Multiple surgical resections for progressive IDH wildtype glioblastoma-is it beneficial?

PURPOSE

The role of repeat resection for recurrent glioblastoma (rGB) remains equivocal. This study aims to assess the overall survival and complications rates of single or repeat resection for rGB.

METHODS

A single-centre retrospective review of all patients with IDH-wildtype glioblastoma managed surgically, between January 2014 and January 2022, was carried out. Patient survival and factors influencing prognosis were analysed, using Kaplan-Meier and Cox regression methods.

RESULTS

Four hundred thirty-two patients were included, of whom 329 underwent single resection, 83 had two resections and 20 patients underwent three resections. Median OS (mOS) in the cohort who underwent a single operation was 13.7 months (95% CI: 12.7-14.7 months). The mOS was observed to be extended in patients who underwent second or third-time resection, at 22.9 months and 44.7 months respectively (p < 0.001). On second operation achieving > 95% resection or residual tumour volume of < 2.25 cc was significantly associated with prolonged survival. There was no significant difference in overall complication rates between primary versus second (p = 0.973) or third-time resections (p = 0.312). The use of diffusion tensor imaging (DTI) guided resection was associated with reduced post-operative neurological deficit (RR 0.37, p = 0.002), as was use of intraoperative ultrasound (iUSS) (RR 0.45, p = 0.04).

CONCLUSIONS

This study demonstrates potential prolongation of survival for rGB patients undergoing repeat resection, without significant increase in complication rates with repeat resections. Achieving a more complete repeat resection improved survival. Moreover, the use of intraoperative imaging adjuncts can maximise tumour resection, whilst minimising the risk of neurological deficit.

Differential effects of group III metabotropic glutamate receptors on spontaneous inhibitory synaptic currents in spine-innervating double bouquet and parvalbumin-expressing dendrite-targeting GABAergic interneurons in human neocortex

Diverse neocortical GABAergic neurons specialize in synaptic targeting and their effects are modulated by presynaptic metabotropic glutamate receptors (mGluRs) suppressing neurotransmitter release in rodents, but their effects in human neocortex are unknown. We tested whether activation of group III mGluRs by L-AP4 changes GABAA receptor-mediated spontaneous inhibitory postsynaptic currents (sIPSCs) in 2 distinct dendritic spine-innervating GABAergic interneurons recorded in vitro in human neocortex. Calbindin-positive double bouquet cells (DBCs) had columnar "horsetail" axons descending through layers II-V innervating dendritic spines (48%) and shafts, but not somata of pyramidal and nonpyramidal neurons. Parvalbumin-expressing dendrite-targeting cell (PV-DTC) axons extended in all directions innervating dendritic spines (22%), shafts (65%), and somata (13%). As measured, 20% of GABAergic neuropil synapses innervate spines, hence DBCs, but not PV-DTCs, preferentially select spine targets. Group III mGluR activation paradoxically increased the frequency of sIPSCs in DBCs (to median 137% of baseline) but suppressed it in PV-DTCs (median 92%), leaving the amplitude unchanged. The facilitation of sIPSCs in DBCs may result from their unique GABAergic input being disinhibited via network effect. We conclude that dendritic spines receive specialized, diverse GABAergic inputs, and group III mGluRs differentially regulate GABAergic synaptic transmission to distinct GABAergic cell types in human cortex.

Surgical and Oncological Score to Estimate the Survival Benefit of Resection and Chemoradiotherapy in Elderly (≥70 Years) Glioblastoma Patients: A Preliminary Analysis Authors

AIMS

Elderly patients with glioblastoma are perceived to face a poor prognosis with perceptions surrounding older age and a relative lack of randomized data contributing. This study aimed to evaluate survival prognosticators in elderly glioblastoma patients to more accurately guide their treatment.

METHOD

The records of 169 elderly (≥70 years) patients with a new diagnosis of glioblastoma who had undergone neurosurgical intervention were retrospectively examined for patient sex, age, performance status, comorbidities, MGMT promoter methylation, surgical intervention and chemoradiation regime. The adjusted survival impact of these factors was determined using Cox proportional hazards model and used to devise a two-stage scoring system to estimate patient survival at the stage of surgical (Elderly Glioblastoma Surgical Score, EGSS) and oncological management (Elderly Glioblastoma Oncological Score, EGOS).

