The prognostic utility of temporalis muscle thickness measured on magnetic resonance scans in patients with intra-axial malignant brain tumours: A systematic review and meta-analysis

Introduction

Sarcopenia is associated with worsened outcomes in solid cancers. Temporalis muscle thickness (TMT) has emerged as a measure of sarcopenia. Hence, this study aims to evaluate the relationship between TMT and outcome measures in patients with malignant intra-axial neoplasms.

Method

We searched Medline, Embase, Scopus and Cochrane databases for relevant studies. Event ratios with 95% confidence intervals (CI) were analysed using the RevMan 5.4 software. Where meta-analysis was impossible, vote counting was used to determine the effect of TMT on outcomes. The GRADE framework was used to determine the certainty of the evidence.

Results

Four outcomes were reported for three conditions across 17 studies involving 4430 patients. Glioblastoma: thicker TMT was protective for overall survival (OS) (HR 0.59; 95% CI 0.46-0.76) (GRADE low), progression free survival (PFS) (HR 0.40; 95% CI 0.26-0.62) (GRADE high), and early discontinuation of treatment (OR 0.408; 95% CI 0.168-0.989) (GRADE high); no association with complications (HR 0.82; 95% CI 0.60-1.10) (GRADE low). Brain Metastases: thicker TMT was protective for OS (HR 0.73; 95% CI 0.67-0.78) (GRADE moderate); no association with PFS (GRADE low). Primary CNS Lymphoma: TMT was protective for overall survival (HR 0.34; 95% CI 0.19-0.60) (GRADE moderate) and progression free survival (HR 0.23; 95% CI 0.09-0.56) (GRADE high).

Conclusion

TMT has significant prognostic potential in intra-axial malignant neoplasms, showing a moderate to high certainty for its association with outcomes following GRADE evaluation. This will enable shared decision making between patients and clinicians.

The Impact of Intracranial Pressure Telesensors: An Observational Propensity-Matched Control Analysis of Service Demand and Costs

BACKGROUND AND OBJECTIVES

Implantable telemetric intracranial pressure (ICP) sensors (telesensors) enable routine, noninvasive ICP feedback, aiding clinical decision-making and attribution of pressure-related symptoms in patients with cerebrospinal fluid shunt systems. Here, we aim to explore the impact of these devices on service demand and costs in patients with adult hydrocephalus.

METHODS

We performed an observational propensity-matched control study, comparing patients who had an MScio/Sensor Reservoir (Christoph Miethke, GmbH & Co) against those with a nontelemetric reservoir inserted between March 2016 and March 2018. Patients were matched on demographics, diagnosis, shunt-type, and revision status. Service usage was recorded with frequencies of neurosurgical admissions, outpatient clinics, scans, and further surgical procedures in the 2 years before and after shunt insertion.

RESULTS

In total, 136 patients, 73 telesensors, and 63 controls were included in this study (48 matched pairs). Telesensor use led to a significant decrease in neurosurgical inpatient admissions, radiographic encounters, and procedures including ICP monitoring. After multivariate adjustment, the mean cumulative saving after 2 years was £5236 ($6338) in telesensor patients (£5498 on matched pair analysis). On break-even analysis, cost-savings were likely to be achieved within 8 months of clinical use, postimplantation. Telesensor patients also experienced a significant reduction in imaging-associated radiation (4 mSv) over 2 years.

CONCLUSION

The findings of this exploratory study reveal that telesensor implantation is associated with reduced service demand and provides net financial savings from an institutional perspective. Moreover, telesensor patients required fewer appointments, invasive procedures, and had less radiation exposure, indicating an improvement in both their experience and safety.

Ambulatory intracranial pressure in humans: ICP increases during movement between body positions

Introduction

Positional changes in intracranial pressure (ICP) have been described in humans when measured over minutes or hours in a static posture, with ICP higher when lying supine than when sitting or standing upright. However, humans are often ambulant with frequent changes in position self-generated by active movement.

Research question

We explored how ICP changes during movement between body positions.

Material and methods

Sixty-two patients undergoing clinical ICP monitoring were recruited. Patients were relatively well, ambulatory and of mixed age, body habitus and pathology. We instructed patients to move back and forth between sitting and standing or lying and sitting positions at 20 s intervals after an initial 60s at rest. We simultaneously measured body position kinematics from inertial measurement units and ICP from an intraparenchymal probe at 100 Hz.

Results

ICP increased transiently during movements beyond the level expected by body position alone. The amplitude of the increase varied between participants but was on average ∼5 mmHg during sit-to-stand, stand-to-sit and sit-to-lie movements and 10.8 mmHg [95%CI: 9.3,12.4] during lie-to-sit movements. The amplitude increased slightly with age, was greater in males, and increased with median 24-h ICP. For lie-to-sit and sit-to-lie movements, higher BMI was associated with greater mid-movement increase (β = 0.99 [0.78,1.20]; β = 0.49 [0.34,0.64], respectively).

Discussion and conclusion

ICP increases during movement between body positions. The amplitude of the increase in ICP varies with type of movement, age, sex, and BMI. This could be a marker of disturbed ICP dynamics and may be particularly relevant for patients with CSF-diverting shunts in situ.

Can clinicians correctly predict intracranial pressure state based on clinical symptoms alone in shunted patients?

BACKGROUND

Clinicians are well-versed in the classical symptoms of low vs. high intracranial pressure (ICP). However, symptoms may not be as predictable of ICP state in shunted patients with chronic symptoms. In this study, we assess whether clinicians can predict high vs. low ICP state in chronically symptomatic shunted patients without any diagnostic clues.

METHODS

A detailed retrospective analysis was performed on 259 patients undergoing ICP monitoring. A total of 17 patients who had a ventriculoperitoneal shunt were identified, with a suspected chronic abnormal ICP state based only on clinical symptoms. Patients with investigations guiding towards a likely pressure state were excluded, e.g., imaging or ophthalmological findings suggestive of ICP state.

RESULTS

Clinical suspicion of ICP state was incorrect in 16 out of 17 cases (P<0.05). The symptoms described by patients were suggestive of abnormal ICP states; however, 13 out of 17 cases demonstrated ICP within the normal range (-1.3 to 5.3 mmHg). Three patients with occipital headaches worse on standing, typical of low-pressure symptoms, were in fact shown to have ICP above 10.0 mmHg.

CONCLUSIONS

This study casts doubt on the utility of classic symptoms in diagnosing abnormal ICP state in chronically symptomatic shunted patients with equivocal adjuncts. Additionally, it highlights the importance of ICP monitoring for this patient group.

The initial intracranial pressure spike phenomenon

BACKGROUND

Elective use of intraparenchymal intracranial pressure (ICP) monitoring is a valuable resource in the investigation of hydrocephalus and other cerebrospinal fluid disorders. Our preliminary study aims to investigate ICP changes in the immediate period following dural breach, which has not yet been reported on.

METHOD

This is a prospective cohort study of patients undergoing elective ICP monitoring, recruited between March and May 2022. ICP readings were obtained at opening and then at 5-min intervals for a 30-min duration.

RESULTS

Ten patients were recruited, mean age 45 years, with indications of a Chiari malformation (n = 5), idiopathic intracranial hypertension (n = 3) or other ICP-related pathology (n = 2). Patients received intermittent bolus sedation (80%) vs general anaesthesia (20%). Mean opening pressure was 22.9 mmHg [± 6.0], with statistically significant decreases present every 5 min, to a total reduction of 15.2 mmHg at 20 min (p = < 0.0001), whereafter the ICP plateaued with no further statistical change.

DISCUSSION

Our results highlight an intracranial opening pressure 'spike' phenomenon. This spike was 15.2 mmHg higher than the plateau, which is reached at 20 min after insertion. Several possible causes exist which require further research in larger cohorts, including sedation and pain response. Regardless of causation, this study provides key information on the use of ICP monitoring devices, guiding interpretation and when to obtain measurements.

Benchtop simulation of the retrosigmoid approach: Validation of a surgical simulator and development of a task-specific outcome measure score

Background

Neurosurgical training is changing globally. Reduced working hours and training opportunities, increased patient safety expectations, and the impact of COVID-19 have reduced operative exposure. Benchtop simulators enable trainees to develop surgical skills in a controlled environment. We aim to validate a high-fidelity simulator model (RetrosigmoidBox, UpSurgeOn) for the retrosigmoid approach to the cerebellopontine angle (CPA).

