Molecular basis of TASL recruitment by the peptide/histidine transporter 1, PHT1

PHT1 is a histidine /oligopeptide transporter with an essential role in Toll-like receptor innate immune responses. It can act as a receptor by recruiting the adaptor protein TASL which leads to type I interferon production via IRF5. Persistent stimulation of this signalling pathway is known to be involved in the pathogenesis of systemic lupus erythematosus (SLE). Understanding how PHT1 recruits TASL at the molecular level, is therefore clinically important for the development of therapeutics against SLE and other autoimmune diseases. Here we present the Cryo-EM structure of PHT1 stabilized in the outward-open conformation. By combining biochemical and structural modeling techniques we propose a model of the PHT1-TASL complex, in which the first 16 N-terminal TASL residues fold into a helical structure that bind in the central cavity of the inward-open conformation of PHT1. This work provides critical insights into the molecular basis of PHT1/TASL mediated type I interferon production.

Plasticity of the binding pocket in peptide transporters underpins promiscuous substrate recognition

Proton-dependent oligopeptide transporters (POTs) are promiscuous transporters of the major facilitator superfamily that constitute the main route of entry for a wide range of dietary peptides and orally administrated peptidomimetic drugs. Given their clinical and pathophysiological relevance, several POT homologs have been studied extensively at the structural and molecular level. However, the molecular basis of recognition and transport of diverse peptide substrates has remained elusive. We present 14 X-ray structures of the bacterial POT DtpB in complex with chemically diverse di- and tripeptides, providing novel insights into the plasticity of the conserved central binding cavity. We analyzed binding affinities for more than 80 peptides and monitored uptake by a fluorescence-based transport assay. To probe whether all 8400 natural di- and tripeptides can bind to DtpB, we employed state-of-the-art molecular docking and machine learning and conclude that peptides with compact hydrophobic residues are the best DtpB binders.

Cryo-EM Structure of an Atypical Proton-Coupled Peptide Transporter: Di- and Tripeptide Permease C

Proton-coupled Oligopeptide Transporters (POTs) of the Major Facilitator Superfamily (MFS) mediate the uptake of short di- and tripeptides in all phyla of life. POTs are thought to constitute the most promiscuous class of MFS transporters, with the potential to transport more than 8400 unique substrates. Over the past two decades, transport assays and biophysical studies have shown that various orthologues and paralogues display differences in substrate selectivity. The E. coli genome codes for four different POTs, known as Di- and tripeptide permeases A-D (DtpA-D). DtpC was shown previously to favor positively charged peptides as substrates. In this study, we describe, how we determined the structure of the 53 kDa DtpC by cryogenic electron microscopy (cryo-EM), and provide structural insights into the ligand specificity of this atypical POT. We collected and analyzed data on the transporter fused to split superfolder GFP (split sfGFP), in complex with a 52 kDa Pro-macrobody and with a 13 kDa nanobody. The latter sample was more stable, rigid and a significant fraction dimeric, allowing us to reconstruct a 3D volume of DtpC at a resolution of 2.7 Å. This work provides a molecular explanation for the selectivity of DtpC, and highlights the value of small and rigid fiducial markers such as nanobodies for structure determination of low molecular weight integral membrane proteins lacking soluble domains.

Structural snapshots of human PepT1 and PepT2 reveal mechanistic insights into substrate and drug transport across epithelial membranes

The uptake of peptides in mammals plays a crucial role in nutrition and inflammatory diseases. This process is mediated by promiscuous transporters of the solute carrier family 15, which form part of the major facilitator superfamily. Besides the uptake of short peptides, peptide transporter 1 (PepT1) is a highly abundant drug transporter in the intestine and represents a major route for oral drug delivery. PepT2 also allows renal drug reabsorption from ultrafiltration and brain-to-blood efflux of neurotoxic compounds. Here, we present cryogenic electron microscopy (cryo-EM) structures of human PepT1 and PepT2 captured in four different states throughout the transport cycle. The structures reveal the architecture of human peptide transporters and provide mechanistic insights into substrate recognition and conformational transitions during transport. This may support future drug design efforts to increase the bioavailability of different drugs in the human body.

Differential Complex Formation via Paralogs in the Human Sin3 Protein Interaction Network

Despite the continued analysis of HDAC inhibitors in clinical trials, the heterogeneous nature of the protein complexes they target limits our understanding of the beneficial and off-target effects associated with their application. Among the many HDAC protein complexes found within the cell, Sin3 complexes are conserved from yeast to humans and likely play important roles as regulators of transcriptional activity. The presence of two Sin3 paralogs in humans, SIN3A and SIN3B, may result in a heterogeneous population of Sin3 complexes and contributes to our poor understanding of the functional attributes of these complexes. Here, we profile the interaction networks of SIN3A and SIN3B to gain insight into complex composition and organization. In accordance with existing data, we show that Sin3 paralog identity influences complex composition. Additionally, chemical cross-linking MS identifies domains that mediate interactions between Sin3 proteins and binding partners. The characterization of rare SIN3B proteoforms provides additional evidence for the existence of conserved and divergent elements within human Sin3 proteins. Together, these findings shed light on both the shared and divergent properties of human Sin3 proteins and highlight the heterogeneous nature of the complexes they organize.

Purification and enzymatic assay of class I histone deacetylase enzymes

The reversible acetylation of histones has a profound influence on transcriptional status. Histone acetyltransferases catalyze the addition of these chemical modifications to histone lysine residues. Conversely, histone deacetylases (HDACs) catalyze the removal of these acetyl groups from histone lysine residues. As modulators of transcription, HDACs have found themselves as targets of several FDA-approved chemotherapeutic compounds which aim to inhibit enzyme activity. The ongoing efforts to develop targeted and isoform-specific HDAC inhibitors necessitates tools to study these modifications and the enzymes that maintain an equilibrium of these modifications. In this chapter, we present an optimized workflow for the isolation of recombinant protein and subsequent assay of class I HDAC activity. We demonstrate the application of this assay by assessing the activities of recombinant HDAC1, HDAC2, and SIN3B. This assay system utilizes readily available reagents and can be used to assess the activity and responsiveness of class I HDAC complexes to HDAC inhibitors.

Radiosurgery following Embolisation and/or Surgery of Brain AVM's

A series of 45 patients who have undergone combined treatment for cerebral arteriovenous malformations (AVM's) is presented. All patients underwent additional radiosurgery after endovascular and/or surgical treatment. Stereotactic radiosurgical treatment using the Gamma knife has been available in our institution since 1992.

