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With increasing evidence for the existence of a cerebral thrombin system, coagulation factor IIa (thrombin) is suspected to influence the pathogenesis of secondary injury progression after intracerebral hemorrhage (ICH). We hypothesized that mechanisms associated with local volume expansion after ICH, rather than blood constituents, activate the cerebral thrombin system and are responsible for detrimental neurological outcome. To test this hypothesis, we examine the local thrombin expression after ICH in a C57BL/6N mouse model in the presence and absence of blood constituents. ICH was established using stereotaxic orthotopic injection of utologous blood (

Large animal models of cerebral ischemia have the potential to increase the translational value of stroke research. This study aims to measure early changes of brain tissue oxygen pressure (ptiOEight juvenile German Landrace pigs received unilateral MCAO via a frontotemporal approach under continuous intraparenchymal multiparametric monitoring. Insufficient reduction (i.e.,50% in both ptiOOnly 1 of 8 animals demonstrated a decrease of50% in both ptiOIntraparenchymal multiparametric measurements of acute changes in ptiO

Purpose: This prototype catheter is a newly-developed distal access catheter featuring a self-expanding, flexible, funnel-shaped tip. The purpose of its design is to reduce the risk of thrombus fragmentation during mechanical thrombectomy and improve first-pass recanalization (TICI 3). In this experimental setup, we preclinically evaluated the effectiveness and navigability of the new catheter. Methods: A vessel model was filled with a blood-like-viscous medium, and the image was projected with the corresponding vessel area by camera transmission to correspond to the conditions in an angiography. Thrombi from porcine blood were placed into the Arteria Carotis interna of the vascular model and subsequently mechanically thrombectomized with a stent retriever. In the first part, the prototype was compared to a standard distal-access-catheter without using an external catheter. (N = 20 for each catheter). In the second part the prototype was inserted through a guiding catheter (n=11) to determine the navigability performance. Results: In the first experimental series, mechanical thrombectomy was successful 19 out of 20 times (95% success rate) for the prototype catheter versus 15 out of 20 times (75% success rate) for the standard distal-access-catheter. In the second experimental series, the prototype catheter achieved first-pass recanalization 10 out of 11 times (91 % success rate) and 1 out of 11 times at second pass (9%). Conclusion: This series of experiments demonstrated higher first-pass recanalization rates for the newly-developed funnel-shaped prototype featuring a self-expanding tip in comparison to a cylindrical standard distal-access-catheter.

Background Anastomotic tension has been linked to leakage and stenosis in esophageal surgery in both adults and children. We aimed to determine the effects of esophageal topography, operative technique, and anastomotic tension on esophageal blood flow. Materials and Methods We divided and reanastomosed the esophagi at the carinal level with increasing levels of anastomotic tension in piglets (n = 10) and sham controls (n = 4). We examined esophageal blood flow pre- and postoperatively using laser Doppler flowmetry at the anastomosis and two predetermined proximal and distal points. Blood flow in relation to distance from the anastomosis was examined by multivariate linear regression. Results Thoracotomy alone did not influence perfusion at the carinal level in shams (Δ = 3.13 laser Doppler units, 95% confidence interval: −3.4 to 9.7, p = 0.2686). We constructed a (F[5,134] = 6.34, p Conclusion Esophageal blood flow is higher at greater distances to the carinal level and hampered by esophageal division and reanastomosis. The extent of resection has less influence than previously assumed. Therefore, leakage and stenosis after esophageal anastomosis may not solely be caused by insufficient anastomotic blood flow.

Implantable sensors continuously transmit information on vital values or biomarker concentrations in bodily fluids, enabling physicians to survey disease progression and monitor therapeutic success. However, currently available technologies still face difficulties with long-term operation and transferability to different analytes. We show the potential of a generalizable platform based on gold nanoparticles embedded in a hydrogel for long-term implanted biosensing. Using optical imaging and an intelligent sensor/reference-design, we assess the tissue concentration of kanamycin in anesthetized rats by interrogating our implanted sensor noninvasively through the skin. Combining a tissue-integrating matrix, robust aptamer receptors, and photostable gold nanoparticles, our technology has strong potential to extend the lifetime of implanted sensors. Because of the easy adaptability of gold nanoparticles toward different analytes, our concept will find versatile applications in personalized medicine or pharmaceutical development.

Clot-retrieval failure and embolism in new territories (ENT) are complications reducing the efficacy of mechanical thrombectomy (MT). Reasons for these problems are clot abruption during stent retriever retraction into the cylindrical tip of a standard distal access catheter (DAC), and antegrade blood flow during retrieval. To overcome these complications, a funnel-shaped tip catheter model was developed and tested. Using an experimental in vitro setup, this study compared the efficacy of a funnel-shaped tip with a standard cylindrical tip in combination with different clot compositions. Mechanical thrombectomy was performed 80 times for each tip, using two stent retrievers (Trevo XP ProVue 3/20 mm and 4/20 mm) and four different clot types (mechanical vs. static preparation, 0-24h vs. 72h clot aging times). Significantly higher first-pass recanalization rates were observed for the funnel-shaped tip, which reached 70.0% vs. 30.0% for the standard tip (absolute difference, 32; relative difference 20.0%, P

Catheter-based ultrasound-thrombolysis has been successfully used in a small clinical trial in order to enhance recombinant tissue plasminogen activator (rtPA)-fibrinolysis, for the treatment of spontaneous intracerebral hemorrhages (ICHs). The aim of this study was to investigate the ultra-early effects of ultrasound on hematoma and the surrounding brain tissue in a porcine ICH-model. To achieve this, 21 pigs with a right frontal ICH were randomly assigned to four groups: (1) drainage (n = 3), (2) drainage + rtPA (n = 6), (3) drainage + ultrasound (n = 6), and (4) drainage + ultrasound + rtPA (n = 6). The hematoma volume assessment was performed using cranial MRI before and after the treatments. Subsequently, the brain sections were analyzed using HE-staining and immunohistochemistry. The combined treatment using rtPA and ultrasound led to a significantly higher hematoma reduction (62 ± 5%) compared to the other groups (Group 1: 2 ± 1%, Group 2: 30 ± 12%, Group 3: 18 ± 8% (p &lt, 0.0001)). In all groups, the MRI revealed an increase in diffusion restriction but neither hyper- or hypoperfusion, nor perihematomal edema. HE stains showed perihematomal microhemorrhages were equally distributed in each group, while edema was more pronounced within the control group. Immunohistochemistry did not reveal any ultra-early side effects. The combined therapy of drainage, rtPA and ultrasound is a safe and effective technique for hematoma-reduction and protection of the perihematomal tissue in regard to ultra-early effects.

