Comparison of head positioning using the Mayfield skull clamp versus padded headrest in anterior cervical discectomy and fusion surgery.

Background: Anterior cervical discectomy and fusion (ACDF) is a commonly implemented surgical intervention for a variety of pathologies affecting the cervical spine. The current literature and daily practice reveal variations on patient head positioning for this procedure with both rigid fixations in the Mayfield skull clamp as well as use of a padded headrest being used. In this study, we therefore examine whether patients undergoing surgery using head positioning in the Mayfield skull clamp versus a padded headrest differ in regard to adverse events, surgical parameters and clinical outcome. Methods: A single-center, retrospective analysis of 121 patients treated with ACDF for degenerative disease, traumatic cervical spine injury and infectious disease between November 2019 and March 2023 was performed. Clinical and imaging data for 59 patients positioned in the Mayfield skull clamp and 62 patients positioned in a padded headrest were evaluated using electronic medical records. In addition to demographic data, surgical indications, procedures performed were analyzed for both groups. Level of training (chief, attending and resident), length of surgery and intraoperative radiation exposure (measured by dose area product and total radiation time) were also examined. Finally, modified Rankin Scale (mRS) preoperatively and at last follow-up as well as adverse events were compared between groups. Results: We found no statistically significant differences between the Mayfield and headrest groups regarding surgical indications (P=0.583), procedures performed (P=0.069), level of training of the surgeon (P=0.218), length of surgery (P=0.752), adverse events (P=0.619) or neurological impairment (P=0.080) following surgical intervention. There was a significant difference regarding dose area product between both groups with patients positioned in the Mayfield skull clamp showing lower mean levels of radiation than those in the headrest group (99 versus 131 cGy/cm2; P=0.003). Conclusions: Patient positioning using the Mayfield skull clamp may reduce required radiation exposure during ACDF procedures versus use of a padded headrest.

Influence of Blood Components on Neuroinflammation, Blood-Brain Barrier Breakdown, and Functional Damage After Acute Subdural Hematoma in Rats.

A central component of injury development after acute subdural hematoma (ASDH) is the increased intracranial pressure and consecutive mechanical reduction of cerebral blood flow (CBF). However, the role of different blood constituents in ASDH as additional lesioning factors remains unclear. This study examines the influence of blood components on neuroinflammation, blood-brain barrier (BBB) breakdown, and functional deficits in a rat model of ASDH. We infused corpuscular (whole blood, whole blood lysate, and red cell blood) and plasmatic (blood plasma, anticoagulated blood plasma, and aqueous isotonic solution) blood components into the subdural space while CBF was monitored. Rats then underwent behavioral testing. Lesion analysis and immunohistochemistry were performed 2 days after ASDH. Inflammatory reaction was assessed using staining for ionized calcium-binding adaptor molecule 1 and glial fibrillary acidic protein, interleukin-1ß, tumor necrosis factor-alpha, and membrane attack complex. Integrity of the BBB was evaluated with albumin and matrix metalloproteinase 9 (MMP9) staining. We observed a significant drop in CBF in the corpuscular group (75% ± 7.5% of baseline) with distinct post-operative deficits and larger lesion volume compared to the plasmatic group (13.6 ± 5.4 vs. 1.3 ± 0.4 mm3). Further, inflammation was significantly increased in the corpuscular group with stronger immunoreaction. After whole blood infusion, albumin and MMP9 immunoreaction were significantly increased, pointing toward a disrupted BBB. The interaction between corpuscular and plasmatic blood components seems to be a key factor in the detrimental impact of ASDH. This interaction results in neuroinflammation and BBB leakage. These findings underscore the importance of performing surgery as early as possible and also provide indications for potential pharmacological targets.

Diffuse Leptomeningeal Glioneuronal Tumor in Adults: Case Report and Literature Review.