Methods

Novice and expert Neurosurgeons and Ear, Nose, and Throat surgeons performed a surgical task using the model - identification of the trigeminal nerve. Experts completed a post-task questionnaire examining face and content validity. Construct validity was assessed through scoring of operative videos employing Objective Structured Assessment of Technical Skills (OSATS) and a novel Task-Specific Outcome Measure score.

Results

Fifteen novice and five expert participants were recruited. Forty percent of experts agreed or strongly agreed that the brain tissue looked real. Experts unanimously agreed that the RetrosigmoidBox was appropriate for teaching. Statistically significant differences were noted in task performance between novices and experts, demonstrating construct validity. Median total OSATS score was 14/25 (IQR 10-19) for novices and 22/25 (IQR 20-22) for experts (p < 0.05). Median Task-Specific Outcome Measure score was 10/20 (IQR 7-17) for novices compared to 19/20 (IQR 18.5-19.5) for experts (p < 0.05).

Conclusion

The RetrosigmoidBox benchtop simulator has a high degree of content and construct validity and moderate face validity. The changing landscape of neurosurgical training mean that simulators are likely to become increasingly important in the delivery of high-quality education. We demonstrate the validity of a Task-Specific Outcome Measure score for performance assessment of a simulated approach to the CPA.

Cerebrospinal fluid production rate in various pathological conditions: a preliminary study

INTRODUCTION

The cerebrospinal fluid (CSF) production rate in humans is not clearly defined but is estimated to be 18-24 ml/h (Trevisi et al Croat Med J 55(4):377-387 (24); Casey and Vries Childs Nerv Syst 5(5):332-334 (8)). A frequent clinical observation is that patients often drain higher volumes of CSF than can be explained by the assumed 'normal' CSF production rate (PRcsf). In the National Hospital for Neurology and Neurosurgery PRcsf was recorded in a variety of common neurosurgical pathologies using LiquoGuard7, an automated peristaltic pump that accurately controls CSF drainage and maintains a pre-set CSF pressure.

METHODS

A prospective observational study was performed from September 2021 onwards, on all patients in the National Hospital for Neurology and Neurosurgery who required CSF drainage as part of their ongoing treatment. The external drain was connected to a LiquoGuard7 pump (Möller Medical GmbH, Fulda, Germany), and the internal software of LiquoGuard7 was used to measure PRcsf. Statistical analysis used SPSS (version 25.0, IBM) by paired t test, comparing measured rates to hypothetical 'normal' CSF production rates calculated and published by Ekstedt (16-34ml/h) (Ekstedt J Neurol Neurosurg Psychiatry 41(4):345-353 (14)), assuming a similar distribution.

RESULTS

PRcsf was calculated in 164 patients. Suspected normal pressure hydrocephalus (n=41): PRcsf of 79ml/h±20SD (p<0.0001). Post-surgical CSF leak (n=26): PRcsf of 90ml/h±20SD (p<0.0001). Subarachnoid haemorrhage (n=34): PRcsf of 143ml/h±9SD (p<0.0001). Intracerebral haemorrhage (n=22): PRcsf of 137ml/h±20SD (p<0.0001). Spinal lesions (n=7): PRcsf of 130ml/h±20SD (p<0.0032). Pituitary adenomas (n=10): PRcsf of 29 ml/h±9SD (p<0.049). Idiopathic intracranial hypertension (n=15): PRcsf of 86ml/h±10SD (p<0.0001). Decompensated long-standing overt ventriculomegaly (n=4): PRcsf of 65ml/h±10SD (p<0.0001). Cerebral infection (n=5): PRcsf of 90ml/h±20SD (p<0.0001).

CONCLUSION

Net CSF production rate may be higher than expected in many conditions, as measured with new device LiquoGuard7 through the study of net flow rate, which may have implications for clinical decisions on CSF diversion. The conventional understanding of CSF production and circulation does not explain the findings of this study. More extensive studies are needed to validate this technique.

Survival and quality of life after CSF diversion in adult patients with leptomeningeal metastasis-associated hydrocephalus: a systematic review and meta-analysis

OBJECTIVE

Leptomeningeal metastasis (LM) is associated with altered CSF flow dynamics in 50%-70% of patients. Approximately 1%-5% of patients develop symptomatic LM-associated hydrocephalus (LM-H), which adversely impacts quality of life (QOL), functional status, and overall survival (OS). There is equipoise for CSF diversion procedures in LM-H. This systematic review and meta-analysis aimed to assess the effect of CSF diversion on OS and QOL in this context.

METHODS

This systematic review was conducted according to the PRISMA guidelines. PubMed/Medline, Embase, Web of Science, and Scopus were searched for articles that evaluated the role of CSF diversion for LM-H due to systemic cancer in adult patients. A meta-analysis was conducted using random effects models, with mean differences and 95% CIs reported. Bias was assessed using the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tool.

RESULTS

Ten eligible studies with a total of 494 patients were included. Two studies reported multivariate HRs for median OS, suggesting no significant effect of shunting on OS (pooled HR 0.42, 95% CI 0.09-1.94, p = 0.27). A difference between preoperative and postoperative Karnofsky Performance Status of mean 17.6 points (95% CI 10.44-24.68, p < 0.0001) was calculated from 4 studies. Across all studies, a symptomatic improvement rate of 67%-100% was observed, with high rates of improvement for headaches and nausea and lower rates for cranial nerve palsies. Complication rates across 9 studies ranged from 0% to 21.1%.

CONCLUSIONS

Based on the present findings, shunting does not improve OS but does relieve symptoms, suggesting that individuals who exhibit certain symptoms should be considered for CSF diversion. The present findings prompt the generation of a standardized decision-making tool and a critical analysis of the individual patient risk-benefit ratio. Implementation of these will optimize surgical management of LM-H patients.

Safety and efficacy of brain biopsy: Results from a single institution retrospective cohort study

Introduction

Brain biopsy provides important histopathological diagnostic information for patients with new intracranial lesions. Although a minimally invasive technique, previous studies report an associated morbidity and mortality between 0.6% and 6.8%. We sought to characterise the risk linked to this procedure, and to establish the feasibility of instigating a day-case brain biopsy pathway at our institution.

Materials and methods

This single-centre retrospective case series study included neuronavigation guided mini craniotomy and frameless stereotactic brain biopsies carried out between April 2019 and December 2021. Exclusion criteria were interventions performed for non-neoplastic lesions. Demographic data, clinical and radiological presentation, type of biopsy, histology and complications in the post-operative period were recorded.

Results

Data from 196 patients with a mean age of 58.7 years (SD+/-14.4 years) was analysed. 79% (n=155) were frameless stereotactic biopsies and 21% (n=41) neuronavigation guided mini craniotomy biopsies. Complications resulting in acute intracerebral haemorrhage and death, or new persistent neurological deficits were observed in 2% of patients (n=4; 2 frameless stereotactic; 2 open). Less severe complications or transient symptoms were noted in 2.5% of cases (n=5). 8 patients had minor haemorrhages in the biopsy tract with no clinical ramifications. Biopsy was non-diagnostic in 2.5% (n=5) of cases. Two cases were subsequently identified as lymphoma. Other reasons included insufficient sampling, necrotic tissue, and target error.

Discussion and conclusion

This study demonstrates that brain biopsy is a procedure with an acceptably low rate of severe complications and mortality, in line with previously published literature. This supports the development of day-case pathway allowing improved patient flow, reducing the risk of iatrogenic complications associated with hospital stay, such as infection and thrombosis.

A case of recurrent flight-induced cerebrospinal fluid shunt overdrainage

Shunted patients often complain of headaches after flights. The effect of air travel on shunt systems is unknown. We describe the case of a patient with longstanding hydrocephalus, who suffered flight-induced clinical deterioration and shunt overdrainage in two independent occasions. The patient, clinically stable for 1.5 and 5 years before each episode, reported severe headaches starting during the descent stages of the air travel. On both occasions, brain MRI imaging demonstrated pronounced ventricular size reduction. This case suggests that flight-induced shunt overdrainage can occur and should be suspected in patients with prolonged headaches and/or clinical deterioration triggered by air travel.

Clinical, Imaging and Neurogenetic Features of Patients with Gliomatosis Cerebri Referred to a Tertiary Neuro-Oncology Centre

INTRODUCTION

Gliomatosis cerebri describes a rare growth pattern of diffusely infiltrating glioma. The treatment options are limited and clinical outcomes remain poor. To characterise this population of patients, we examined referrals to a specialist brain tumour centre.

