A common tumour in a rare location: a single centre case series of cerebellar glioblastoma

Although glioblastoma is the commonest primary brain tumour in adults, its location in the cerebellum is extremely rare. We present thirteen cases (3 female, 10 male; median age at presentation 56 [age range 21-77]) of surgically managed, histologically confirmed, primary cerebellar glioblastoma (cGB) over a 17 year period (2005-2022). Pre-operative radiological diagnosis was challenging given cGB rarity, although MRI demonstrated ring enhancement in all cases. Surgical management included posterior fossa craniectomy and debulking in 11 cases and burr hole biopsy in two. CSF diversion was necessary in four cases. No evidence of IDH or ATRX gene mutations was found when tested. Survival ranged from 1 to 22 months after diagnosis (mean 10.9 months). We also seek to understand why glioblastoma is rare in this location and discuss potential reasons for this. We hypothesise that increasing anatomical distance from germinal regions and decreased local endogenous neural stem cell activity (which has been associated with glioblastoma) may explain why glioblastoma is rare in the cerebellum. We hereby seek to add to the limited literature on cGB as this is the largest UK cGB series to date.

Beating a skullduggerous infantile hemispheric high-grade glioma

A case of infantile hemispheric high grade glioma in a five-month-old boy is presented. Striking images of a 'beaten copper pot' skull were concerning at first, but with a successful surgical and oncological plan he is well three years later, displaying only minor signs of developmental delay.

A Reappraisal of the Pathophysiology of Cushing Ulcer: A Narrative Review

In 1932, Harvey Cushing described peptic ulceration secondary to raised intracranial pressure and attributed this to vagal overactivity, causing excess gastric acid secretion. Cushing ulcer remains a cause of morbidity in patients, albeit one that is preventable. This narrative review evaluates the evidence pertaining to the pathophysiology of neurogenic peptic ulceration. Review of the literature suggests that the pathophysiology of Cushing ulcer may extend beyond vagal mechanisms for several reasons: (1) clinical and experimental studies have shown only a modest increase in gastric acid secretion in head-injured patients; (2) increased vagal tone is found in only a minority of cases of intracranial hypertension, most of which are related to catastrophic, nonsurvivable brain injury; (3) direct stimulation of the vagus nerve does not cause peptic ulceration, and; (4) Cushing ulcer can occur after acute ischemic stroke, but only a minority of strokes are associated with raised intracranial pressure and/or increased vagal tone. The 2005 Nobel Prize in Medicine honored the discovery that bacteria play key roles in the pathogenesis of peptic ulcer disease. Brain injury results in widespread changes in the gut microbiome in addition to gastrointestinal inflammation, including systemic upregulation of proinflammatory cytokines. Alternations in the gut microbiome in patients with severe traumatic brain injury include colonization with commensal flora associated with peptic ulceration. The brain-gut-microbiome axis integrates the central nervous system, the enteric nervous system, and the immune system. Following the review of the literature, we propose a novel hypothesis that neurogenic peptic ulcer may be associated with alterations in the gut microbiome, resulting in gastrointestinal inflammation leading to ulceration.

Psychrobacter piechaudii shunt infection: first report of human infection

Psychrobacter piechaudii is a recently described species of Gram-negative bacteria in the Moraxellaceae family. No cases of human infection due to this species have been described before. We report the case of an ex-premature infant girl with hydrocephalus secondary to intraventricular haemorrhage who underwent multiple cerebrospinal fluid (CSF) shunt operations. She ultimately developed Psychrobacter piechaudii meningitis, presenting as ventriculoperitoneal shunt dysfunction and wound leak, which necessitated removal of the shunt, a period of external ventricular drainage and antibiotics. We found this organism to be sensitive to intravenous ceftazidime (50 mg/kg) and ciprofloxacin, and a 7-10 day treatment course prior to shunt re-insertion (and 3 week total course) was sufficient. The patient is well post-operatively. To the best of our knowledge, this is the first reported case of Psychrobacter piechaudii infection in a human.