Introduction: Diffuse leptomeningeal glioneuronal tumor (DLGNT), a new addition to the 2016 World Health Organization (WHO) classification, is a rare childhood neoplasm presenting with disseminated leptomeningeal enhancement and an occasional intraparenchymal mass. Diagnosis is often impeded by infectious/immunological differentials, necessitating a biopsy to confirm the diagnosis. We report an adult male with DLGNT without hydrocephalus, which is rare in patients with cerebellar masses. Case Presentation: A 56-year-old man presented with headaches, vertigo, diplopia, impaired hearing, and gait imbalance over 6 months. Magnetic resonance imaging showed a cystic right cerebellar mass with its leptomeningeal dissemination but without hydrocephalus. Cerebrospinal fluid analysis revealed elevated proteins with CD56-positive tumor cells. Cerebellar lesion biopsy verified the diagnosis of DLGNT (WHO Grade 3) with KIAA1549::BRAF fusion and 1p deletion. Radiotherapy was prematurely aborted due to clinical deterioration. The patient was subsequently discharged to palliative home care and lost to follow-up. Conclusion: We conducted the first review of all 34 adult DLGNT cases, including ours (one of the oldest), hitherto published in the literature. The majority presented with signs and symptoms of increased intracranial pressure. 52.0% of adult DLGNT patients were alive at follow-up. DLGNT should be considered in the differential diagnoses of diffuse leptomeningeal enhancement in imaging. Further studies comparing pediatric and adult subgroups of DLGNT are needed to evaluate histopathological prognosticators and standardize therapy for both subpopulations.

The Role of Tumor-Associated Hypothalamic Involvement in Surgical Treatment and Long-Term Outcome in Adult Patients with Craniopharyngioma.

INTRODUCTION: Hypothalamic invasion in pediatric patients with craniopharyngioma negatively influences clinical outcomes. It has been shown that radiologic classification of hypothalamic invasion can effectively predict surgical strategies to minimize postoperative comorbidities in pediatric patients. However, no comparative analysis has been performed in adult patients with craniopharyngioma. This study implements the previously established radiologic classification to characterize postoperative morbidity, surgical outcome, and distress in adult patients with craniopharyngioma. METHODS: Electronic medical records of 22 adult patients with craniopharyngioma were used to analyze patient demographics, surgical data, endocrinologic and ophthalmologic status, and histopathology in a retrospective single-center study. Questionnaires regarding postoperative distress (National Comprehensive Cancer Network Distress Thermometer and Problem List), comorbidities (Charlson Comorbidity Index), employment status, and need for supportive care were distributed. Magnetic resonance imaging scans were categorized according to Puget et al. RESULTS: Patients with hypothalamic involvement show significantly higher rates of postoperative diabetes insipidus and higher scores on the National Comprehensive Cancer Network Distress Thermometer. This significant difference was lost when considering postoperative Puget grades. Puget grades 1 and 2 were found to be associated with the use of a subfrontal surgical approach (hazard ratio, 4.080; confidence interval, 1.153-14.431; P = 0.029). CONCLUSIONS: Our results point toward a possible predictive role of preoperative hypothalamic invasion for postoperative diabetes insipidus as well as higher perceived levels of distress after surgery, which may be established in larger patient cohorts. Furthermore, a subfrontal surgical approach seems to be predicted by tumors with hypothalamic invasion. In this case, preoperative magnetic resonance imaging grading may help guide the planning of an optimal surgical strategy for adults with craniopharyngioma to reduce postoperative morbidity.

Effectiveness of outpatient parenteral antimicrobial therapy (OPAT) for patients with cranial infection.

Objective: Outpatient parenteral antimicrobial therapy (OPAT) is a well-established and cost-effective method for improving the efficient use of healthcare resources. However, only a few centres in Germany perform it. Here we analysed OPAT for the treatment of patients with cranial infections in our neurosurgical department. Methods: This retrospective study analysed patients with cranial infections and the need for intravenous (i.v.) antimicrobial treatment between 2018 and 2021.All diagnosed intracranial infections were defined into two infection categories such as long-term antimicrobial treatment and short-term antimicrobial treatment. All included patients were discharged with a peripherally inserted central catheter (PICC) line. Prior to discharge, all patients received training in the safe administration of their medications via the PICC line. The duration of OPAT and the rate of readmission after OPAT were analysed. Results: We identified a total of 45 patients treated with OPAT for cranial infections. Intradural involvement was present in 40 cases (88.9%). The average length of hospital stay for this cohort after surgical treatment was 45 ± 15 days. 5 patients were treated for soft tissue/skin infection. Surgery was not required in this cohort. The mean hospital stay for this cohort was 8 ± 6 days. Gram-positive organisms were isolated in most cases (53.3%). The most common pathogens were Staphylococcus aureus followed by other Staphylococcus species. For all included patients, OPAT was performed after discharge for an average of 43.1 ± 14 days. There were five cases of readmission due to treatment failure. No serious adverse events or complications of OPAT were observed. Conclusion: OPAT enables better patient-centred healthcare close to home. The length of hospital stay can be reduced and adverse events due to prolonged hospitalisation can be avoided.