METHODS

We analysed demographic data, presenting symptoms, imaging, histology and genetics, and survival in individuals referred to a multidisciplinary team meeting over a 10-year period.

RESULTS

In total, 29 patients fulfilled the inclusion criteria with a median age of 64 years. The most common presenting symptoms were neuropsychiatric (31%), seizure (24%) or headache (21%). Of 20 patients with molecular data, 15 had IDH wild-type glioblastoma, with an IDH1 mutation most common in the remainder (5/20). The median length of survival from MDT referral to death was 48 weeks (IQR 23 to 70 weeks). Contrast enhancement patterns varied between and within tumours. In eight patients who had DSC perfusion studies, five (63%) had a measurable region of increased tumour perfusion with rCBV values ranging from 2.8 to 5.7. A minority of patients underwent MR spectroscopy with 2/3 (66.6%) false-negative results.

CONCLUSIONS

Gliomatosis imaging, histological and genetic findings are heterogeneous. Advanced imaging, including MR perfusion, could identify biopsy targets. Negative MR spectroscopy does not exclude the diagnosis of glioma.

Integration of a personalised mobile health (mHealth) application into the care of patients with brain tumours: proof-of-concept study (IDEAL stage 1)

Objectives

Brain tumours lead to significant morbidity including a neurocognitive, physical and psychological burden of disease. The extent to which they impact the multiple domains of health is difficult to capture leading to a significant degree of unmet needs. Mobile health tools such as Vinehealth have the potential to identify and address these needs through real-world data generation and delivery of personalised educational material and therapies. We aimed to establish the feasibility of Vinehealth integration into brain tumour care, its ability to collect real-world and (electronic) patient-recorded outcome (ePRO) data, and subjective improvement in care.

Design

A mixed-methodology IDEAL stage 1 study.

Setting

A single tertiary care centre.

Participants

Six patients consented and four downloaded and engaged with the mHealth application throughout the 12 weeks of the study.

Main outcome measures

Over a 12-week period, we collected real-world and ePRO data via Vinehealth. We assessed qualitative feedback from mixed-methodology surveys and semistructured interviews at recruitment and after 2 weeks.

Results

565 data points were captured including, but not limited to: symptoms, activity, well-being and medication. EORTC QLQ-BN20 and EQ-5D-5L completion rates (54% and 46%) were impacted by technical issues; 100% completion rates were seen when ePROs were received. More brain cancer tumour-specific content was requested. All participants recommended the application and felt it improved care.

Conclusions

Our findings indicate value in an application to holistically support patients living with brain cancer tumours and established the feasibility and safety of further studies to more rigorously assess this.

Characterization of patients with idiopathic normal pressure hydrocephalus using natural language processing within an electronic healthcare record system

OBJECTIVE

Idiopathic normal pressure hydrocephalus (iNPH) is an underdiagnosed, progressive, and disabling condition. Early treatment is associated with better outcomes and improved quality of life. In this paper, the authors aimed to identify features associated with patients with iNPH using natural language processing (NLP) to characterize this cohort, with the intention to later target the development of artificial intelligence-driven tools for early detection.

METHODS

The electronic health records of patients with shunt-responsive iNPH were retrospectively reviewed using an NLP algorithm. Participants were selected from a prospectively maintained single-center database of patients undergoing CSF diversion for probable iNPH (March 2008-July 2020). Analysis was conducted on preoperative health records including clinic letters, referrals, and radiology reports accessed through CogStack. Clinical features were extracted from these records as SNOMED CT (Systematized Nomenclature of Medicine Clinical Terms) concepts using a named entity recognition machine learning model. In the first phase, a base model was generated using unsupervised training on 1 million electronic health records and supervised training with 500 double-annotated documents. The model was fine-tuned to improve accuracy using 300 records from patients with iNPH double annotated by two blinded assessors. Thematic analysis of the concepts identified by the machine learning algorithm was performed, and the frequency and timing of terms were analyzed to describe this patient group.

RESULTS

In total, 293 eligible patients responsive to CSF diversion were identified. The median age at CSF diversion was 75 years, with a male predominance (69% male). The algorithm performed with a high degree of precision and recall (F1 score 0.92). Thematic analysis revealed the most frequently documented symptoms related to mobility, cognitive impairment, and falls or balance. The most frequent comorbidities were related to cardiovascular and hematological problems.

CONCLUSIONS

This model demonstrates accurate, automated recognition of iNPH features from medical records. Opportunities for translation include detecting patients with undiagnosed iNPH from primary care records, with the aim to ultimately improve outcomes for these patients through artificial intelligence-driven early detection of iNPH and prompt treatment.

Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Archimedean Spirals Form at Low Flow Rates in Confined Chemical Gardens

We describe and study the formation of confined chemical garden patterns. At low flow rates of injection of cobalt chloride solution into a Hele-Shaw cell filled with sodium silicate, the precipitate forms with a thin filament wrapping around an expanding "candy floss" structure. The result is the formation of an Archimedean spiral structure. We model the growth of the structure mathematically. We estimate the effective density of the precipitate and calculate the membrane permeability. We set the results within the context of recent experimental and modeling work on confined chemical garden filaments.

Image-Guided Magnetic Thermoseed Navigation and Tumor Ablation Using a Magnetic Resonance Imaging System

Medical therapies achieve their control at expense to the patient in the form of a range of toxicities, which incur costs and diminish quality of life. Magnetic resonance navigation is an emergent technique that enables image-guided remote-control of magnetically labeled therapies and devices in the body, using a magnetic resonance imaging (MRI) system. Minimally INvasive IMage-guided Ablation (MINIMA), a novel, minimally invasive, MRI-guided ablation technique, which has the potential to avoid traditional toxicities, is presented. It comprises a thermoseed navigated to a target site using magnetic propulsion gradients generated by an MRI scanner, before inducing localized cell death using an MR-compatible thermoablative device. The authors demonstrate precise thermoseed imaging and navigation through brain tissue using an MRI system (0.3 mm), and they perform thermoablation in vitro and in vivo within subcutaneous tumors, with the focal ablation volume finely controlled by heating duration. MINIMA is a novel theranostic platform, combining imaging, navigation, and heating to deliver diagnosis and therapy in a single device.

Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

CEST MRI provides amide/amine surrogate biomarkers for treatment-naïve glioma sub-typing

PURPOSE

Accurate glioma classification affects patient management and is challenging on non- or low-enhancing gliomas. This study investigated the clinical value of different chemical exchange saturation transfer (CEST) metrics for glioma classification and assessed the diagnostic effect of the presence of abundant fluid in glioma subpopulations.

METHODS

Forty-five treatment-naïve glioma patients with known isocitrate dehydrogenase (IDH) mutation and 1p/19q codeletion status received CEST MRI (B_1rms = 2μT, T_sat = 3.5 s) at 3 T. Magnetization transfer ratio asymmetry and CEST metrics (amides: offset range 3-4 ppm, amines: 1.5-2.5 ppm, amide/amine ratio) were calculated with two models: 'asymmetry-based' (AB) and 'fluid-suppressed' (FS). The presence of T2/FLAIR mismatch was noted.

RESULTS

IDH-wild type had higher amide/amine ratio than IDH-mutant_1p/19q^codel (p < 0.022). Amide/amine ratio and amine levels differentiated IDH-wild type from IDH-mutant (p < 0.0045) and from IDH-mutant_1p/19q^ret (p < 0.021). IDH-mutant_1p/19q^ret had higher amides and amines than IDH-mutant_1p/19q^codel (p < 0.035). IDH-mutant_1p/19q^ret with AB/FS mismatch had higher amines than IDH-mutant_1p/19q^ret without AB/FS mismatch ( < 0.016). In IDH-mutant_1p/19q^ret, the presence of AB/FS mismatch was closely related to the presence of T2/FLAIR mismatch (p = 0.014).

CONCLUSIONS

CEST-derived biomarkers for amides, amines, and their ratio can help with histomolecular staging in gliomas without intense contrast enhancement. T2/FLAIR mismatch is reflected in the presence of AB/FS CEST mismatch. The AB/FS CEST mismatch identifies glioma subgroups that may have prognostic and clinical relevance.

Effect of position on intracranial pressure and compliance: a cross-sectional study including 101 patients

OBJECTIVE

A better understanding of the effect of position on intracranial pressure (ICP) and compliance is important for the development of treatment strategies that can restore normal cerebrospinal fluid (CSF) dynamics. There is limited knowledge on the effect of position on intracranial compliance. In this cross-sectional study the authors tested the association of pulse amplitude (PA) with position and the day/night cycle. Additionally, they describe the postural ICP and PA changes of patients with "normal" ICP dynamics.