Meta-Analysis of Apparent Diffusion Coefficient in Pediatric Medulloblastoma, Ependymoma, and Pilocytic Astrocytoma

BACKGROUND

Medulloblastoma, ependymoma, and pilocytic astrocytoma are common pediatric posterior fossa tumors. These tumors show overlapping characteristics on conventional MRI scans, making diagnosis difficult.

PURPOSE

To investigate whether apparent diffusion coefficient (ADC) values differ between tumor types and to identify optimum cut-off values to accurately classify the tumors using different performance metrics.

STUDY TYPE

Systematic review and meta-analysis.

SUBJECTS

Seven studies reporting ADC in pediatric posterior fossa tumors (115 medulloblastoma, 68 ependymoma, and 86 pilocytic astrocytoma) were included following PubMed and ScienceDirect searches.

SEQUENCE AND FIELD STRENGTH

Diffusion weighted imaging (DWI) was performed on 1.5 and 3 T across multiple institution and vendors.

ASSESSMENT

The combined mean and standard deviation of ADC were calculated for each tumor type using a random-effects model, and the effect size was calculated using Hedge's g.

STATISTICAL TESTS

Sensitivity/specificity, weighted classification accuracy, balanced classification accuracy. A P value < 0.05 was considered statistically significant, and a Hedge's g value of >1.2 was considered to represent a large difference.

RESULTS

The mean (± standard deviation) ADCs of medulloblastoma, ependymoma, and pilocytic astrocytoma were 0.76 ± 0.16, 1.10 ± 0.10, and 1.49 ± 0.16 mm² /sec × 10^-3 . To maximize sensitivity and specificity using the mean ADC, the cut-off was found to be 0.96 mm² /sec × 10^-3 for medulloblastoma and ependymoma and 1.26 mm² /sec × 10^-3 for ependymoma and pilocytic astrocytoma. The meta-analysis showed significantly different ADC distributions for the three posterior fossa tumors. The cut-off values changed markedly (up to 7%) based on the performance metric used and the prevalence of the tumor types.

DATA CONCLUSION

There were significant differences in ADC between tumor types. However, it should be noted that only summary statistics from each study were analyzed and there were differences in how regions of interest were defined between studies.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 3.

An explanation for Terson syndrome at last: the glymphatic reflux theory

Terson Syndrome (TS) describes the presence of intraocular hemorrhage in patients with intracranial hemorrhage, typically subarachnoid hemorrhage. Despite TS being a well-defined and frequently occurring phenomenon, its pathophysiology remains controversial. This review will present the current understanding of TS, with view to describing a contemporary and more plausible pathomechanism of TS, given recent advances in ophthalmic science and neurobiology. Previously proposed theories include a sudden rise in intracranial pressure (ICP) transmitted to the optic nerve sheath leading to rupture of retinal vessels; or intracranial blood extending to the orbit via the optic nerve sheath. The origin of blood in TS is uncertain, but retinal vessels appear to be an unlikely source. In addition, an anatomical pathway for blood to enter the eye from the intracranial space remains poorly defined. An ocular glymphatic system has recently been described, drainage of which from the globe into intracranial glymphatics is reliant on the pressure gradient between intraocular pressure and intracranial pressure. The glymphatic pathway is the only extravascular anatomical conduit between the subarachnoid space and the retina. We propose that subarachnoid blood in skull base cisterns near the optic nerve is the substrate of blood in TS. Raised ICP causes it to be refluxed through glymphatic channels into the globe, resulting in intraocular hemorrhage. We herewith present glymphatic reflux as an alternative theory to explain the phenomenon of Terson Syndrome.