Increased Body Mass Index Correlates with Less Favorable Postoperative Outcomes After Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea: A Retrospective Cohort Study.

OBJECTIVE: Obstructive sleep apnea is associated with high morbidity. Hypoglossal nerve stimulation (HNS) has become a novel (neuro-) surgical treatment strategy for obstructive sleep apnea, demonstrating good success rates. Beyond predefined inclusion and exclusion criteria, no precise data are available, enabling individual preoperative risk assessment. To improve preoperative risk stratification, this study analyzed individual patient factors that affect outcomes of HNS. METHODS: Fourteen patients treated with unilateral HNS were analyzed retrospectively. Assessed risk factors included: hypertension, diabetes mellitus, depression, smoking, alcohol consumption, body mass index (BMI), and disease duration. Treatment success was defined as a reduction in the postoperative apnea-hypopnea index (AHI) to ≤20 events/hour, with a relative reduction of at least 50% compared to baseline. RESULTS: A significant reduction in the postoperative apnea-hypopnea index was observed in all patients (P < 0.0001). BMI correlated significantly with postoperative AHI scores (95% confidence interval, 0.1519-0.8974; P = 0.018). Significant treatment success was observed in 50% of patients. Compared with the "Excellent Responder group," the "Responder group" demonstrated a significantly higher BMI (95% confidence interval, 1.174-6.226; P = 0.0078). Diabetes, hypertension, disease duration, smoking, depression, and alcohol consumption were not significantly associated with AHI reduction. CONCLUSIONS: Our findings suggest that BMI may be an independent risk factor for the response to HNS, with patients who had less benefit from therapy having significantly higher BMI than "Excellent Responders." Therefore, carefully selecting patients is crucial in obtaining optimal outcomes with HNS therapy, especially those with a high BMI.

Early Onset of Rapid Lesion Growth in an Acute Subdural Hematoma Model in Rats.

OBJECTIVE: Acute subdural hematoma (ASDH) leads to the highest mortality rates of all head injuries with secondary brain damage playing a pivotal role in terms of morbidity and mortality. In patients with ASDH, a delay in surgery leads to disproportional mortality. The benefit of (very) early therapy is therefore, a target of ongoing research. As the process of delayed brain damage in ASDH has not yet been described, this study therefore aimed to examine secondary lesion growth in an experimental rat model of ASDH to define the ideal timing for testing potential neuroprotective therapies. METHODS: Cerebral blood flow was monitored during ASDH induction with 300 µl of autologous blood. Lesion growth was characterized using Hematoxylin-Eosin- , Cresyl-Violet-, and Fluoro-Jade B-staining for early signs of neuronal degeneration. Histological evaluations were performed between 15 minutes and 24 hours after ASDH. RESULTS: There was a significant reduction of cerebral blood flow after ASDH. Fluoro-Jade B-positive cells were visible 15 minutes after ASDH in the lesioned hemisphere. Nonlinear growth of lesion volume from 3.7 ± 0.4 mm3 to 17.5 ± 0.6 mm3 was observed at 24 hours in Hematoxylin-Eosin-staining. CONCLUSIONS: The most damage develops between 15 minutes and 1 hour and again between 2 and 6 hours after ASDH. The time course of lesion growth supports the approach of early surgery for patients. It furthermore constitutes a basis for further ASDH research with more clearly defined time windows for therapy in animal models.

Variants of the Anterior Subtemporal Approach to the Gasserian Ganglion and Related Structures: An Anatomical Study With Relevant Implications for Keyhole Surgery.