METHODS

This single-center retrospective study included patients with suspected and/or confirmed CSF dynamics abnormalities who had been examined with elective 24-hour ICP monitoring between October 2017 and September 2019. Patients had been enrolled in a short exercise battery including four positions: supine, lumbar puncture position in the left lateral decubitus position, sitting, and standing. Each position was maintained for 2 minutes, and mean ICP and PA were calculated for each position. The 24-hour day and night median ICP and PA data were also collected. Linear regression models were used to test the correlation of PA with position and day/night cycle. All linear regressions were corrected for confounders. The postural ICP monitoring results of patients without obvious ICP dynamics abnormality were summarized.

RESULTS

One hundred one patients (24 males and 77 females) with a mean age of 39 ± 13years (mean ± standard deviation) were included in the study. The adjusted linear regression models demonstrated a significant association of ICP with position and day/night cycle, with upright (sitting and standing) and day ICP values lower than supine and night ICP values. The adjusted linear regression model was also significant for the association of PA with position and day/night cycle, with upright and day PA values higher than supine and night PA results. These associations were confirmed for patients with and without shunts. Patients without clear ICP dynamics abnormality had tighter control of their postural ICP changes than the other patients; however, the difference among groups was not statistically significant.

CONCLUSIONS

This is the largest study investigating the effect of postural changes on intracranial compliance. The results of this study suggest that PA, as well as ICP, is significantly associated with posture, increasing in upright positions compared to that while supine. Further studies will be needed to investigate the mechanism behind this association.

Deep Exclusive Electroproduction of π^{0} at High Q^{2} in the Quark Valence Regime

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Brain MRI and Ophthalmic Biomarkers of Intracranial Pressure

OBJECTIVE

To evaluate the utility of brain MRI and ophthalmic biomarkers for the prediction of intracranial hypertension, we have studied the association between 6 biomarkers and 24-hour intracranial pressure (ICP) monitoring results in 45 patients.

METHODS

This single-center observational study includes patients who underwent 24-hour ICP monitoring, brain MRI (within 3 months), and ophthalmic assessment (during ICP monitoring). Six biomarkers were investigated: pituitary gland shape, vertical tortuosity of the optic nerve, distension of the optic nerve sheath, optic disc protrusion (MRI), papilledema (slit lamp biomicroscopy), and spontaneous venous pulsations (SVP, infrared video recordings).

RESULTS

Forty-five patients (mean age 39 ± 14 years, 38 women) met the inclusion criteria. All 6 biomarkers had a significant association with 24-hour ICP. Concave pituitary gland was observed with moderately elevated median ICP. Protrusion of the optic disc (MRI), papilledema, and absence of SVP were associated with the highest median ICP values. Twenty patients had raised ICP (median 24-hour ICP >5.96 mm Hg, cutoff obtained through Youden index calculation). Patients with all normal biomarkers had normal median ICP in 94% (standard error 6%) of the cases. All patients with ≥3 abnormal biomarkers had intracranial hypertension. The combination of at least 1 abnormal biomarker in MRI and ophthalmic assessments was highly suggestive of intracranial hypertension (area under the curve 0.94, 95% confidence interval 0.93-0.94) CONCLUSIONS: Brain MRI and ophthalmic biomarkers can noninvasively guide the management of patients with suspected CSF dynamics abnormalities. Patients with multiple abnormal biomarkers (≥3) or a combination of abnormal MRI and ophthalmic biomarkers are likely to have intracranial hypertension and should be managed promptly.

Implementation of the Vinehealth application, a digital health tool, into the care of patients living with brain cancer

e13582

Background: Cancers of the brain lead to significant neurocognitive, physical and psychological morbidities. Digital technologies provide a novel platform to capture and evaluate these needs. Mobile health (mHealth) applications typically focus on one aspect of care rather than addressing the multimodal needs of the demographic of these patients. The Vinehealth application aims to address this by tracking symptoms, delivering machine learning-based personalised educational content, and facilitating reminders for medications and appointments. Where mHealth interventions traditionally lack the evidence-based approach of pharmaceuticals, this study acts as an initial step in the rigorous assessment of a new digital health tool. Methods: A mixed methodology approach was applied to evaluate the Vinehealth application as a care delivery adjunct. Patients with brain cancer were recruited from the day of their procedure ± 7 days. Over a 12-week period, we collected real-world and ePRO data via the application. We assessed qualitative feedback from mixed-methodology surveys and semi-structured interviews at onboarding and after two weeks of application use. Results: Six participants enrolled of whom four downloaded the application; four completed all interviews. One patient set up their device incorrectly and so couldn't receive the questionnaires; excluding this patient, the EQ-5D-5L and EORTC QLQ-BN20 completion rates were 100% and 83% respectively. Average scores (±SD) at onboarding and offboarding were EQ-5D-5L: 2.07±1.28 and 1.73±1.22, and QLQ-BN20: 13.33 and 22.5. In total: 212 symptoms, 174 activity, and 47 medication data points were captured, and 113 educational articles were read. Participants were generally optimistic about application use. All users stated they would recommend Vinehealth and expressed subjective improvements in care. Accessibility issues in the ePRO delivery system which impacted completion rate were identified and have subsequently been fully addressed. Conclusions: This feasibility study showed acceptable patient use, led to a subjective improvement in care, and demonstrated effective collection of real-world and validated ePRO data. This provides a strong basis to further explore the integration of the Vinehealth application into brain cancer care. This study will inform the design of a larger, more comprehensive trial continuing to evaluate improvements in care delivery through data collection, educational support and patient empowerment.

966 Implementation of Regional Scalp Blockade for Painless Removal of ICP Bolts: A Quality Improvement Project

Introduction

Intracranial pressure (ICP) monitoring through insertion of a bolt is a common neurosurgical procedure for diagnosing cerebrospinal fluid disorders. The first step of our quality improvement project identified ICP bolt removal the most painful part of the procedure. We implemented and tested the efficacy of a scalp nerve block for bolt removal.

Method

Two groups were identified: (A) receiving oral analgesia only and (B) receiving ipsilateral supraorbital and supratrochlear nerve blocks. We then retrospectively compared satisfaction ratings of insertion versus removal process for the two bolt types using a telephonic questionnaire

Results

Eighty-five patients had ICP bolts (32M:53F, mean age 42.7±16.0 SD). Fifty-four were removed with oral analgesia (A) and 31 with oral and regional anaesthesia (B). Removal experience was reported as worse for group A than for group B (p &lt; 0.01). Most patients (66%) reported would have preferred local anesthetic during removal. No complications occurred from the block.

Conclusions

Regional nerve blocks are a safe and effective adjuvant for the painless removal of frontal ICP monitoring bolts. The final stage of the project was to implement nerve blocks as standard practice for bolt removal, to improve patient experience.

Second surgery for progressive glioblastoma: a multi-centre questionnaire and cohort-based review of clinical decision-making and patient outcomes in current practice

PURPOSE

Glioblastoma prognosis is poor. Treatment options are limited at progression. Surgery may benefit, but no quality guidelines exist to inform patient selection. We sought to describe variations in surgical management at progression, highlight where further evidence is needed, and build towards a consensus strategy.

METHODS

Current practice in selection of patients with progressive GBM for second surgery was surveyed online amongst specialists in the UK and Europe. We complemented this with an assessment of practice in a retrospective cohort study from six United Kingdom neurosurgical units. We used descriptive statistics to analyse the data.

RESULTS

234 questionnaire responses were received. Maintaining or improving patient quality of life was key to decision making, with variation as to whether patient age, performance status or intended extent of resection was relevant. MGMT methylation status was not important. Half considered no minimum time after first surgery. 288 patients were reported in the cohort analysis. Median time to second surgery from first surgery 390 days. Median overall survival 815 days, with no association between time to second surgery and time to death (p = 0.874).

CONCLUSIONS

This is the most wide-ranging examination of contemporaneous practice in management of GBM progression. Without evidence-based guidelines, the variation is unsurprising. We propose consensus guidelines for consideration, to reduce heterogeneity in decision making, support data collection and analysis of factors influencing outcomes, and to inform clinical trials to establish whether second surgery improves patient outcomes, or simply selects to patients already performing well.