Aim of the study. To analyse the therapeutic potential of granulocyte-colony stimulating factor (G-CSF) treatment using a rat model of traumatic sciatic nerve lesion. Clinical rationale for the study. G-CSF has proven strong neurotrophic properties in various models of ischaemic and traumatic brain injury. Fewer studies exist regarding the influence of G-CSF on posttraumatic peripheral nerve regeneration. Currently, the possibilities of pharmacological prevention or treatment of mechanical nerve injury are limited, and there is an urgent need to find new treatment strategies applicable in clinical situations. Material and methods . A controlled traumatic right sciatic nerve lesion was set using a waterjet device. Three treatment groups were created. In the first group, G-CSF was administered after sciatic nerve injury. The second group received G-CSF before and after trauma, while the third group was treated with glucose 5%-solution. Sciatic nerve function was assessed clinically and electrophysiologically at day 1, and after weeks 1, 2, 4 and 6. Additionally, α-motoneurons of the spinal cord and sciatic nerve fibres were counted at week 6. Results. Clinically, rats in both G-CSF groups improved faster compared to the control group. Additionally, animals treated with G-CSF had a significantly better improvement of motor potential amplitude and motor nerve conduction velocity at week 6 (p < 0.05). Histologically, G-CSF treatment resulted in a significantly higher number of α-motoneurons and small myelinated nerve fibres compared to placebo treatment (p < 0.05). Conclusions and clinical implications. Under G-CSF treatment, the recovery of motor nerve conduction velocity and amplitude was enhanced. Further, signs of nerve regeneration and preservation of α-motoneurons were observed. These results indicate that G-CSF might accelerate and intensify the recovery of injured nerves. Thus, treatment with G-CSF may be beneficial for patients with peripheral nerve damage, and should be explored in further clinical studies.

Adequate removal of blood clots by minimally invasive surgery seems to correlate with a better clinical outcome in patients with intracerebral hemorrhages (ICHs). Moreover, neurotoxic effects of recombinant tissue plasminogen activator have been reported. The aim of this study was to improve fibrinolysis using an intra-clot ultrasound application with tenecteplase and urokinase in our established ICH clot model. One hundred thirty clots were produced from 25 or 50 mL of human blood, incubated for different periods and equipped with drainage, through which an ultrasound catheter was placed in 65 treatment clots for 1 h, randomly allocated into three groups: administration of ultrasound, administration of 60 IU of tenecteplase or administration of 30,000 IU urokinase. Relative end weights were compared. This study found a significant increase in thrombolysis caused by a combination of ultrasound and fibrinolytic drugs, whereas ultrasound and tenecteplase are significantly more effective in the treatment of larger and aged clots.

Objective Hematoma lysis with recombinant tissue plasminogen activator (rtPA) has emerged as an alternative therapy for spontaneous intracerebral and intraventricular haemorrhage (ICH and IVH). However, the MISTIE III and CLEAR III trial failed to show significant improvement of favourable outcomes. Besides experimental and clinical trials revealed neurotoxic effects of rtPA. The demand for optimization of fibrinolytic therapy persists. Herein, we used our recently devised clot model of ICH to systematically analyse fibrinolytic properties of rtPA, tenecteplase and urokinase. Methods In vitro clots of human blood (size: 25 ml and 50 ml; age: 1.5 tenecteplase, 24 tenecteplase and 48 tenecteplase) were produced and equipped with a catheter into the clot core for drug delivery and drainage. Various doses of tenecteplase and urokinase with different treatment periods were examined (overall 117 clots), assessing the optimal dose and treatment time of these fibrinolytics. Clots were weighed before and at the end of treatment. These results were compared with clots treated with 1 mg rtPA or with 0.9% sodium chloride solution. Results The optimal treatment scheme of tenecteplase was found to be 100 IU with an incubation time of 30 min, for urokinase it was 50 000 IU with an incubation time of 20 min. The relative clot end weight of tenecteplase and urokinase (31.3±11.9%, 34.8 ±7.7%) was comparable to rtPA (36.7±10.7%). Larger clots were more effectively treated with tenecteplase compared to the control group (P=0.0013). urokinase and tenecteplase had similar lysis rates in aged clots and 90 min clots. One and two repetitive treatments with tenecteplase were as effective as two and three cycles of urokinase. Conclusions In our in vitro clot model we could determine optimal treatment regimens of tenecteplase (100 IU, 30 min) and urokinase (50 000 IU, 20 min). Urokinase and tenecteplase were comparable in their fibrinolytic potential compared to 1mg rtPA in small clots and showed an effective lysis in aged clots. tenecteplase was more effective in larger clots.

One limitation of mechanical thrombectomy (MT) is clot migration during procedure. This might be caused by abruption of the trapped thrombus at the distal access catheter (DAC) tip during stent-retriever retraction due to the cylindrical shaped tip of the DAC. Aiming to solve this problem, this study evaluates the proof-of-concept of a new designed funnel-shaped tip, in an experimental in vitro setting. Two catheter models, one with a funnel-shaped tip and one with a cylindrical-shaped tip, were compared in an experimental setup. For MT a self-made vessel model and thrombi generated from pig’s blood were used. MT was performed 20 times for each device using two different stent-retrievers, 10 times respectively. For the funnel-shaped model: for both stent-retrievers (Trevo XP ProVue 3/20 mm; Trevo XP ProVue 4/20 mm) MT was successful at first pass in 9/10 (90%), respectively. For the cylindrical-shaped model: MT was successful at first pass in 5/10 (50%) with the smaller stent-retriever and in 6/10 (60%) with the larger stent-retriever. The experiments show a better recanalization rate for funnel-shaped tips, than for cylindrical-shaped tips. These results are indicating a good feasibility for this new approach, thus the development of a prototype catheter seems reasonable.

