Long-term feasibility of the new sutureless excimer laser-assisted non-occlusive anastomosis clip in a pig model.

BACKGROUND: High flow bypass surgery can be a last resort procedure for patients suffering from complex neurovascular pathology. Temporary occlusion of a recipient artery in these patients could result in debilitating neurological deficits. We developed a sutureless, mechanical anastomotic connection device, the SELANA clip (Sutureless Excimer Laser-Assisted Non-occlusive Anastomosis clip: SEcl). In the present study, we aim to determine the long-term non-inferiority of the SEcl technique compared with historical data of the conventional ELANA anastomosis technique. METHODS: A total of 18 SEcl bypasses were created on the carotid artery in a porcine model in 6 different survival groups. Mean application times, flap retrieval rates, hemostasis, patency, flow, endothelialization, and remodeling were assessed. RESULTS: The mean application time of the SEcl anastomoses was 15.2 ± 9.6 min, which was faster compared with the conventional ELANA anastomoses. The flap retrieval rate of the SEcl anastomoses was 86% (32/37). Direct hemostasis was achieved in 89% (33/37) SEcl anastomoses. Patency in all surviving animals was 94% (17/18). Bypass flow after six months was 156.5 ± 24.7 mL/min. Full endothelialization of the SEcl pins was observed after 3 weeks. CONCLUSION: The SEcl technique is not inferior to the ELANA technique regarding patency, flap retrieval rate, flow, and endothelialization. On the basis of a significantly shorter application time and superior hemostasis, the SEcl technique could be preferable over the ELANA technique. A pilot study in patients is a logical next step based on our current results.

Neuronavigation and surgery of intracerebral tumours.

Approximately four decades after the successful clinical introduction of framebased stereotactic neurosurgery by Spiegel and Wycis, frameless stereotaxy emerged to enable more elaborate image guidance in open neurosurgical procedures. Frameless stereotaxy, or neuronavigation, relies on one of several different localizing techniques to determine the position of an operative instrument relative to the surgical field, without the need for a coordinate frame rigidly fixed to the patients' skull. Currently, most systems are based on the optical triangulation of infrared light sources fixed to the surgical instrument. In its essence, a navigation system is a three-dimensional digitiser that correlates its measurements to a reference data set, i.e. a preoperatively acquired CT or MRI image stack. This correlation is achieved through a patient-to-image registration procedure resulting in a mathematical transformation matrix mapping each position in 'world space' onto 'image space'. Thus, throughout the remainder of the surgical procedure, the position of the surgical instrument can be demonstrated on a computer screen, relative to the CT or MRI images. Though neuronavigation has become a routinely used addition to the neurosurgical armamentarium, its impact on surgical results has not yet been examined sufficiently. Therefore, the surgeon is left to decide on a case-by-case basis whether to perform surgery with or without neuronavigation. Future challenges lie in improvement of the interface between the surgeon and the neuronavigator and in reducing the brainshift error, i.e. inaccuracy introduced by changes in tissue positions after image acquisition.

The ELANA technique: high flow revascularization of the brain.

High flow revascularization of the brain is hampered by the fact that temporary occusion of a major cerebral artery is necessary to create the distal anastomosis, which may result in brain ischemia. The excimer laser-assisted non-occlusive anastomosis (ELANA) technique circumvents this problem. In this paper we elucidate the development of a non-occlusive way to make anastomoses to the major cerebral arteries.

Timing of aneurysm surgery in subarachnoid haemorrhage--an observational study in The Netherlands.