Comprehensive evaluation of an advanced street canyon air pollution model

A street canyon pollution dispersion model is described which accounts for a wide range of canyon geometries including deep and/or asymmetric canyons. The model uses up to six component sources to represent different effects of street canyons on the dispersion of road traffic emissions. The final concentration is a weighted sum of the component concentrations dependent on output point location; canyon geometry; and wind direction relative to canyon orientation. Conventional approaches to modeling pollution in street canyons, such as the "Operational Street Pollution Model" (OSPM), do not account for canyons with high aspect ratios, pavements, and building porosity, so are not applicable for all urban morphologies. The new model has been implemented within the widely used, street-level resolution ADMS-Urban air quality model, which is used for air quality assessment and forecasting in cities such as Hong Kong where high-rise buildings form deep and complex street canyons. The new model is evaluated in relation to measured pollutant concentration data from the "Optimisation of modelling methods for traffic pollution in streets" (TRAPOS) project and routine measurements from 42 monitoring sites in London. Comparisons have been made between modeling using the new canyon model; a simpler approach to canyon modeling based on the OSPM formulation; and without any inclusion of canyon effects. The TRAPOS dataset has been used to highlight the model's ability to replicate the dependence of concentration on wind speed and direction, and also to show improved model performance for the prediction of high concentration values, which is particularly important for model applications such as planning and assessment. The London dataset, in which the street canyons are less well defined, has also been used to demonstrate improved model performance for this advanced approach compared to the simpler methods, by categorizing the measurement locations according to site type (background, near-road, and strong canyon). Implications: Currently available air dispersion models do not allow for a number of geometric features that influence air dispersion within street canyon environments. The new advanced street canyon model described in this paper accounts for: emissions from each road carriageway separately; canyon asymmetry; canyon porosity; and pavements. The extensive model evaluation presented shows that the new model demonstrates good performance, better than more basic approaches in which the complex geometries that define "canyons" are neglected.

Ultra-low-pressure hydrocephalic state in NPH: benefits of therapeutic siphoning with adjustable antigravity valves

BACKGROUND

Idiopathic normal-pressure hydrocephalus (NPH) is a condition of the elderly treated by ventriculoperitoneal shunt (VP) insertion. A subset of NPH patients respond only temporarily to shunt insertion despite low valve opening pressure. This study aims to describe our experience of patients who benefit from further CSF drainage by adding adjustable antigravity valves and draining CSF at ultra-low pressure.

METHODS

Single-centre retrospective case series of patients undergoing shunt valve revision from an adjustable differential pressure valve with fixed antigravity unit to a system incorporating an adjustable gravitational valve (Miethke proSA). Patients were screened from a database of NPH patients undergoing CSF diversion over 10 consecutive years (April 2008-April 2018). Clinical records were retrospectively reviewed for interventions and clinical outcomes.

RESULTS

Nineteen (10F:9M) patients underwent elective VP shunt revision to a system incorporating an adjustable gravitational valve. Mean age 77.1 ± 7.1 years (mean ± SD). Eleven patients (58%) showed significant improvement in walking speed following shunt revision. Fourteen patients/carers (74%) reported subjective improvements in symptoms following shunt revision.

CONCLUSIONS

Patients presenting symptoms relapse following VP shunting may represent a group of patients with ultra-low-pressure hydrocephalus, for whom further CSF drainage may lead to an improvement in symptoms. These cases may benefit from shunt revision with an adjustable gravitational valve, adjustment of which can lead to controlled siphoning of CSF and drain CSF despite ultra-low CSF pressure.

Amide proton transfer MRI can accurately stratify gliomas according to their IDH mutation and 1p/19q co-deletion status

2561

Background: Amide proton transfer (APT) MRI provides sensitive metrics at the amides and amines offsets from the water resonance and has been shown in small cohorts to differentiate low from high grade gliomas with better diagnostic performance than diffusion- and perfusion-weighted MRI. The purpose of our study was to assess APT-MRI performance to stratify gliomas according to their IDH mutation and 1p/19q status. Methods: Forty-five patients with primary gliomas and diffuse astrocytomas (26 WHO grade II, 11 WHO grade III, 8 WHO grade IV) underwent prospectively multi-parametric MRI with APT imaging at 3T scanner. The molecular classification identified 9 patients with IDH-wildtype, 1p/19q retained and 36 with IDH-mutant (22 had 1p/19q-retained, 14 had 1p/19q-codeleted). Tumour segmentations were manually created and the masks were superimposed on the calculated magnetisation transfer ratio asymmetry (MTRasym) spectra and proton transfer ratio APT maps. Individual and group analysis was conducted to analyse the statistical differences between quantitative imaging parameters for the IDH mutation and 1p/19q codeletion statuses. Results: The MTRasym spectra showed a clear difference between IDH-wildtype and IDH-mutant gliomas, with the IDH-mutant gliomas presenting a stronger contribution in the amines (p < 0.001). In IDH-mutant 1p/19q-retained and IDH-mutant 1p/19q-codeleted, the MTRasym spectra showed similarities in shape with higher intensity (approx. 60%) for the IDH-mutant 1p/19q-retained gliomas over the entire spectrum indicating an increased content in amines and amides in IDH-mutant 1p/19q-retained (p < 0.01). Notably, the latter entities showed higher amides levels than the IDH-wildtype gliomas (p < 0.03). Conclusions: APT-MRI shows a remarkable potential to disentangle the protein metabolism in gliomas, to link metabolic patterns to the IDH and 1p/19q status and hence provide robust surrogate biomarkers for non-invasive histomolecular classification with potential use as treatment monitoring tools.

Combined structural and perfusion MRI enhanced by machine learning may outperform standalone modalities and radiological expertise in high-grade glioma surveillance: A proof-of-concept study

e14528

Background: Treatment monitoring in patients with High-Grade Glioma (HGG) and identification of disease progression, remains a major challenge in clinical neurooncology. We aimed to develop a support vector machine (SVM) classifier utilising combined longitudinal conventional and Dynamic Susceptibility Contrast (DSC) perfusion MRI to classify between Stable Disease (SD), Pseudoprogression (PsP) and Progressive Disease (PD) in glioma patients under surveillance. Methods: Conventional (269) and perfusion (62) MRI studies of HGG patients acquired between 2012 and 2018 were prospectively analysed. Study participants were separated into two groups: Group I with a single DSC time point (64 participants) and Group II with multiple DSC time points (19 participants). The SVM classifier was trained using all available MRI for each group. Classification accuracy was assessed for the use of features extracted from different feature dataset and time point combinations and compared to the experienced radiologists’ predictions. Results: The study included 64 participants (mean age: 48.5 ± 12.8 yrs [standard deviation], 24 female). SVM classification based on combined perfusion and structural features outperformed standalone datasets across all groups. For the clinically relevant classification step (SD/PSP vs PD), both feature combination as well as the addition of multiple DSC time points, improved classification performance (lowest median error rate: 0.016). The SVM algorithm outperformed radiologists in predicting lesion destiny in both groups. Optimal performance was observed in Group II, in which SVM sensitivity/specificity/accuracy was 100/91.67/94.7% for analysis based on the first time point and 85.71/100/ 94.7% based on multiple time points compared to 60/78/68% and 70/90/84.2% for the respective radiologist classifications. In Group I, the SVM also exceeded radiologist predictions, albeit by a smaller margin and resulted in sensitivity/specificity of 86.49/75.00/81.53% (SVM) compared to 75.7/68.9/73.84% (radiologists). Conclusions: Our results indicate that the addition of multiple longitudinal perfusion time points as well as the combination of structural and perfusion features significantly enhance classification outcome in treatment monitoring of HGGs and machine-learning-assisted diagnosis has potentially superior accuracy than the radiologist's visual evaluation and expertise.