RESULTS

The median overall survival (mOS) of the cohort was 28.8 weeks. Gross-total and subtotal resection were associated with improved survival compared to biopsy alone (respective mOS 65.3 and 28.1 vs 15.7 weeks, p&lt;0.001). Hypofractionated radiotherapy (40Gy in 15 fractions) with Temozolomide was non-inferior to the Stupp protocol, p=0.72. Exploratory subgroup analysis revealed a significant benefit of Temozolomide-based approaches in MGMT-methylated patients as well as a trend towards improved survival in MGMT-unmethylated patients. Our EGSS and EGOS scores successfully estimated survival in this retrospective cohort with 65% and 73% accuracy.

CONCLUSION

Where appropriate and safe, elderly glioblastoma patients may benefit from surgical resection and combined chemoradiotherapy with Temozolomide. The proposed EGSS and EGOS scores take into account important prognostic factors to help guide which patients should receive such treatment.

The Value of Diffusion Tractography for Awake Surgery

AIMS

Despite evidence of correspondence with intraoperative stimulation, there remains limited data on MRI diffusion tractography (DT)’s sensitivity to predict morbidity after brain tumour resection. Our aims were: (1) evaluate DT against subcortical stimulation mapping and performance changes during and following awake surgery; (2) evaluate the use of early post-operative DT to predict recovery from post-surgical deficits.

METHOD

We performed a retrospective review our first 100 awake neurosurgery procedures using DTneuronavigation. Intra-operative stimulation and performance outcomes were assessed to classify DT predictions for sensitivity and specificity calculations.

RESULTS

Between 2014 and 2019 a total of 91 adult brain tumour patients (mean age 49.2 years) underwent 100 awake surgeries with subcortical stimulation. The sensitivity and specificity of pre-operative DT predictions were 92.2% and 69.2%, varying among tracts. Post-operative deficits occurred after 41 procedures (39%), but were prolonged (&gt;3 months) in only 4 patients (4%). Post-operative DT was available in 51 patients and confirmed surgical preservation of tracts. Post-operative DT anticipated complete recovery in a patient with supplementary motor area syndrome, and indicated infarct-related damage to corticospinal fibers associated with delayed, partial recovery in a second patient.

CONCLUSION

Pre-operative DT provided very accurate predictions of the spatial location of tracts in relation to a tumour. As expected, however, the presence of a tract did not provide information on its functional status, resulting in variable DT specificity among individual tracts. While prolonged deficits were rare in our series, DT in the immediate post-operative period offered additional information to monitor neurological deficits and anticipate recovery potential.

Surgical and oncological score to estimate the survival benefit of resection and chemoradiotherapy in elderly (≥70 years) glioblastoma patients: a preliminary analysis

Background

Elderly patients with glioblastoma are perceived to face a poor prognosis with perceptions surrounding older age and a relative lack of randomized data contributing. This study evaluated survival prognosticators in elderly glioblastoma patients to more accurately guide their treatment.

Methods

The records of 169 elderly (≥70 years) patients with a new diagnosis of glioblastoma who had undergone neurosurgical intervention were retrospectively examined for patient sex, age, performance status, comorbidities, MGMT promoter methylation, surgical intervention, and chemoradiation regime. The adjusted survival impact of these factors was determined using Cox proportional hazards model and used to devise a two-stage scoring system to estimate patient survival at the stage of surgical (Elderly Glioblastoma Surgical Score, EGSS) and oncological management (Elderly Glioblastoma Oncological Score, EGOS).

Results

The median overall survival (mOS) of the cohort was 28.8 weeks. Gross-total and subtotal resection were associated with improved survival compared to biopsy alone (respective mOS 65.3 and 28.1 vs 15.7 weeks, P < .001). Hypofractionated radiotherapy (40Gy in 15 fractions) with Temozolomide was noninferior to the Stupp protocol, P = .72. Exploratory subgroup analysis revealed a significant benefit of Temozolomide-based approaches in MGMT-methylated patients as well as a trend towards improved survival in MGMT-unmethylated patients. Our EGSS and EGOS scores successfully estimated survival in this retrospective cohort with 65% and 73% accuracy.

