Pre-Chiasmatic, Single Injection of Autologous Blood to Induce Experimental Subarachnoid Hemorrhage in a Rat Model

Despite advances in treatment over the last decades, subarachnoid hemorrhage (SAH) continues to carry a high burden of morbidity and mortality, largely afflicting a fairly young population. Several animal models of SAH have been developed to investigate the pathophysiological mechanisms behind SAH and to test pharmacological interventions. The pre-chiasmatic, single injection model in the rat presented in this article is an experimental model of SAH with a predetermined blood volume. Briefly, the animal is anesthetized, intubated, and kept under mechanical ventilation. Temperature is regulated with a heating pad. A catheter is placed in the tail artery, enabling continuous blood pressure measurement as well as blood sampling. The atlantooccipital membrane is incised and a catheter for pressure recording is placed in the cisterna magna to enable intracerebral pressure measurement. This catheter can also be used for intrathecal therapeutic interventions. The rat is placed in a stereotaxic frame, a burr hole is drilled anteriorly to the bregma, and a catheter is inserted through the burr hole and placed just anterior to the optic chiasm. Autologous blood (0.3 mL) is withdrawn from the tail catheter and manually injected. This results in a rise of intracerebral pressure and a decrease of cerebral blood flow. The animal is kept sedated for 30 min and given subcutaneous saline and analgesics. The animal is extubated and returned to its cage. The pre-chiasmatic model has a high reproducibility rate and limited variation between animals due to the pre-determined blood volume. It mimics SAH in humans making it a relevant model for SAH research.

Prompt closure versus gradual weaning of extraventricular drainage for hydrocephalus in adult patients with aneurysmal subarachnoid haemorrhage: a systematic review protocol with meta-analysis and trial sequential analysis

INTRODUCTION

In Neuro Intensive Care Units (NICU) and neurosurgical units, patients with an external ventricular drain (EVD) due to hydrocephalus following aneurysmal subarachnoid haemorrhage (SAH) are commonly seen. Cessation of the EVD involves the dilemma of either closing the EVD directly, or gradually weaning it before removal. Development of increased intracranial pressure (ICP) and acute hydrocephalus with subsequent need of a permanent shunt has been associated with prompt closure of theEVD, whereas increased risk of infection with possible spreading to the brain and subsequent patient fatality is suspected in connection to a longer treatment as seen in gradual weaning. Sparse data exist on the recommendation of cessation strategy and patients are currently being treated on the basis of personal experience and expert opinion. The objective of this systematic review is to assess the available evidence from clinical trials on the effects of prompt closure versus gradual weaning of EVD treatment for hydrocephalus in adult patients with SAH.

METHODS AND ANALYSIS

We will search for randomised clinical trials in major international databases. Two authors will independently screen and select references for inclusion, extract data and assess the methodological quality of the included randomised clinical trials using the Cochrane risk of bias tool. Any disagreement will be resolved by consensus. We will analyse the extracted data using Review Manager and trial sequential analysis. To assess the quality of the evidence, we will create a 'Summary of Findings' table containing our primary and secondary outcomes using the GRADE assessment.

ETHICS AND DISSEMINATION

Results will be published widely according to the interest of the society. No possible impact, harm or ethical concerns are expected doing this protocol.

TRIAL REGISTRATION NUMBER

PROSPERO CRD42018108801.

CSF hypersecretion versus impaired CSF absorption in posthemorrhagic hydrocephalus: a systematic review

BACKGROUND

The molecular mechanisms underlying development of posthemorrhagic hydrocephalus (PHH) remain elusive. The aim of this systematic review was to evaluate existing literature on increased CSF secretion and impaired CSF absorption as pathogenic contributors to CSF accumulation in neonatal and adult PHH.

METHODS

The systematic review was conducted in accordance with the PRISMA guidelines. Relevant studies published before March 11th, 2023, were identified from PubMed and reference lists. Studies were screened for eligibility using predefined inclusion and exclusion criteria. Data from eligible studies were extracted and potential sources of bias were evaluated.

RESULTS

Nineteen studies quantified CSF production rates and/or CSF absorption capacity in human patients with PHH or animals with experimentally induced PHH. Increased CSF production was reported as early as 24 h and as late as 28 days post ictus in six out of eight studies quantifying CSF production rates in animals with experimentally induced PHH. Impaired CSF absorption was reported in all four studies quantifying CSF absorption capacity in human patients with PHH and in seven out of nine studies quantifying CSF absorption capacity in animals with experimentally induced PHH. Impaired CSF absorption was reported as early as 30 min and as late as 10 months post ictus.