The treatment strategy for brain AVM's has changed since that time. The possibility for total cure of partially embolised AVM's, where other treatment options had been exhausted, increased with adjunctive radiosurgery. Complex or giant AVM's in eloquent areas can now be treated using radiosurgery after embolisation and/or microsurgery, with minor risk of neurological deficit.

In all 45 patients treated since September 1992 at the University of Vienna, embolisation was performed to reduce the size of the nidus in order to facilitate surgical resection or radiosurgical treatment.

In 37 patients radiosurgery was performed after endovascular treatment only, and in 8 patients radiosurgery was performed after embolisation and surgery. All AVM's were classified according to Spetzler's Grading System. 31 patients (68.9%) were classified as Grade 3 or 4. Two patients (4.5%) were classified as Grade 5.

In a mean follow up time of 16 months (range 2–40), there were 15 complete obliterations and 2 patients with unexpected residual AVM after two years.

Of patients who required staged radiosurgical therapy, 12 have been followed for less than two years after their final procedure. In an additional 12 patients the follow-up period is less than 12 months. 4 patients were lost to follow up. There is a morbidity of 8.8% and no mortality in this patient group.

Early Clinical Outcome of Patients with Ruptured Cerebral Aneurysms Treated by Endovascular (GDC) or Microsurgical Techniques

Over the past 3.5 years 220 patients with aneurysmal subarachnoid hemorrhage were treated in the Department of Neurosurgery University of Vienna Medical School using either endovascular techniques (Guglielmi Detachable Coils) or open craniotomy with aneurysm clipping.

A retrospective analysis was undertaken to assess whether any difference in outcome could be correlated with the treatment choice.

The patients were stratified as to 1) Hunt and Hess grade at time of treatment, 2) method of treatment, and 3) clinical outcome at 2–4 weeks following treatment.

The outcomes in this population of patients were consistent with recent published series regardless of whether the aneurysms were treated with microvascular surgery or endovascular surgery.

There was a trend toward better outcome in a relatively small sub-group of patients presenting as Hunt and Hess grade III who were treated by the endovascular method. Guglielmi detachable coils have been available for a relatively short time, and although early results are promising, the ultimate long-term efficacy of the coils will have to be assessed.

Endovascular mechanical recanalization of acute ischaemic stroke in octogenarians

BACKGROUND

Multiple studies have shown a clinical benefit of thrombectomy in acute ischaemic stroke, but most of them excluded octogenarians. The purpose of this study was to compare the outcomes between octogenarians and younger patients after thrombectomy.

MATERIALS AND METHODS

One hundred and sixty-six patients with large cerebral artery occlusion and consecutive thrombectomy were evaluated and divided into two patient age groups: younger than 80 years and older than 80 years. We compared recanalization rates, complications experienced, disability, death after discharge and at a 90-day follow-up between these age groups.

RESULTS

Sixty-eight percent of octogenarians and 72 % of younger patients were registered with successful recanalization (p = 1.0). There was no significant difference in symptomatic intracerebral haemorrhage between the groups (p = 0.32). However, octogenarians had a significantly lower rate of good clinical outcome (24 % vs. 48 %; p = 0.008) and a higher mortality rate (36 % vs. 12 %; p = 0.0013).

CONCLUSION

Octogenarians have a lower chance of good clinical outcome and a higher mortality rate despite successful recanalization. Nevertheless, 24 % of octogenarians were documented with mRS ≤2. As this age group of octogenarians will grow prospectively, careful patient selection should be mandatory when considering octogenarians for thrombectomy.

KEY POINTS

• Careful patient selection for thrombectomy should be mandatory in octogenarians. • Octogenarians have a higher mortality rate despite successful recanalization. • Nearly one-third of octogenarians were documented with a good clinical outcome.

Comparison of Endovascular Treatment Versus Conservative Medical Treatment in Patients With Acute Basilar Artery Occlusion

Introduction:

Basilar artery occlusion (BAO) causes mortality up to 90%.

Methods:

A total of 99 patients with BAO received either endovascular (endovascular mechanical recanalization and/or intra-arterial with optional intravenous thrombolysis [IVT] as bridging concept) or conservative medical treatment (IVT and/or medical oral therapy). Outcome parameters were measured in accordance with the thrombolysis in cerebral infarction (TICI), National Institutes of Health Stroke Scale (NIHSS), and modified Rankin Scale (mRS) scores.

Results:

In all, 78% underwent endovascular and 22% conservative medical treatment. The NIHSS at admission was 20 in both the groups. Postprocedurally, 36% (95% confidence interval: 26%-48%) of the endovascular group and 9% (21%-64%) of the conservative group reached TICI 3 ( P = .017). In all, 30% of the endovascular group and 9% of the conservative group were documented with TICI 2b ( P = .057). At 90 days follow-up, 45% (31%-60%) of the endovascular-treated patientsand no patient (0%-25%) of the conservative-treated group reached mRS ≤2 ( P = .012).

Conclusion:

Endovascular treatment of BAO provides a better chance to survive this severe condition with good clinical outcome.

3D computerized occlusion rating of embolized experimental aneurysms using noninvasive 1.5T MR imaging

BACKGROUND AND PURPOSE

For embolized cerebral aneurysms, the initial occlusion rate is the most powerful parameter to predict aneurysm rerupture and recanalization. However, the occlusion rate is only estimated subjectively in clinical routine. To minimize subjective bias, computer occlusion-rating (COR) was successfully validated for 2D images. To minimize the remaining inaccuracy of 2D-COR, COR was applied to 1.5T 3D MR imaging.

MATERIALS AND METHODS

Twelve experimental rabbit aneurysms were subjected to stent-assisted coil embolization followed by 2D DSA and 3D MR imaging. Subjective occlusion-rate (SOR) was estimated. Linear parameters (aneurysm length, neck width, parent vessel diameter) were measured on 2D DSA and 3D MR imaging. The occlusion rate was measured by contrast medium-based identification of the nonoccluded 2D area/3D volume in relation to the total aneurysm 2D area/3D volume. 2D and 3D parameters were statistically compared.

RESULTS

There were no limiting metallic artifacts by using 3D MR imaging. Linear parameters (millimeters) were nearly identical on 2D DSA and 3D MR imaging (aneurysm length: 7.5 ± 2.6 versus 7.4 ± 2.5, P = .2334; neck width: 3.8 ± 1.0 versus 3.7 ± 1.1, P = .6377; parent vessel diameter: 2.7 ± 0.6 versus 2.7 ± 0.5, P = .8438), proving the high accuracy of 3D MR imaging. COR measured on 3D MR imaging was considerably lower (61.8% ± 26.6%) compared with the following: 1) 2D-COR (65.6% ± 27.1%, P = .0537) and 2) 2D-SOR estimations (69.2% ± 27.4%, P = .002). These findings demonstrate unacceptable bias in the current clinical standard SOR estimations.