Conclusions

Where appropriate and safe, elderly glioblastoma patients may benefit from surgical resection and combined chemoradiotherapy with Temozolomide. The proposed EGSS and EGOS scores take into account important prognostic factors to help guide which patients should receive such treatment.

P14.24 Estimating survival outcomes in elderly (70+ years) patients with primary glioblastoma

BACKGROUND

Elderly patients with glioblastoma are perceived to face a poor prognosis, with perceptions around older age and a relative lack of randomized data raising a concern about their undertreatment. The EANO guidelines recommend &gt;70-year-old patients with good performance status to undergo maximal safe resection followed by hypofractionated (40 Gy in 15 fractions, i.e. RT40/15) radiotherapy with or without concurrent and adjuvant Temozolomide (TMZ), depending on MGMT promoter methylation. This study evaluated the relative survival impact of biological, histological, surgical and oncological factors and aimed to devise a scoring system to estimate the survival of elderly glioblastoma patients, with an aim to more accurately guide treatment in this cohort.

METHODS

The records of 169 elderly (≥70 years) patients with a new diagnosis of IDH-wild type glioblastoma were retrospectively examined for gender, age, WHO performance status (PS), comorbidities, MGMT methylation, surgical intervention and chemoradiation regime. The adjusted survival impact of these factors was determined using Cox proportional hazards model and used to devise a two-stage scoring system to estimate survival of patients at the stage of surgical (Elderly Glioblastoma Surgical Score, EGSS) and oncological management (Elderly Glioblastoma Oncological Score, EGOS).

RESULTS

The overall median survival (MS) of the cohort was 28.8 weeks. Subtotal resection (MS=27.7 weeks, 95%CI 24.1–31.6 weeks, HR=0.58) and gross-total resection (MS=77.8 weeks, 95%CI 67.0–88.6 weeks, HR=0.36) were associated with significant overall survival benefit compared to biopsy alone (MS=18.2 weeks, 95%CI 15.7–20.7 weeks, HR=5.23), p&lt;0.05. Hypofractionated radiation with Temozolomide (RT40/15+TMZ, MS=60.9 weeks, 95%CI 49.9–71.8 weeks, HR=0.13) was non-inferior to the Stupp protocol (RT60/30+TMZ, MS=50.6 weeks, 95%CI 32.4–66.7 weeks, HR=0.11), p=0.72. Negative prognosticators included age above 75 years, biopsy alone and no chemoradiotherapy. Subgroup analysis revealed that MGMT unmethylated 70–75 year old patients who received the Stupp protocol had significantly improved overall survival (MS=57.6 weeks, 95%CI 27.7–88.1 weeks) compared to standard of care RT40/15 alone (MS=29.7 weeks, 95%CI 7.1–51.6 weeks), p=0.002. EGSS and EGOS scores estimated survival with 65% and 73% accuracy, respectively.

CONCLUSION

When appropriate and safe, a subgroup of elderly glioblastoma patients may benefit from more aggressive surgical and oncological management. The proposed EGSS and EGOS scores takes into account important prognostic factors to help guide which patients should receive such treatment.

Diffusion tractography for awake craniotomy: accuracy and factors affecting specificity

Introduction

Despite evidence of correspondence with intraoperative stimulation, there remains limited data on MRI diffusion tractography (DT)’s sensitivity to predict morbidity after neurosurgical oncology treatment. Our aims were: (1) evaluate DT against subcortical stimulation mapping and performance changes during and after awake neurosurgery; (2) evaluate utility of early post-operative DT to predict recovery from post-surgical deficits.

Methods

We retrospectively reviewed our first 100 awake neurosurgery procedures using DT- neuronavigation. Intra-operative stimulation and performance outcomes were assessed to classify DT predictions for sensitivity and specificity calculations. Post-operative DT data, available in 51 patients, were inspected for tract damage.