CONCLUSIONS

The pathological CSF accumulation in PHH likely arises from a combination of increased CSF secretion and impaired CSF absorption, which may manifest at different time scales following a hemorrhagic event. Emergent evidence on increased CSF secretion by the choroid plexus may herald a paradigm shift in our understanding of PHH.

Relevancy of radiographic features in elbow fractures

PURPOSE

To correlate radiographic and clinical findings of elbow fractures.

MATERIAL AND METHODS

A retrospective study was made of 110 consecutive adult elbow fractures of various types involving the humerus, the ulna, and the radius.

RESULTS

Twenty-seven fractures with radiographically conspicuous distortions healed. Of these only 15 had clinical sequelae. Five had clinical sequelae without showing conspicuous radiographic distortions after healing.

CONCLUSION

For radiographic evaluation and classification purposes, it would seem to be important to note the status of the capitellum, the capitellum-trochlear plane, and the combination of a distal humerus and a proximal ulna fracture. The outcome of common olecranon fractures and injuries to the radial head would seem to depend less on a detailed radiographic description.

Adjuvant radiotherapy and stereotactic radiosurgery in grade 3 meningiomas - a systematic review and meta-analysis

Malignant meningioma is a rare, aggressive form of meningioma. Radiation is commonly included in treatment guidelines either as adjuvant radiotherapy (RT) or stereotactic radiosurgery (SRS). Nevertheless, the treatment recommendations are not supported by prospective comparative trials and systematical, critical evaluation of supportive evidence is lacking. For this systematic review, studies analyzing the effectiveness of adjuvant RT and SRS in grade 3 (gr. 3) meningioma were reviewed. Thirty studies met the inclusion criteria for qualitative synthesis, and 6 studies were assessed in quantitative analysis. In quantitative analysis, the weighted average of hazard ratios for adjuvant RT in univariate analyses of overall survival (OS) was 0.55 (CI: 0.41; 0.69). The median 5-year OS after adjuvant RT in gr. 3 meningiomas was 56.3%, and the median OS ranged from 24 to 80 months for patients treated with adjuvant RT versus 13 to 41.2 months in patients not treated. For SRS, the 3-year progression free survival was 0% in one study and 57% in another. The 2-year OS ranged from 25 to 75% in 2 studies. The quality of evidence was rated as "very low" in 14 studies analyzed, and considerable allocation bias was detected. Treatment toxicity was reported in 47% of the studies. The severity, according to the CTCAE, ranged from grades I-V and 5.3 to 100% of patients experienced complications. Adjuvant RT is usually considered standard of care for WHO grade 3 meningiomas, although supporting evidence was of low quality. Better evidence from registries and prospective trials can improve the evidence base for adjuvant fractionated RT in malignant meningiomas.

Should neurosurgeons continue to work in the absence of personal protective equipment during the COVID-19 era?

The COVID-19 pandemic has resulted in a widespread shortage of personal protective equipment (PPE). Many healthcare workers, including neurosurgeons, have expressed concern about how to safely and adequately perform their medical responsibilities in these challenging circumstances. One of these concerns revolves around the pressing question: should providers continue to work in the absence of adequate PPE? Although the first peak of the COVID-19 crisis seems to have subsided and supply of PPE has increased, concerns about insufficient PPE availability remain. Inconsistent supply, limited efficacy, and continued high demand for PPE, combined with the continued threat of a second COVID-19 wave, mean that the issues surrounding PPE availability remain unresolved, including a duty to work. This paper offers an ethical investigation of whether neurosurgeons should perform their professional responsibilities with limited availability of PPE. We evaluate ethical considerations and conflicting duties and thereby hope to facilitate providers in making a well-considered personal and moral decision about this challenging issue.

Prompt closure versus gradual weaning of external ventricular drainage for hydrocephalus in adult patients with aneurysmal subarachnoid haemorrhage: a systematic review

OBJECTIVES

To summarise the evidence on benefits and harms of prompt closure versus gradual weaning of external ventricular drainage (EVD) in patients with hydrocephalus following aneurysmal subarachnoid haemorrhage (aSAH) based on randomised clinical trials (RCTs) in humans.

SETTING

RCTs comparing prompt closure versus gradual weaning of EVD in adult patients with hydrocephalus following aSAH were included.

