Diffusion-weighted magnetic resonance imaging for detection of postoperative intracranial pyogenic abscesses in neurosurgery.

BACKGROUND: Diffusion-weighted magnetic resonance imaging (MRI-DWI) is the modality of choice for detecting intracranial abscesses; however, it is unclear whether prior brain surgery has an influence on its diagnostic value. Thus, we assessed the robustness of MRI-DWI and determination of an ADC cutoff value for detecting intracranial abscesses in patients who underwent brain surgery. METHODS: We retrospectively evaluated 19 patients prior to surgery for postoperative supratentorial parenchymal abscesses by means of MRI-DWI. Forty randomly selected patients with routine postoperative MRI-DWI were used for comparative analyses. Clinical and serum biomarkers (C-reactive protein, interleukin-6, white blood cell count) as well as from results of early postoperative imaging findings (computed tomography and/or MRI scan) were recorded. Additionally, ADC values, T1±gadolinium, and T2/fluid-attenuated inversion recovery sequences were investigated. RESULTS: After initial surgery, early postoperative control imaging showed evidence of hemorrhage and/or hemostatic agents within the resection cavity in 10/19 patients of the abscess group and in 16/40 patients of the control group. No postoperative ischemia was detected. Neither hemostatic agents nor blood affected the mean ADC values in both the reference group (blood 2.96 ± 0.22 × 10-3 mm2/s vs. no blood 2.95 ± 0.26 × 10-3 mm2/s, p = 0.076) and in the abscess group (blood 0.87 ± 0.07 × 10-3 mm2/s vs. no blood 0.76 ± 0.06 × 10-3 mm2/s, p = 0.128). The mean ADC value within the resection cavity was significantly lower in the abscess group (1.5 T 0.88 ± 0.41 vs. 2.88 ± 0.20 × 10-3 mm2/s, p < .01; 3.0 T 0.75 ± 0.24 vs. 3.02 ± 0.26 × 10-3 mm2/s, p < 0.01). The optimal ADC cut-off for the differentiation of an abscess from normal postoperative findings was found at 1.87 × 10-3 mm2/s (area-under-the-curve 1.0, sensitivity = 100%, specificity = 100%). Moreover, no differences between the abscess patients and the control group were seen with respect to the analyzed serum biomarkers. CONCLUSION: MRI-DWI provides a robust tool to discriminate postoperative abscess formation from normal postoperative changes.

Successful mechanical thrombectomy in a three-year-old boy with cardioembolic occlusion of both the basilar artery and the left middle cerebral artery.

BACKGROUND: Paediatric stroke is a potentially life-threatening emergency and requires immediate treatment to improve clinical outcome. In contrast to adult treatment recommendations, little is known about safety and efficacy of thrombolysis and mechanical thrombectomy in children. CASE DESCRIPTION AND CONCLUSION: We report on a three-year-old boy with a cardioembolic intracranial two-vessel occlusion and successful therapy with thrombolysis and mechanical thrombectomy. Furthermore, this case emphasizes the need of standardized protocols for acute management of paediatric stroke.

Immediate and 12 months follow up of function and lead integrity after cranial MRI in 356 patients with conventional cardiac pacemakers.

BACKGROUND: Conventional cardiac pacemakers are still often regarded as a contraindication to magnetic resonance imaging (MRI). We conducted this study to support the hypothesis that it is safe to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if close supervision and monitoring as well as adequate pre- and postscan programming is provided. METHODS: We followed up 356 patients (age 61.3 ± 9.1 yrs., 229 men) with single (n = 132) or dual chamber (n = 224) cardiac pacemakers and urgent indication for a cranial MRI for 12 months. The scans were performed at 1.5T. During the scan patients were monitored with a 3-lead ECG and pulse oximetry. Prior to the scan pacemakers were programmed according to our own protocol. RESULTS: All 356 scans were completed without complications. No arrhythmias were induced, programmed parameters remained unchanged. No pacemaker dysfunction was identified. Follow-up examinations were performed immediately, 2 weeks, 2, 6, and 12 months after the scan. There was no significant change of pacing capture threshold (ventricular 0.9 ± 0.4 V@0.4 ms, atrial 0.9 ± 0.3 V@0.4 ms) immediately (ventricular 1.0 ± 0.3 V@0.4 ms, atrial 0.9 ± 0.4 V@0.4 ms) or at 12 months follow-up examinations (ventricular 0.9 ± 0.2 V@0.4 ms, atrial 0.9 ± 0.3 V@0.4 ms). There was no significant change in sensing threshold (8.0 ± 4.0 mV vs. 8.1 ± 4.2 mV ventricular lead, 2.0 ± 0.9 mV vs. 2.1 ± 1.0 mV atrial lead) or lead impedance (ventricular 584 ± 179 Ω vs. 578 ± 188 Ω, atrial 534 ± 176 Ω vs. 532 ± 169 Ω) after 12 months. CONCLUSIONS: This supports the evidence that patients with conventional pacemakers can safely undergo cranial MRI in a 1.5T system with suitable preparation, supervision and precautions. Long term follow-up did not reveal significant changes in pacing capture nor sensing threshold.

