Endovascular treatment of intracranial aneurysms with parent vessel reconstruction using balloon and self expandable stents.

BACKGROUND AND PURPOSE: To assess the feasibility and results of parent vessel stent reconstruction with balloon expandable and self-expandable stents in the treatment of intracranial aneurysms. METHODS: In a total of 18 aneurysms balloon expandable (group A) and self expandable (group B) stents were used in 9 cases each. Stent implantation alone was used in 3 cases, and additional coil packing in the other 15. RESULTS: Stents were successfully deployed in 8 out of 9 in group A and in 9 out of 9 cases in group B. Nearly complete occlusion was achieved in all but one case. At 3 or 6 months stable occlusion was found in 4 group A and 2 group B patients, progressive thrombosis in 3 cases in both groups, and recanalisation in 1 case in group B. Late follow up at 1-4 years demonstrated one progressive thrombosis one recanalisation and 1 stable occlusion in 3 group A, and 2 stable occlusions in 2 group B. patients. Complications included one aneurysm perforation in group A, one in-stent thrombosis and a distal arterial perforation in group B and one groin hematoma in both groups. CONCLUSION: Stent reconstruction of intracranial arteries harbouring aneurysms is feasible and may result in aneurysm thrombosis without coil packing in some cases. Self expanding stents seem to provide a higher rate of success. Aggressive antiplatelet treatment increases the risk of hemorrhagic complications.

Histopathologic evaluation of aneurysms treated with Guglielmi detachable coils or matrix detachable microcoils.

BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the degree of organization and fibrocellular tissue development in aneurysms treated with bare platinum or biologically active microcoils. METHODS: Twelve aneurysms were removed at autopsy between 1-18 days and another 2 between 2-3 months posttreatment. Four aneurysms were surgically removed between 6 months and 3 years following treatment. One aneurysm removed at 8 days and another at 6 months were treated with bioactive (Matrix) coils; the other 16 with bare platinum (Guglielmi detachable coils; GDCs). All specimens were embedded in plastic, stained with hematoxilin-eosin and elastin and examined by light microscopy. RESULTS: All specimens removed within 3 weeks demonstrated intra-aneurysmal thrombus, without signs of organization or fibrotic tissue formation over the neck regardless of the type of coils used. In the GDC-treated aneurysms, evidence of early thrombus organization was observed within 2-3 months, and completed yet imperfect fibrocellular reaction together with residual thrombus at 2-3 years. In the Matrix-treated specimens, the aneurysm cavity was completely filled with granulation tissue corresponding to still ongoing fibrocellular reaction at 6 months, including newly formed blood vessels, smooth muscle cells, and collagen deposition without signs of residual thrombus. CONCLUSIONS: Our results indicate that in aneurysms treated with bare platinum coils thrombus organization does not occur until late after treatment and may remain imperfect for years. In one aneurysm studied 8 days following treatment with Matrix coils, no difference was noted compared to aneurysms treated with bare platinum coils. In another aneurysm examined 6 months following packing with Matrix coils, the histologic changes support the hypothesis that the biologically active polymer may accelerate aneurysm healing.

[Radiosurgery of the brain at the beginning of the 21st century: gamma knife with C-table]. / Sugár agysebészet a XXI. Század hajnalán: a gamma-kés C-modell automata pozícionáló robot rendszerrel.