PARTICIPANTS

Patients aged equal to or greater than 18 years with an EVD due to hydrocephalus following aSAH were eligible for inclusion.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes were all-cause mortality, any serious adverse event, rate of ventriculoperitoneal (VP) shunt placement and quality of life. Secondary outcomes were patients with shunt failure, hospital and neuro intensive care unit (NICU) length of stay (LOS) and complications related to treatment with an EVD. Data permitted report of rate of VP shunt placement, and hospital and NICU LOS.

RESULTS

Six studies were assessed in full text. One RCT with 81 patients was included. Rate of VP shunt placement was 63.4% in the rapid weaning group (ie, prompt closure of the EVD; 41 patients) and 62.5% in the gradual weaning group (40 patients; p=0.932). LOS in hospital and NICU was significantly shorter in the rapidly weaned group compared with the gradually weaned group (mean 19.1 vs 21.5 days in hospital (p=0.03); and mean 14.1 vs 16.9 days in NICU (p=0.0002)). Data were insufficient to conduct meta-analysis, trial sequential analysis or subgroup analysis of heterogeneity and sensitivity. One RCT is currently ongoing.

CONCLUSIONS

We found insufficient evidence to favour any of the two strategies for EVD discontinuation in patients with hydrocephalus following aSAH.

PROSPERO REGISTRATION NUMBER

CRD42018108801.

Negligible In Vitro Recovery of Macromolecules from Microdialysis Using 100 kDa Probes and Dextran in Perfusion Fluid

Microdialysis is applied in neurointensive care to monitor cerebral glucose metabolism. If recoverable, macromolecules may also serve as biomarkers in brain disease and provide clues to their passage across the blood-brain barrier. Our study aimed to investigate the in vitro recovery of human micro- and macromolecules using microdialysis catheters and perfusion fluids approved for clinical use. In vitro microdialysis of a bulk solution containing physiological or supraphysiological concentrations of glucose, lactate, pyruvate, human IgG, serum albumin, and hemoglobin was performed using two different catheters and perfusion fluids. One had a membrane cut-off of 20 kDa and was used with a standard CNS perfusion fluid, and the other had a membrane cut-off of 100 kDa and was perfused with the same solution supplemented with dextran. The flow rate was 0.3 µl/min. We used both push and push-pull methods. Dialysate samples were collected at 2-h intervals for 6 h and analyzed for relative recovery of each substance. The mean relative recovery of glucose, pyruvate, and lactate was > 90% in all but two sets of experiments. In contrast, the relative recovery of human IgG, serum albumin, and hemoglobin from both bulk solutions was below the lower limit of quantification (LLOQ). Using a push-pull method, recovery of human IgG, serum albumin, and hemoglobin from a bulk solution with supraphysiological concentrations were above LLOQ but with low relative recovery (range 0.9%-1.6%). In summary, exchanging the microdialysis setup from a 20 kDa catheter with a standard perfusion fluid for a 100 kDa catheter with a perfusion solution containing dextran did not affect the relative recovery of glucose and its metabolites. However, it did not result in any useful recovery of the investigated macromolecules at physiological levels, either with or without a push-pull pump system.

A national study of burnout, psychosocial work environment, and moral distress among neurosurgical doctors in Denmark

BACKGROUND

Burnout is a condition of mental, emotional, and physical enervation affecting personnel working in human services and has been reported high among neurosurgical doctors. However, previous burnout reports are based on low response rates and measured by the Maslach Burnout inventory, which for several reasons has proven problematic. Burnout has not previously been investigated among neurosurgical doctors in Denmark. With this study we measure the prevalence of burnout among neurosurgical doctors in Denmark with sustainable methodology and a clinically relevant burnout interpretation.

METHODS

Burnout was measured among neurosurgical doctors in Denmark using the Copenhagen Burnout Inventory (CBI) consisting of three subscales measuring personal burnout, work-related burnout and patient-related burnout. To gain better understanding of factors contributing to burnout, the psychosocial working conditions and moral distress was measured using the Danish Psychosocial Work Environment Questionnaire (DPQ) and a questionnaire of eight items previously used to assess moral distress.

RESULTS

With 73 responders and a response rate of 90.1%, clinically relevant burnout was reported in 27.4% in personal burnout, 16.5% in work-related burnout and 5.5% in patient-related burnout. Cohort members with children living at home experienced a significant higher degree of burnout regarding work-related burnout and patient-related burnout. Within the DPQ domains of 'Demands at work' and 'Work organization and job content', several moderate to strong correlations were observed between specific sub-dimensions and both personal and work-related burnout. Higher levels of the domain 'Interpersonal relations' was moderately correlated with lower levels of both personal and work-related burnout. In the testing of moral distress, only 2 responders (2.7%) scored as 'somewhat injured'.