EPEN-24. SIOP EPENDYMOMA II: CENTRAL EPENDYMOMA MANAGEMENT ADVISORY GROUP – THE UK EXPERIENCE

Paediatric Ependymoma is the second most common malignant brain tumour of childhood with approximately 50% of cases recurring. It has been described as a “surgical” disease since patients who have undergone a gross total surgical resection (GTR) have a better prognosis than those who have a subtotal resection (STR). Analysis of the UKCCSG/SIOP 1992 04 clinical trial has shown that only 49% of cases had a GTR, with 5-year survival rates for STR of 22–47% and GTR of 67–80%. As part of the SIOP II Ependymoma trial the UK established a panel of experts in the treatment of Ependymoma from Neuro-oncology, Neuro-radiology and Neuro-surgery. Meeting weekly, cases are discussed to provide a consensus on radiological review, ensuring central pathological review, trial stratification and whether further surgery should be advocated on any particular case. Evaluation of the first 68 UK patients has shown a GTR in 47/68 (69%) of patients and STR in 21/68 (31%) of patients. Following discussion at EMAG it was felt that 9/21 (43%) STR patients could be offered early second look surgery. Following this 2nd look surgery the number of cases with a GTR increased to 56/68 (82%). There has been a clear increase in the number of patients for whom a GTR has been achieved following discussion at EMAG and prior to them moving forwards with their oncological treatment. This can only have beneficial effects in decreasing their risk of tumour recurrence or CSF dissemination and also in reducing the target volume for radiotherapy.

P57 An innovative approach to workplace based didactic teaching in neurosurgery: initial experience

Objectives

To increase the amount and quality of didactic teaching by commissioning an in-house Diploma course using distance-learning methodologies to supplement regular departmental teaching sessions.

Design

Web-based course consisting of 9 modules covering the breadth of neurosurgical topics. A Diploma was conferred by the Head of Service upon successful completion of all modules.

Subjects

To date, eleven learners (junior doctors at F1/F2/SHO level) have started the Diploma, including doctors from outside our department.

Methods

Learners download a module, dedicate a period of self-study and then discuss the module with their Tutor. To complete a module, a learner would be expected to demonstrate to the Tutor that their knowledge was at ST2 standard as described in the neurosurgical curriculum. Assessment of modules was documented on learners’ existing portfolios.

Results

By way of feedback, all learners (100%) strongly agreed that the Diploma was useful for their day to day job, that it helped understand management of acute neurosurgical problems, that it was interesting, that they would recommend it to a friend/colleague and that support received from the Course Tutor was helpful.

Conclusions

Learners reportedly enjoyed the self-directed, flexible aspect of the Diploma and found that it promoted interactive discussions with registrars and consultants. Feedback obtained externally through HEE and GMC was highly praiseworthy of the Diploma. We intend to continue to offer this course.

Glioblastoma multiforme metastatic to lung in the absence of intracranial recurrence: case report

We present the case of a 65 year old gentleman who underwent craniotomy and debulking of a left temporal glioblastoma multiforme (GBM). Post-operatively he received chemotherapy and radiotherapy with good response demonstrated on interval MRI scans. At 17 months post-diagnosis and in the absence of clinical or radiological recurrence, he presented with respiratory distress. He was found to have an exudative right-sided pleural effusion, nodular pleural thickening, a hilar mass and associated lymphadenopathy. Percutaneous pleural biopsy revealed metastatic GBM. Systemic GBM metastasis despite good response to oncological treatments and in the absence of intracranial recurrence is exceedingly rare. We review the literature concerning extra-neuraxial GBM metastasis and speculate why this phenomenon is extremely rare.

Successful treatment of giant cavernous carotid artery aneurysm in a child using a flow diverter stent

Giant intracranial aneurysms are extremely rare in children. We present such a case, describe angiographic appearances and successful treatment using a flow diverter stent.

Recurrent Bell's palsy following ventriculoperitoneal shunt insertion: an unusual case to face

We present the case of a 15 year old boy who developed transient lower motor neuron facial weakness on two separate occasions shortly after ventriculoperitoneal shunt insertion. Both episodes, each of which occurred on the ipsilateral side to shunt insertion, were transient, self-limiting and were managed medically with a course of oral steroids. We believe this is the first reported case of Bell's palsy after this type of surgery in a child. Potential pathophysiological mechanisms are discussed.

A cracking shot! depressed skull fracture sustained from a golf ball in a 16-year old

Depressed skull fractures sustained from golf balls are quite rare. We report such a case in a 16-year old, and demonstrate its appearance in a 3D CT reconstruction.