The goal of stereotactic radiosurgery by definition is "the delivery of a single, high dose of radiation allowing the precise and complete destruction of chosen target structures containing healthy and/or pathological cells, without significant concomitant or late radiation damage to adjacent tissues". This effect is obtained by the precise focusing of multiple low energy radiation beams crossing at the target. Three different techniques can be used for radiosurgery: linear accelerator (LINAC) based radiosurgery, Bragg-peak (proton) therapy and Gamma Knife radiosurgery. Leksell Gamma Knife (LGK) is a dedicated neurosurgical device for brain surgery to destroy predetermined intracranial targets through the intact skull. It operates via the radiobiological effect of stereotactically directed, highly focused ionizing gamma-beams of 201 cobalt-60 sources. The LGK offers the best precision of target during irradiation. The mechanical accuracy is about 0.3 mm, which makes it particularly suitable for highly sophisticated neurosurgical interventions. Radiosurgery was originally developed to treat functional neurological disorders, but soon after its introduction cerebral arteriovenous malformations, and brain tumors became the main targets for the technique. Since the first LGK installation at the Sophiahemmet Hospital, Stockholm, Sweden in 1967, over 150,000 patients have already been treated in more than 150 units worldwide. The accumulated clinical experience with the LGK has established this method as the "golden standard" of radiosurgery. In December 1999, a new development, the LGK Model-C was installed at the Centre Gamma Knife, Université Libre de Bruxelles, Hôpital Académique Erasme, Brussels, Belgium. This was followed by completion of two similar units in Krefeld, Germany, and at the Presbyterian University Hospital, Pittsburgh, Pennsylvania, U.S.A. The major innovation in the design of the LGK Model-C is the robotic Automatic Positioning System, which allows computer-controlled automatic and sequential positioning of multiple shots during treatment. Thus all steps of the procedure are performed through an unbroken digital chain, from stereotactic image acquisition to the control of the irradiation sequence. This represents a significant achievement which increases the accuracy and practicality of the treatment. The technical details of the method are described, and the main treatment indications are reviewed.

[Neuronavigation in pediatric neurosurgery]. / Neuronavigáció a gyermek-idegsebészetben.

The precise orientation in the intracranial space is essential for the minimal invasive neurosurgical interventions. The CT and MR based neuro-navigation permits small, targeted exposures on the skull, and intraoperatively gives exact graphic-interactive guidance to the targeted intracranial lesions. The use of neuro-navigation can shorten the time of surgery and diminish the surgical mortality and morbidity. The favourable experiences of the first 21 neuro-navigation aided operations in pediatric patients performed in the National Institute of Neurosurgery (Budapest, Hungary) with the Vector Vision Neuro-navigation System (BrainLAB Gmbh, Germany) are discussed.

[Neurosurgery using the Gamma Knife]. / Gamma-kés idegsebészet.

Gamma Knife radiosurgery is a neurosurgical technique dedicated to treat a wide spectrum of intracranial pathologies. Radiosurgery is a method employing a single fraction of high dose ionizing radiation beams focused on the stereotactically defined intracranial target volume through the intact skull. This precise irradiation of intracranial volumes can necrotize the targeted cell mass--as in treatments of tumors and functional syndromes--or may induce certain biological effects in the target tissue-as in treatments of AVM's and epilepsy--without imposing a significant risk on the neighboring intact neural tissues. The clinical application of Gamma Knife includes a wide range of neurosurgical indications, such as treatments of arteriovenosus malformations, pituitary adenomas, craniopharyngiomas, meningiomas, vestibular schwannomas, gliomas, metastatic tumors, as well as functional neurosurgical syndromes, such as trigeminal neuralgia, extra-pyramidal dysfunctions, epilepsy, pain- and psychiatric syndromes. The clinical effect of irradiation is not immediate, it becomes detectable on follow up studies after a few months. The application of the technique is determined by the histological type, size and location of the pathology. Gamma Knife has evolved to become an established alternative to opened cranial surgery in certain cases with low morbidity and no mortality, offering a safe neurosurgical treatment for inoperable as well as operable lesions that carry significantly high surgical risk. In our review we present the technical and radiobiological principles, clinical indications, limitations and outcome results of this method. Our data are based on the practice and results of the Lars Leksell Center for Gamma Surgery, Department of Neurosurgery, University of Virginia, Charlottesville, Virginia, USA (Director: Ladislau Steiner dr.).

[Positron emission tomography ia an effective tool in modern oncology]. / A pozitronemissziós tomográfia a korszerü onkológiai ellátás hatékony eszköze.