CONCLUSION

Neurosurgical doctors in Denmark report relatively low prevalence of clinically relevant burnout. However, doctors with children living at home exhibited higher levels of work- and patient-related burnout. Our findings highlight the psychosocial work environment as a significant factor contributing to burnout, while moral distress appears to have a limited impact on the development of burnout in the study population.

[Arachnoid cysts can be associated with cognitive and affective symptoms]

Arachnoid cysts are frequent incidental findings on brain scans. Traditionally, they are regarded as harmless, congenital structures which do not require surgical treatment. In the rare cases where surgery is indicated it can be due to haemorrhage, hydrocephalus or cranial nerve affection caused by the cyst. However, recent literature suggests a correlation between arachnoid cysts and cognitive and affective symptoms. The hypothesised pathomechanisms include pressure, affected neuronal or glial metabolism and inflammation. If this is correct a more active approach might benefit the patients as suggested in this review.

Brain hypoxia and metabolic crisis are common in patients with acute brain injury despite a normal intracranial pressure

Patients with acute brain injury are vulnerable to secondary deterioration, which may go undetected by traditional monitoring. However, multimodal neuromonitoring of brain tissue oxygen tension (PbtO2) and energy metabolism may be able to detect such episodes. We report a retrospective, observational study of 94 patients with aneurysmal subarachnoid haemorrhage (SAH) or traumatic brain injury (TBI) who underwent multimodal neuromonitoring during admission. We examined the co-occurrence of pathological neuromonitoring values: elevated intracranial pressure (ICP, > 20 mmHg), inadequate cerebral perfusion pressure (CPP, < 60 mmHg), brain hypoxia (PbtO2 < 20 mmHg), and metabolic crisis (lactate/pyruvate ratio > 40 and a glucose level < 0.2 mmol/L in cerebral microdialysate). Mixed effects linear regression demonstrated significant associations between abnormal ICP/CPP, cerebral hypoxia and metabolic crisis. However, brain hypoxia occurred in 40% and 31% of observations in patients with SAH and TBI, respectively, despite normal concurrent values of ICP. Similarly, metabolic crisis was observed in 8% and 16% of measurements for SAH and TBI, respectively, despite a normal ICP. The pattern was identical for CPP. In conclusion, although all neuromonitoring variables are interrelated, brain hypoxia and metabolic crisis are common despite an absence of abnormalities in conventional monitoring. Multimodal neuromonitoring may help identify such episodes and guide individualised treatment.

OTEH-3. Targeted Gene-Expression analysis during malignant transformation in primary and secondary malignant meningioma

Background

Malignant meningiomas comprise 2–5% of all meningiomas. The process of malignant transformation when benign meningiomas (WHO grade I-II) become malignant (WHO grade III) has not previously been investigated in sequential tumour surgeries. Upregulation of FOXM1 expression and DREAM-complex repression have shown phenotypical subgroups correlating with WHO grade and aggressiveness. We investigated the RNA expression of 30 genes central to meningioma biology and 770 genes involved in neuroinflammatory pathways in primary and secondary malignant meningioma patients who underwent one to several operations.

Methods

We identified a cohort of consecutive malignant meningioma patients treated at Rigshospitalet, Copenhagen from 2000–2020 (n=51) and gathered their malignant tumours and previous WHO grade I/II tumours. The malignant cohort (MC) was counter matched with a benign cohort (BC) where patients had no recurrences during follow-up. RNA expression signatures from 140 samples from the MC and 51 samples from the BC were analysed with the Nanostring Neuroinflammation panel customized with 30 genes known to be relevant in meningioma phenotypes.

Results

49% of MC patients had a previous grade I/II meningioma making them secondary malignant meningioma patients. Progression-free survival calculated from first malignant surgery to first recurrence or death showed no significant difference in the primary vs. secondary patients. Preliminary results of single-gene analysis of MC tumours showed FOXM1, MYBL2, TOP2A, BIRC5 expression was higher in WHO grade III samples. Gene-expression signatures in the individual patients and gene ontology enrichment analyses are in process.

Conclusions

FOXM1, MYBL2, TOP2A, BIRC5 RNA expression levels seem to rise during malignant progression across patients. Gene-expression analysis using the Nanostring technology is feasible and a potentially powerful tool to distinguish meningiomas prone to malignant transformation from truly benign meningiomas.