BACKGROUND: There is still lack of evidence on the optimal timing of surgery in patients with aneurysmal subarachnoid haemorrhage. Only one randomised clinical trial has been done, which showed no difference between early and late surgery. Other studies were observational in nature and most had methodological drawbacks that preclude clinically meaningful conclusions. We performed a retrospective observational study on the timing of aneurysm surgery in The Netherlands over a two-year period. METHOD: In eight hospitals we identified 1,500 patients with an aneurysmal subarachnoid haemorrhage. They were subjected to predefined inclusion criteria. We included all patients who were admitted and were conscious at any one time between admission and the end of the third day after the haemorrhage. We categorised the clinical condition on admission according the World Federation of Neurological Surgeons (WFNS) grading scale. Early aneurysm surgery was defined as operation performed within three days after onset of subarachnoid haemorrhage; intermediate surgery as performed on days four to seven, and late surgery as performed after day seven. Outcome was classified as the proportion of patients with poor outcome (death or dependent) two to four months after onset of subarachnoid haemorrhage. We calculated crude odds ratios with late surgery as reference. We distinguished between management results (reconstructed intention to treat analysis) and surgical results (on treatment analysis). The results were adjusted for the major prognosticators for outcome after subarachnoid haemorrhage. FINDINGS: We included 411 patients. There were 276 patients in the early surgery group, 36 in the intermediate surgery group and 99 in the late surgery group. On admission 78% were in good neurological condition (WFNS I-III). MANAGEMENT RESULTS: Overall, 93 patients (34%) operated on early had a poor outcome, 13 (36%) of those with intermediate surgery and 37 (37%) in the late surgery group had a poor outcome. For patients in good clinical condition on admission and planned for early surgery the adjusted odds ratio (OR) was 1.3 (95% CI 0.5 to 3.0). The adjusted OR for patients admitted in poor neurologicalcondition (WFNS IV-V) and planned for early surgery was 0.1 (95% CI 0.0 to 0.6). SURGICAL RESULTS: For patients in good clinical condition on admission who underwent early operation the adjusted OR was 1.1 (95% CI 0.4 to 3.2); it was 0.2 (95% CI 0.0 to 0.9) for patients admitted in poor clinical condition. CONCLUSIONS: In this observational study we found no significant difference in outcome between early and late operation for patients in good clinical condition on admission. For patients in poor clinical condition on admission outcome was significantly better after early surgery. The optimal timing of surgery is not yet settled. Ideally, evidence on this issue should come from a randomised clinical trial. However, such a trial or even a prospective study are unlikely to be ever performed because of the rapid development of endovascular coiling.

The ELANA technique: constructing a high flow bypass using a non-occlusive anastomosis on the ICA and a conventional anastomosis on the SCA in the treatment of a fusiform giant basilar trunk aneurysm.

A patient with a partially thrombosed fusiform giant basilar trunk aneurysm presented with devastating headache and symptoms of progressive brain stem compression. Having an aneurysm inaccessible for endovascular treatment, and after failing a vertebral artery balloon occlusion test, he was offered bypass surgery in order to exclude the aneurysm from the cerebral circulation and relieve his symptoms. A connection between the intracranial internal carotid artery and the superior cerebellar artery was created whereupon the basilar artery was ligated just distally to the aneurysm. The proximal anastomosis on the internal carotid artery was made using the excimer laser-assisted non-occlusive anastomosis (ELANA) technique, while a conventional end-to-side anastomosis was used for the distal anastomosis on the superior cerebellar artery. Intra-operative flowmetry showed a flow through the bypass of 40 ml/min after ligation of the basilar artery. An angiogram 24 hours later showed normal filling of the bypass and the vessels supplied by it, but also disclosed a subtotal occlusion of the proximal ipsilateral middle cerebral artery with delayed filling distally. The patient, who had a known thrombogenic coagulopathy, died the following day. Autopsy showed no signs of ischemia in the territories supplied by the bypass, but a thrombus in the proximal middle cerebral artery and massive acute hemorrhagic infarction with swelling in its territory and uncal herniation. Multiple fresh thrombi were found in the lungs. The ELANA anastomosis showed re-endothelialisation without thrombus formation on the inside.

Clinical evaluation of stereotactic brain biopsies with an MKM-mounted instrument holder.