Adjuvant chemotherapy for brain tumors delivered via a novel intra-cavity moldable polymer matrix

Introduction

Polymer-based delivery systems offer innovative intra-cavity administration of drugs, with the potential to better target micro-deposits of cancer cells in brain parenchyma beyond the resected cavity. Here we evaluate clinical utility, toxicity and sustained drug release capability of a novel formulation of poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) microparticles.

Methods

PLGA/PEG microparticle-based matrices were molded around an exvivo brain pseudo-resection cavity and analyzed using magnetic resonance imaging and computerized tomography. Invitro toxicity of the polymer was assessed using tumor and endothelial cells and drug release from trichostatin A-, etoposide- and methotrexate-loaded matrices was determined. To verify activity of released agents, tumor cells were seeded onto drug-loaded matrices and viability assessed.

Results

PLGA/PEG matrices can be molded around a pseudo-resection cavity wall with no polymer-related artifact on clinical scans. The polymer withstands fractionated radiotherapy, with no disruption of microparticle structure. No toxicity was evident when tumor or endothelial cells were grown on control matrices invitro. Trichostatin A, etoposide and methotrexate were released from the matrices over a 3-4 week period invitro and etoposide released over 3 days invivo, with released agents retaining cytotoxic capabilities. PLGA/PEG microparticle-based matrices molded around a resection cavity wall are distinguishable in clinical scanning modalities. Matrices are non-toxic invitro suggesting good biocompatibility invivo. Active trichostatin A, etoposide and methotrexate can be incorporated and released gradually from matrices, with radiotherapy unlikely to interfere with release.

Conclusion

The PLGA/PEG delivery system offers an innovative intra-cavity approach to administer chemotherapeutics for improved local control of malignant brain tumors.

Recapitulation of tumor heterogeneity and molecular signatures in a 3D brain cancer model with decreased sensitivity to histone deacetylase inhibition

Introduction

Physiologically relevant pre-clinical ex vivo models recapitulating CNS tumor micro-environmental complexity will aid development of biologically-targeted agents. We present comprehensive characterization of tumor aggregates generated using the 3D Rotary Cell Culture System (RCCS).

Methods

CNS cancer cell lines were grown in conventional 2D cultures and the RCCS and comparison with a cohort of 53 pediatric high grade gliomas conducted by genome wide gene expression and microRNA arrays, coupled with immunohistochemistry, ex vivo magnetic resonance spectroscopy and drug sensitivity evaluation using the histone deacetylase inhibitor, Vorinostat.

Results

Macroscopic RCCS aggregates recapitulated the heterogeneous morphology of brain tumors with a distinct proliferating rim, necrotic core and oxygen tension gradient. Gene expression and microRNA analyses revealed significant differences with 3D expression intermediate to 2D cultures and primary brain tumors. Metabolic profiling revealed differential profiles, with an increase in tumor specific metabolites in 3D. To evaluate the potential of the RCCS as a drug testing tool, we determined the efficacy of Vorinostat against aggregates of U87 and KNS42 glioblastoma cells. Both lines demonstrated markedly reduced sensitivity when assaying in 3D culture conditions compared to classical 2D drug screen approaches.

Conclusions

Our comprehensive characterization demonstrates that 3D RCCS culture of high grade brain tumor cells has profound effects on the genetic, epigenetic and metabolic profiles of cultured cells, with these cells residing as an intermediate phenotype between that of 2D cultures and primary tumors. There is a discrepancy between 2D culture and tumor molecular profiles, and RCCS partially re-capitulates tissue specific features, allowing drug testing in a more relevant ex vivo system.