BACKGROUND: The advantages and limitations of different craniotomy positions and approach trajectories to the gasserian ganglion (GG) and related structures using an anterior subtemporal approach have not been studied systematically. Knowledge of these features is of importance when planning keyhole anterior subtemporal (kAST) approaches to the GG to optimize access and minimize risks. METHODS: Eight formalin-fixed heads were used bilaterally to assess temporal lobe retraction (TLR), trigeminal exposure, and relevant anatomical aspects of extra- and transdural classic anterior subtemporal (CLAST) approaches compared with slightly dorsally and ventrally allocated corridors. RESULTS: TLR to the GG and foramen ovale was found to be lower via the CLAST approach (P < 0.001). Using the ventral variant, TLR to access the foramen rotundum was minimized (P < 0.001). The overall TLR was maximal using the dorsal variant (P < 0.001) owing to interposition of the arcuate eminence. An extradural CLAST approach required wide exposure of the greater petrosal nerve (GPN) and middle meningeal artery (MMA) sacrifice. Both maneuvers were spared using a transdural approach. Using CLAST, medial dissection >39 mm can enter the Parkinson triangle, jeopardizing the intracavernous internal carotid artery. The ventral variant enabled access to the anterior portion of the GG and foramen ovale without the need for MMA sacrifice or GPN dissection. CONCLUSIONS: The CLAST approach provides high versatility to approach the trigeminal plexus, minimizing TLR. However, an extradural approach jeopardizes the GPN and requires MMA sacrifice. The risk of cavernous sinus violation exists when progressing medially beyond 4 cm. The ventral variant has some advantages to access the ventral structures and avoid MMA and GPN manipulation. In contrast, the usefulness of the dorsal variant is rather limited owing to the greater TLR required.

The Brain Pre-Metastatic Niche: Biological and Technical Advancements.

Metastasis, particularly brain metastasis, continues to puzzle researchers to this day, and exploring its molecular basis promises to break ground in developing new strategies for combatting this deadly cancer. In recent years, the research focus has shifted toward the earliest steps in the formation of metastasis. In this regard, significant progress has been achieved in understanding how the primary tumor affects distant organ sites before the arrival of tumor cells. The term pre-metastatic niche was introduced for this concept and encompasses all influences on sites of future metastases, ranging from immunological modulation and ECM remodeling to the softening of the blood-brain barrier. The mechanisms governing the spread of metastasis to the brain remain elusive. However, we begin to understand these processes by looking at the earliest steps in the formation of metastasis. This review aims to present recent findings on the brain pre-metastatic niche and to discuss existing and emerging methods to further explore the field. We begin by giving an overview of the pre-metastatic and metastatic niches in general before focusing on their manifestations in the brain. To conclude, we reflect on the methods usually employed in this field of research and discuss novel approaches in imaging and sequencing.

The Beneficial Effect of Preoperative Exercise on Postoperative Clinical Outcome, Quality of Life and Return to Work after Microsurgical Resection of Spinal Meningiomas.

OBJECTIVE: While outcomes of surgical treatment for spinal meningiomas are well-described within the literature, factors affecting early return to work as well as long-term health related quality of life remain unclear. METHODS: In this retrospective study, patients with spinal meningioma and surgical treatment from two university-level neurosurgical institutions between 2008 and 2021 were analyzed. Time to return to work, physical activities and long-term health related quality of life (assessed by telephone interviews using the EQ-5D-5L health status measure and visual analogue scale (EQ VAS) were analyzed. RESULTS: We identified a total of 196 patients who underwent microsurgical resection of spinal meningioma between January 2008 and December 2021. Of those, 130 patients of working age were included and analyzed. The median follow-up time was 96 months. All included patients returned to work. The median time of return to work was 45 days for the whole cohort. Patients who preoperatively performed physical activity returned to work significantly earlier compared to patients who did not (p < 0.001). Furthermore, younger age (p = 0.033) and absence of obesity (p = 0.023) correlated significantly with earlier return to work. Significant differences were also observed in all 5 EQ-5D-5L dimensions between patients with and without preoperative physical activity. CONCLUSIONS: Despite the benign nature of spinal meningioma preoperative physical activity and physiological body weight are associated with favorable postoperative outcome, higher quality of life and early return to work.