Background A novel multiparameter brain sensor (MPBS) allows the simultaneous measurement of brain tissue oxygenation (ptiO2), cerebral blood flow (CBF), intracranial pressure (ICP), and brain temperature with a single catheter. This laboratory investigation evaluates the MPBS in an animal model in relation to established reference probes. Methods The study group consisted of 17 juvenile male pigs. Four MPBS and four reference probes were implanted per pig and compared simultaneously. The measured parameters were challenged by standardized provocations such as hyperoxia, dobutamine, and norepinephrine application, hypercapnia and hypoxia in combination with and without a controlled cortical impact (CCI) injury. Mean values over 2 min were collected for predefined time points and were analyzed using Bland–Altman plots. Results The protocol was successfully conducted in 15 pigs of which seven received CCI. ICP and ptiO2 were significantly influenced by the provocations. Subtraction of MPBS from reference values revealed a mean difference (limits of agreement) of 3.7 (− 20.5 to 27.9) mm Hg, − 2.9 (− 7.9 to 2.1) mm Hg, and 5.1 (− 134.7 to 145.0) % for ptiO2, ICP, and relative CBF, respectively. Conclusions The MPBS is a promising measurement tool for multiparameter neuromonitoring. The conducted study demonstrates the in vivo functionality of the probe. Comparison with standard probes revealed a deviation which is mostly analogous to other multiparameter devices. However, further evaluation of the device is necessary before it can reliably be used for clinical decision making. Electronic supplementary material The online version of this article (10.1007/s12028-018-0541-9) contains supplementary material, which is available to authorized users.

Background Fluorescent-guided techniques in vascular neurosurgery can be demonstrated via black and white indocyanine green videoangiography (ICG-VA). Multispectral imaging (MFL) is a new method, which overlaps fluorescence with the white light and provides a fluorescent white light augmented reality image to the surgeon. Objective To investigate (a) whether MFL can enhance the visualization of the blood-flow with simultaneous visualization of the anatomic structures and (b) if MFL can ergonomically improve the microvascular surgical treatment compared to ICG-VA. Methods A digital imaging of the blood flow after intravenous injection of ICG on 7 pigs was performed in real time under white light, standard fluorescence, and MFL. The blood flow was interrupted with a surgical clip, demonstrating the blockage of the blood flow. We prospectively included 30 patients with vascular deformities. The vasculature was visualized on the microscope's monitor and through the microscope's eyepiece. Results In the animal experiment, the visualization of the anatomy and the blood flow under MFL produced high resolution images. The occlusion of blood vessels demonstrated sufficiently the blockage of tissue perfusion and its reperfusion after clip removal. During all 30 surgical cases, the MFL technique and the direct delivery of the pseudo-colored image through the eyepiece allowed for enhanced anatomic and dynamic data. Conclusion MFL was shown to be superior to the classic ICG-VA, delivering enhanced data and notably improving the workflow due to the simultaneous and precise white light visualization of the blood flow and the surrounding anatomic structures.

International journal of environmental research and public health : IJERPH 18(8), 4344 (2021). doi:10.3390/ijerph18084344, Published by MDPI AG, Basel

While clinically the safety and efficacy of waterjet resection of brain tumors have been shown, evidence that waterjet dissection improves tumor resection radicality in comparison with conventional techniques is still missing. In the present study, resection radicality and tumor-free long-term survival of both techniques were evaluated in a C6-glioma model.Fifty-thousand C6-glioma cells were stereotactically transplanted in the left frontal lobe of 100 male Sprague-Dawley rats. After MRI-scanning for evaluation of tumor extension, microsurgical tumor resection was performed with conventional techniques (n=50) or with the waterjet dissector at pressures of 6bar (n=50). Twenty-five animals of each group were sacrificed after surgery for histological analysis. For analysis of survival after tumor resection, twenty-five animals of each group were followed-up to analyze tumor-free survival using the Kaplan Meier method.In the waterjet group, the resection cavity was free of C6-tumor cells in 10/25 (40%) rats showing a trend (p=0.3) towards better resection radicality compared to the rats that were treated conventionally (7/10; 28%). R1-resection with up to 250C6 cells/object slice was found in 14/25 (56%) rats after waterjet dissection compared to 6/25 (24%) rats treated conventionally showing significance (p0.01). Probability of survival was 38% after 2 weeks and 20% after 6 months in the waterjet group compared to 30% and 16% respectively in the conventional group. Diffuse tumor cell spreading with possible influence on survival was shown in 47/50 rats.In this experimental model, waterjet tumor resection did reveal significantly better resection radicality compared to the conventional technique. Although a direct transfer of these results to human glioma surgery is prohibited, the waterjet technique might contribute to the best possible resection radicality in human gliomas. Nevertheless, tumor cell spreading remains a major problem. Further studies have to address that the surgical results - in deed - improve the postoperative outcome.

Background Acute subdural hemorrhage (ASDH) is a severe consequence of traumatic brain injury. The occurrence of subdural blood increases the lethality of these patients independent of the amount of blood or elevated intracranial pressure. Thrombin is one of the potential harmful blood components. Possible harmful effects of thrombin are mediated via the Protease-activated-receptor-1 (PAR1) and thus, translating the acute Thrombin release after ASDH into cell loss. The objectives of the present study were twofold, namely to examine (1) the impact of direct thrombin inhibition in the acute phase after hemorrhage on the long-term histological and functional deficits and (2) the early inhibition of PAR1 activation by thrombin with the selective antagonist SCH79797 on lesion volume at 14 days after ASDH. The effects of thrombin on the lesion size were investigated in two separate experiments via (1) direct thrombin inhibition in the subdural infused blood (Argatroban 600 µg) as well as by (2) intraventricular injection of the PAR-1 antagonist SCH79797 (1 µg or 5 µg). Lesion volume and behavior deficits using a neurological deficit score and a motor function test (beam balance test) were analyzed as outcome parameters at 14 days after injury. Results 59 Male Sprague–Dawley rats received a subdural infusion of 300 µl autologous blood or sham operation. Lesion volume at 14 days after ASDH tended to be smaller in the Argatroban-treated group when compared to the vehicle group (8.1 ± 1.1 vs. 10.1 ± 2.3 mm2, n.s.). Motor deficits in the beam balance test were not significantly less severe in the Argatroban-treated group. Animals treated with SCH79797 also showed a trend towards dose-dependent decreased lesion volume in comparison to the vehicle-treated group (1 μg: 4.3 ± 0.7 mm3; 5 μg: 3.8 ± 1.1 mm3; vehicle: 6.5 ± 2.0 mm3, n.s). Conclusions Thrombin inhibition in the subdural blood and local cerebral blockade of PAR-1 cause a tendency towards reduced lesion volume or functional recovery. All results show a trend in favor of the acute treatment on the outcome parameters. Our results suggests that thrombin could be an important blood-derived factor during acute subdural hemorrhage that translates its deleterious effects in concert with other blood-induced factors.