OBJECT: The aim of this study was to assess the clinical usefulness and accuracy of robot-assisted frameless stereotactic brain biopsies with a recently introduced MKM-mounted instrument holder. METHODS: Twenty-three patients with intracranial lesions participated in this study. Depending on the size of the intracranial lesion, fiducials for image-to-patient co-ordinate transformation consisted either of bone screws or adhesive markers. Shortly after surgery, postoperative MRI-imaging was performed to demonstrate the location of the biopsy site. These images were compared with the preoperative images to assess the biopsy localisation error. RESULTS: Postoperative biopsy sites could be demonstrated in six patients with bone screws and in 14 with adhesive markers. These two subgroups yielded average biopsy localisation errors of 3.3 mm (SD 1.7 mm) and 4.5 mm (SD 2.0 mm) respectively. This difference was not statistically significant. One biopsy was located in a liquefied haematoma. All others yielded pathological tissue. There were two postoperative haemorrhages, of which only one was temporarily symptomatic. There was no mortality in the first 30 days after surgery. CONCLUSIONS: Robot-assisted frameless point-stereotactic techniques represent an alternative to frame-based techniques for the performance of stereotactic biopsies.

Cerebral revascularization.

During the last 10 years, there has been a revival of interest in cerebral revascularization procedures. Not only have significant progressions in surgical techniques been published, the use of more advanced diagnostic methods has led to a widening of the indications for cerebral bypass surgery. The purpose of this review is to outline the current techniques for extracranial-to-intracranial (EC/IC) and intracranial-to-intracranial (IC/IC) bypass surgery, as well as to identify the current indications for revascularization procedures based on the available literature. The excimer laser-assisted non-occlusive anastomosis (ELANA) technique is described in more detail because we think that this technique almost completely eliminates the risk of cerebral ischemia due to the temporary vessel occlusion which is currently used in conventional anastomosis techniques.

Neurobehavioral status and health-related quality of life in newly diagnosed high-grade glioma patients.

PURPOSE: To evaluate the health-related quality of life (HRQOL) and cognitive functioning of high-grade glioma patients in the postneurosurgical period. PATIENTS AND METHODS: The HRQOL, as assessed by the Short-Form Health Survey-36, tumor-specific symptoms, and objective and subjective neuropsychologic functioning, of 68 newly diagnosed glioma patients were compared with that of 50 patients with non-small-cell lung cancer (NSCLC) and to age- and sex-matched healthy controls. The association between tumor lateralization, extent of resection, and use of medication, and the HRQOL outcomes was also investigated. RESULTS: The HRQOL of the two patient groups was similar but significantly lower than that of the healthy controls. Glioma patients reported significantly more neurologic symptoms and poorer objective and subjective neuropsychologic functioning than the NSCLC patients. Using healthy controls as the reference group, cognitive impairment assessed at the individual patient level was observed in all glioma patients and 52% of the NSCLC patients. Poor performance on timed tasks in the glioma group could be attributed, in large part, to visual and motor deficits. Tumor lateralization was found to affect neuropsychologic functioning in a predictable manner. The extent of resection was not related significantly to neuropsychologic functioning. Corticosteroid use was associated with better recognition memory, whereas antiepileptic drug use was correlated negatively with working memory capacity. CONCLUSION: The general HRQOL of glioma patients is similar to that of patients with NSCLC. However, they suffer from a number of condition-specific neurologic and neuropsychologic problems that have a significant impact on their daily lives in the postsurgical period, before treatment with radiotherapy.

Flow quantification of the non-occlusive excimer laser-assisted EC-IC bypass.

