the results to the relevant literature in order to clarify which therapeutic regimen seems to be optimum at the present time. In all of our five patients the lesion was completely obliterated, as proven by angiography, with favorable clinical results and low morbidity. Several other clinical series confirm our results, so we conclude that combined endovascular therapy and microsurgery is the optimum treatment for these lesions.

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.

Long-term outcome after local intra-arterial fibrinolysis of basilar artery thrombosis

Thrombolytic therapy of acute basilar artery (BA) thrombosis has been shown to reduce mortality and avoid a fatal outcome. Objective of this study was to investigate the long-term clinical outcome following intra-arterial fibrinolysis of occlusions of the BA. We retrospectively analyzed the clinical records and neuroradiologic results of 20 consecutive patients who had intra-arterial fibrinolysis of acute occlusions of the BA between 1982 and 1990. All patients were followed neurologically for a period of up to 12 years, including assessment of the Barthel index (BI) and brain CT or MRI studies. At the time of treatment, 6 patients were somnolent and 14 comatose, and tetraparesis was present in 15. The time between the onset of symptoms and treatment ranged from 1 to 48 h. The mortality rate was 35% (7/20 patients). Functional outcome was excellent in 9, 78%, of 13 survivors (BI <85). During the cumulative follow-up period (125 patient years) there was 1 death from myocardial infarction and 1 death from pneumonia. Vascular events during follow-up were myocardial infarction (n = 3) and a single cerebral transient ischemic attack. Despite the fact that our series was biased towards patients with severe symptoms, 65% (13/20) survived, and 78% of the survivors reached independence in daily life. These results provide evidence that local fibrinolysis of BA occlusion reduces mortality, and the long-term prognosis of the survivors is better than previously thought. None of our patients had a further stroke during the follow-up period, which indicates that acute BA occlusion is not a strong indicator for advanced arteriosclerotic disease.