Safety and feasibility of outpatient parenteral antimicrobial therapy for patients with spinal infection.

Outpatient parenteral antimicrobial therapy (OPAT) is a cost-effective method of administering intravenous antimicrobial therapy. Although OPAT is well established in the UK and US healthcare systems, few centres in Europe perform it. Here we analysed OPAT for the treatment of patients with spinal infections at our institution. In this retrospective study, patients with spinal infection who required intravenous (i.v.) antimicrobial treatment between 2018 and 2021 were analysed. The duration of short-term antimicrobial treatment for skin and soft tissue infections and complex infections requiring long-term antimicrobial treatment, such as spinal bone or joint infections, were analysed. All patients were discharged with a peripherally inserted central catheter (PICC) line. Prior to discharge, all patients received training in the safe administration of their medications via the PICC line. The duration of OPAT and the rate of readmission after OPAT were analysed. For this study a total of 52 patients who were treated via OPAT due to spinal infections were analyzed. In 35 cases (69.2%) complex spinal infection was reason for i.v. antimicrobial therapy. Surgery was required in 23 of these 35 patients (65.7%). The average hospital stay for these patients was 12 ± 6 days. The remaining 17 patients were treated for an infection of the soft tissue or the skin and hospital stay for these patients was on average 8 ± 4 days. Gram-positive organisms were isolated in 64.4%. Staphylococcus aureus followed by other Staphylococcus species, was the most common detected organism. After discharging i.v. antimicrobial treatment was given for an average of 20 ± 14 days. The duration of antimicrobial treatment for soft tissue was 10.8 ± 8 days, and for complex infections 25.1 ± 18 days. The mean follow-up was 21 ± 14 months. There was one case of readmission due to treatment failure. There were no difficulties encountered in implementing OPAT. OPAT is a feasible and effective option for delivering intravenous antimicrobial therapy to patients with spinal infections who can be managed without hospitalisation. OPAT offers patient-centred treatment at home while avoiding the risks associated with hospitalisation, with high levels of patient satisfaction.

Surgical management and clinical outcome of cervical, thoracic and thoracolumbar spinal tuberculosis in a middle-European adult population.

Spinal tuberculosis is due to globalization no longer a disease limited to developing nations. It remains in Germany a rarity and still a difficult diagnosis. Here we analyzed patients with spinal tuberculosis treated at our neurosurgical department. According to the infected anatomic segment, patients were assigned in one of three groups. Surgery was performed when neurological deficit due to mechanical compression, deformity, instability, severe pain, necrotic bone or failure to respond to anti-tuberculous treatment were observed. We identified 34 patients with spinal tuberculosis who underwent surgical treatment. In the cervical spinal tuberculosis group, there were 15 cases (46.9%) In most cases treatment consisted of spinal instrumentation. In the thoracic group, 10 cases (29.4%) were observed. The treatment was performed by dorsolateral spinal instrumentation. For the thoracolumbar group, 9 cases (26.4%) were observed. In most cases dorsolateral spinal instrumentation was performed. One patient in the first group and one patient in the third group relapsed after operation. A second surgery was necessary. Patients with chronic back pain, immigration background and/or neurological deficit spinal TB should be considered as a differential diagnosis. Combined surgical intervention and medical treatment is associated with a favorable outcome.

In-vivo time course of organ uptake and blood-brain-barrier permeation of poly(L-lactide) and poly(perfluorodecyl acrylate) nanoparticles with different surface properties in unharmed and brain-traumatized rats.