Background Catheter-based lysis with recombinant tissue plasminogen activator (rtPA) is a well-established therapy for spontaneous intracerebral hemorrhage (ICH). The effectiveness of this therapy can be increased with ultrasound, but the optimal conditions are not yet clearly established. Using a novel in vitro system of blood clots previously developed by our group, we investigated various parameters of intralesional sonothrombolysis using an endosonography catheter in combination with rtPA. Methods Standardized human blood clots were equipped with a drainage catheter and weighed before and after 4 treatments: control (drainage only), rtPA only, ultrasound only and the combination of rtPA+ultrasound. The effectiveness of ultrasound was further analysed in terms of optimal frequency, duration and distance to the probe. Temperature and acoustic peak rarefaction pressure (APRP) were assessed to analyse potential adverse effects and quantify lysis. Histo-morphological analysis of the treated clots was performed by H&E staining and confocal laser scanning microscopy using fluorescent fibrinogen. Results The combined treatment rtPA+ultrasound achieved the highest lysis rates with a relative weight of 30.3%±5.5% (p≤0.0001) compared to all other groups. Similar results were observed when treating aged clots. Confocal fluorescent microscopy of the treated clots revealed a rarefied fibrin mesh without cavitations. No relevant temperature increase occurred (0.53±0.75°C). The optimal insonation treatment time was 1 hour. APRP measurements showed a lysis threshold of 515.5±113.4 kPa. Application of 10 MHz achieved optimal lysis and lysis radius, while simultaneously proving to be the best frequency for morphologic imaging of the clot and surrounding tissue. Conclusions These promising data provide the basis for an individualized minimal invasive ICH therapy by rtPA and sonothrombolysis independent of ICH age.

BackgroundTranscranial Doppler (TCD) was shown to enhance intravascular fibrinolysis by rtPA in ischemic stroke. Studies revealed that catheter-based administration of rtPA induces lysis of intracerebral hemorrhages (ICH). However, it is unknown whether TCD would be suitable to enhance rtPA-induced fibrinolysis in patients with ICH. The aim of this study was to assess the potential of TCD to enhance rtPA-induced fibrinolysis in an in vitro clot system.MethodsReproducible human blood clots of 25 ml were incubated in a water bath at 37°C during treatments. They were weighed before and after 6 different treatments: (I) control (incubation only), (II) rtPA only, (III) one Doppler probe, (IV) two Doppler probes placed vis-à-vis, (V) one probe and rtPA and (VI) two probes and rtPA. To quantify lysis of the blood clots and attenuation of the Doppler through a temporal squama acoustic peak rarefaction pressure (APRP) was measured in the field of the probes. Temperature was assessed to evaluate possible side effects.ResultsClot weight was reduced in all groups. The control group had the highest relative end weight of 70.2%±7.2% compared to all other groups (pConclusionsTCD significantly enhances rtPA-induced lysis of blood clots, and the effect is amplified by using multiple probes. Our results indicate that bitemporal TCD insonation of hematomas could be a new and safe approach to enhance fibrinolysis of ICH´s treated with intralesional catheter and rtPA.

Acute subdural hemorrhage (ASDH) is common and associated with severe morbidity and mortality. To date, the role of spontaneous cortical spreading depression (sCSD) in exaggerating secondary injury after ASDH, is poorly understood. The present study contains two experimental groups: First, we investigated and characterized the occurrence of sCSD after subdural blood infusion (300 μL) via tissue impedance (IMP) measurement in a rat model. Second, we compared the occurrence and influence of sCSD on lesion growth and neurological deficit in the presence and absence of whole blood constituents. In the first experimental group, three IMP traits could be distinguished after ASDH: no sCSD, recurrent sCSD, and constant elevated IMP (anoxic depolarization [AD]). In the second experimental group, sCSD occurred more often after autologous blood, compared with paraffin oil infusion. Lesion volume 7 days post-ASDH was 27.3 ± 6.8 mm

Intestinal electrical stimulation via implants is already used to treat several disorders like constipation or incontinence. Stimulation parameters are most often empiric and not based on systematic studies. One prerequisite to evaluate effects of intestinal electrical stimulation is a direct assessment of intestinal motility. Some common methods are strain gauge transducers or manometry. With both the methods, it is not possible to record the exact 3-D movement. Therefore, we established a new method to record gastrointestinal motility with ultraminiaturized accelerometers, directly glued to the outer surface of the stomach, small intestine, and colon. With this technique, we were able to record precise local motility changes after electrical stimulation. Due to the low energy demand and the small size of the system, it is potentially useful for chronic measurements at multiple sites of the intestinal tract. We will present our first results regarding stimulation-dependent motility changes using up to eight implanted accelerometers in an acute pig model.

Although fibrinolytic therapy is an upcoming treatment for intracerebral haemorrhage (ICH), standard guidelines are lacking, and some clinical issues persist. Here, we used our recently devised clot model of ICH to systematically analyse effects of irrigation and cerebrospinal fluid (CSF) on fibrinolysis.In vitro clots of human blood (25 ml) were generated and a catheter irrigation system was applied to deliver fluid/treatment. Clots were weighed before and after treatment and compared to rtPA treatment alone. First various drainage periods (15, 30 and 60 min; n = 3 each) and irrigation rates (0, 15, 90 and 180 ml/h; n = 3-5 each) were tested, followed by rtPA administration (1 mg, 15 min incubation) at each irrigation rate. Potential fibrinolytic effect of CSF was examined by incubation with 5 ml healthy vs. haemorrhagic CSF (n = 3 each). To assess a washout effect treatment with saline (0.9%), rtPA (1 mg) and high-rate irrigation (180 ml/h) were compared with measuring plasminogen level before and after. Furthermore clots were treated with a combination of plasminogen (150% serum concentration) and rtPA (1 mg).Relative clot end weights after 60 min irrigation system treatments were 66.3 ± 3.8% (0 ml/h), 46.3 ± 9.5% (15 ml/h), 46.5 ± 7.1% (90 ml/h) and 53.3 ± 4.1% (180 ml/h). At a lower irrigation rate (15 ml/h), relative end weights were lowest (49.5 ± 4.6%) after 60 min (15 min: 62 ± 4.3%, p = 0.016; 30 min: 62.90 ± 1.88%, p = 0.012). The combination of rtPA and irrigation produced following relative end weights: 0 ml/h, 35 ± 3.2%; 15 ml/h, 32.1 ± 5.7%; 90 ml/h, 36.7 ± 6.3% and 180 ml/h, 41.9 ± 7.5%. No irrigation (0 ml/h) versus rtPA alone showed a significant difference (p 0.0001) in higher clot weight reduction by rtPA. Similar rtPA+15 ml/h irrigation achieved a significant higher weight reduction compared to 15 ml/h irrigation alone (p = 0.0124). No differences were evident at 90 and 180 ml/h irrigation rates with and without rtPA. Healthy (55.1 ± 5%) or haemorrhagic (65.2 ± 6.2%) CSF showed no fibrinolytic activity. Plasminogen levels in clots declined dramatically ( 80% initially to 10%) after 1 mg single rtPA dosing and high-rate (180 ml/h) irrigation. The fibrinolytic benefit of adding plasminogen to rtPA was marginal.In our in vitro clot model, irrigation combined with rtPA (vs. rtPA alone) conferred no added lytic benefit. Likewise, exposure to haemorrhagic CSF did not increase clot lysis.