Mechanical thrombectomy in basilar artery thrombosis: technical advances and safety in a 10-year experience.

PURPOSE: Multiple endovascular devices have been used for mechanical thrombectomy (MT) in basilar artery occlusion (BAO) for >10 years. Based on a single-center experience during the course of one decade, we present data on safety and efficacy of previous MT devices compared with modern stent retriever and suction thrombectomy. MATERIALS AND METHODS: Eighty-one patients (29 women, 52 men, mean age 61.5 years, range 17-90) with angiographically confirmed BAO that had been treated by MT between 2001 and 2011 were retrospectively evaluated. Patients in group 1 (n = 60) had been treated between 2001 and 2008 with different devices available at that time. Patients in group 2 (n = 21) had been treated by modern stent retriever or local suction devices between 2008 and 2011. Recanalization rate, needle to recanalization time, procedure-related complications, and distal embolization of thrombotic material were recorded and compared. RESULTS: Recanalization rates of 95% were high in both groups. Procedure-related dissection (n = 5) and subarachnoid hemorrhage (n = 9) occurred in group 1 but not in group 2 (p < 0.016). Needle-to-recanalization time was less than half in group 2 compared with group 1 (54.6 vs. 132.3 min, p < 0.01). Frequency of distal embolization was comparable in both groups (47%). CONCLUSION: High recanalization rates have been achieved since the introduction of MT in BAO. However, modern stent retriever and suction devices allow for safer and more rapid recanalization compared with previous MT devices.

Endovascular mechanical recanalisation after intravenous thrombolysis in acute anterior circulation stroke: the impact of a new temporary stent.

PURPOSE: Treatment of acute stroke by endovascular mechanical recanalisation (EMR) has shown promising results and continues to be further refined. We evaluated the impact of a temporary stent compared with our results using other mechanical devices. MATERIALS AND METHODS: We analysed clinical and radiological data of all patients who were treated by EMR after intravenous thrombolysis for acute carotid T- and middle-cerebral artery (M1) occlusions at our centre between 2007 and 2011. A comparison was performed between those patients in whom solely the stent-retriever was applied (group S) and those treated with other devices (group C). RESULTS: We identified 14 patients for group S and 16 patients for group C. Mean age, National Institute of Health Stroke Scale score, and time to treatment were 67.1 years and 16.5 and 4.0 h for group S and 61.1 years and 17.6 and 4.5 h for group C, respectively. Successful recanalisation (thrombolysis in cerebral infarction scores ≥IIb) was achieved in 93% of patients in group S and 56% of patients in group C (P < 0.05). Mean recanalisation times for M1 occlusions were 23 min (group S) and 29 min (group C) and for carotid-T occlusions were 39 min (group S) and 50 min (group C), and 45% of the patients in group S and 33% in group C had a favourable outcome (Modified Rankin Scale score ≤2). CONCLUSION: The findings suggest an improvement in recanalisation success by the application of a temporary stent compared with previously used devices. These results are to be confirmed by larger studies.

Hyperdense basilar artery sign-a reliable sign of basilar artery occlusion.

INTRODUCTION: We aimed to investigate the value of the hyperdense basilar artery (HBA) sign and of basilar artery (BA) attenuation measurements as predictors of basilar artery occlusion (BAO) on nonenhanced cranial CT (NECT). METHODS: Forty-one consecutive patients with proven BAO in CT angiography, who had undergone NECT for initial evaluation (30 males, 11 females) were retrospectively included. Another 41 age-matched patients without BAO were included as a control group. The NECT scans of both groups were assessed by three independent blinded readers (staff, fellow, and resident) in a randomized reading order using a standardized semiquantitative questionnaire. Visual BA hyperdensity, including the presence of HBA sign (hyperdensity scores of 4 and 5/5), was assessed, quantitative BA attenuation was measured in a region of interest (ROI), and diagnosis of BAO was made before and after ROI measurements. For statistical analysis, multivariate mixed effects models, likelihood ratio tests, and receiver operating characteristics techniques were applied. RESULTS: HBA sign had a relatively low sensitivity (60.98-65.85%), specificity (70.73-90.24%), and accuracy (65.85-75.61%) for the presence/absence of BAO on NECT. Optimal cut-off points were 40-42 HU (sensitivity, 68.29-78.05%; specificity, 75.61-82.93%; accuracy, 74.39-80.49%). CONCLUSION: In basilar artery occlusion, quantitative measurement of BA attenuation can slightly improve the diagnostic predictiveness of NECT. However, even with optimal cut-off values, the sensitivity is too low to serve as the sole diagnostic decision-making tool.