A total of 399 positron emission tomography (PET) examinations were carried out with a GE 4096 Plus PET scanner during the past 5 years on patients referred to the National Institute of Oncology in Budapest. The majority (n = 316) of these investigations were performed with the use of [18F]-fluorodezoxyglucose (FDG) to map the glucose metabolism; [11C]-methionine PET was indicated in 79 cases to detect protein transport and metabolism. The perfusion tracer [15O]-butanol was applied in only 4 cases to answer certain oncology-related, differential diagnostic questions. The oncological examinations were related to primary diagnostics, staging/restaging and therapy monitoring. In the staging/restaging and therapy monitoring of known tumours, conclusive results were achieved in 81-82% of the cases by using either FDG or [11C]-methionine as tracer. The concordant numerical data indicated that the PET investigation provides a definite answer to the question of the presence or absence of viable tumour tissue, with similar effectivity in any of the above indications, no matter whether FDG or [11C]-methionine is used. The search for occult primary tumours was the most frequent indication within the primary diagnostics: 10 (37%) primaries were localized by using FDG PET in the 27 investigated cases. This is a remarkably high value, especially in view of the failure of all the conventional diagnostic procedures carried out prior to the PET investigations. Application of PET may be indicated in all cases when the ultimate question is a non-invasive estimation of viable tumorous tissue.

[Speech activation SPECT measurements in the determination of hemispheric dominance]. / Beszédaktivációs SPECT vizsgálatok a féltekei dominancia meghatározásában.

Cognitive activity leads to an increased regional cerebral blood flow (rCBF) and energy metabolism in both cerebral hemispheres. In order to assess the reliability of rCBF-SPECT measurements in hemispheric dominance (Broca's area) speech activation SPECT studies were performed in nine patients. Patients (men, n = 6; women, n = 3, mean age: 33.8 +/- 13.8 years) with diagnosis of epilepsy (n = 7) and AVM (n = 2) participated in the preoperative study. Two SPECT studies were performed in each case, one in rest, and one during speech activation. 740 MBq of 99mTc-HMPAO/ECD was injected and stereo TCD monitoring was performed during the three minutes of speech activation. The acquisition was performed by a dual-head ADAC Solus Epic Atlas SPECT camera (ADAC Laboratories, Milpitas, USA). RCBF SPECT measurements were analyzed visually and by a special region-of-interest (ROI) program. The hemispheric dominance profiles were established on the basis of the respective blood flow velocity values obtained by fTCD and cortical hyperperfusion measured by SPECT. The neuropsychological test battery, used in the present study, was developed in our institute. The results of rCBF-SPECT studies highly correlated with the lateralization of hemispheric dominance measured by fTCD. There was a significant increase of rCBF in the inferior posterior frontal cortex (Broca's area, p < 0.0003). The non-invasive speech activation rCBF-SPECT measurement is a highly reliable and useful method in the determination of hemispheric dominance. SPECT studies are especially useful in cases where the performance of fTCD measurements are impossible due to the lack of temporal bone window or occlusive cerebral arterial disease.

[The gamma-knife in stereotaxic surgery. A new era in brain surgery]. / A gamma-kés stereotaxiás sugársebészetröl. Uj korszak az agysebészetben.

The gamma knife is a dedicated neurosurgical equipment for brain surgery to treat predetermined intracranial normal or pathological targets through the intact skull without damaging the surrounding normal brain tissue. The operating method is called radiosurgery and it works with the biological effect of stereotactically directed, highly focused ionizing beams of 201 independent cobalt-60 sources. The treatment is a single day procedure with obvious advantages over the invasive conventional craniotomy-related surgery. It has the benefits of increased biological efficacy of the irradiation along with decreased hospital stay and side effects. The device and radiosurgery was originally developed to treat functional neurological diseases, but very soon arteriovenous malformations and tumours became the main objects for the method, and a new dimension opened in the treatment of brain pathologies with difficult access. The first gamma knife was installed in Stockholm, Sweden in 1968. Since then 85 units have been set up, and more than 70,000 patients were treated with the device worldwide. The simple management technique and high mechanical and beam accuracy made the gamma knife a reliable and effective tool for its intended purpose over 30 years now. This review summarizes the history of the device, the basic radiation physics and biology related to stereotactic radiosurgery, the description of the unit and the possibilities and limits of the treatment modality.

Sterically inhomogenous viscoelastic behavior of human saccular cerebral aneurysms.