Interpretation of lumbar cerebrospinal fluid leukocytosis after cranial surgery: The relevance of aseptic meningitis

Raised white cell count (WCC) in lumbar CSF is a commonly used marker of meningitis. The effect of cranial neurosurgery per se on lumbar WCC is not established. At this single centre, many patients undergo ICPM followed by lumboperitoneal shunt (LPS), with lumbar CSF WCC samples taken during insertion. We aimed to determine the effect of ICP bolt insertion on lumbar CSF WCC. We undertook a retrospective analysis of lumbar CSF samples in patients who had recently undergone 24-h ICPM. Thirty-three patients (16F:7M) aged 43.31 ± 12.1 years (mean ± SD) had lumbar CSF samples after ICPM. Fourteen had CSF sampled within 6 weeks and 19 after 6 weeks of ICPM. Twenty-five samples were taken during LPS insertion, 5 during lumbar drainage/puncture and 3 during LPS revision. All 33 patients were afebrile at the point of CSF sampling. The mean lumbar WCC within 6 weeks of ICPM was significantly higher than the mean lumbar WCC after 6 weeks, being 15.4 ± 18.0 and 2.32 ± 1.79 cells/microlitre respectively respectively. There was no significant increase in RBC. In patients with raised CSF WCC, 60% of raised WCC were predominantly lymphoctyes and 40% predominantly neutrophils. Only one patient grew an organism (S. aureus). We conclude that lumbar CSF WCC can be raised following minor intracranial surgery, despite no clinical sign of infection. We caution against using lumbar CSF WCC values independently as the only marker of infection following neurosurgery.

Malignant Meningioma: An International Multicentre Retrospective Study

BACKGROUND

In contrast to benign meningiomas, malignant meningiomas (MM) are rare and associated with an unfavourable prognosis. Reports on MM concern fairly small cohorts, often comprising less than 30 cases.

OBJECTIVE

To describe the outcome MM and identify factors that may influence survival.

METHODS

Pathology reports and clinical data of 178 patients treated between 1989 and 2017 for a MM at 6 different international institutions were retrospectively reviewed. Seventy-six patients (42.7%) had a previous history of grade I or grade II meningioma. The patients underwent a total of 380 surgical resections and 72.5% received radiotherapy. Median follow-up was 4.5 yr.

RESULTS

At data collection, 111 patients were deceased (63.4%) and only 23 patients (13.7%) were alive without any residual tumor on the most recent scan. Median overall survival was 2.9 yr, 95% confidence interval [CI; 2.4, 4.5]. Overall survival rates at 1, 5, and 10 yr, respectively, were: 77.7%, 95% CI [71.6, 84.3], 40%, 95% CI [32.7, 49], and 27.9%, 95% CI [20.9, 37.3]. In the multivariable analysis, age at MM surgery <65 yr (hazard ratio [HR] = 0.44, 95% CI [0.29, 0.67], P < .001), previous benign or atypical meningioma surgery (HR = 1.9, 95% CI [1.23, 2.92], P = .004), completeness of resection (HR = 0.51, 95% CI [0.34, 0.78], P = .002), and adjuvant radiotherapy (HR = 0.64, 95% CI [0.42, 0.98], P = .039) were established as independent prognostic factors for survival.

CONCLUSION

This large series confirms the poor prognosis associated with MM, the treatment of which remains challenging. Patients under 65-yr-old with primary MM may live longer after complete resection and postoperative radiotherapy. Even with aggressive treatments, local control remains difficult to achieve.

Computer-Assisted Versus Manual Planning for Stereotactic Brain Biopsy: A Retrospective Comparative Pilot Study

BACKGROUND

Stereotactic brain biopsy is among the most common neurosurgical procedures. Planning an optimally safe surgical trajectory requires careful attention to a number of features including the following: (1) traversing the skull perpendicularly; (2) minimizing trajectory length; and (3) avoiding critical neurovascular structures.

OBJECTIVE

To evaluate a platform, SurgiNav, for automated trajectory planning in stereotactic brain biopsy.

METHODS

A prospectively maintained database was searched between February and August 2017 to identify all adult patients who underwent stereotactic brain biopsy and for whom postoperative imaging was available. In each case, the standard preoperative, T1-weighted, gadolinium-enhanced magnetic resonance imaging was used to generate a model of the cortex. A surgical trajectory was then generated using computer-assisted planning (CAP) , and metrics of the trajectory were compared to the trajectory of the previously implemented manual plan (MP).

RESULTS

Fifteen consecutive patients were identified. Feasible trajectories were generated using CAP in all patients, and the mean angle determined using CAP was more perpendicular to the skull than using MP (10.0° vs 14.6° from orthogonal; P = .07), the mean trajectory length was shorter (38.5 vs 43.5 mm; P = .01), and the risk score was lower (0.27 vs 0.52; P = .03).

CONCLUSION

CAP for stereotactic brain biopsy appears feasible and may be safer in selected cases.

Improved Prediction of Surgical Resectability in Patients with Glioblastoma using an Artificial Neural Network

In managing a patient with glioblastoma (GBM), a surgeon must carefully consider whether sufficient tumour can be removed so that the patient can enjoy the benefits of decompression and cytoreduction, without impacting on the patient’s neurological status. In a previous study we identified the five most important anatomical features on a pre-operative MRI that are predictive of surgical resectability and used them to develop a simple, objective, and reproducible grading system. The objective of this study was to apply an artificial neural network (ANN) to improve the prediction of surgical resectability in patients with GBM. Prospectively maintained databases were searched to identify adult patients with supratentorial GBM that underwent craniotomy and resection. Performance of the ANN was evaluated against logistic regression and the standard grading system by analysing their Receiver Operator Characteristic (ROC) curves; Area Under Curve (AUC) and accuracy were calculated and compared using Wilcoxon signed rank test with a value of p < 0.05 considered statistically significant. In all, 135 patients were included, of which 33 (24.4%) were found to have complete excision of all contrast-enhancing tumour. The AUC and accuracy were significantly greater using the ANN compared to the standard grading system (0.87 vs. 0.79 and 83% vs. 80% respectively; p < 0.01 in both cases). In conclusion, an ANN allows for the improved prediction of surgical resectability in patients with GBM.

Natural history of ventriculomegaly in adults: a cluster analysis

OBJECTIVE

Chronic ventriculomegaly in the absence of raised intracranial pressure (ICP) is a known entity in adult hydrocephalus practice. The natural history and indication for treatment is, however, poorly defined. A highly heterogeneous group, some adults with ventriculomegaly are asymptomatic, while others have life-threatening deteriorations. The authors hypothesized that the various presentations can be subtyped and represent different stages of decompensation. A cluster analysis was performed on a cohort of patients with chronic ventriculomegaly with the aim of elucidating typical clinical characteristics and outcomes in chronic ventriculomegaly in adults.

METHODS

Data were collected from 79 patients with chronic ventriculomegaly referred to a single center, including demographics, presenting symptoms, and 24-hour ICP monitoring (ICPM). A statistical cluster analysis was performed to determine the presence of subgroups.

RESULTS

Four main subgroups and one highly dissimilar group were identified. Patients with ventriculomegaly commonly have a perinatal event followed by one of four main presentations: 1) incidental ventriculomegaly with or without headache; 2) highly symptomatic presentation (including reduced consciousness) and raised ICP; 3) early presenting with symptoms of headache and nausea (with abnormal pulsatility); and 4) late presenting with features common to normal pressure hydrocephalus. Each symptomatic group has characteristic radiological features, ICPM, and responses to treatment.

CONCLUSIONS

Cluster analysis has identified subgroups of adult patients with ventriculomegaly. Such groups may represent various degrees of decompensation. Surgical interventions may not be equally effective across the subgroups, presenting an avenue for further research. The identified subtypes provide further insight into the natural history of this lesser studied form of hydrocephalus.

Approach to Slitlike Ventricles: Parietal-Occipital versus Frontal Burr Catheter Entry Sites

BACKGROUND

Slit ventricles can be a challenging target during shunt catheter insertion. Traditionally, the frontal approach has been considered optimal for small ventricles. At this center, routine use of electromagnetic (EM) stereotactic guidance (Stealth, Medtronic, Dublin, Ireland) has enabled a parietooccipital (P-O) burr hole approach to the frontal horns. We compare shunt placement and revisions required for patients with slit ventricles who had shunts inserted via a P-O approach versus frontal shunt.

METHODS

We studied a retrospective cohort of patients with slit ventricles and a ventricular shunt inserted using EM guidance between 2012 and 2018. Slitlike ventricles were defined as the widest point of the lateral ventricle <3 mm. Outcome measures included placement accuracy and survival using the Kaplan-Meier curve. Optimal final catheter tip location was considered to be the frontal horn of the ipsilateral lateral ventricle.

RESULTS

Eighty-two patients (77 female, 5 male) aged 34.9 ± 10.8 years (mean ± standard deviation) had ventricular shunts inserted for idiopathic intracranial hypertension (n = 63), chiari/syrinx (n = 8), congenital (n = 10), and pseudomeningocele (n = 1). Of those identified, 35 had primary P-O shunts and 46 had frontal shunts. Overall, 94% of cases had the catheter tip sitting in the frontal horn. The P-O approach was just as accurate as the frontal approach. Eight P-O shunts and 9 frontal shunts required revision over a 60-month period. There was no significant different in shunt survival between the 2 approaches (P = 0.37).