CONCLUSIONS

3D-COR of embolized aneurysms is easily feasible. Its accuracy is superior to that of the clinical standard 2D-SOR. The difference between 3D-COR and 2D-COR approached statistical significance. 3D-COR may add objectivity to the ability to stratify the risk of rerupture in embolized cerebral aneurysms.

Classification of Non-Aneurysmal Subarachnoid Haemorrhage: CT Correlation to the Clinical Outcome

To propose a new computed tomography (CT)-based classification system for nonaneurysmal subarachnoid haemorrhage (SAH), which predicts patients' discharge clinical outcome and helps to prioritize appropriate patient management. A 5-year, retrospective, two-centre study was carried out involving 1486 patients presenting with SAH. One hundred and ninety patients with nonaneurysmal SAH were included in the study. Initial cranial CT findings at admission were correlated with the patients' discharge outcomes measured using the Modified Rankin Scale (MRS). A CT-based classification system (type 1 e 4) was devised based on the topography of the initial haemorrhage pattern. Seventy-five percent of the patients had type 1 haemorrhage and all these patients had a good clinical outcome with a discharge MRS of 1. Eight percent of the patients presented with type 2 haemorrhage, 62% of which were discharged with MRS of 1 and 12% of patients had MRS 3 or 4. Type 3 haemorrhage was found in 10%, of which 16% had good clinical outcome, but 53% had moderate to severe disability (MRS 3 and 4) and 5% were discharged with severe disability (MRS 5). Six percent of patients presented with type 4 haemorrhage of which 42% of the patients had moderate to severe disability (MRS 3 and 4), 42% had severe disability and one-sixth of the patients died. Highly significant differences were found between type 1 (1a and 1b) and type 2 (p 1/4 0.003); type 2 and type 3 (p 1/4 0.002); type 3 and type 4 (p 1/4 0.001). Haemorrhages of the type 1 category are usually benign and do not warrant an extensive battery of clinical and radiological investigations. Type 2 haemorrhages have a varying prognosis and need to be investigated and managed along similar lines as that of an aneurysmal haemorrhage with emphasis towards radiological investigation. Type 3 and type 4 haemorrhages need to be extensively investigated to find an underlying cause.

Use of CT angiography in comparison with other imaging techniques for the determination of embolus and remnant size in experimental aneurysms embolized with hydrogel filaments

BACKGROUND AND PURPOSE

Beam-hardening artifacts in CTA can be greatly reduced by using metal-free coils for aneurysm embolization. We compared the embolic masses and remnants of experimental rabbit aneurysms coiled with hydrogel filaments by using DSA, CTA and histology.

MATERIALS AND METHODS

Embolization of 12 rabbit bifurcation aneurysms was performed with detachable hydrogel filaments. Six aneurysms were embolized as completely as possible, and 6 aneurysms were embolized incompletely to intentionally leave remnants. Three aneurysms in each group underwent follow-up at 4 and 13 weeks. DSA, MRA, and CTA were performed immediately before sacrifice. The harvested aneurysms were evaluated histologically. For each imaging technique, the areas of the embolic mass and remnant were determined by using image analysis. Results were compared by using paired t tests.

RESULTS

CTAs were suitable for quantification of the embolus and remnant areas because only small streaking artifacts were evident. The areas of the embolus were larger on CTA compared with DSA and histologic sections. The areas of the remnant were larger on CTA and MRA compared with DSA and histologic sections. Like DSA and MRA, CTA was suitable for determining whether aneurysm retreatment was necessary, provided that loops of hydrogel filaments were not present in the parent artery.

CONCLUSIONS

We demonstrated that CTA is a technique with potential for surveillance of aneurysms treated with hydrogel filaments. Additional work is required to determine the accuracy of the technique compared with currently accepted imaging modalities of DSA and MRA.

Treatment of acute middle cerebral artery occlusion with a Solitaire AB stent: preliminary experience

We report our initial experience with a Solitaire AB neurovascular remodeling stent device in performing cerebral embolectomy in seven patients presenting to our institution with acute stroke who were resistant to iv thrombolytic drug treatment. The main inclusion criteria were: National Institutes of Health Stroke Scale (NIHSS) score ≥10; treatment performed within 8 h from the onset of symptoms and no large hypodensity on CT; and occlusion of a major cerebral artery on the CT angiogram. An admission and a post-interventional NIHSS score were calculated for all patients by two different neurologists. Efficacy was assessed radiologically by post-treatment thrombolysis in myocardial infarction (TIMI) scores and clinically by a 30-day Modified Rankin Scale (MRS) score. The mean duration of neurointerventional treatment was 84 min. All interventions were successful, with TIMI scores of 2 or 3 achieved in 100% of patients. There was one procedural complication in our series owing to a self-detached stent and one patient had a small asymptomatic basal ganglia haemorrhage. There was improvement of more than 4 points on the NIHSS score in 5 (72%) of the patients following treatment, of whom 4 (57%) had a 30-day MRS score of ≤2. The use of a Solitaire stent in acute stroke was safe, time-efficient and encouraging; however, a larger sample size will be required to further evaluate the use of this device, which could benefit a significant number of stroke patients.

Histological demonstration of healing in experimental aneurysms

INTRODUCTION

Recanalisation of aneurysms after interventional therapy is still an unsolved problem. The aim of this study is to demonstrate the angiographic and histological evidence of healing after endovascular embolisation of experimental aneurysms.

METHODS

We evaluated the healing reaction in experimental aneurysms treated with HydroCoils and platinum coils. After microsurgical construction of aneurysms in 24 rabbits, embolisation was performed. Four animals were sacrificed immediately after embolisation and 5 after 1 month, 3 months and 6 months, respectively, the remaining served as control group. Serial plastic-embedded ground sections of the parent arteries-aneurysm complexes were evaluated by light microscopy.

RESULTS

Thrombus organisation in the aneurysms resulted in fibrovascular tissue formation between bare platinum and HydroCoils from the walls of the aneurysms towards the centre of the sac over time. In the clefts between HydroCoils only thin strands of granulation tissue were observed. From one month on, there was a neointimal layer covering the coil mass at the aneurysm orifice.

CONCLUSION

Progressive occlusion by the expanding hydrogel polymers on the coils seemed to result in a durable healing reaction in the aneurismal sac in a short-term follow-up period.

Angiographic and histologic comparison of experimental aneurysms embolized with hydrogel filaments

BACKGROUND AND PURPOSE

The embolization of aneurysms with hydrogel filaments allow postprocedural CT and MR imaging studies without artifacts. We compared the performance of 3 hydrogel filament formulations in rabbit experimental aneurysms by using angiography and histologic samples.