Pediatric high-grade glioma: identification of poly(ADP-ribose) polymerase as a potential therapeutic target

Pediatric high-grade gliomas (World Health Organization grades III and IV astrocytomas) remain tumors with a very poor prognosis for which novel therapeutic strategies are needed. Poly(ADP-ribose) polymerase (PARP) is known to have multiple functions in tumors, including single-strand DNA repair and induction of caspase-independent apoptosis. PARP has been suggested as a therapeutic target in adult malignancies, and this study examines whether it could also be a potential target in pediatric high-grade glioma. Tissue microarrays containing 150 formalin-fixed pediatric high-grade gliomas were examined by immunohistochemistry for levels of PARP and expression of apoptosis inducing factor (AIF). Full retrospective clinical and survival data were available for this cohort. Stratification and statistical analysis was performed to assess the effect of PARP status on prognosis. The level of PARP immunopositivity had a statistically significant inverse correlation (P = .019) with survival in supratentorial pediatric high-grade glioma. AIF staining was notable for its absence in the majority of tumors but with moderate levels of expression in surrounding normal brain. PARP is expressed at high levels in many pediatric high-grade gliomas, and in these tumors, the ability of PARP to activate AIF appears to have been lost. PARP may therefore represent a promising therapeutic target for these lesions and warrants evaluation in clinical trials.

Stereotactic brain biopsy: an audit of sampling reliabilityin a clinical case series

Stereotactic brain biopsy is the current gold standard procedure to obtain a neuropathological diagnosis. An audit of 207 stereotactic cases, between January 1997 and December 2000 was carried out. The aim was to determine the optimum number of target sites required to make the final diagnosis and thereby set up recommendations for future practice. The overall diagnostic success rate was 89.3%. A significant positive correlation between the number of targets taken and the probability of achieving the final diagnosis was seen. In a subset of glioblastoma cases 96.1% of the tumours could have been confidently diagnosed on the basis of any two of the targets chosen, although often more targets were taken than this. The recommendations made by the audit were: (i) in cases where it is suspected the lesion does not require grading, one target site should be taken and further sites should only be taken if the first proves to be non diagnostic; (ii) in suspected glial series tumours, two targets should be routinely taken, with further sites taken only if these prove inconclusive on intraoperative smear.

The role of neuroendoscopy in the management of brain tumours

Neuroendoscopy is increasingly used in the management of brain tumours and tumour related hydrocephalus and this study reviews the efficacy of neuroendoscopic interventions in this unit in patients with brain tumours. A series of 87 neuroendoscopic operations carried out in 77 patients with brain tumours over a 6-year period is reported. The age range of the patients was from 5 months to 70 years (median 13 years). In 56 cases (64%) presentation was with a newly-diagnosed tumour and hydrocephalus. The majority of the remaining patients had varying degrees of worsening hydrocephalus on the background of a previously diagnosed tumour. Neuroendoscopic third ventriculostomy (NTV) was successful in relieving hydrocephalus in the short term in 63/66 cases (95%) and in the longer term in 55/66 cases (83%). Neuroendoscopic tumour biopsies were successful in providing a tissue diagnosis in 17/28 cases (61%) and four extensive and three partial resections of tumour were carried out. There were two deaths within 30 days of the procedure with only one of these, secondary to intraventricular haemorrhage, directly related to neuroendoscopy. Few significant complications were noted otherwise. For selected intraventricular and paraventricular tumours neuroendoscopy offers the opportunity to combine relief of hydrocephalus with tumour biopsy and sampling of CSF in a single procedure.

The management of brain tumours

Current knowledge on the biology and clinical features of brain tumours is reviewed with particular reference to the most commonly occurring tumours - gliomas, meningiomas and metastases. Unfortunately, the enormous increase in understanding of the biology of these tumours over recent years has not, as yet, been paralleled by advances in treatment or improvements in clinical outcome. Developing adjuvant therapies, ranging from novel means of delivery of radiotherapy and new chemotherapy agents to gene therapy and anti-angiogenic agents, are currently being explored and offer some hope for improvement in our ability to treat these tumours over the next few decades.

The effectiveness of neuroendoscopic interventions in children with brain tumours

OBJECT

The purpose of this study was to review the efficacy of neuroendoscopic interventions in children with brain tumours and tumour-related hydrocephalus.

METHODS

In all, 61 consecutive neuroendoscopic operations carried out in 53 children with brain tumours over a 6-year period were reviewed. The patients ranged in age from 5 months to 18 years (median 9 years). Forty of 61 presentations were with a newly diagnosed tumour and hydrocephalus - the remainder predominantly had a known tumour and worsening hydrocephalus.