BACKGROUND: For six years, we used the Excimer laser-assisted nonocclusive anastomosis technique for high-flow revascularization of the brain in patients with either nonclippable and noncoilable giant aneurysms of the internal carotid or basilar artery or progressive stroke associated with occlusive disease of the internal carotid artery. The aim of this study is to assess the blood flow capacity of this type of Extra-Intracranial bypass and its haemodynamic behaviour over time. METHODS: Twenty-six patients with a giant aneurysms and 8 patients with occlusive disease of the internal carotid artery were treated with the nonocclusive Excimer laser assisted EC-IC bypass. intra-operatively, direct measurements of flow in the EC-IC bypass were performed in all patients (Transonic Systems, Inc., Ithaca. NY). Postoperatively, follow up measurements of flow were performed with MR angiography in 14 patients with a giant aneurysm after occluding the internal carotid artery, and 7 patients with occlusive carotid disease. RESULTS: The mean flow in the laser assisted bypasses in the group of patients with a giant aneurysm was 158 ml/min after ligation or balloon occlusion of the ICA. The mean flow of the laser assisted bypass in the group of patients with ICA occlusive disease was 130 ml/min. A comparison with data on flow capacity of conventional EC IC bypasses is made. A demonstrated increase of flow in the bypass during follow up is discussed from a haemodynamic point of view. CONCLUSIONS: The results of this study demonstrate that the flow capacity of the nonoccluding excimer laser assisted bypass is much higher than the capacity of the conventional, more peripherally located conventional EC IC bypass, and should therefore be denoted as High-Flow EC IC bypass. Consequently, this type of bypass can be a powerful and safe tool in new revascularization strategies.

Bilateral vertebral artery balloon occlusion for giant vertebrobasilar aneurysms.

We describe the clinical presentation, radiological and clinical results in six consecutive patients with a giant vertebrobasilar aneurysm treated by bilateral vertebral artery balloon occlusion. Five patients presented with headache and signs of brain-stem compression and one with subarachnoid haemorrhage. In all patients vertebral artery balloon occlusion was performed. In four, this followed successful test occlusion. In one patient, who did not tolerate the test occlusion, a bypass from the external carotid to the posterior cerebral artery preceded definitive vertebral artery occlusion. One patient underwent bypass surgery prior to test occlusion. At 6-22 months follow-up three patients had a good functional outcome and showed unchanged size or shrinkage of the aneurysm on MRI. Three other patients died; one from recurrent haemorrhage, and two probably from delayed brain-stem ischaemia. The presence of two large posterior communicating arteries predicted good functional outcome, which was also related to the clinical condition at presentation, and the degree of brain-stem compression and oedema on MRI. Bilateral vertebral artery balloon occlusion can be considered in patients with otherwise untreatable giant vertebrobasilar aneurysms. If test occlusion is not tolerated, a surgical bypass to the posterior circulation can be considered.

Analysis of the results obtained in 120 patients with large acoustic neuromas surgically treated via the translabyrinthine-transtentorial approach.

OBJECT: The authors review the results of a series of 120 acoustic neuromas that were surgically treated via the translabyrinthine-transtentorial approach between 1986 and 1999. METHODS: The authors retrospectively evaluated a series of 120 acoustic neuromas with extrameatal diameters of 2 cm or greater, 99 (82.5%) of which had diameters longer than 3 cm. Complete tumor removal, as ascertained using computerized tomography or magnetic resonance imaging, was achieved in 110 patients (91.7%). The facial nerve was anatomically preserved in 97 patients (80.8%). The main postoperative complications were cerebrospinal fluid (CSF) leakage through the scalp wound (13.3%) requiring surgical revision in 2.5%, meningitis (9.2%), CSF rhinorrhea (6.7%) requiring surgical revision in 2.5%, and epileptic seizures (the only permanent complication) requiring medication (3.3%). There was no death directly related to the surgery. Long-term follow-up examination of the facial nerve revealed recovery of function to the level of House-Brackmann Grade I or II in 56.2% of the patients. CONCLUSIONS: The results and complications presented in this series are comparable to those reported in the literature. The authors conclude that the combined translabyrinthine-transtentorial approach is a safe route for removing acoustic neuromas with a diameter of 2 cm or greater.

An MKM-mounted instrument holder for frameless point-stereotactic procedures: a phantom-based accuracy evaluation.