MATERIALS AND METHODS

Embolization of 35 rabbit elastase or bifurcation aneurysms was performed with 3 different formulations of detachable hydrogel filaments, including 1) polyethylene glycol opacified with aromatic iodine (PEG-I; n = 12), 2) polyethylene glycol opacified with barium sulfate (PEG-B; n = 12), or 3) polypropylene glycol opacified with barium sulfate (PPG-B; n = 11). Follow-up angiography was performed before the rabbits were killed at 2 (n = 7), 6 (n = 9), 10 (n = 8), or 26 (n = 11) weeks. Angiographic occlusion was scored according to the Raymond scale, and interval changes were assessed. The harvested aneurysms were evaluated on histologic examination. From the sections, we determined the percentage of the sac excluded from the vasculature and occupied by embolic devices by using image analysis. We compared results using the analysis of variance/t test or chi(2) test.

RESULTS

The mean number of devices used to treat aneurysms in the PPG-B group was significantly greater than that used for the other 2 groups, though aneurysm volumes were similar among groups. Compared with immediate posttreatment occlusion scores, mean angiographic occlusion at follow-up was increased for all 3 hydrogel filament groups. On histologic examination, thrombus organization, neointima formation, and inflammation were similar to that observed in rabbit experimental aneurysms with other embolic devices containing platinum coils.

CONCLUSIONS

The embolization of experimental aneurysms with hydrogel filaments resulted in durable angiographic and histologic occlusion from 2 to 26 weeks. With improvements, hydrogel filaments free from metallic coils show promise for endovascular use.

Visual worsening after incomplete coiling of a small asymptomatic aneurysm: case report and review of the literature

OBJECTIVE

Complications with increased mass effect on surrounding structures have as yet only been noted after coiling of large, giant, and thrombosed aneurysms. We describe a case of optic chiasm compression after incomplete coil embolization of a small ICA aneurysm and discuss the potential mechanisms causing this phenomenon.

CASE REPORT

A 57-year-old male presented with an incidental, 7-mm diameter, C2 segment, ICA aneurysm. Endovascular intervention with platinum coils resulted in 80% obliteration. Approximately three weeks later the patient developed visual changes which progressed over 10 days to a homonymous hemianopsia with a central scotoma. A pterional craniotomy was performed to decompress and to definitively clip the aneurysm. Histological evaluation of the aneurysm showed sinusoidal vessels, filled with proliferated endothelial cells and being encapsulated by fibrous tissue, suspicious for exposure to systemic blood pressure.

CONCLUSION

Even small aneurysms undergoing incomplete coil embolization may affect surrounding, eloquent neural structures due to unexpected tissue formation in the aneurysm.

Cartilage and bone neoformation in rabbit carotid bifurcation aneurysms after endovascular coil embolization

Occurrence and histomorphology of cartilage and bone neoformations was retrospectively evaluated in rabbit experimental aneurysms after endovascular coil embolization. During product development, 115 carotid bifurcation aneurysms were treated with hydrogel-containing devices (HydroCoil or target, n=77; HydroSoft or target, n=28; prototype Hydrogel-only, n=10; MicroVentionTerumo, Aliso Viejo, CA). Additional 29 aneurysms were treated with standard (n=22) or with degradable polymer-covered (n=7) platinum coils. After 4 to 52 weeks, the retrieved aneurysms were methylmethacrylate embedded, and ground sections were surface-stained with Rapid Bone Stain and Giemsa solution. Cartilage and/or bone tissue was assessed by light microscopy; respective tissue areas in the aneurysms were determined by computerized histomorphometry. Cartilage neoformation was observed from 26 to 52 weeks. Single chondrocytes to hyaline or fibrous cartilage areas, occupying up to 29% of the aneurysm cavity, were found in 6 aneurysms, treated with HydroCoil (n=4), Hydrogel-only (n=1), and resorbable polymer (n=1) devices. Chondral ossification associated cartilage neoformation in 2 of these 4 HydroCoil-treated aneurysms. Membranous woven and lamellar bone ossicles were observed from 13 to 52 weeks in 7 aneurysms, treated with HydroCoil (n=3) and platinum coil (n=4) devices. Altogether, cartilage and/or bone neoformation was observed in 13 (9%) of 144 rabbit bifurcation aneurysms treated with various embolic devices. Incidence was low until 26 weeks, but increased at 52 weeks in both, HydroCoil and standard platinum coil treated aneurysms. As the neoformations were predominantly located in proximity to the aneurysm neck, they could be related to the long-term mechanobiology of cell differentiation during fibrovascular healing of blood flow-exposed embolized aneurysms.

Electronic database for documentation of microsurgical and endovascular treatment of intracranial aneurysms: technical note

The authors present an electronic database for the documentation and inter-group comparison of patients subjected to microsurgical and/or endovascular therapy of ruptured and unruptured intracranial aneurysms.

Long-term functional effects of aneurysmal subarachnoid haemorrhage with special emphasis on the patient's view

Although physical and emotional dysfunction appears to be quite frequent even among independent survivors of aneurysmal subarachnoid haemorrhage (SAH), these symptoms may easily be missed on routine follow-up examinations. To assess the long-term functional effects of SAH and to outline possible treatment approaches, a cross-sectional study using multidimensional measures of relevant areas of function was performed on 40 independent survivors. After an average follow-up period of 22 months, patients were selected and enrolled following a pre-designed protocol. The comprehensive test battery consisted of subjective and objective measures of physical, psychological and social function and relationships between the different levels of assessment were calculated. We found a considerable proportion of cognitive, emotional and physical dysfunction in this sample, but on the subjective level, the majority of the patients stated satisfaction with life in general. Mild cognitive dysfunction was frequently missed and causes distress in the family. Mild to moderate depression was underdiagnosed, although such an emotional dysfunction influences working capacity and quality of life. Referral to rehabilitation centers appears to be restricted to patients with severe impairments. Our results help to alert the neurosurgeon to these possible symptoms and show the urgent need for a prospective, interdisciplinary and multidimensional follow-up of SAH survivors.

Does (99m)Tc-Sestamibi in high-grade malignant brain tumors reflect blood-brain barrier damage only?