To clarify the mechanism leading to the development and rupture of intracranial aneurysms, tensile strength and viscoelastic parameters of 22 human saccular aneurysms were investigated. Meridional and circumferential strips from the thin and the thick part of the aneurysm sack and 18 control strips from the basilar artery of 8 patients with pathologies not affecting the cerebral arterial system were studied. The length of the strips was increased in 200- microm steps, while distending force was recorded. Tensile strength and viscoelastic parameters were computed. In both directions, tensile strength of thick strips was significantly lower than that of controls. In the meridional direction, tensile strength of thin strips was significantly larger than that of thick ones (14.5 +/- 4.1 x 10(6) vs. 7.5 +/- 2.0 x 10(6) dyn/cm2, p < 0.05). In the circumferential direction, thin strips tore at lower strain values than thick ones (29 +/- 4 vs. 55 +/- 16%, p < 0.05). Viscoelastic parameters changed in parallel. In circumferential direction, values of thick and thin strips were significantly lower than those of controls. In the meridional direction, values of thin strips were significantly higher than those of the thick ones. These observations show that characteristic mechanical deterioration and steric inhomogeneities accompany the loss of smooth muscle cells and the derangement of connective tissue elements in the wall of intracranial aneurysms, which may explain certain steps in their initiation, enlargement and rupture.

[First Hungarian experiences with positron emission tomography (PET) studies. Members of the PET working group]. / Elsö hazai tapasztalatok pozitron emissziós tomográfiás (PET) vizsgálatokkal. PET munkacsoport tagjai.

Diagnostic investigations commenced on the 28th of June 1994 in Hungary's and Central Europe's first PET Centre at the University Medical School of Debrecen. The Centre is equipped with a GE 4096 Plus whole body PET scanner. A metabolic tracer, 18F-deoxy-D-glucose (FDG), was used in the investigations. During the first 15 months 249 PET investigations were made in the Centre of which 242 were diagnostic and 7 normal subjects served as control for the patient studies with brain scans. The number of oncological indications (intra- and extracranial tumours, Hodgkin's lymphomas) was n = 105 (43.4% of the 242 diagnostic examinations), neurological investigations (without intracranial tumours) formed the dominant group (n = 117; 48.3%), whereas the number of cardiological indications was 20 (8.3%). The oncological studies included those of intracranial tumours (n = 76; 31.4%); thyroid tumours (n = 9; 3.7%); Hodgkin's lymphomas (n = 7; 2.9%) and other extracranial tumours (n = 13; 5.4%). The distribution of different neurological and psychiatric investigations was as follows: localization of focal epileptogen zone (n = 60; 24.8%); differential diagnosis of dementias (n = 30; 12.4%); exploration of cerebrovascular diseases (n = 10; 4.1%); and other neurological diseases (n = 17; 7.0%). The main objective of the cardiological PET investigations was the exploration of viable myocardium. The present paper overviews both the procedures (including administrative issues, as well) and the results of the first 249 FDG-PET investigations.

Treatment of cystic craniopharyngiomas with yttrium-90 colloid solution.

The authors analyzed long-term follow-up data to assess the value of intracavitary irradiation with stereotactically implanted beta-emitting radioisotope (90)Y-silicate colloid for the treatment of craniopharyngiomas. Fifty-seven craniopharyngiomas in 42 patients were selected for retrospective analysis. The yttrium-90 was implanted intracavitally, using computerized tomography-guided and three-dimensional stereotactic treatment planning. The cumulative dose aimed at the inner surface of the cyst wall was 300 Gy. An average of 75% shrinkage of the initial cyst volume was observed. In 18 cases the reduction was more than 91%, and the cyst disappeared totally in 11 cases. A 50% decrease in cyst volume was usually apparent between the 2nd and 4th months. A 70% decrease in cyst volume was seen by the 5th and 6th months and an 80% reduction by the 7th and 8th months. Cysts that were unchanged remained so throughout the observation period. The time course of volume reduction could be expressed mathematically by the formula of 0.73 X e(-0.62 X T) + 0.27, where "e" is the basic number of natural logarithm and "T" is the time expressed in months. Mean survival duration after intracavitary irradiation was 9.4 years. The shrinkage of the cyst was a consequence of fibrosis of the wall, as seen on histopathological examination. The neuroophthalmological prognosis was favorable only when the optic disc was normal or nearly normal at the time of the treatment. In the presence of preexisting optic atrophy, visual deterioration proved to be irreversible. The long-term results support the view that intracavitary (90)Y-irradiation is a noninvasive and very effective method of treatment for craniopharyngioma cysts. Because of the 1.1 mm half-life decay of beta irradiation, it cannot influence the solid part of the tumor; therefore, the best result can be expected in solitary cysts.