Results

91 adult brain tumor patients (mean 49.2 years, 43 women) underwent 100 awake surgeries with subcortical stimulation between 2014 and 2019. Sensitivity and specificity of pre-operative DT predictions were 92.2% and 69.2%, varying among tracts. Post-operative deficits occurred after 41 procedures (39%), but were prolonged (> 3 months) in only 4 patients (4%). Post-operative DT in general confirmed surgical preservation of tracts. Post-operative DT anticipated complete recovery in a patient with supplementary motor area syndrome, and indicated infarct-related damage to corticospinal fibers associated with delayed, partial recovery in a second patient.

Conclusions

Pre-operative DT provided very accurate predictions of the spatial location of tracts in relation to a tumor. As expected, however, the presence of a tract did not inform its functional status, resulting in variable DT specificity among individual tracts. While prolonged deficits were rare, DT in the immediate post-operative period offered additional potential to monitor neurological deficits and anticipate recovery potential.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03795-7.

Raman spectroscopy to differentiate between fresh tissue samples of glioma and normal brain: a comparison with 5-ALA-induced fluorescence-guided surgery

OBJECTIVE

Raman spectroscopy is a biophotonic tool that can be used to differentiate between different tissue types. It is nondestructive and no sample preparation is required. The aim of this study was to evaluate the ability of Raman spectroscopy to differentiate between glioma and normal brain when using fresh biopsy samples and, in the case of glioblastomas, to compare the performance of Raman spectroscopy to predict the presence or absence of tumor with that of 5-aminolevulinic acid (5-ALA)-induced fluorescence.

METHODS

A principal component analysis (PCA)-fed linear discriminant analysis (LDA) machine learning predictive model was built using Raman spectra, acquired ex vivo, from fresh tissue samples of 62 patients with glioma and 11 glioma-free brain samples from individuals undergoing temporal lobectomy for epilepsy. This model was then used to classify Raman spectra from fresh biopsies from resection cavities after functional guided, supramaximal glioma resection. In cases of glioblastoma, 5-ALA-induced fluorescence at the resection cavity biopsy site was recorded, and this was compared with the Raman spectral model prediction for the presence of tumor.

RESULTS

The PCA-LDA predictive model demonstrated 0.96 sensitivity, 0.99 specificity, and 0.99 accuracy for differentiating tumor from normal brain. Twenty-three resection cavity biopsies were taken from 8 patients after supramaximal resection (6 glioblastomas, 2 oligodendrogliomas). Raman spectroscopy showed 1.00 sensitivity, 1.00 specificity, and 1.00 accuracy for predicting tumor versus normal brain in these samples. In the glioblastoma cases, where 5-ALA-induced fluorescence was used, the performance of Raman spectroscopy was significantly better than the predictive value of 5-ALA-induced fluorescence, which showed 0.07 sensitivity, 1.00 specificity, and 0.24 accuracy (p = 0.0009).

CONCLUSIONS

Raman spectroscopy can accurately classify fresh tissue samples into tumor versus normal brain and is superior to 5-ALA-induced fluorescence. Raman spectroscopy could become an important intraoperative tool used in conjunction with 5-ALA-induced fluorescence to guide extent of resection in glioma surgery.

A Noninvasive Comparison Study between Human Gliomas with IDH1 and IDH2 Mutations by MR Spectroscopy

The oncogenes that are expressed in gliomas reprogram particular pathways of glucose, amino acids, and fatty acid metabolism. Mutations in isocitrate dehydrogenase genes (IDH1/2) in diffuse gliomas are associated with abnormally high levels of 2-hydroxyglutarate (2-HG) levels. The aim of this study was to determine whether metabolic reprogramming associated with IDH mutant gliomas leads to additional ¹H MRS-detectable differences between IDH1 and IDH2 mutations, and to identify metabolites correlated with 2-HG. A total of 21 glioma patients (age= 37 ± 11, 13 males) were recruited for magnetic resonance spectroscopy (MRS) using semi-localization by adiabatic selective refocusing pulse sequence at an ultra-high-field (7T). For 20 patients, the tumor mutation subtype was confirmed by immunohistochemistry and DNA sequencing. LCModel analysis was applied for metabolite quantification. A two-sample t-test was used for metabolite comparisons between IDH1 (n = 15) and IDH2 (n = 5) mutant gliomas. The Pearson correlation coefficients between 2-HG and associated metabolites were calculated. A Bonferroni correction was applied for multiple comparison. IDH2 mutant gliomas have a higher level of 2-HG/tCho (total choline=phosphocholine+glycerylphosphorylcholine) (2.48 ± 1.01vs.0.72 ± 0.38, Pc < 0.001) and myo-Inositol/tCho (2.70 ± 0.90 vs. 1.46 ± 0.51, Pc = 0.011) compared to IDH1 mutation gliomas. Associated metabolites, myo-Inositol and glucose+taurine were correlated with 2-HG levels. These results show the improved characterization of the metabolic pathways in IDH1 and IDH2 gliomas for precision medicine.