CONCLUSIONS

EM-guided placement has enabled the P-O approach to be as safe and with equivalent survival to frontal approach. The accuracy of shunt placement between the 2 approaches was similar.

Implementation of duty of candour within neurosurgery: a national survey and framework for improved application in clinical practice

INTRODUCTION

Statutory duty of candour was introduced in November 2014 for NHS bodies in England. Contained within the regulation were definitions regarding the threshold for what constitutes a notifiable patient safety incident. However, it can be difficult to determine when the process should be implemented. The aim of this survey was to evaluate the interpretation of these definitions by British neurosurgeons.

MATERIALS AND METHODS

All full (consultant) members of the Society of British Neurological Surgeons were electronically invited to participate in an online survey. Surgeons were presented with 15 cases and asked to decide in the case of each one whether they would trigger the process of duty of candour. Cases were stratified according to their likelihood and severity.

RESULTS

In all, 106/357 (29.7%) members participated in the survey. Responses varied widely, with almost no members triggering the process of duty of candour in cases where adverse events were common (greater than 10% likelihood) and required only outpatient follow-up (7/106; 6.6%), and almost all members doing so in cases where adverse events were rare (less than 0.1% likelihood) and resulted in death (102/106; 96.2%). However, there was clear equipoise in triggering the process of duty of candour in cases where adverse events were uncommon (0.1-10% likelihood) and resulted in moderate harm (38/106; 35.8%), severe harm (57/106; 53.8%) or death (49/106; 46.2%).

CONCLUSION

There is considerable nationwide variation in the interpretation of definitions regarding the threshold for duty of candour. To this end, we propose a framework for the improved application of duty of candour in clinical practice.

FP1-2 Implementation of duty of candor regulation within neurosurgery: a national cross-sectional survey

Objectives

Statutory Duty of Candor was introduced in 2014 for NHS bodies in England. Contained within the regulation were definitions regarding the threshold for what constitutes a notifiable patient safety incident. The aim of this survey was to evaluate the interpretation of these definitions by British neurosurgeons.

Methods

Full members of the SBNS were electronically invited to participate in an online survey. Surgeons were presented with 15 cases and asked to decide in each one whether they would trigger the process of Duty of Candor. Cases were stratified according to their likelihood and severity.

Results

In all, 106/357 (29.7%) members participated in the survey. Responses varied widely with almost no members triggering the process of Duty of Candor in cases where adverse events were likely (>10% likelihood) and required only outpatient follow up (7/106; 6.6%), and almost all members doing so in cases where adverse events were rare (<0.1% likelihood) and resulted in death (102/106; 96.2%). However, there was clear equipoise in triggering the process of Duty of Candor in cases where adverse events were unlikely (0.1%–10% likelihood) and resulted in moderate harm (38/106; 35.8%), severe harm (57/106; 53.8%), or death (49/106; 46.2%).

Conclusions

There is considerable nationwide variation in the interpretation of definitions regarding the threshold for Duty of Candor; this has important implications with some providers at risk of penalties, and others unduly burdened by the associated administrative processes.

TM3-8 Use of adjustable anti-gravity devices in NPH patients with delayed post-shunt deterioration

Objectives

A subset of idiopathic Normal Pressure Hydrocephalus (NPH) patients respond to VP shunt insertion temporarily. Adjustable anti-gravity devices are designed to control position-induced CSF drainage changes; we aim to assess to effect of using these devices to achieve controlled overdrainage in temporary shunt responders.

Design

A single-centre retrospective study of patients undergoing VP shunt valve revision from an adjustable differential pressure valve with fixed anti-siphon (ProGAV +Shuntassistant) to a system incorporating an adjustable anti-siphon valve (ProGAV +ProSA) (April 2013-April 2018).

Subjects

21 patients diagnosed with temporary shunt-responsive NPH who improved on high volume shunt reservoir tap (10M: 11F). Mean age at first VP shunt insertion was 74.5±7.87 years.

Methods

Medical records were retrospectively reviewed for demographics, interventions and clinical outcomes.

Results

Mean duration until revision with a ProSA valve was 31.5±16.8 months (mean ±SD). Mean follow up was 31.4±15.9 months. Of 20 patients with sufficient follow-up, 12 made objective improvements in walking and/or neuropsychological test outcome. 15 patients made subjective improvements in mobility or cognitive impairment.

Conclusions

VP shunting with adjustable differential pressure valves and fixed antigravity devices may not drain sufficient CSF for optimum management of low pressure hydrocephalus. Addition of adjustable anti-gravity devices at lower shunt settings in temporary shunt responders may improve outcome.

TM3-5 Venous sinus stenting for IIH: what are the long-term outcomes?

Objectives

Idiopathic intracranial hypertension (IIH) is associated with dural venous sinus stenosis (DVSS). This is increasingly treated with endovascular insertion of stents. Clinical and manometric improvements after stent placement have been described. However, there is little data reporting further need for CSF diversion, complication rates and sustained improvements in ICP.

Design

Single centre case series.

Subjects

Twenty-four IIH patients underwent stent insertion on discovery of DVSS with medical management ongoing.

Methods

Clinical notes, radiographic reports and 24 hour ICP monitoring data before and after stent placement was collected.

Results

After 1089.2±107.1 days, 6 patients remained symptomatic and went onto require CSF diversion, 75.0% did not require CSF diversion. One patient developed stent thrombosis requiring VKA anticoagulation for 3 months, this patient also developed new stenosis proximal to the stent at 2 years. A second patient developed in-stent stenosis requiring balloon angioplasty at 2 years and subsequent repeat stenting at 3 years. Eleven patients had 24 hour ICP monitoring at baseline and a mean of 231.9±129.5 days after DVSS stent placement. The mean reduction in ICP was 7.92±1.80 mmHg (p<0.01) and PA was 2.84±0.84 mmHg (p<0.01).

Conclusions

DVSS stenting is a viable endovascular therapy for IIH with modest long-term patency and ICP reduction. However, a quarter of stented patients required subsequent CSF diversion to manage their symptoms.

WP1-9 Treatment implications of parkinson’s disease in normal pressure hydrocephalus

Objectives

Patients with Parkinson’s disease (PD) presenting with worsening gait and ventriculomegaly could have underlying normal pressure hydrocephalus (NPH). We aim to identify features of concurrent PD and NPH, assess investigations and benefits of intervention.

Design

Single-centre retrospective cohort study of patients diagnosed with PD and NPH, presenting to neurosurgery between April 2004 – April 2018.

Subjects

24 patients (20M: 4F) with concurrent PD and NPH, mean age 74.5±6.49 years (mean ±SD). 22 patients were diagnosed with PD prior to NPH diagnosis.

Methods

Medical records were studied for demographics, symptoms, and response to ventriculoperitoneal (VP) shunting. Chi-square test was used to compare frequency of post-operative symptoms against a local database of NPH patients.

Results

All patients presented to neurosurgery with gait disturbances, 21/24 with cognitive impairment, and 18/24 with urinary incontinence. 19 patients underwent VP shunt insertion; 5 patients were not suitable having failed a lumbar drain trial. Patients with PD and NPH improved in walking test outcomes and in urinary continence similarly to other NPH patients. Cognitive impairment did not respond well to VP shunting in patients with concurrent PD, significantly less than NPH patients without PD (p<0.01).

Conclusions

Diagnosis of NPH in patients with PD is a complex clinical problem due to frequent overlap of symptoms. Benefits may be gained if this subset of patients do reach neurosurgical services and receive intervention.

TM3-4 The effect of acetazolamide on intracranial pressure: primary study with prolonged continuous intracranial pressure monitoring

Objectives

Acetazolamide has frequently been used as a first-line treatment for idiopathic Intracranial Hypertension (IIH) and other disorders which lead to a non-acute rise in intracranial pressure (ICP). The effect of acetazolamide has been observed through lumbar puncture, however the effect of acetazolamide on ICP has not been studied in continuous ICP measurement.

Design

A retrospective study of a prospectively built ICP database

Subjects

All patients with continuous ICP monitoring demonstrating 24 hours on and 24 hours off acetazolamide were included in the study.