Detailed imaging of the normal anatomy and pathologic conditions of the cavernous region at 3 Tesla using a contrast-enhanced MR angiography.

INTRODUCTION: The purpose of this study was to evaluate the potential of a high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) at 3 Tesla for the delineation of the cavernous sinus (CS) anatomy both under normal and under pathological conditions. METHODS: Fifteen patients without pathologies in the CS and ten patients with pituitary adenomas were included. The CE-MRA was performed on a 3-Tesla scanner and analyzed collaboratively by two readers. The cranial nerves (CNs) within the CS, namely CNIII, CNIV, CNV1, CNV2, and CNVI, were identified in both patient groups. In the adenoma patients it was also assessed whether and to which extend the adenoma invaded the CS and the spatial relationship between tumor and CNs was determined. RESULTS: In the patients with normal CS anatomy, CNIII could be identified in 100%, CNIV in 86.7%, and CNV1, CNV2, as well as CNVI in 100% of analyzed sides. Pituitary adenomas invaded the CS unilaterally (right side) in four patients, and bilaterally in six patients. In patients with adenomas, the CN could be identified and differentiated from the tumor in the following percentages: CNIII in 100%, CNIV in 70%, both CNV1 and CNV2 in 90%, and CNVI in 100%. In all these cases, the tumor-nerve spatial relationship could be visualized. CONCLUSIONS: 3-Tesla CE-MRA allows detailed imaging of the complex anatomy of the CS and its structures. In adenoma patients, it clearly visualizes the spatial relationship between tumor and CNs, and thus might be helpful to optimize presurgical planning.

Endovascular mechanical recanalisation of acute carotid-T occlusions: a single-center retrospective analysis.

PURPOSE: Acute carotid-T occlusion generally responds poorly to thrombolysis. Endovascular mechanical thrombectomy (EMT) seems to be a promising alternative. However, there are few data on EMT in carotid-T occlusions. MATERIALS AND METHODS: We reviewed data of 14 consecutive patients with acute carotid-T occlusions treated with mechanical recanalisation devices. A clot separation/aspiration system was used in 11 patients; different other mechanical retriever devices were used in seven patients; and stents were used in four patients. Modified Rankin Scale scores at 90 days were recorded to assess functional outcome. RESULTS: Six women and eight men were included in the study. Mean patient age was 59.2 years; median National Institute of Health Stroke Scale score on admission was 19; and mean time to treatment was 4.2 h. Successful recanalisation (Thrombolysis in Myocardial Infarction [TIMI] score II and III) was achieved in 11 patients (78.6%). Seven patients (50.0%) were treated with more than one device, leading to successful recanalisation in six of these patients (85.7%). Subarachnoid haemorrhage and large space-occupying bleedings occurred in one (7.1%) and three (21.4%) patients, respectively. At follow-up, three patients (21.4%) were functionally independent, and six (42.9%) had died. CONCLUSION: When applying different mechanical devices, we found a high recanalisation rate. However, discrepancy between recanalisation and clinical outcome remained. More data are needed to assess the effect of the different methods on the prognoses of stroke patients.

Central retinal artery occlusion: local intra-arterial fibrinolysis versus conservative treatment, a multicenter randomized trial.