Binding deficits in visual short-term memory in patients with temporal lobe lobectomy

Classical views of the medial temporal lobe (MTL) have established that it plays a crucial role in long-term memory (LTM). Here we demonstrate, in a sample of patients who have undergone anterior temporal lobectomy for the treatment of pharmacoresistant epilepsy, that the MTL additionally plays a specific, causal role in short-term memory (STM). Patients (n=22) and age-matched healthy control participants (n=26) performed a STM task with a sensitive continuous report measure. This paradigm allowed us to examine recall memory for object identity, location and object-location binding, independently on a trial-by-trial basis. Our findings point to a specific involvement of MTL in object-location binding, but, crucially, not retention of either object identity or location. Therefore the MTL appears to perform a specific computation: binding disparate features that belong to a memory. These results echo findings from previous studies, which have identified a role for the MTL in relational binding for LTM, and support the proposal that MTL regions perform such a function for both STM and LTM, independent of the retention duration. Furthermore, these findings and the methodology employed here may provide a simple, sensitive and clinically valuable means to test memory dysfunuction in MTL disorders.

Group II Metabotropic Glutamate Receptors Mediate Presynaptic Inhibition of Excitatory Transmission in Pyramidal Neurons of the Human Cerebral Cortex

Group II metabotropic glutamate receptor (mGluR) ligands are potential novel drugs for neurological and psychiatric disorders, but little is known about the effects of these compounds at synapses of the human cerebral cortex. Investigating the effects of neuropsychiatric drugs in human brain tissue with preserved synaptic circuits might accelerate the development of more potent and selective pharmacological treatments. We have studied the effects of group II mGluR activation on excitatory synaptic transmission recorded from pyramidal neurons of cortical layers 2-3 in acute slices derived from surgically removed cortical tissue of people with epilepsy or tumors. The application of a selective group II mGluR agonist, LY354740 (0.1-1 μM) inhibited the amplitude and frequency of action potential-dependent spontaneous excitatory postsynaptic currents (sEPSCs). This effect was prevented by the application of a group II/III mGluR antagonist, CPPG (0.1 mM). Furthermore, LY354740 inhibited the frequency, but not the amplitude, of action potential-independent miniature EPSCs (mEPSCs) recorded in pyramidal neurons. Finally, LY354740 did slightly reduce cells' input resistance without altering the holding current of the neurons recorded in voltage clamp at -90 mV. Our results suggest that group II mGluRs are mainly auto-receptors that inhibit the release of glutamate onto pyramidal neurons in layers 2-3 in the human cerebral cortex, thereby regulating network excitability. We have demonstrated the effect of a group II mGluR ligand at human cortical synapses, revealing mechanisms by which these drugs could exert pro-cognitive effects and treat human neuropsychiatric disorders.

A comparison of 2-hydroxyglutarate detection at 3 and 7 T with long-TE semi-LASER