To enable the use of the Mehrkoordinaten Manipulator (MKM) robotic navigation system for frameless point stereotactic procedures, a new instrument holder is presented. A phantom-based accuracy study was performed in which this new method was compared with frame-based procedures performed using the Brown-Roberts-Wells (BRW) stereotactic frame. The authors acquired computerized tomography scans of a test phantom, consisting of 19 acrylic plastic target rods on a circular base. These images were used in frame-based (BRW) and frameless (MKM) localization experiments. In both cases the authors calculated the distances between the actual target positions and the positions reached stereotactically. The mean application accuracy (target registration error) was 0.68 mm when the BRW frame was used and 0.96 mm when the MKM system was used after manual repositioning of the microscope (p < 0.001). Positioning accomplished using robotics only demonstrated a slightly larger inaccuracy: 1.47 mm (p < 0.005). Because the surgeon is concerned with the largest error in an individual case rather than the mean error in a large number of cases, the mean + three standard deviations was also compared. This value differed very little between the manually positioned MKM system and the BRW frame (2.04 mm and 1.84 mm, respectively). Although repeatability per target appeared to be slightly better when the BRW frame was used, accuracy was more homogeneous over the phantom volume when the MKM system was used (both differences were not significant). In conclusion, the accuracy of point stereotactic procedures performed using an instrument holder attached to the system is comparable with the accuracy of procedures involving a stereotactic frame. Moreover, the frameless techniques and robotic features of the MKM enable a more surgeon- and patient-friendly stereotactic procedure.

Frontal lobe damage and thalamic volume changes.

The aim of this study was to investigate whether frontal lobe damage affects thalamic volume in humans. Ipsilateral and contralateral thalamic areas were measured in 0.5T T1-weighted sagittal magnetic resonance images in 12 patients, first at the time of their surgery for relief of a unilateral frontal lobe brain tumor and at follow-up approximately 2 years later. A 5% decrease in ipsilateral and 4.5% increase in contralateral thalamic area was found over time (F(1,11) = 6.15, p < 0.05). We conclude that unilateral frontal lobe damage results in a decrease in the ipsilateral thalamus and an increase in the contralateral thalamus in humans in vivo. The findings may have implications for the interpretation of the reported changes in thalamic volume in neuropsychiatric diseases.

Carotid balloon occlusion for large and giant aneurysms: evaluation of a new test occlusion protocol.

OBJECTIVE: Validation of a new angiographic test occlusion protocol before carotid balloon occlusion in patients with carotid aneurysms. METHODS: Carotid occlusion was considered for 29 consecutive patients. From 1993 to 1995, test occlusion in four patients consisted of clinical observation for 30 minutes and during electroencephalographic registration. From 1996 onward, test occlusion in 25 patients consisted of clinical observation and angiography of collateral vessels. Permanent balloon occlusion was performed only when the cortical veins in both the occluded and the collateral vascular territories filled synchronously. RESULTS: Two of the four patients with normal clinical and electroencephalographic findings during test occlusion developed delayed hypoperfusion infarction after permanent carotid occlusion. Seventeen of 25 patients (68%) demonstrated both clinical and angiographic tolerance, and no ischemic events occurred after permanent carotid occlusion. In one patient with clinical tolerance but angiographic nontolerance, permanent carotid occlusion had to be performed, which resulted in delayed hypoperfusion infarction. In two patients with angiographic nontolerance, venous filling became synchronous after bypass surgery. Long-term clinical follow-up showed an alleviation of the symptoms of mass effect in 14 of 21 patients (67%). Magnetic resonance imaging follow-up (range, 3-70 mo) revealed a reduction in the size of the aneurysm in 19 of 21 patients (90%). CONCLUSION: Test occlusion with clinical and angiographic control is reliable, safe, and simple to perform.

Outcome in patients with symptomatic occlusion of the internal carotid artery.