Function and viability of every cell is dependent on the proper control of its shape and volume. In the brain, which is protected by a rigid outer shell, cell-volume regulation is of particular importance, since large volume changes affect cerebral perfusion and, hence, function. Neuronal activation leads to constant changes of the ionic and metabolic composition of the brain’s extracellular space. These changes are buffered by astrocytes on the expense of constant changes in cell volume. Under pathological conditions, the ability of astrocytes to maintain the homeostasis of the brain is overwhelmed and permanent cell swelling, cytotoxic edema, occurs. The current chapter describes the principles and mechanisms of cell-volume regulation in vertebrate cells and deals with the striking differences between cell-volume regulation in cells of the central nervous system and those located outside the brain, specifically under pathological conditions.

arXiv:1611.05693v1.-- et al., Establishing a reliable communication interface between the brain and electronic devices is of paramount importance for exploiting the full potential of neural prostheses. Current microelectrode technologies for recording electrical activity, however, evidence important shortcomings, e.g. challenging high density integration. Solution-gated field-effect transistors (SGFETs), on the other hand, could overcome these shortcomings if a suitable transistor material were available. Graphene is particularly attractive due to its biocompatibility, chemical stability, flexibility, low intrinsic electronic noise and high charge carrier mobilities. Here, we report on the use of an array of flexible graphene SGFETs for recording spontaneous slow waves, as well as visually evoked and also pre-epileptic activity in vivo in rats. The flexible array of graphene SGFETs allows mapping brain electrical activity with excellent signal-to-noise ratio (SNR), suggesting that this technology could lay the foundation for a future generation of in vivo recording implants., JAG, BMB, and SD acknowledge support by the German Research Foundation (DFG) in the framework of the Priority Program 1459 Graphene, the Nanosystems Initiative Munich (NIM), and the Graphene Flagship (Contract No. 604391). JAG, BMB, SD, LR, AH and OK acknowledge support by the European Union under the NeuroCare FP7 project (Grant Agreement 280433). NTC, JW, and MVS-V acknowledge support by the EU FF7 FET CORTICONIC contract 600806. BMB, NTC, AGB, JW, SD, RV, MVS-V and JAG received funding for this project from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 696656. ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295).

Visceral malperfusion after coronary artery bypass grafting (CABG) results in high morbidity and mortality. This study was designed to evaluate the effect of CABG performed by surgical techniques on visceral perfusion and function.Pigs (n = 28) were studied in four groups: I. Sham; II. Off-pump coronary artery bypass grafting (OPCAB): 1 h stabilizer with 40 min intracoronary shunt; III. Extracorporeal circulation (ECC): 1 h ECC with 40 min aortic cross-clamping and cardioplegic arrest; IV. Impella: 1 h left ventricular blood-pump support and stabilizer with 40 min intracoronary shunt. A left internal mammary to left anterior descending coronary artery bypass was performed in Groups II-IV. All animals were observed for a further 240 min. During the experiment haemodynamics, creatinine clearance, intestinal fatty acid binding protein (iFABP), pancreatic (lipase and amylase) and liver enzymes (α-glutathione s-transferase, glutamate-oxaloacetate transaminase (GOT), gamma-glutamyl transferase (GGT), glutamate dehydrogenase and glutamate-pyruvate transaminase (GPT)) were measured. Visceral perfusion (VP) was assessed in both kidneys, intestine, pancreas, liver and spleen with 15 µm fluorescent microspheres.During OPCAB surgery, VP decreased slightly. Renal functional parameters, iFABP, pancreatic and liver enzymes remained unchanged. ECC and Impella led to significantly reduced renal, pancreatic and intestinal blood flow (P0.05). Creatinine clearance, pancreatic and liver (GPT, GGT) enzymes were significantly decreased only after ECC (P0.05). ECC and Impella resulted in a significantly increased iFABP level (P0.05). GOT was elevated significantly after surgery in Groups II, III and IV (P0.05).CABG with ECC or Impella leads to impaired visceral blood flow and function. OPCAB minimizes these procedure associated alterations.

Until today, brain tumors especially glioblastoma are difficult to treat and therefore, results in a poor survival rate of 0-14% over five years. To overcome this problem, the development of novel therapeutics as well as optimization of neurosurgical procedures to remove the tumor tissue are subject of intensive research. The main problem of the tumor excision, as the primary clinical intervention is the diffuse infiltration of the tumor cells in unaltered brain tissue that complicates the complete removal of residual tumor cells. In this context, we are developing novel approaches for the label-free discrimination between tumor tissue and unaltered brain tissue in real-time during the surgical process. Using our impedance spectroscopy-based measurement system in combination with flexible microelectrode arrays we could successfully demonstrate the discrimination between a C6-glioma and unaltered brain tissue in an in vivo rat model. The analysis of the impedance spectra revealed specific impedance spectrum shape characteristics of physiologic neuronal tissue in the frequency range of 10-500 kHz that were significantly different from the tumor tissue. Moreover, we used an adapted equivalent circuit model to get a deeper understanding for the nature of the observed effects. The impedimetric label-free and real-time discrimination of tumor from unaltered brain tissue offers the possibility for the implementation in surgical instruments to support surgeons to decide, which tissue areas should be removed and which should be remained.