Endogenous opioid mechanisms in hypothalamic blood flow autoregulation during haemorrhagic hypotension and angiotensin-induced acute hypertension in cats.

The influence of naloxone-induced general opiate receptor blockade on hypothalamic blood flow autoregulation was investigated in anaesthetized, artificially ventilated, temperature controlled cats. In order to study the changes of the hypothalamic blood flow (H2-gas clearance technique) at the lower limit of autoregulation systemic arterial pressure was reduced in a stepwise manner to 100, 80, 60 and 40 mmHg, by haemorrhage. Autoregulatory mechanisms of the hypothalamic vessels remained effective and hypothalamic blood flow showed no significant reduction until the arterial pressure was reduced to 60 mmHg in the vehicle-treated control cats. General opiate receptor blockade by 1 mg kg-1 mL-1 i.v. injected naloxone resulted in a significant reduction of the autoregulatory capacity of the hypothalamic vessels: the blood flow followed passively the arterial pressure fall already from 100 mmHg mean arterial pressure. The effect of opiate receptor blockade on the upper limit of the autoregulation was studied during acute arterial hypertension, induced by angiotensin-II infusion (25 micrograms 0.1 mL-1 min-1 i.v.). Hypothalamic blood flow remained remarkably steady following angiotensin-II infusion in the saline-treated control animals. Naloxone pretreatment (1 mg kg-1 mL-1 i.v.), however, induced a significant downward shift of the upper limit of the autoregulation, and hypothalamic blood flow started to increase in the 125-145 mmHg arterial pressure range. The narrowing of the autoregulatory range following general opiate receptor blockade suggests an important role of endogenous opioid peptides in hypothalamic blood flow autoregulatory mechanisms both in hypotensive and in hypertensive conditions.

Tumors of the cerebellopontine angle. Changing policy in treatment.

One hundred and twenty-six cases of cerebellopontine angle tumors with various histologies are presented. Results of 75 operated vestibular neurinomas, 22 meningiomas, and 16 tumors with other histologies are discussed. The method of irradiation and non-radical surgery may be an alternative for treatment.

Regional heterogeneity and differential vulnerability of cerebral and spinal vascular CO2-responsiveness during graded haemorrhagic hypotension.

Regional inhomogeneity of cerebrovascular CO2-sensitivity as well as its changes at three different levels of standardized haemorrhagic hypotension were studied in ten distinct brain and spinal cord regions of anesthetized, ventilated cats. Regional cerebral blood flow was measured with radiolabelled microspheres in hypocapnic, normocapnic, and hypercapnic conditions, and CO2-responsiveness was determined from the equation of the slopes of the best fit regression lines to the obtained flow values. It was concluded that in normotensive, normoxic cats response of the cerebral and spinal vessels to PaCO2 alterations can be assigned to four major categories. The CO2-responsiveness of a brain region is not solely determined by the rate of its basal steady state blood flow: CO2-reactivity of the hypothalamus was significantly different from that of any other investigated regions with almost identical steady state flow values. Vulnerability of the cerebrovascular CO2-sensitivity during hypotension was different from region to region, with the vessels of the pons-medulla oblongata region being the most sensitive to haemorrhage. Reduced regional cerebral and spinal CO2-responsiveness during haemorrhage is not a consequence of a reduced L-arginine supply for nitric oxide generation since administration of an excess amount of the precursor L-arginine failed to restore the haemorrhage-induced reduction of regional CO2-sensitivity at the 60 mm Hg mean arterial pressure level.