Abnormally high levels of the 'oncometabolite' 2-hydroxyglutarate (2-HG) occur in many grade II and III gliomas, and correlate with mutations in the genes of isocitrate dehydrogenase (IDH) isoforms. In vivo measurement of 2-HG in patients, using magnetic resonance spectroscopy (MRS), has largely been carried out at 3 T, yet signal overlap continues to pose a challenge for 2-HG detection. To combat this, several groups have proposed MRS methods at ultra-high field (≥7 T) where theoretical increases in signal-to-noise ratio and spectral resolution could improve 2-HG detection. Long echo time (long-TE) semi-localization by adiabatic selective refocusing (semi-LASER) (TE = 110 ms) is a promising method for improved 2-HG detection in vivo at either 3 or 7 T owing to the use of broad-band adiabatic localization. Using previously published semi-LASER methods at 3 and 7 T, this study directly compares the detectability of 2-HG in phantoms and in vivo across nine patients. Cramér-Rao lower bounds (CRLBs) of 2-HG fitting were found to be significantly lower at 7 T (6 ± 2%) relative to 3 T (15 ± 7%) (p = 0.0019), yet were larger at 7 T in an IDH wild-type patient. Although no increase in SNR was detected at 7 T (77 ± 26) relative to 3 T (77 ± 30), the detection of 2-HG was greatly enhanced through an improved spectral profile and increased resolution at 7 T. 7 T had a large effect on pairwise fitting correlations between γ-aminobutyric acid (GABA) and 2-HG (p = 0.004), and resulted in smaller coefficients. The increased sensitivity for 2-HG detection using long-TE acquisition at 7 T may allow for more rapid estimation of 2-HG (within a few spectral averages) together with other associated metabolic markers in glioma.

Resting connectivity predicts task activation in pre-surgical populations

Injury and disease affect neural processing and increase individual variations in patients when compared with healthy controls. Understanding this increased variability is critical for identifying the anatomical location of eloquent brain areas for pre-surgical planning. Here we show that precise and reliable language maps can be inferred in patient populations from resting scans of idle brain activity. We trained a predictive model on pairs of resting-state and task-evoked data and tested it to predict activation of unseen patients and healthy controls based on their resting-state data alone. A well-validated language task (category fluency) was used in acquiring the task-evoked fMRI data. Although patients showed greater variation in their actual language maps, our models successfully learned variations in both patient and control responses from the individual resting-connectivity features. Importantly, we further demonstrate that a model trained exclusively on the more-homogenous control group can be used to predict task activations in patients. These results are the first to show that resting connectivity robustly predicts individual differences in neural response in cases of pathological variability.

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A method for identifying eloquent areas in the brain from resting fMRI is proposed.

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It uses supervised learning to predict task contrasts from resting connectivity.

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Good predictions were obtained in controls and in pre-surgical patient populations.

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Patient diagnoses included epilepsy, tumours, and vascular lesions.

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Language maps in patients could be predicted from models trained on controls.

Primary intraosseous meningioma: an osteosclerotic bone tumour mimicking malignancy

BACKGROUND

Sclerotic tumours of the calvarial bones are rare and may be due to primary and secondary bone tumours as well as extradural tumours of meningeal origin.

CASE PRESENTATION

We report a case of primary intraosseous meningioma (PIM) which arose in the frontal bone of a 63 year old woman who complained of progressive pain and thickening of the right skull. Radiology showed a large osteosclerotic lesion in the right frontal bone. Histology showed an intraosseous lesion containing dense fibrous tissue in which there were scattered cells that expressed epithelial membrane antigen and progesterone receptor. The tumour was partially resected and 3 years after operation has not recurred.

CONCLUSIONS

PIM is a rare tumour which needs to be distinguished from primary/secondary osteosclerotic calvarial bone tumours.

Improved localisation for 2-hydroxyglutarate detection at 3T using long-TE semi-LASER

2-hydroxyglutarate (2-HG) has emerged as a biomarker of tumour cell IDH mutations that may enable the differential diagnosis of glioma patients. At 3 Tesla, detection of 2-HG with magnetic resonance spectroscopy is challenging because of metabolite signal overlap and a spectral pattern modulated by slice selection and chemical shift displacement. Using density matrix simulations and phantom experiments, an optimised semi-LASER scheme (TE = 110 ms) improves localisation of the 2-HG spin system considerably compared to an existing PRESS sequence. This results in a visible 2-HG peak in the in vivo spectra at 1.9 ppm in the majority of IDH mutated tumours. Detected concentrations of 2-HG were similar using both sequences, although the use of semi-LASER generated narrower confidence intervals. Signal overlap with glutamate and glutamine, as measured by pairwise fitting correlation was reduced. Lactate was readily detectable across glioma patients using the method presented here (mean CLRB: (10±2)%). Together with more robust 2-HG detection, long TE semi-LASER offers the potential to investigate tumour metabolism and stratify patients in vivo at 3T.