It was tested to what extend torsional acoustic resonators can serve to in vivo differentiate between healthy and tumorous brain tissue. The resonators employed consist of crystalline quartz. They are cylindrically shaped. The resonance frequency at the fundamental is 78 kHz. The best correlation between the shifts of resonance frequency and resonance bandwidth, on the one hand, and the state of the tissue, on the other, was found when analyzing ratios of the shifts in resonance frequency and resonance bandwidth. These ratios are independent of contact area. Taking data on the fundamental mode as well as the third overtone further improved the efficiency and precision of the technique. These results suggest that torsional resonators can serve as diagnostic tools in neurosurgery.

Acute subdural hematoma (ASDH) is associated with high morbidity and mortality. Whether the volume effect of the hematoma and increase of intracranial pressure (ICP) or the local effect of blood are responsible for this severe pathophysiology is unclear. Therefore, we compared subdural infusion of autologous blood and paraffin oil in a rat model of ASDH. In a histological study, we investigated the effects on acute ICP, cerebral perfusion pressure (CPP), cerebral blood flow (CBF), tissue oxygen changes, and brain damage at 2, 24, and 96 h post-infusion. Inflammatory reaction was analyzed by immuno-staining for microglia (ionized calcium binding adaptor molecule 1 [Iba1]) and activated astrocytes (glial fibrillary acidic protein [GFAP]). Besides acute ICP and CBF changes, we investigated the development of behavior (neuroscore and beamwalk test) for up to 4 days after injury in a behavioral study. Despite comparably increased ICP, there was a more pronounced lesion growth in the blood infusion group during the first 96 h. Further, there was an increased peri-lesional immunoreactive area of Iba1 and GFAP 96 h post-infusion, primarily in the blood infusion group, whereas hippocampal damage was comparable in both infusion groups. In the behavioral evaluation, paraffin-infused animals showed a better recovery, compared with the blood infusion group. In conclusion, comparable acute time-course of ICP, CPP, and CBF clearly indicates that the differences in lesion size, inflammatory reaction, and behavioral deficits after blood- and paraffin oil-induced ASDH are partially due to blood constituents. Therefore, current data suggest that subdural hematomas should be completely removed as quickly as possible; decompression alone may not be sufficient to prevent secondary brain damage.

Objective/Background Aim of the current study was to localize and differentiate between tumor (glioma) and healthy tissue in rat brains on a cellular level. Near-infrared multiphoton microscopy takes advantage of the simultaneous absorption of two or more photons to analyze various materials such as cell and tissue components via the observation of endogenous fluorophores such as NAD(P)H, FAD, porphyrins, melanin, elastin, and collagen, with a very high resolution, without inducing the problems of photo-bleaching on out-of-focus areas. Methods In vitro and in vivo studies on healthy rat brains as well as C6 glioma cell line allografts have been performed. Near-infrared laser pulses (λ = 690–1060 nm, τ ∼140 fs) generated by an ultrafast Ti:Sapphire tunable laser system (Chameleon, Coherent GmbH, Santa Clara, CA) were coupled into a laser scanning microscope (LSM 510 META, Carl Zeiss, Germany) to observe high quality images. Results Several image acquisitions have been performed by varying the zoom scale of the multiphoton microscope, image acquisition time and the wavelength (765, 840 nm) to detect various tissue components. With a penetration depth of ∼200 µm in vitro and about 30–60 µm in vivo into the brain tissue it was possible to differentiate between tumor and healthy brain tissue even through thin layers of blood. Conclusion Near-infrared multiphoton microscopy allows the observation and possibly differentiation between tumor (glioma) and healthy tissue in rat brains on a cellular level. Our findings suggest that a further miniaturization of this technology might be very useful for scientific and clinical applications in neurosurgery. Lasers Surg. Med. 44: 719–725, 2012. © 2012 Wiley Periodicals, Inc.

Please cite this paper as: Bierbach B, Scheewe J, Derfuss T, Krug A, Schramm R, Dahm M, Kuroczynski W, Kempski O, Horstick G. Continuous regional myocardial blood flow measurement: validation of a near-infrared laser Doppler device in a porcine model. Microcirculation 19: 485–493, 2012. Abstract Objective: RMBF measurement is a major concern in various clinical and experimental settings, but no validated device for RMBF is currently available. Methods: An LVP-triggered laser Doppler to measure RMBF was validated by simultaneous fluorescent MS RMBF in a porcine LAD flow reduction model (n = 10 pigs). The laser probe was positioned on the left ventricle’s anterior wall. LAD blood flow reduction was achieved by a shaft-driven occluder positioned proximal to the transit-time flow meter measuring coronary blood flow. RMBF was measured at baseline; after the reduction of LAD blood flow to 70% and 30% of baseline; at 20 and 120 minutes of reperfusion; and, finally, 15 minutes after LAD occlusion. Results: Laser Doppler RMBF (LDU) correlated strongly with MS RMBF under all tested conditions: baseline (epicardial 194.7 ± 41.9, endocardial 130.2 ± 29.2); 70% baseline-flow (epicardial 160.4 ± 27.7, endocardial 112.1 ± 15.1); 30% baseline-flow (epicardial 44.3 ± 5.5, endocardial 32.9 ± 9); 20 minutes reperfusion (epicardial 175.8 ± 33.6, endocardial 126.5 ± 30); 120 minutes reperfusion (epicardial 146.3 ± 31.1, endocardial 107.1 ± 29.7); and complete LAD occlusion (epicardial 10.5 ± 5.8 endocardial 1.4 ± 0.3) (r = 0.986–0.962, p