(99m)Tc-Sestamibi (MIBI) has been successfully applied in recurrent glioblastoma. The aim of this study was to evaluate the incremental diagnostic information of MIBI as a tumor-avid radiopharmaceutical compared with (99m)Tc-pertechnetate ((99m)Tc) as sole indicator of the integrity of the blood-brain barrier. Twenty-five patients with confirmed recurrent brain tumors were included. MIBI SPET was performed 10 min after injection of 555 MBq MIBI intravenously with a triple-headed gamma camera equipped with LE-UHR-PAR collimators over 360 degrees (3 degrees /step) and stored in a 128(2) matrix. Identical acquisition parameters were used for (99m)Tc SPET, which was acquired 3 h after injection of 740 MBq (99m)Tc. Normalized tumor uptake (NU) was calculated from attenuation-corrected transaxial slices. In addition, tumor/plexus, tumor/nasopharynx, and tumor/parotid gland ratios were assessed in both studies. No statistically significant differences were detected for the mean NU of tumor tissue with MIBI (0.26 +/- 0.10) and (99m)Tc (0.39 +/- 0. 33) and for the tumor/nasopharynx and tumor/parotid gland ratios; only the tumor/plexus ratio was significantly higher for (99m)Tc than for MIBI (p < 0.05). In conclusion, our data indicate that MIBI scintigraphy in brain tumors at 10 min postinjection reveals no additional visual information over that provided by the conventional (99m)Tc-pertechnetate brain scan, and in addition, tracer retention reflects primarily blood-brain barrier damage.

Preoperative embolization of hypervascular skull base tumors

The purpose of the present study is to review the results and complications of preoperative embolization of hypervascular skull base tumors at a neurosurgical center with a team of neurosurgeons cross-experienced in the application of both microsurgery and endovascular techniques. One hundred and twenty-eight endovascular approaches were performed in 66 patients treated for skull base meningiomas (n = 41), paragangliomas of the temporal bone (n = 18), and juvenile nasopharyngeal angiofibromas (n = 7). One death and 2 permanent disabilities were attributable to endovascular therapy. These complications occurred early in our experience (1982-1989) and were related to thromboembolic events rather than complications of transcatheter embolization itself. Our current standard is to perform transfemoral superselective embolizations with either finely corpuscular embolizing substances (PVA particles) or cyanoacrylates (NBCA) under local anesthesia. Using this protocol no embolization-related complications have occurred over the last 9 years. We thus conclude that preoperative embolization of hypervascular skull base tumors can be accomplished safely with the endovascular techniques now available.

Preoperative embolization of intracranial meningiomas: a 17-years single center experience

The purpose of the present report is to review the evolution of endovascular therapy at our center as utilized for the preoperative embolization of intracranial meningiomas over a 17-years period (1982-1998). This study is based upon a consecutive series of 63 patients who underwent preoperative embolization of intracranial meningiomas. Total or subtotal angiographic devascularization of the tumor parenchyma was accomplished in 38 patients (60.3%) who had tumors with either an external carotid artery supply only (n = 30) or with contributions from the cavernous carotid artery, ophthalmic artery, vertebral artery, or pial feeders which were feasible for selective embolization (n = 8). Partial tumor embolizations were attained in the remaining 25 patients (39.7%) because 1. the remanent feeders were considered easily accessible to surgical control in the early stages of dissection, 2. the feeding branches were inaccessible for a microcatheter approach, or 3. superselective microcatheter positions allowing for safe embolization without reflux of embolic material into physiological branches were not achieved. Overall, 97 of 126 tumor feeders identified angiographically were catheterized to selective embolization (77%). Three embolization related complications occurred early in our experience (1982-1989) using techniques which no longer meet standards of treatment. In light of the remarkable evolution of endovascular techniques over the 17-years study period, however, we conclude that preoperative embolization of intracranial meningiomas can be performed safely with the endovascular tools currently available.

Endovascular management of patients with cerebral arteriovenous malformations

The endovascular management of brain arteriovenous malformations (AVMs) is a part of the therapeutic AVM strategy. In selected cases, endovascular therapy may lead to a total and permanent cure, but in most cases it will be an adjunctive therapy to microsurgery or radiosurgery. Embolization of brain AVMs is still a technical challenge that requires experience and skill on the part of the physician and requires a further improvement of tools, but it has made brain AVMs curable.

Clinical and angiographic results of endosaccular coiling treatment of giant and very large intracranial aneurysms: a 7-year, single-center experience

OBJECTIVE

To evaluate whether the objectives of surgical treatment, i.e., prevention of aneurysmal rebleeding, relief of aneurysmal mass effect, and prevention of embolic complications, are met by endosaccular coiling treatment applied to giant and very large wide-necked aneurysms.

METHODS

Thirty patients with 31 giant or very large aneurysms were considered to show unacceptable risk/benefit ratios for open surgery and were treated using the Guglielmi detachable coil (GDC) method between 1992 and 1998.

RESULTS

With endosaccular GDC treatment, 73.3% of the population experienced excellent to good recoveries (Glasgow Outcome Scale scores of 4 or 5), with a 13.3% procedure-related morbidity rate and a 6.7% procedure-related mortality rate. Two hemorrhaging episodes occurred after GDC treatment (annual bleeding rate, 2.5%; 2 hemorrhaging episodes/79.2 patient-yr). Symptoms related to aneurysmal mass effect were improved for 45.5% of the patients presenting with signs of neural compression. Among 23 patients with 24 aneurysms who were available for angiographic follow-up assessment, complete or nearly complete occlusion was observed for 17 aneurysms (71%; angiographic follow-up period, 24.3 +/- 19.6 mo, mean +/- standard deviation). A single total embolization served as definitive treatment for only 12.5% of the giant aneurysms and 31% of the very large aneurysms.

CONCLUSION

Endosaccular GDC treatment of giant and very large aneurysms was accomplished with procedure-related morbidity and mortality rates comparable to those for open surgery performed by experts. However, because coil stability was unsatisfactory, we suggest that the GDC method should currently be reserved for individuals who are considered poor candidates for open surgery.

Pseudoaneurysm of the internal carotid artery after shrapnel injury in World War II: demonstration by CT angiography with 3D MIP reconstruction

A case of pseudoaneurysm of the left internal carotid artery (ICA) after shrapnel injury is demonstrated by intra-arterial digital subtraction angiography (DSA) and computed tomography angiography (CTA) with subtraction technique. Although the pseudoaneurysm was well demonstrated by intra-arterial DSA, CTA was the only modality to demonstrate the three-dimensional shape of the perfused part of pseudoaneurysm and the aneurysmal neck, which affected the therapeutic strategy. The CTA technique is useful in the assessment of large pseudoaneurysms and for therapeutic planning.

Gross and microscopic histopathological findings in aneurysms of the human brain treated with Guglielmi detachable coils

OBJECT

The histopathological characteristics of aneurysms obtained at autopsy or surgery 3 days to 54 months after being treated with Guglielmi detachable coils (GDCs) were assessed.