OBJECTIVES: to assess whether the risk of recurrent ischaemic stroke in patients with symptomatic internal carotid artery (ICA) occlusion has changed over the past decades, to determine risk factors for the occurrence of ischaemic stroke and to assess the risk of endarterectomy (CEA) of a severe contralateral ICA stenosis. DESIGN: retrospective cohort study. PATIENTS AND METHODS: patients with symptomatic ICA occlusion were identified from duplex registry files between 1991 and 1995. Information was obtained on vascular risk factors, performance of CEA for a contralateral ICA stenosis and on recurrence of ischaemic stroke. The rate of complications occurring within 30 days after CEA of the contralateral ICA in patients with symptomatic ICA occlusion was compared with the risk of CEA in patients with asymptomatic ICA occlusion and severe contralateral ICA stenosis (symptomatic or asymptomatic). RESULTS: ninety-seven patients were identified. Mean follow-up time was 26 months. The annual risk of (non-)fatal stroke was 5.3% for all strokes (95% CI 2. 9%-9.6%) and 3.8% for ipsilateral stroke (95% CI 1.9%-7.7%). Hyperlipidaemia and severe stenosis of the contralateral ICA were independent risk factors. Twenty-two of 32 patients with a severe stenosis of the contralateral ICA underwent CEA, of which one patient died and three suffered a minor ischaemic stroke. The perioperative risk of CEA in the control group of 20 patients with asymptomatic contralateral ICA occlusion was 0% (0 of 20). CONCLUSIONS: outcome in patients with symptomatic ICA occlusion has not substantially improved over the years. CEA for severe stenosis of the contralateral ICA carried a relatively high risk in our series, but deserves to be studied in a controlled design.

Scanning electron microscopic evaluation of nonocclusive excimer laser-assisted anastomosis in rabbits.

BACKGROUND: The nonocclusive Excimer laser-assisted bypass technique has been described in previous studies and proved to be a promising bypass operation in vascular brain surgery. Little is known about the morphological regeneration process of the laser-assisted anastomosis in time. By way of a scanning electron microscopic study we examined the way in which the anastomosis site created by the nonocclusive Excimer laser-assisted anastomosis technique becomes endothelialized. METHODS: In 14 rabbits the internal jugular vein was placed in a loop on the abdominal aorta. The distal anastomosis was made using the nonocclusive Excimer laser-assisted technique. The proximal anastomosis was made either laser-assisted or conventional end-to-side. After clipping of the aorta between the two anastomoses sites the vein served as a bypass. To evaluate the endothelialization at the laser-assisted anastomosis site in time, a scanning electron microscopic study was performed. RESULTS: In the first hours after the bypass operation a new intimal surface is formed by fibrin and activated platelets. Some leukocytes are seen during the first days. The endothelialization process of the laser-assisted anastomosis site begins one day after the operation. The gradual endothelialization process evolved along two lines. First, endothelial cells grow from the side of the aorta to the bypass. Second, after one day solitary (blood-borne) endothelial cells deposit on the laser edge and the sutures, covering the platelet aggregates. CONCLUSIONS: The endothelialization of the Excimer laser-assisted anastomosis is more or less completed 9 days after the operation. The edge created by the laser becomes smoother after a few days and is gone for the most part after 9 days.

[High-flow transcranial bypass for prevention of brain ischemia]. / Transcraniële bypass met grote doorstroming ter preventie van hersenischemie.

In patients in whom the internal carotid artery has to be occluded because of the presence of an intracranial giant aneurysm or an infiltrating skull base tumour and in patients with brain ischaemia, whose internal carotid artery has been occluded spontaneously on the basis of atherosclerosis, a transcranial bypass can be created. Since the beginning of the seventies 'low-flow bypasses' are made in which a branch of the superficial temporal artery is connected with a cortical branch of the middle cerebral artery. Because of the small calibre of the blood vessels involved the desired effect on the brain circulation is limited. Thanks to the nonocclusive Excimer laser-assisted anastomosing technique, developed by Tulleken et al. in the last fifteen years, it is now possible to create a high-flow bypass in a safe way. A donor vessel, e.g. the V. saphena magna, is connected at one end to the external carotid artery and at the other to the intracranial part of the internal carotid artery beyond the pathological lesion. The mean flow through the bypass was 140 ml/min in about 90 patients. For example, in three patients, a woman aged 45 with rightsided progressive ophthalmoplegia due to a giant aneurysm, a woman aged 31 years with an aneurysm in the right middle ear and a man with a chemodectoma at the base of the skull, a transcranial high-flow bypass was created nonocclusively, after which the internal carotid artery was closed without any problems.