Background: Traumatic brain injury (TBI) has a dramatic impact on mortality and quality of life and the development of effective treatment strategies is of great socio-economic relevance. A growing interest exists in using polymeric nanoparticles (NPs) as carriers across the blood-brain barrier (BBB) for potentially effective drugs in TBI. However, the effect of NP material and type of surfactant on their distribution within organs, the amount of the administrated dose that reaches the brain parenchyma in areas with intact and opened BBB after trauma, and a possible elicited inflammatory response are still to be clarified. Methods: The organ distribution, BBB permeation and eventual inflammatory activation of polysorbate-80 (Tw80) and sodiumdodecylsulfate (SDS) stabilized poly(L-lactide) (PLLA) and poly(perfluorodecyl acrylate) (PFDL) nanoparticles were evaluated in rats after intravenous administration. The NP uptake into the brain was assessed under intact conditions and after controlled cortical impact (CCI). Results: A significantly higher NP uptake at 4 and 24 h after injection was observed in the liver and spleen, followed by the brain and kidney, with minimal concentrations in the lungs and heart for all NPs. A significant increase of NP uptake at 4 and 24 h after CCI was observed within the traumatized hemisphere, especially in the perilesional area, but NPs were still found in areas away from the injury site and the contralateral hemisphere. NPs were internalized in brain capillary endothelial cells, neurons, astrocytes, and microglia. Immunohistochemical staining against GFAP, Iba1, TNFα, and IL1ß demonstrated no glial activation or neuroinflammatory changes. Conclusions: Tw80 and SDS coated biodegradable PLLA and non-biodegradable PFDL NPs reach the brain parenchyma with and without compromised BBB by TBI, even though a high amount of NPs are retained in the liver and spleen. No inflammatory reaction is elicited by these NPs within 24 h after injection. Thus, these NPs could be considered as potentially effective carriers or markers of newly developed drugs with low or even no BBB permeation.

Implementation of the "No ICU - Unless" approach in postoperative neurosurgical management in times of COVID-19.

Following elective craniotomy, patients routinely receive 24-h monitoring in an intensive care unit (ICU). However, the benefit of intensive care monitoring and treatment in these patients is discussed controversially. This study aimed to evaluate the complication profile of a "No ICU - Unless" strategy and to compare this strategy with the standardized management of post-craniotomy patients in the ICU. Two postoperative management strategies were compared in a matched-pair analysis: The first cohort included patients who were managed in the normal ward postoperatively ("No ICU - Unless" group). The second cohort contained patients routinely admitted to the ICU (control group). Outcome parameters contained detailed complication profile, length of hospital and ICU stay, duration to first postoperative mobilization, number of unplanned imaging before scheduled postoperative imaging, number and type of intensive care interventions, as well as pre- and postoperative modified Rankin scale (mRS). Patient characteristics and clinical course were analyzed using electronic medical records. The No ICU - Unless (NIU) group consisted of 96 patients, and the control group consisted of 75 patients. Complication rates were comparable in both cohorts (16% in the NIU group vs. 17% in the control group; p = 0.123). Groups did not differ significantly in any of the outcome parameters examined. The length of hospital stay was shorter in the NIU group but did not reach statistical significance (average 5.8 vs. 6.8 days; p = 0.481). There was no significant change in the distribution of preoperative (p = 0.960) and postoperative (p = 0.425) mRS scores in the NIU and control groups. Routine postoperative ICU management does not reduce postoperative complications and does not affect the surgical outcome of patients after elective craniotomies. Most postoperative complications are detected after a 24-h observation period. This approach may represent a potential strategy to prevent the overutilization of ICU capacities while maintaining sufficient postoperative care for neurosurgical patients.

Motor excitability in bilateral moyamoya vasculopathy and the impact of revascularization.

OBJECTIVE: Motor cortical dysfunction has been shown to be reversible in patients with unilateral atherosclerotic disease after cerebral revascularization. Moyamoya vasculopathy (MMV) is a rare bilateral stenoocclusive cerebrovascular disease. The aim of this study was to analyze the corticospinal excitability and the role of bypass surgery in restoring cortical motor function in patients by using navigated transcranial magnetic stimulation (nTMS). METHODS: Patients with bilateral MMV who met the criteria for cerebral revascularization were prospectively included. Corticospinal excitability, cortical representation area, and intracortical inhibition and facilitation were assessed by nTMS for a small hand muscle (first dorsal interosseous) before and after revascularization. The clinically and/or hemodynamically more severely affected hemisphere was operated first as the leading hemisphere. Intra- and interhemispheric differences were analyzed before and after direct or combined revascularization. RESULTS: A total of 30 patients with bilateral MMV were examined by nTMS prior to and after revascularization surgery. The corticospinal excitability was higher in the leading hemisphere compared with the non-leading hemisphere prior to revascularization. This hyperexcitability was normalized after revascularization as demonstrated in the resting motor threshold ratio of the hemispheres (preoperative median 0.97 [IQR 0.89-1.08], postoperative median 1.02 [IQR 0.94-1.22]; relative effect = 0.61, p = 0.03). In paired-pulse paradigms, a tendency for a weaker inhibition of the leading hemisphere was observed compared with the non-leading hemisphere. Importantly, the paired paradigm also demonstrated approximation of excitability patterns between the two hemispheres after surgery. CONCLUSIONS: The study results suggested that, in the case of a bilateral chronic ischemia, a compensation mechanism between both hemispheres seemed to exist that normalized after revascularization surgery. A potential role of nTMS in predicting the efficacy of revascularization must be further assessed.