The beneficial effects of hypertonic saline on neuronal survival and on cerebral blood flow have been shown in several animal models of global and focal brain ischemia. Because of the potential benefits of hypertonic solutions, it is hypothesized that hydroxyethyl starch enhances cerebral blood flow and improves long-term outcome after cardiac arrest and cardiopulmonary resuscitation in an animal model.Laboratory animal study.University animal research laboratory.Fifty-nine male Sprague-Dawley rats.Rats were randomized to receive either 7.2% saline/6% hypertonic saline hydroxyethyl starch (4 mL/kg) or vehicle (NaCl 0.9 %) after 9 mins of asphyxic cardiac arrest and cardiopulmonary resuscitation. Local cerebral blood flow and physiologic parameters were evaluated during arrest and early restoration of spontaneous circulation. Survival and neurologic assessment were evaluated over a 7-day observation period. Animals received 5-bromo-2-deoxyuridine for 6 days. Neuronal injury and neurogeneration (5-bromo-2-deoxyuridine positive neurons) were quantified on day 7 after cardiac arrest and cardiopulmonary resuscitation.Hypertonic saline hydroxyethyl starch treatment resulted in an accentuated local cerebral blood flow during early reperfusion, compared to the vehicle group. Animal survival and neurologic outcome were not altered between groups. Neurohistopathological injury was present in hippocampal CA1 and neocortex with no effects of hypertonic saline hydroxyethyl starch on neuronal survival. Increased neurogeneration was found in the dentate gyrus after cardiac arrest/cardiopulmonary resuscitation, which was not influenced by hypertonic saline hydroxyethyl starch administration.Despite promising results in other models of brain injury, hypertonic saline hydroxyethyl starch failed to improve the outcome when administered after asphyxic cardiac arrest/cardiopulmonary resuscitation in rats. One major difference between the cardiac arrest/cardiopulmonary resuscitation model and other models of brain ischemia is that the effects of asphyxic cardiac arrest involve the whole organism (post-cardiac arrest syndrome) and not exclusively the brain leading to a more severe injury. This might explain why hypertonic saline hydroxyethyl starch has failed to improve outcome in the present model.

A recent research reveals that complement activation exacerbates cerebral infarction. However, involvement of the lectin pathway, (the third complement activation pathway) in cerebral ischemia is not well studied. In this study, we investigated the appearance of mannose-binding lectin (MBL) in ischemic brain tissue. Male Wistar rats ( n = 25) were divided into three groups: untreated control, sham, and vein occlusion (VO). Rats in the VO group had two adjacent photochemically occluded cortical veins. Regional cerebral blood flow (rCBF) was measured in the sham and VO groups. Rats were perfusion-fixed at 72 h in the sham group and at 3, 24, and 72 h after inducing ischemia in the VO group. Neuronal immunoreactivity for MBL, C1q, C3, and C5b-9 was graded on a scale from 0 (no staining) to 4 (strong immunoreactivity). rCBF significantly decreased in the VO group compared to the sham group. Immunohistochemical staining results were negative in the control group. MBL immunoreactivity was significant increased at 24 and 72 h after inducing ischemia in the VO group compared to the sham group. After inducing ischemia, C1 immunoreactivity was significantly increased at 3, 24, and 72 h, while C3 immunoreactivity increased at 72 h. C5b-9 immunoreactivity exhibited a tendency for only positive staining. In brain tissue after focal cerebral ischemia, MBL expression, as well as C1q and C3, appeared at 3 h, peaked at 24 h, and was maintained at 72 h. These results suggest that an MBL inhibitor administered during the relatively early ischemic phase might attenuate tissue damage.

Physiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion-MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs with and without prospective slice tracking under both free-breathing and breath-hold conditions. To avoid influences by residual contrast agent concentration time courses were analyzed. Median myocardial blood flow values and interquartile ranges with prospective slice tracking under free-breathing and in a breath-hold were (1.04, interquartile range = 0.58 mL/min/g) and (1.20, interquartile range = 0.59 mL/min/g), respectively. This is in agreement with published positron emission tomography values. In measurements without prospective slice tracking (1.15, interquartile range = 1.58 mL/min/g), the interquartile range is significantly (P < 0.012) larger because of residual cardiac motion. In conclusion, prospective slice tracking reduces motion-induced variations of myocardial blood flow under both during breath-hold and under conditions of free-breathing.

Sonothrombolysis is a promising modality for acute stroke treatment. In vitro data suggest a duty cycle dependence of sonothrombolytic efficacy of low-frequency applications. The aim of our study was to examine its impact on safety issues in a rat model of middle cerebral artery occlusion. Rats were exposed to transcranial 60-kHz ultrasound with varied duty cycles. To determine effects on the inner ear, the acoustic threshold was determined in additional healthy animals (acoustic evoked potentials). A short duty cycle (20%) resulted in significant adverse effects (ischemic volume, hemorrhage, functional outcome), which was not observed in longer duty cycle (80%). Continuous-wave insonation produced high rates of mortality and subarachnoid hemorrhage. Hearing was impaired independent of duty cycle. In conclusion, cerebral side effects may be efficiently reduced by modulation of pulsed parameters, which is in line with data on an improved efficacy with longer duty cycle. However, side effects on the auditory system were found to be independent of parameter settings.

To identify genes that are involved in ischemia response of the brain, we have evaluated changes of gene expression in rat cerebrum after 15 min complete global ischemia, followed by reperfusion for 1 h, 6 h or 24 h. The expression profiles of approximately 30,000 transcripts from three subjects in each group (including sham-operated controls) were monitored employing oligonucleotide microarrays. About 20,000 transcripts were detectable in rat brains. The levels of 576 transcripts (approximately 2.9%) were significantly altered in response to experimental ischemia. 419 transcripts were up- and 157 downregulated; 39 transcripts changed after 1 h reperfusion, 174 after 6 h and 462 after 24 h. Results from quantitative real-time reverse transcription PCR of 18 selected genes showed excellent agreement with the microarray data. There is surprisingly little overlap between gene regulation patterns at different reperfusion times (only seven genes displayed significant changes in transcript levels at all reperfusion times. Several genes that were previously unknown to be involved in ischemia-response have been identified. Analyses of gene ontology patterns and the most strongly regulated transcripts showed that the immediate response to an ischemia/reperfusion is mediated by the induction of specific transcription factors and stress genes. Delayed gene expression response is characterised by inflammation and immune-related genes. These results support the hypothesis that the brain's response to ischemia is an active, specific and coordinated process.