Three underdogs among galenic veins: anatomical analysis and literature review of surgical relevant veins in the quadrigeminal cistern

Recent studies (Alaou-Ismaili et al. 2020; Kilic et al. Eur J Radiol 56:212-219, 2005) among experienced sub-specialized neurosurgeons described divergent perceptions of surgical risk for venous sacrifice in posterior fossa surgery. Three galenic veins stood out as controversial in venous risk assessment and underexplored in the literature: the internal occipital vein (IOV), the precentral cerebellar vein (PCV), and the superior vermian vein (SVV). We have conducted a narrative review based on a systematic literature search to analyze terminology and anatomic descriptions and to suggest a coherent synthesis of published data on these veins. A systematic PubMed literature search was carried out using the keywords: "posterior fossa," "venous anatomy," and "radiology." Relevant radiological, microsurgical, and anatomical articles were selected if they described the anatomy of the three veins. Anatomical descriptions were analyzed with hermeneutic methodology alongside the articles' radiological and anatomical dissection pictures. New illustrations were created to depict the synthesized image of the venous anatomy. A total of 13 articles described the anatomy and terminology of the relevant veins. The descriptions of the IOV included smaller non-occipital vessels that confused the identification of the vessel. IOV is analyzed to be the vein draining the primary visual cortex, which drains into the vein of Galen (VG). The PCV and SVV enter the VG from below and are fused in almost half of all studied patients, creating a third vessel by the name of the superior cerebellar vein. A conscientious narrative review and hermeneutic analysis produced a synthesized, uniform picture of terminology and anatomy. Consensus on anatomical descriptions and definitions are indispensable for validation of anatomy, research into anatomical variation, for surgical planning and documentation.

Correction to: Clinical Chiari syndrome or anatomical Chiari malformation? A conundrum revisited

An incorrect set of affiliations for two authors (Tiit Illimar Mathiesen and Andreas K. Demetriades).

Posthemorrhagic Hydrocephalus in Patients with Subarachnoid Hemorrhage Occurs Independently of CSF Osmolality

The molecular mechanisms underlying the development of posthemorrhagic hydrocephalus (PHH) remain incompletely understood. As the disease pathogenesis often cannot be attributed to visible cerebrospinal fluid (CSF) drainage obstructions, we here aimed to elucidate whether elevated CSF osmolality following subarachnoid hemorrhage (SAH) could potentiate the formation of ventricular fluid, and thereby contribute to the pathological CSF accumulation observed in PHH. The CSF osmolality was determined in 32 patients with acute SAH after external ventricular drainage (EVD) placement and again upon EVD removal and compared with the CSF osmolality from 14 healthy control subjects undergoing vascular clipping of an unruptured aneurism. However, we found no evidence of elevated CSF osmolality or electrolyte concentration in patients with SAH when compared to that of healthy control subjects. We detected no difference in CSF osmolality and electrolyte content in patients with successful EVD weaning versus those that were shunted due to PHH. Taken together, elevated CSF osmolality does not appear to underlie the development of PHH following SAH. The pathological CSF accumulation observed in this patient group must thus instead be attributed to other pathological alterations associated with the abnormal presence of blood within the CSF compartments following SAH.

Translocator protein (TSPO) expression in neoplastic cells and tumor-associated macrophages in meningiomas

Meningiomas are the most common primary intracranial tumors and show extensive infiltration of macrophages. The mitochondrial membrane protein translocator protein (TSPO) has been used as an in vivo marker of microglia and macrophage activation to visualize neuroinflammation. However, it is unknown which cell types express TSPO in meningiomas. Immunohistochemistry of 38 WHO grade 1-3 meningiomas was subjected to segmentation and deep learning classification of TSPO expression to either Iba1-positive tumor-associated macrophages (TAMs) or all other (mainly neoplastic) cells. A possible association between clinical data and TSPO expression intensities was also investigated. TAMs accounted for 15.9%-26% of all cells in the meningioma tissue. Mean fluorescence intensity of TSPO was significantly higher in TAMs (p < 0.0001), but the mass of neoplastic cells in the tumors exceeded that of TAMs. Thus, the summed fluorescence intensity of TSPO in meningioma cells was 64.1% higher than in TAMs (p = 0.0003). We observed no correlation between TSPO expression intensity and WHO grade. These results indicate that both macrophage-lineage and neoplastic cells in meningiomas express TSPO and that the SPECT-TSPO signal in meningiomas mainly reflects the latter; TSPO is expressed equally in parenchymal activated and resting macrophage/microglia lineage cells.