METHODS

Seventeen aneurysms were obtained at autopsy and one was removed at surgery. Fourteen were examined histologically with the coils in situ. Naked coils embedded in an unorganized thrombus were found in those aneurysms that had been treated with coils within 1 week earlier. An incomplete replacement of the intraluminal blood clot by fibrous tissue and a partial membranous covering at the aneurysm orifice were observed in those aneurysms that had been treated with coils between 2 and 3 weeks prior to examination. One small aneurysm treated 6 weeks before harvesting showed formation of an endothelium-lined layer of connective tissue at the orifice. Collagen-rich vascularized tissue surrounding the coils was found in an aneurysm removed at surgery 54 months after coil implantation. Interestingly, six (50%) of 12 aneurysms (two small, three large, and one giant) that had been deemed 100% occluded on initial angiography showed tiny open spaces between the coils at the neck on gross examination.

CONCLUSIONS

Endothelialization of the aneurysm orifice following placement of GDCs can occur; however, it appears to be the exception rather than the rule. In large aneurysms the process of intraaneurysm clot organization seems to be delayed and incomplete; tiny open spaces between the coils and an incomplete membranous covering in the region of the neck are frequently encountered. Further longitudinal studies are required to establish the spectrum of healing profiles that may direct our efforts in modifying the GDC system to produce a more stable long-term result.

Variant arteriovenous fistula of the superior sagittal sinus--case report

A 57-year-old male presented with a rare variant of dural arteriovenous fistula, located in the wall of an unobstructed superior sagittal sinus. Drainage occurred through a cortical vein no longer connected to its parent sinus, which filled up a cluster of transmedullary running veins, one of which was the presumed site of hemorrhage. Arterial blood was supplied via the external carotid artery branches. This type of fistula seriously increases the risk of hemorrhage in the patient and therefore requires complete obliteration. Attempts to embolize the fistula failed. The draining vein was isolated and coagulated resulting in permanent occlusion of the fistula. The fistula probably developed through a process of thrombophlebitis and revascularization via arterioles of the vein rather than previous occlusion of the sinus.

Treatment of basilar artery bifurcation aneurysms by using Guglielmi detachable coils: a 6-year experience

OBJECT

The authors retrospectively analyzed the results of their 6-year experience in the treatment of basilar artery (BA) bifurcation aneurysms by using Guglielmi detachable coils (GDCs).

METHODS

This analysis involved 45 BA tip aneurysms in 16 men and 29 women who ranged in age from 23 to 78 years (mean 50 years). Seventy-five percent of the aneurysms had ruptured and 25% remained unruptured. Of the group whose aneurysms hemorrhaged, 14 patients were Hunt and Hess Grade I or II and 20 were Hunt and Hess Grades III to V; 32 patients were treated within 2 weeks of their subarachnoid hemorrhage (SAH). Initially, treatment with GDCs was limited to poor-grade high-risk patients who refused surgery or patients in whom surgery proved unsuccessful. Later in the study, good-grade patients with narrow-necked aneurysms were also treated using GDCs. The length of clinical follow up ranged from 1 to 72 months (average 27.4 months) in the 37 surviving patients. In 33 of the 45 aneurysms treated with coil placement, good to excellent results were achieved. There were 12 poor results (27%) including one in a patient from the non-SAH group who suffered a thrombotic complication due to an underlying vasculitis. Eight deaths were recorded in this group of 45 patients. One of these deaths was caused by a complication related to anesthesia, one by unknown causes, and six resulted from complications of the disease. One patient rebled on the 2nd day after the endovascular procedure. The mortality and permanent morbidity rates directly related to the intervention were 2.2% and 4.4%, respectively. Angiographic studies obtained immediately postintervention demonstrated 99 to 100% occlusion in 30 (67%) of the aneurysms; nine (20%) were more than 90% occluded; and six (13%) were less than 90% occluded by the GDCs. Follow-up angiograms were obtained in 31 patients between 2 and 72 months after coil placement. Nineteen (61%) of the follow-up angiograms revealed stable results (that is, no change from initial treatment). Twelve of the 31 showed coil compaction, but only eight of these lesions could accept additional coils. In large aneurysms recanalization was seen in 57%, and some of the larger lesions required as many as four embolizations (mean 1.7) to achieve optimal occlusion. When small-necked aneurysms were analyzed as a subset, a stable angiographic result was seen in 92%.

CONCLUSIONS

Use of GDCs led to excellent clinical and angiographic results in the majority of patients with BA tip aneurysms included in this limited follow-up study. Rebleeding was encountered in one of the 34 previously ruptured BA aneurysms treated with GDCs, and no hemorrhages have been documented in the 11 unruptured aneurysms treated with GDCs in this series. Long-term follow-up studies are necessary before it is possible to compare adequately the treatment of aneurysms with coil placement to the gold standard of aneurysm clipping.

Coiling of recurrent and residual cerebral aneurysms after unsuccessful clipping

We treated four patients with 3 recurrent and 1 residual aneurysm after surgical clipping by using Guglielmi detachable coils (GDCs). Three subjects presented after a second subarachnoid hemorrhage (SAH) occurring between 10 and 25 years after the first bleeding. Early postoperative angiography of the fourth patient showed an incompletely clipped aneurysm. In three poor grade patients we observed one good outcome, one fair result and one death due to the sequelae of SAH. One good grade patient remained in excellent condition postoperatively. Three aneurysms were totally occluded and in one a more than 90% occlusion was achieved with GDCs. We consider the treatment with GDC a viable alternative to reoperation in all patients with recurrent or residual aneurysms following failed attempt at surgical obliteration.

Anticipation in familial cavernous angioma: ascertainment bias or genetic cause

OBJECTIVES

Anticipation has been linked to unstable trinucleotide repeats in many neurological disorders. We examined the hypothesis of genetic anticipation in familial cavernous angioma (FCA) of the central nervous system.

MATERIAL AND METHODS

The mean ASO of affected individuals was compared between successive generations in 55 families. Intergenerational pair-wise comparisons were employed to avoid several ascertainment biases. Regarding severity of disease both type of manifestation and number of cavernous angiomas were compared between generations.

RESULTS

The mean ASO decreased significantly both from the first to the second generation (31.6 vs 17.8 years; P = 0.000) and from the second to the third generation (17.8 vs 6.7 years; P = 0.002). The pair-wise comparisons also showed significantly earlier ASO. No clear evidence for anticipation with regard to severity of disease was found.

CONCLUSIONS

Molecular genetic studies will determine whether trinucleotide repeats are the underlying mechanism for our observation of anticipation in FCA.