Recent studies have raised concerns about the safety of low frequency ultrasound in transcranial therapeutic application in cerebral ischemia. This study was designed to evaluate safety aspects and potential deleterious effects of low frequency, 60 kHz ultrasound in treatment of experimental middle cerebral artery occlusion (MCAO) in rats. Forty-five male Wistar rats were submitted to either temporary (90 min; groups I and II) or permanent MCAO (groups III and IV) using the suture technique. All animals received recombinant tissue plasminogen activator (rt-PA) starting 90 min after the beginning of occlusion. Groups I and III were additionally treated with 60 kHz ultrasound (time average acoustic intensity 0.14 W/cm2, duty cycle 50%). Outcome assessment consisted of magnetic resonance imaging (MRI) and clinical evaluation after 5 and 24 h, and histology (perfusion fixation after 24 h). Overall mortality was higher in animals treated with ultrasound (43% versus 29% in controls). Most animals died during the insonation period (25% in group I, 36% in group III, no animals in the corresponding control groups; p < 0.05). Histology revealed disseminated microscopic intracerebral bleeding and subarachnoid hemorrhage as one possible cause of death. After temporary occlusion, the hemispheric ischemic lesion volume was more than doubled in animals treated with ultrasound (20.3% ± 14.1% versus 8.6% ± 5.1% in controls; p < 0.05). No difference in lesion volume was seen after permanent MCAO. Neurological assessment showed impairment of hearing as an additional specific side effect in ultrasound treated animals (65%, no impairment in controls). Although the results are not directly transferable to the human setting, this study clearly demonstrates the potential limitations of low frequency therapeutic ultrasound and the importance of pre-clinical safety assessment. (E-mail: max.nedelmann@neuro.med.uni-giessen.de)

We aimed to determine whether 3-nitropropionic acid (3-NPA) preconditioning protects rat livers against warm ischemia/reperfusion injury. We hypothesized that 3-NPA mediates its protective effects by Bcl-2 upregulation. Brown-Norway rats (200 g) were injected with 3-NPA (10 mg/kg intraperitoneally) 24 h before 90 min of selective warm in situ ischemia. In additional experiments, 30-day survival was studied after 90 min of warm liver ischemia and resection of nonischemic liver tissue. We demonstrate increased mRNA and protein levels of Bcl-2 by real-time polymerase chain reaction, immunohistochemistry, and Western blot analysis in 3-NPA-pretreated rats. All treated animals survived, whereas all untreated rats died within 3 days after selective ischemia and resection of the nonischemic tissue. This corresponded well with a significant decrease of caspases 3 and 9 activity at 1 h of reperfusion after preconditioning with 3-NPA as compared with untreated rats. The histological sections showed protection of liver tissue after 3-NPA by reduction of apoptotic and oncotic tissue damage. Lipid peroxidation in liver tissue was reduced after 3-NPA preconditioning. We show that subtoxic doses of the mitochondrial toxin 3-NPA induces tolerance to warm liver ischemia in rats associated by synthesis of Bcl-2. Bcl-2 upregulation might protect against the postischemic burst of reactive oxygen species and therefore reduces apoptotic- and oncotic-related cell death.

Traumatic brain injury (TBI) is often complicated by acute subdural hemorrhage (ASDH) with a high mortality rate. The pathophysiological mechanisms behind such an injury type and the contribution of blood to the extent of an injury remain poorly understood. Therefore, the goals of this study were to establish a porcine ASDH model in order to investigate pathomechanisms of ASDH and to compare effects induced by blood or sheer volume. Thus, we infused 2, 5, and 9 mL of blood (up to 15% of intracranial volume), and we compared a 5-mL blood and paraffin oil volume to separate out effects of extravasated blood on brain tissue. An extended neuromonitoring was applied that lasted up to 12 h after injury and included intracranial pressure (ICP), cerebral perfusion pressure (CPP), tissue oxygen concentration (ptiO(2)), biochemical markers (glutamate, lactate), somatosensory evoked potentials (SEP), brain water content, and histological assessment (Lesion Index [LI]). Volume-dependent changes were detected mainly during the first hours after injury. ICP increased to significant levels (p0.05) of 36.89 +/- 1.59, 15.52 +/- 0.48, and 11.25 +/- 0.35 mm Hg after 9, 5, and 2 mL of subdural blood, respectively (sham, 4.85 +/- 0.06 mm Hg). The ptiO(2) dropped drastically after 9 mL of subdural blood without recovery in both hemispheres to below 20% of baseline, but was affected little after 2 and 5 mL in the acute monitoring period (maximal drop to 71% of baseline). Later, 5 mL of blood led to a significant increase of ptiO(2) compared to 2 mL ipsilaterally (p0.05). Glutamate and lactate showed a comparable pattern with a long-lasting increase after 9 mL of blood and short-lasting changes after 2 and 5 mL. The two smaller volumes caused an increased brain swelling (2 mL, 80.60 +/- 0.34%; 5 mL, 81.20 +/- 0.66%; p0.05 vs. sham), a significant LI (sham, 6.4 +/- 1.4; 2 mL, 30.0 +/- 0.95; 5 mL, 32.1 +/- 1.2; p0.05 vs. sham), and a reduced SEP amplitude (5 mL, p0.05 vs. baseline) at the end of the experiment. A 9-mL led to herniation during the experiment causing dramatical brain swelling and acute histological damage. Comparison of blood volume with paraffin oil showed no significance, indicating that volume alone determines the acute pathophysiological processes leading to a rapidly developing histological damage. Additional effects due to blood contact with brain tissue (e.g., inflammation) may be detected only at later time points (12 h).

The direct endonasal or transoral transclival approaches to the skull base permit effective, minimally invasive surgery along the clivus. Developing long-term, effective techniques to prevent cerebrospinal fluid (CSF) leaks and their consequences (infection and delayed healing) remains a major challenge. In this study we describe a method of bone reconstruction newly developed by us, which uses a custom designed silicone plug for bone replacement after minimally invasive skull base surgery with a low incidence of postoperative CSF leaks. German Landrace pigs were used to test the efficiency of the new technique. Twelve craniotomies were performed in six pigs using a subtemporal approach and subsequently the dura was opened. After these preparations the craniotomy defects were occluded with a silicone ball, which had a near spherical shape. The ball elastically adapts to the bone defect. Each pig also received an intracranial pressure (ICP) catheter and a subdural catheter for later fluorescein injection. Then we increased ICP by infusion of artificial CSF and detected fluorescein leaks from the craniotomy using ultraviolet illumination and a photomacroscope equipped with appropriate filters and a charge-coupled device camera. In all pigs we increased ICP to 75-80 mmHg by infusing 25-30 mL saline containing 0.05% sodium fluorescein. For the first four craniotomies infusions were interrupted after CSF leaks occurred due to technical failures, which were subsequently rectified. The following eight craniotomies were watertight without CSF leakage. This novel medical device allows a leak-proof closure of bone defects after minimally invasive craniotomies; no additional surgery or other therapies were necessary. The application of the silicone plug, which is made of a cost-effective and biocompatible material, is easy and fast, making use of a specially developed toolkit.