PURPOSE: The reported outcomes of central retinal artery occlusion (CRAO) with or without treatment vary considerably. Although local intra-arterial fibrinolysis (LIF) using recombinant tissue plasminogen activator (rtPA) is a promising treatment, outcomes have not been compared in randomized trials. DESIGN: Prospective randomized multicenter clinical trial (the European Assessment Group for Lysis in the Eye Study) to compare treatment outcome after conservative standard treatment (CST) and LIF for acute nonarteritic CRAO. PARTICIPANTS: Between 2002 and 2007, 9 centers in Austria and Germany recruited 84 patients (40 received CST, 44 received LIF), and data for 82 patients were analyzed. METHODS: Patients (age 18-75 years) with CRAO, symptoms for 20 hours or less, and best-corrected visual acuity (BCVA) <0.5 logarithm of the minimum angle of resolution (logMAR) were randomized to the CST or LIF group. MAIN OUTCOME MEASURES: The primary end point was BCVA after 1 month; the secondary end point was safety. RESULTS: The mean interval between first symptoms and therapy was 10.99+/-5.49 hours (CST) and 12.78+/-5.77 hours (LIF). The mean BCVA (logMAR) improved significantly in both groups (CST: -0.44 [standard deviation 0.55]; LIF: -0.45 [standard deviation 0.55]; both P < 0.0001) and did not differ between groups (P=0.69). Clinically significant visual improvement (> or = 0.3 logMAR) was noted in 60.0% (CST) and 57.1% (LIF) of patients. Two patients in the CST group (4.3%) and 13 patients in the LIF group (37.1%) had adverse reactions. Because of apparently similar efficacy and the higher rate of adverse reactions in the LIF group, the study was stopped after the first interim analysis at the recommendation of the data and safety monitoring committee. CONCLUSIONS: In light of these 2 therapies' similar outcomes and the higher rate of adverse reactions associated with LIF, we cannot recommend LIF for the management of acute CRAO. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Sensitivity and reliability of language laterality assessment with a free reversed association task--a fMRI study.

OBJECTIVE: The aim of the study was to evaluate the sensitivity and reliability of assessing hemispheric language dominance with functional magnetic resonance imaging (fMRI) using a 'free reversed association task.' METHODS: Thirty-nine healthy subjects (13 dextrals, 13 sinistrals and 13 bimanuals) underwent two repeated fMRI sessions. In the active phases sets of words were presented via headphones, and an associated target item was named. During the baseline phases a standard answer was given after listening to unintelligible stimuli. Data were preprocessed with SPM, and then laterality indices (LI) and reliability coefficients (RC) were calculated. RESULTS: Extensive frontal, temporal and parietal activations were found. Seventy-eight percent of the subjects showed left-hemispheric dominance, 5% showed right-hemispheric dominance, and 17% had bilateral language representations. The incidence of right-hemispheric language dominance was 4.3 times higher in a left-hander with a handedness quotient (HQ) of -90 than in a right-hander with a HQ of +90. The RC was 0.61 for combined ROIs (global network). Strong correlations were found between the two session LIs (r = 0.95 for the global network). CONCLUSION: 'Free reversed association' is a sensitive and reliable task for the determination of individual language lateralization. This suggests that the task may be used in a clinical setting.

Cranial CT with 64-, 16-, 4- and single-slice CT systems-comparison of image quality and posterior fossa artifacts in routine brain imaging with standard protocols.

Posterior fossa artifacts constitute a characteristic limitation of cranial CT. To identify practical benefits and drawbacks of newer CT systems with reduced collimation in routine cranial imaging, we aimed to investigate image quality, posterior fossa artifacts and parenchymal delineation in non-enhanced CT (NECT) with 1-, 4-, 16- and 64-slice scanners using standard scan protocols. We prospectively enrolled 25 consecutive patients undergoing NECT on a 64-slice CT. Three groups with 25 patients having undergone NECT on 1-, 4- and 16-slice CT machines were matched regarding age and sex. Standard routine CT parameters were used on each CT system with helical acquisition in the posterior fossa; the parameters varied regarding collimation and radiation dose. Three blinded readers independently assessed the cases regarding image quality, infra- and supratentorial artifacts and delineation of brain parenchymal structures on a five-point ordinal scale. Reading orders were randomized. A proportional odds model that accounted for the correlated nature of the data was fit using generalized estimating equations. Posterior fossa artifacts were significantly reduced, and the delineation of infratentorial brain structures was significantly improved with the thinner collimation used for the newer CT systems (p<0.001). No significant differences were observed for midbrain structures (p>0.5). The thinner collimation available on modern CT systems leads to reduced posterior fossa artifacts and to a better delineation of brain parenchyma in the posterior fossa.

Cavernous malformations of the brainstem: three-dimensional-constructive interference in steady-state magnetic resonance imaging for improvement of surgical approach and clinical results.