Experimental bifurcation aneurysm: a model for in vivo evaluation of endovascular techniques

An experimental aneurysm model for in vivo testing of endovascular techniques is described. The aneurysm is produced surgically in the neck of the rabbit by partial anastomosis of the left to the right common carotid artery, thus creating an arterial bifurcation. Subsequently, a venous pouch is sutured into the artificial bifurcation. The size of the arteries, coagulation profile and hemodynamic features in this aneurysm model closely mimic human conditions. Surgical technique and our preliminary experience with this model are discussed.

Endovascular therapy of idiopathic cavernous aneurysms over 11 years

PURPOSE

We report our experience with 42 patients with 48 cavernous carotid aneurysms, of whom 32 were treated with endovascular techniques and 10 were managed conservatively.

METHODS

The 48 aneurysms were divided into two subgroups by location: 23 were at the C-3 portion of the carotid artery (small, saccular aneurysms with an epidural, partly intracavernous location) and 25 originated at the C4-5 segment (large or giant often fusiform aneurysms with a true intracavernous location). Morphologic features in both groups correlated well with differences in clinical presentation and also influenced therapy. Sixteen of the 25 C4-5 aneurysms (all large or giant) were treated by balloon occlusion of the parent artery, four (with narrow necks) were treated with Guglielmi detachable coils (GDCs), and five were not treated (asymptomatic or minimally symptomatic). Twelve of 13 C-3 aneurysms were treated with GDCs. Ten C-3 aneurysms were not treated.

RESULTS

Ophthalmoplegia resolved or improved in nine of 12 patients treated with parent artery occlusion. All aneurysms treated by carotid occlusion thrombosed. Twelve of the 17 aneurysms treated with GDCs were 100% filled by the coils, four were 80% to 95% filled, and one was only 40% filled. Seven of the 100% filled aneurysms remained completely occluded, two showed slight coil compaction, and in three, follow-up angiography was not available. Among the incompletely filled aneurysms, two remained unchanged, one showed progressive thrombosis, a fourth revealed coil compaction, and in one, follow-up angiography was not available. One thromboembolic stroke and three transient ischemic attacks occurred perioperatively, for a permanent morbidity of 3.5% and a transient morbidity of 9%. There was no mortality. Mean clinical follow-up was 33 months; mean angiographic follow-up of patients treated with GDCs was 11 months.

CONCLUSION

Surgically difficult cavernous aneurysms can be obliterated by embolization with excellent clinical results. Detachable coils have become an important endovascular tool, especially for narrow-necked cavernous aneurysms of the C-3 segment, which can be protected against rupture in the subarachnoid space in most cases.

In vitro training model for endovascular embolization of cerebral aneurysms

We present a new in vitro model for the training of endovascular embolizations of cerebral aneurysms. The technique and laboratory set-up described allow the embolization of thin-walled, transparent silicone aneurysm models under "semi-physiologic" conditions, i.e., in a closed circulation with pulsatile flow and pressure, simulating the hemodynamic conditions encountered in biologic systems.

Treatment of post-traumatic carotico-cavernous fistulae using electrolytically detachable coils: technical aspects and preliminary experience

We treated six patients with post-traumatic cavernous carotid fistulae by electrothrombosis using Guglielmi's new electrolytically detachable coils. The transarterial endovascular route was chosen in five and the transvenous in one case. Exophthalmos, chemosis and/or an audible bruit disappeared immediately after therapy or in the following month in all patients suffering from these symptoms. Third and sixth cranial nerve palsies resolved in three of four patients. Clinical results were excellent in three, good in two and fair in one. In this last patient massive thrombosis of an enormously dilatated superior ophthalmic vein occurred after treatment of a giant longstanding fistula, leading to unilateral visual impairment and increased sixth nerve palsy. In our first patient the intracavernous carotid artery was occluded by balloons after coil embolisation because of improper coil position and the fear of possible thromboembolic events. Angiographic cure was demonstrated in all cases by angiograms 1-6 months after therapy. The characteristics of these new coils are easy use, manoeuvreability and retrievability. They conform ideally to the shape of the vessel lumen to be obliterated and produce practically no trauma to the vessel walls. Furthermore, they can be positioned in the sinus close to the orifice of the fistula. In the last two cases partial occlusion of the fistula was sufficient to initiate the process of complete thrombosis, and delayed, complete occlusion was observed after 1 month. In our opinion this new device is not only a major contribution to treatment of intracranial aneurysms, but may also improve the results of treatment of carotico-cavernous fistulae.

False aneurysms of the intracavernous carotid artery--report of 7 cases

We present 7 cases of false intracavernous carotid artery aneurysms. Four occurred after trauma and three were caused iatrogenically. Two of the latter occurred in patients with pituitary adenomas, one after transsphenoidal microsurgery and the other after yttrium [YI90] seed implantation into the sella. The third iatrogenic aneurysm was seen shortly after transcavernous tumour surgery. In five of our seven patients massive, delayed, life-threatening epistaxis was the leading symptom. All traumatic cases were associated with immediate unilateral blindness or blurred vision and with skull base fractures. One of these had a concomitant carotid cavernous fistula. Treatment of choice of our 5 recent cases was permanent balloon occlusion of the intracavernous carotid artery at the level of the lesion. Collateral circulation was evaluated prior to definitive carotid occlusion using a balloon test occlusion. During the balloon test adequate collateral circulation was defined as symmetric angiographic filling of both hemispheres. Awake patients were neurologically examined continuously. In unconscious patients transcranial Doppler sonography, electroencephalographic and somatosensory evoked potential monitoring was used in addition. Intra-operative heparin administration was not reversed with protamin. A postoperative continuous heparin infusion was not found necessary. In our two early cases this technique was not available: In the first case we accomplished aneurysm occlusion by a surgically introduced Fogarty balloon catheter. Our second patient needed surgical trapping of the involved carotid after early unsuccessful attempts of selective aneurysm occlusion. After treatment no further epistaxis occurred. Follow-up angiography showed persistent aneurysm occlusion. The results were excellent in 5 cases and good in 1 case. One patient with bilateral lesions suffered a stroke after occlusion of the second, remaining carotid artery, despite functioning bilateral extra-intracranial bypasses. Four years later there is a mild dysphasia still present in this patient. The mean follow-up time was 75.6 months.

Repermeation of partially embolized cerebral arteriovenous malformations: a clinical, radiologic, and histologic study

PURPOSE

To describe the pattern and time course of embolization-related tissue lesions and repermeation of the intranidal cast after endovascular embolization of cerebral arteriovenous malformations (AVMs) with N-butyl cyanoacrylate (NBCA).

METHODS

We retrospectively reviewed the records of 26 patients who were treated by endovascular embolization with NBCA and subsequent surgical extirpation to look for embolization-related tissue lesions and repermeation of the cast. A residual flow through the malformation was identified on preoperative angiograms in every case.