CONCLUSIONS

Neuroendoscopic third ventriculostomy (NTV) successfully relieved hydrocephalus in the short term in 45 of 47 cases and in the longer term in 39 of 47 cases. Neuroendoscopic biopsy provided definitive tissue diagnosis in 10 of 16 cases and 5 tumours were resected. There was 1 postoperative death, which not directly related to the neuroendoscopy and few significant complications otherwise. Neuroendoscopic methods allow effective immediate and longer term control of hydrocephalus as well as the opportunity for CSF sampling and tumour biopsy in selected cases.

Can experimental models of rodent implantation glioma be improved? A study of pure and mixed glioma cell line tumours

To evaluate the hypothesis that co-implantation of different rodent glioma cell lines might result in experimental brain tumours that more closely resemble human gliomas the neuropathology and immunocytochemical features of implantation gliomas derived from single cell lines (C6, A15A5, F98), two cell lines admixed 50:50 prior to implantation (C6 + F98 and C6 + A15A5) and three cell lines equally admixed (C6 + A15A5 + F98) was studied in the adult Wistar rat. Tumours grew consistently following implantation of the single and the two admixed cell lines, however tumour growth following triple mix implantation was considerably and consistently impaired. The tumours derived from admixed cell lines showed regional heterogeneity with areas characteristic of both the primary cell lines. Foci of lymphocytic infiltrates, tumoural necrosis, often with pseudopallisading, and peritumoural edema were consistent features of all tumours. Limited parenchymal and more extensive perivascular tumoural invasion was seen predominantly in tumours containing the C6 cell line. There were no significant differences in GFAP, vimentin and HSP70 staining between the mixed tumours, although the pure F98 and A15A5 tumours were, unlike the pure C6 gliomas, S-100 negative. Using PCNA expression as a measure of the tumour proliferation all except the tumours derived from the three cell lines mix, which had a staining index of 7-10%, had focal staining indices in viable tumour of between 40-80%. There was focal positive staining in both perilesional brain and in regions of all tumours for the macrophage markers ED-1 and ED-2. None of the three cell lines stained in vitro for either ED1 and ED2 but all were constitutively positive in vitro for OX-6, a proposed marker for antigen presenting cells. The macrophage and lymphocytic response suggest a vigorous but largely ineffective immunological response had been mounted against all tumours. The consistent failure of the triple mix tumours to grow is unexplained. This work has shown the feasibility of producing 'mixed' cell line experimental gliomas by combining two cell lines at the time of innoculation. However, the relative failure to produce (i) mixed tumours that have properties not inherent to either parent cell line and (ii) implantation glioma with three cell lines suggest there are limits to this approach. Admixture of cell lines at the time of implantation therefore does not make experimental glioma models that more closely resemble natural gliomas, and also has some particular disadvantages. This experimental approach is therefore not recommended for use in the study of tumour biology and in evaluating the effectiveness of novel therapies.

Avoidable deaths still occur after large bowel surgery. Scottish Audit of Surgical Mortality, Royal College of Surgeons of Edinburgh

BACKGROUND

Postoperative death following large bowel surgery is relatively infrequent and no large study has analysed the cause of all deaths comprehensively and critically.

METHODS

In-hospital deaths following large bowel surgery in South-East Scotland were reviewed by independent assessors. The audit was confidential but not anonymous. Independent assessors' reports were returned to consultants.

RESULTS

The audit documented 187 deaths. The independent assessors noted an adverse event in 78 patients (42 per cent). Twenty-six deaths (14 per cent) occurred following an anastomotic leak. A further 43 deaths (23 per cent) occurred because surgery was delayed (17) or there was undue delay in making the initial diagnosis (12) or recognizing a developing complication (14). Consultants operated on only half the patients classed as American Society of Anesthesiologists grade IV or V, or undergoing a second or subsequent operation.

CONCLUSION

Half the patients dying in this study had identifiable deficiencies in their management. There is a clear need for greater consultant input with critically ill patients.