The Cerebral Thrombin System Is Activated after Intracerebral Hemorrhage and Contributes to Secondary Lesion Growth and Poor Neurological Outcome in C57Bl/6 Mice.

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 (n = 10) or silicone oil as inert volume substance (n = 10) into the striatum. Intracranial pressure (ICP), cerebral blood flow (CBF), and mean arterial blood pressure (MAP) were monitored during and 30 min after the procedure. No significant differences between ICP, CBF, and MAP were found between both groups. Prothrombin messenger RNA expression was upregulated early after ICH. Immunohistochemistry showed an increase of perilesional thrombin in both groups (blood, 4.24-fold; silicone, 3.10-fold), whereas prothrombin fragment (F1.2) was elevated only in the absence of whole blood. Thrombin expression is colocalized with neuronal antigen expression. After 24 h, lesion size and neuronal loss were similar. Perihematomal thrombin correlated with increased neuronal loss and detrimental neurological outcome in vivo. In our study, we demonstrate, for the first time, that the local cerebral thrombin system is activated after ICH and that this activation is independent of the presence of whole-blood constituents. In our study, neuronal damage is driven by local thrombin expression and leads to an adverse clinical outcome.

Occurrence of Spontaneous Cortical Spreading Depression Is Increased by Blood Constituents and Impairs Neurological Recovery after Subdural Hematoma in Rats.

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 mm3 after blood and 3.4 ± 2.1 mm3 after paraffin oil infusion. Subgroup analysis showed larger lesion size in animals with sCSD, than in those without. Further, occurrence of sCSD led to worse neurological outcomes in both groups. sCSD occurs early after ASDH and does not depend on the presence of whole blood constituents. However, numbers and degree of sCSD are more frequent and severe after autologous blood infusion, compared with an inert volume substance. The occurrence of sCSD leads to lesion growth and worse neurological outcome. Thus, our data advocate close monitoring and targeted treatment of sCSD after ASDH evacuation.

Thrombin contributes to the injury development and neurological deficit after acute subdural hemorrhage in rats only in collaboration with additional blood-derived factors.

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.

The ejector loop reactor: Application for microbial fermentation and comparison with a stirred-tank bioreactor.

Ejector loop reactors (ELR) are successfully used in industrial chemical processes for gas/liquid reactions. They achieve higher mass transfer rates compared to the stirred-tank reactor (STR) at comparable specific power input. Insufficient oxygen transport and shear stress induced growth inhibition are limiting parameters during microbial fermentation. Due to its better mass transfer characteristics, the ELR was expected to have beneficial effects on biomass and recombinant protein production. One concern, however, was whether the ELR's shear stress characteristics would have a negative effect. This study evaluated the suitability of using the Buss-Loop® Reactor (BLR), one of the most advanced ELR technologies, as a bioreactor. The well-studied STR was used as a reference. A lab scale BLR was adapted for microbial fermentation. Mass transfer rates and specific power inputs were within the same order of magnitude in the ELR and the reference STR. Maximum k L a values of 207 and 205 h-1 at power inputs of 6.9 and 9.7 W/L were measured in the ELR and STR, respectively. During batch fermentation of Escherichia coli K12 MG1655, maximum cell densities were higher in the ELR (OD600 of 22) than in the STR (OD600 of 18). Green fluorescence protein (GFP) production with pGS1 was comparable; however, more GFP was released into the media in the ELR. This indicates higher cell disruption compared to the STR. Despite this drawback of the first prototype, our work clearly demonstrates the potential of the ELR as a system for microbial fermentations.