OBJECTIVE: The indications for resection of cavernous malformations (CMs) of the brainstem include neurological deficits, (recurrent) hemorrhage, and surgically accessible location. In particular, knowledge of the thickness of the parenchymal layer and of the CM's spatial relation to nuclei, tracts, cranial nerves, and vessels is critical for planning the surgical approach. We reviewed the operative treatment of 13 patients with 14 brainstem CMs, with special regard to refined three-dimensional (3D)-constructive interference in steady-state (CISS) magnetic resonance imaging (MRI). METHODS: Patients were evaluated neurologically and by conventional spin-echo/fast spin-echo and 3D-CISS MRI. Surgery was performed with the use of microsurgical techniques and neurophysiological monitoring. RESULTS: Eleven CMs were located in the pons/pontomedullary region; 10 of the 11 were operated on via the lateral suboccipital approach. Three CMs were located near the floor of the fourth ventricle and operated on via the median suboccipital approach, with total removal of all CMs. Results were excellent or good in 10 patients; one patient transiently required tracheostomy, and two patients developed new hemipareses/ataxia with subsequent improvement. Not only did 3D-CISS sequences allow improved judgment of the thickness of the parenchymal layer over the lesion compared with spin-echo/fast spin-echo MRI, but 3D-CISS imaging also proved particularly superior in demonstrating the spatial relation of the lesion to fairly "safe" entry zones (e.g., between the trigeminal nerve and the VIIth and VIIIth nerve groups) by displaying the cranial nerves and vessels within the cerebellopontine cistern more precisely. CONCLUSION: Surgical treatment of brainstem CMs is recommended in symptomatic patients. Especially in patients with lesions situated ventrolaterally, the 3D-CISS sequence seems to be a valuable method for identifying the CM's relation to safe entry zones, thereby facilitating the surgical approach.

Stent-angioplasty of intracranial vertebral and basilar artery stenoses in symptomatic patients.

BACKGROUND: To present our two-center treatment results with stent angioplasty of intracranial vertebrobasilar stenoses in symptomatic patients. MATERIAL AND METHODS: Between 2001 and 2003, 21 patients with 22 stenoses, refractory to medical therapy, who underwent elective stenting of intracranial vertebrobasilar stenoses were retrospectively analyzed. All patients had ischemic events clinically referable to the stenoses. Only high-grade stenoses of at least 80% were treated. Clinical evaluation was done based on the modified ranking scale (MRS). RESULTS: In all cases, the stent deployment turned out to be technically successful and control angiography demonstrated the elimination of the high-grade stenoses. A minor residual stenoses was still detectable in six cases. According to the MRS, clinical outcome improved in the case of four patients, seemed unchanged in 14 and worsened in three. The clinical morbidity rate amounted to 14%. Clinical follow-up was available for 13 patients after 9 months with no recurrent symptoms and angiographic follow-up was available after 10 months. Re-stenoses occurred in two cases without clinical symptoms. Retreatment was not done. CONCLUSION: According to our data, stent angioplasty for symptomatic intracranial vertebrobasilar stenoses can be a treatment alternative in case of recurrent symptoms despite medical therapy; particularly, for stenoses of type Mori A or B.

Treatment of basilar artery embolism with a mechanical extraction device: necessity of flow reversal.

BACKGROUND AND PURPOSE: The success of local fibrinolysis in vertebrobasilar thromboembolism depends on the volume and composition of the clot. Since thrombolysis can also be time consuming and cause bleeding, we investigated the feasibility of a mechanical clot retraction device based on a nitinol basket advanced through a microcatheter. METHODS: Five patients with acute embolism of the basilar artery who presented with progressive stroke and impaired consciousness were included in a multicenter study (Neuronet Evaluation in Embolic Stroke Disease [NEED]). In 3 patients flow reversal was induced with the use of silicone balloons or coaxial catheters. Three patients required additional fibrinolysis. RESULTS: The device failed to retrieve the clots in our first 2 patients with distal basilar artery embolism. After successful recanalization by local fibrinolysis, both patients survived, 1 disabled and 1 with little residual impairment. In the next 3 patients the anterograde flow in the basilar artery was reversed during the short retraction period by temporarily blocking the vertebral or subclavian arteries. Two of these patients were completely recanalized by solely mechanical means; the third patient needed additional fibrinolysis before also being recanalized. All 3 patients survived: 1 remained disabled, 1 had almost a full recovery, and 1 became asymptomatic the day after the procedure. CONCLUSIONS: Mechanical thrombus extraction seems to be a feasible method for preventing infarction by rapid, complete, and safe recanalization of the basilar artery. We recommend the use of flow control to support retrieval of the thrombus (which the proximal flow would otherwise keep in place like a cork) and to protect the distal vessels from embolization by fragments.