Methods

Patients median ICP and median pulse amplitude over 24 hour monitoring period on and off Diamox was assessed.

Results

12 patients (9F, 3M) underwent ICP monitoring with data collected during the same admission. 8 patients had IIH, 1 Chiari Malformation, 3 new diagnostic ICP procedures. 10 patients saw a reduction in ICP while on acetazolamide. Overall, patients experienced a Median reduction of 1.14 mmHg (Mean 1.16 mmHg, Range 4.24 to −4.445 mmHg). Patients (n9) who were on ≥1 g of acetazolamide per day experienced a median reduction in ICP of 1.595 mmHg (Mean 1.91 mmHg, Range 4.24–0.5 mmHg).

Conclusions

Our data suggests acetazolamide can reduce ICP quickly following commencement, however this reduction was relatively small. The effect seems greater with a higher dose. Larger numbers of patients are required to gain a greater understanding into the significance of acetazolamide on ICP, particularly the affect at larger doses.

TM1-3 Improved prediction of surgical resectability in patients with glioblastoma multiforme using an artificial neural network

Objectives

In managing a patient with glioblastoma multiforme (GBM), a surgeon must weigh up whether sufficient tumour can be removed so that the patient can enjoy the benefits of decompression and cytoreduction, without impacting on the patient’s neurological status. In a previous study we identified the five most important anatomical features on a pre-operative MRI that are predictive of surgical resectability and used them to develop a grading system. The aim of this study was to apply an artificial neural network (ANN) to improve the prediction of surgical resectability.

Methods

A prospectively maintained database was searched between February and August 2017 to identify all adult patients with supratentorial GBM that underwent resection. Pre-operative MRI scans were scored using the aforementioned grading system and post-operative scans assessed to determine the extent of resection. Performance of the standard grading system and ANN were then evaluated by analysing their Receiver Operator Characteristic curves; Area Under Curve (AUC) and accuracy were calculated and compared using the t-­test with a value of p<0.05 considered significant.

Results

In all, 47 patients were included, of which 18 (38.3%) were found to have complete excision. The AUC and accuracy were significantly greater using the ANN compared to the standard grading system (0.87 vs. 0.79 and 0.81 vs. 0.77 respectively; p<0.01 in both cases).

Conclusions

An ANN allows for improved prediction of surgical resectability in patients with GBM.

WP1-15 Computer-assisted versus manual planning for stereotactic brain biopsy: retrospective comparative pilot study

Objectives

Stereotactic brain biopsy is among the most common neurosurgical procedures. Planning a safe surgical trajectory requires careful attention to a number of features including:

traversing the skull perpendicularly;

avoiding critical neurovascular structures; and

minimising trajectory length.

The aim of this study was to develop a platform, SurgiNav, for automated trajectory planning in stereotactic brain biopsy.

Methods

A prospectively maintained database was searched between February and August 2017 to identify all adult patients that underwent stereotactic brain biopsy in whom post-operative imaging was available. In each case, the standard pre-operative T1-weighted gadolinium-enhanced MRI was used to generate models of the cortex and vasculature. A surgical trajectory was then generated using automated computer-assisted planning (CAP) and metrics compared to the trajectory of the implemented manual plan (MP) using the paired T-test.

Results

15 consecutive patients were identified; who had a diagnostic biopsy and there were no immediate complications. Feasible trajectories were generated using CAP in 12 patients, and in these the mean trajectory length using CAP was comparable to MP (31.7 mm vs. 37.1 mm; p=0.3), and mean angle was similarly perpendicular from orthogonal (9.3° vs. 15.3° p=0.1), but the risk-metric was significantly lower (0.16 vs. 0.48; p=0.03).

Conclusions

Computer-assisted planning for stereotactic brain biopsy appears feasible in most cases and may be safer in selected cases.

TM3-3 Correlation of lumbar puncture opening pressure with 24 hours intraparenchymal ICP monitoring: the effects of position on ICP

Objectives

Lumbar Puncture opening pressure in lateral decubitus has been considered the gold standard method of intracranial pressure (ICP) measurement for many years. The use of continuous intraparenchymal ICP monitoring is more recent and there is no consensus regarding what can be considered normal ICP with this method of measurement. A conversion factor between lumbar puncture opening pressure and 24 hours ICP monitoring could provide a better insight on the interpretation of ICP. This study investigates the differences between 24 hours ICP and ICP in lumbar puncture position.

Design

Single centre prospective observational study.

Subjects

Fifty-four patients (42F:12M, mean age 38±12 years) were included.

Methods

Patients investigated with 24 hours ICP monitoring who underwent a short exercise battery during the monitoring period were included. The exercise battery was standardised; patients were asked to stay in a supine, sitting, standing and lumbar puncture position for 2 min each.Mean ICP and pulse amplitude were calculated for each position.

Results

The mean 24 hours ICP was 4.9 mmHg (±6.9 SD) and the mean ICP in lumbar puncture position was 14.1 mmHg (±8.9 SD). The average increase in lumbar puncture position was 9.1 mmHg (±5.9 SD). Patients with normal lumbar puncture position ICP (<12 mmHg) had an average 24 hours ICP of 1.4 mmHg (±2.81 SD).

Conclusions

Our results suggest that ICP measured in lumbar puncture position is on average 9.1 mmHg higher than 24 hours ICP results. Larger studies will be needed to confirm these findings.

WP1-8 Radiographic markers of disturbances in CSF dynamics: correlating imaging with 24-hour ICP monitoring

Objectives

Disorders with chronically elevated ICP have salient imaging findings associated with the sella turcica and optic nerves. We aim to quantify the degree of correlation between imaging features and ICP.

Design

Prospective case-cohort study.

Subjects

One-hundred and twenty-six patients (35M:91F) underwent ICPM with recent MR imaging.

Methods

T1-saggital views for sella volume, optic nerve vertical tortuosity, then T2-axial views for optic nerve sheath distension were blindly reviewed against respective median ICP and pulse amplitudes (PA). Imaging was triple reviewed for discordant values.

Results

The mean ICP of four sella morphologies (full/flat/concave/empty) were 1.2, 4.8, 8.4 and 16.7 mmHg respectively (p<0.01). AUROC for sella morphology predicting ICP was 0.81. This measurement was able to detect minimum ICP of 5.3 mmHg with 73.0% sensitivity and specificity, 73.0% PPV and 69.8% NPV. The mean PA values were 4.0, 5.2, 6.1 and 9.6 mmHg respectively (p<0.01). AUROC for sella morphology predicting PA was 0.78. This measurement was able to detect minimum PA of 5.47 mmHg with 76.3% sensitivity, 79.5% specificity, 63.5% PPV and 81.0% NPV. Mean PA values for vertical tortuosity (nil/uni/bi) were 5.2, 7.1 and 7.0 mmHg respectively (p<0.05). Mean ICP values for rail tracking (nil/uni/bi) were 4.5, 7.5 and 15.7 mmHg respectively (p<0.01). Mean PA values were 5.2, 5.8 and 8.0 mmHg respectively (p<0.0001).

Conclusions

Combined radiological features of ICP are promising non-invasive markers for raised ICP.

WP1-10 Prevalence of normal pressure hydrocephalus in falls clinic patients

Objectives

Patients with idiopathic Normal Pressure Hydrocephalus (iNPH) present with Hakim Adams triad and radiological findings suggestive of iNPH. We compare the presence of clinical and radiological signs of iNPH present in patients presenting to falls clinic at a District General Hospital with the general population.

Design

Retrospective analysis of patients referred to falls clinic (January 2017 to December 2017) and interpretation of CT or MRI head imaging with Evans index.

Subjects

Falls clinic patients presenting to a District General Hospital outpatient clinic.

Methods

Retrospective cohort of patients admitted to a single District General Hospital with falls and recent CT or MRI head. An Evans Index above 0.35 was used as an indicator of hydrocephalic ventricular enlargement.

Results

371 patients were seen in one year. 216 had previous CT or MRI head. 6.75% of all patients seen in falls clinic (11.6% who have had brain imaging) have hydrocephalic ventricular enlargement. This is compared to 4.5% in a study of patients aged 70 and over in a normal population.1

Conclusions

Patients seen in Falls clinic have an increased probability of having radiological signs consistent with idiopathic normal pressure hydrocephalus.

Reference

Jaraj D, Marlow T, Jensen C, Skoog I, Wikkelso C. Prevalence of idiopathic normal-pressure hydrocephalus. Neurology2014April 22;82(16):1449–1454.