RESULTS

Pattern and time course of embolization-related tissue lesions were typical. Until 3 months after embolization, repermeation of embolized structures did not occur. In contrast, repermeation was found in every patient who had surgery later than 3 months after the first embolization (n = 13; 50%). In these cases, histologic examination of the resected nidus disclosed capillary structures inside the lumen of embolized vessels. Capillaries were traced immunohistochemically with antibodies against membrane-bound factor VIII. No parameter other than the interval between the first embolization and surgery was found to relate to the repermeation of the cast.

CONCLUSION

Intranidal recapillarization can occur later than 3 months after the first embolization with NBCA if total and solid casting of the nidus was not accomplished.

Evolution of different therapeutic strategies in the treatment of cranial dural arteriovenous fistulas--report of 30 cases

30 cases of cranial dural arteriovenous fistuals, treated between 1983 and 1992, are reported. Twelve presented with an aggressive clinical course including intracranial haemorrhage, progredient neurological deficit, medically intractable seizures, and cerebellar symptoms. The other 18 patients had a more benign clinical presentation with audible bruit, exophthalmus, chemosis, and cranial nerve dysfunction. One of the latter had symptoms of pseudotumour cerebri due to sinus occlusion with contralateral sinus stenosis. The most common location was at the transverse sinus, followed by the cavemous sinus, the tentorial ring, and the orbita. Four vessel angiography verified the diagnosis and demonstrated all fistulas, mainly supplied by branches of the external carotid artery. 16 of 18 benign lesions were treated by endovascular therapy alone. Two recent patients received adjuvant stereotactic radiosurgery. Among these 18 patients 2 remained untreated, one because of spontaneous fistula thrombosis prior to therapy and one because of poor medical condition. 12 of 16 treated benign dural fistulas were partially occluded. In 6 of them spontaneous fistula thrombosis occurred during the following months. Total endovascular obliteration was achieved in the remaining 4 patients. 7 of 12 aggressive fistulas were embolized only, one of them having additional radiosurgery. Two of them were totally obliterated and five partially. Surgery was performed in the remaining 5 aggressive fistulas. Complete microsurgical excision was achieved in 2 and partial in further two, who presented initially with a life-threatening intracerebral clot. In one early case ligation of the external carotid artery was done, which is now obsolete. Over all 20 of 28 treated patients became asymptomatic or improved clinically. 3 of the remaining 8 patients were unchanged, two deteriorated despite therapy, and 3 worsened after therapy. All of the latter complications occurred early in our series due to thromboembolic events during the procedure. One surgical patient suffered from a new facial nerve palsy postoperatively. Follow up time in all treated patients was between 1 and 139 months with a mean of 48,3 months.

GDC-system embolization for brain aneurysms - location and follow-up

GDC (Guglielmi detachable coil)-embolization for the treatment of brain aneurysms was first published by Guglielmi in 1991 and has become an integral part of the treatment strategy for cerebral aneurysms in many places around the world. Low morbidity and mortality rates are set against the limited possibilities of aneurysm neck occlusion, especially in large necked aneurysms. Depending on the architecture and on the kind of coil distribution, recanalization of the neck is more or less frequent. Nevertheless, rebleeding rates are low. In our series of 211 brain aneurysms from March 1992 to June 1994, 74 (35%) patients underwent GDC-embolization. 4 patients received combined treatment (GDC-embolization and subsequent surgery). Follow-up angiography was performed on 41 patients (55%) at periods of 6, 12, and 24 months (mean follow-up 8 months). To demonstrate the results in a graphic display, the aneurysms were grouped according to location and size. The analysis of the follow-up results shows the highest occlusion stability in aneurysms of the basilar tip, followed by aneurysms of the PICA origin, the basilar trunk and the PCA. Less stability was obtained in aneurysms of the PCom followed by MCA, Acom and aneurysms of the internal carotid (C1, ophthalmic). Aneurysms of the posterior circulation show generally better results than those located in the anterior circulation. This makes (in combination with the increased surgical difficulties of aneurysms in the posterior fossa) the GDC-treatment especially useful for posterior circulation aneurysms.

Endosaccular occlusion of basilar artery bifurcation aneurysms using electrically detachable coils

Thirteen patients with basilar artery bifurcation aneurysms, treated by electrothrombosis using electrically detachable coils, are presented. Nine of them presented after hemorrhage, two with mass effect, and two were found coincidentally with other ruptured aneurysms. Selection for endovascular therapy was based on the following criteria: 1) poor clinical condition (Hunt and Hess III-V); 2) high surgical risk; 3) age and poor medical condition; 4) morphological features (small necked aneurysms). With endovascular Guglielmi detachable coils aneurysm occlusion ranging from 70-100% was achieved in all cases. All five small necked and two large broad necked aneurysms were totally occluded. Two large aneurysms had a 95% occlusion and two other large aneurysms were 90% occluded. In another patient with a large broad based aneurysm only an 80% occlusion was achieved, because of tortuosity of the vertebrobasilar system. Our last patient, who presented as grade V clinically, was partially treated with a 70% aneurysmal occlusion. The clinical results were excellent in 10 and good in 2. The only poor outcome was seen in the grade V patient. There was no morbidity or mortality related to therapy. The only complication was an asymptomatic dissecting aneurysm at the origin of the vertebral artery. Angiographic follow up time ranged from 6 to 20 months with a mean of 9 months. Four patients were treated too recently to have their angiographic follow up at 6 months. Two patients were lost to follow up. Clinical follow up ranged from 1 to 17 months with a mean of 8.9 months. The analysis of our cases clearly shows that aneurysms, which were densely packed with coils, especially if small necked, were less likely to be reperfused and showed a longlasting stable result. Large broad based aneurysms were more likely to be reopened by blood flow after the first procedure, especially if loosely filled with coils, and needed up to 3 interventions to achieve a satisfying result, whereas later in the series a high percentage rate of occlusion was seen after the first procedure. We consider now also a less than 100% occlusion acceptable, because most of the aneurysms will rupture at the dome, which was occluded in all our cases. We conclude, that this new endovascular method is a viable alternative in the treatment of posterior circulation aneurysms with a high surgical risk, in old patients and those in poor clinical and medical condition.

Radiosurgery in the treatment of cerebral AVMs

Radiosurgery of AVM's is gaining in popularity and is advocated by many for the treatment of lesions less than 3 cm in diameter. During a 17 month period 33 patients with cerebral AVM's were treated with radiosurgery. All regions of the brain were represented in the series including brain stem. A mean follow-up of 10.8 months revealed a 6% rebleed rate and a 9% total complication rate. Multimodality therapy including embolization and surgery is recommended for the treatment of AVM's and radiosurgery is seen as an important adjunctive treatment option.