MR angiography as a screening tool for intracranial aneurysms: feasibility, test characteristics, and interobserver agreement.

OBJECTIVE: MR angiography may be an appropriate tool to screen for unruptured intracranial aneurysms. Feasibility, test characteristics, and interobserver agreement in evaluation of MR angiograms were assessed by members of the MARS (Magnetic resonance Angiography in Relatives of patients with Subarachnoid hemorrhage) Study Group. SUBJECTS AND METHODS: We screened 626 first-degree relatives of a consecutive series of 193 patients with subarachnoid hemorrhage examined at two institutions. We used MR imaging and MR angiography (three-dimensional time-of-flight imaging at both institutions and additional three-dimensional phase-contrast imaging at one institution). Three observers independently assessed the MR angiograms. Conventional angiography was performed in relatives with possible or definite aneurysms on MR angiography and was considered the standard of reference. RESULTS: Thirty-three aneurysms were found in 25 (4%; 95% confidence interval [CI], 3-6%) of 626 relatives. Thirteen (8%) of 169 relatives who refused screening had MR-related reasons; an additional six persons could not be screened because of contraindications for MR imaging (pregnancy, n = 1; claustrophobia, n = 5). The positive predictive value of MR angiography was 100% (95% CI, 79-100%) for "definite" aneurysms and 58% (95% CI, 28-85%) for "possible" aneurysms. Sensitivity of MR angiography was estimated at 83% (95% CI, 65-94%) and specificity at 97% (95% CI, 94-98%). Interobserver agreement in the evaluation of MR angiograms was poor (kappa < .30), probably because different diagnostic strategies used by individual observers resulted in different use of the assessment category "possible aneurysm." CONCLUSION: MR angiography is a feasible screening tool for detection of intracranial aneurysms. Positive predictive value, sensitivity, and specificity are acceptable when at least two neuroradiologists independently assess MR angiograms.

Prognostic relevance of MIB-1 immunoreactivity, S-phase fraction, 5-bromo-2'-deoxyuridine labeling indices, and mitotic figures in gliomas.

Prognostic relevance of cell proliferation markers was evaluated in 27 glioma patients. By 1) flow cytometry (FCM), i.e., S-phase fraction (SPF), and BrdUrd-labeling index (LIfcm); 2) immunohistochemistry (IHC), i.e., BrdUrd-labeling index (LIihc) and MIB-1 immunoreactivity (MIB-1 LIihc); and 3) histologic examination, i.e., the presence or absence of cells in mitoses, were assessed. A longer local progression free survival (LPFS) was significantly associated with low SPF, low LIfcm, and low MIB-1 LIihc. For LIihc, no significant association was found. LIfcm appeared to be a more promising prognosticator than MIB-1 LIihc. In comparison with this marker, the presence or absence of mitotic figures appeared to be an even stronger prognosticator. Prognostic significance of LIfcm appeared to be of importance in low-grade gliomas. The number of patients in our study is limited. Our findings were: 1) the presence or absence of cells in mitoses (M-phase activity) appeared to be of more prognostic significance than LIfcm (S-phase activity) and MIB-1 LIihc (non-G0-phase activity); 2) of the tested experimental cell proliferation markers, LIfcm appeared to be of more prognostic significance than MIB-1 LIihc, SPF, and LIihc; and 3) LIfcm is likely to be an important prognosticator in low-grade gliomas and is, therefore, not definitive and only of potential interest.