Major role of nitric oxide in the mediation of regional CO2 responsiveness of the cerebral and spinal cord vessels of the cat.

The role of nitric oxide (NO) in the mediation of cerebrovascular CO2 responsiveness was studied in 10 distinct brain and spinal cord regions of the anesthetized, ventilated, temperature-controlled, normoxic cat. Regional CBF was measured with 15-micron radiolabeled microspheres in hypocapnic, normocapnic, and hypercapnic conditions. CO2 responsiveness of each region was determined from the equation of the best-fit regression lines to the obtained flow values. The effect of altered endothelial and/or neuronal NO synthesis on CO2 responsiveness was studied following either selective blockade of the NO synthase enzyme by N omega-nitro-L-arginine methyl ester (L-NAME; 3 or 30 mg/kg i.v.) or simultaneous administration of L-NAME (3 mg/kg i.v.) and a large dose of the NO precursor L-arginine (30 mg/kg i.v.). Blockade of NO synthesis by 30 mg/kg L-NAME resulted in a significant reduction of the steady-state regional blood flow values and in an almost complete abolition of the CO2 sensitivity in each region studied. Changes of the basal flow values as well as the reduction of the regional CO2 sensitivity were dose dependent. Hypothalamic, sensorimotor cortical, and cerebellar regions were the areas most sensitive to the NO blockade. Impaired CO2 responsiveness following NO synthase inhibition, however, was reversed in these regions by simultaneous administration of a large dose of intravenously injected L-arginine. These findings suggest a major role of nitric oxide in the mediation of regional cerebrovascular CO2 responsiveness in cats.

Early surgery for ruptured cerebral aneurysm.

Preliminary experience with 150 consecutive cases of ruptured cerebral aneurysms operated on within 48 hours is reported. The rationale of this emergency procedure is to prevent early rerupture and also to prevent neurological ischaemic consequences of the subarachnoid haemorrhage likely to develop in the first week after a rupture. The acceptable outcome of the surgically treated cases (87% excellent and good outcome) has been favourably matched to those of a group of equal number of consecutive cases seen in suitable condition for surgery within 48 hours by medical personnel but that remained unoperated for various reasons. The incidence of delayed neurological ischaemia as the definite cause of death is lower in the group operated on in the acute stage than those with delayed surgery, although the overall incidence of clinical vasospasm does not seem significantly lower than in the delayed surgery group.

Stroke rehabilitation: a method and evaluation.

Subjects of this study were 53 patients who presented with cerebrovascular stroke and who took part in a rehabilitation programme that included the basic elements of Bobath's concept and Peto's Conductive Education. The protocol called for a three point assessment: on admission to the rehabilitation ward and at one month and one year after entry. Baseline and follow-up examinations included clinical and laboratory tests, CT scan, cerebral blood flow studies and angiography. Motor functions were evaluated by the Rivermead Motor Assessment and dependence (ADL) was measured by the Barthel index. Neuropsychological evaluations were also made using Benton's test, Bourdon's letter cancellation test and the Wechsler Adult Intelligence Scale. Significant improvement was found in functional conditions both one month and one year after entry. There was a strong correlation between the Rivermead Motor Assessment and the Barthel index. The Rivermead Motor Assessment proved to be the most sensitive indicator of improvement in relation to the size and site of the infarct.

Contralateral approach to bilateral and ophthalmic aneurysms.

In a previous survey, we found a high incidence of fatal rupture of an unclipped aneurysm in patients with multiple aneurysms. To deal with this problem, we introduced a more vigorous technique that accesses aneurysms previously considered unapproachable during one operating session. Attempts were made to clip middle cerebral and ophthalmic aneurysms contralateral to the operative exposure. We have successfully clipped contralateral aneurysms of the posterior communicating artery when bilateral aneurysms were present. We have also used this contralateral approach successfully with single ophthalmic and proximal carotid aneurysms that pointed medially. We review the cases of 39 patients with 43 intracranial aneurysms operated from the contralateral side and present the surgical technique in relation to the angiographic findings.