Noninvasive Quantification of 2-Hydroxyglutarate in Human Gliomas with IDH1 and IDH2 Mutations

Mutations in the isocitrate dehydrogenase genes (IDH1/2) occur often in diffuse gliomas, where they are associated with abnormal accumulation of the oncometabolite 2-hydroxyglutarate (2-HG). Monitoring 2-HG levels could provide prognostic information in this disease, but detection strategies that are noninvasive and sufficiently quantitative have yet to be developed. In this study, we address this need by presenting a proton magnetic resonance spectroscopy ((1)H-MRS) acquisition scheme that uses an ultrahigh magnetic field (≥ 7T) capable of noninvasively detecting 2-HG with quantitative measurements sufficient to differentiate mutant cytosolic IDH1 and mitochondrial IDH2 in human brain tumors. Untargeted metabolomics analysis of in vivo (1)H-MRS spectra discriminated between IDH-mutant tumors and healthy tissue, and separated IDH1 from IDH2 mutations. High-quality spectra enabled the quantification of neurochemical profiles consisting of at least eight metabolites, including 2-HG, glutamate, lactate, and glutathione in both tumor and healthy tissue voxels. Notably, IDH2 mutation produced more 2-HG than IDH1 mutation, consistent with previous findings in cell culture. By offering enhanced sensitivity and specificity, this scheme can quantitatively detect 2-HG and associated metabolites that may accumulate during tumor progression, with implications to better monitor patient responses to therapy.

Thalamo-Cortical Disruption Contributes to Short-Term Memory Deficits in Patients with Medial Temporal Lobe Damage

Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction. We used diffusion-weighted magnetic resonance imaging-based tractography to identify anatomical subdivisions in patients with MTL epilepsy. From these, we measured resting-state functional connectivity with detailed cortical divisions of the frontal, temporal, and parietal lobes. Whereas thalamo-temporal functional connectivity reflected LTM performance, thalamo-prefrontal functional connectivity specifically predicted STM performance. Notably, patients with hippocampal volume loss showed thalamic volume loss, most prominent in the pulvinar region, not detected in patients with normal hippocampal volumes. Aberrant thalamo-cortical connectivity in the epileptic hemisphere was mirrored in a loss of behavioral association with STM performance specifically in patients with hippocampal atrophy. These findings identify thalamo-cortical disruption as a potential mechanism contributing to STM deficits in the context of MTL damage.

Asphaltene detection using surface enhanced Raman scattering (SERS)

Surface enhanced Raman spectroscopy using a gold substrate and excitation at 514 nm can detect sub parts per million quantities of asphaltene and thereby petroleum.

Diagnostic and prognostic markers in gliomas - an update

Gliomas are the most common primary central nervous system tumour seen in adults. There have been many advances over the last two decades as we widen our search for a molecular basis of gliomagenesis. Many biomarkers have been discovered to be important in the management of gliomas, including 1p19q co-deletion, MGMT promoter methylation, BRAF and IDH1 mutations. In this review, we attempt to summarise the available literature on these biomarkers and their use in the diagnosis and management of gliomas. We pay special attention to the recently discovered IDH1 mutation, which is already proving to be a valuable new marker for favourable prognosis and may also indicate a greater response to therapy. 1p19q co-deletions have been shown to delineate a clinically distinct tumour type and are now routinely tested for in certain situations and can help direct treatment. MGMT promoter methylation is one of the most commonly studied biomarkers in gliomas. It has been shown to be a strong positive prognostic marker in gliomas, with positive tumours being more sensitive to chemotherapy. However, a lack of alternatives means that it is not yet a routine mutation tested for clinically. BRAF mutations are new markers found in pilocytic astrocytomas. Although the prognostic value of such mutations is not yet known, they may play a significant role in the diagnosis and treatment of such tumours. IDH1 mutations are 'the new kid on the block' and seem to play a central role in the pathogenesis of gliomas. They represent an independent and favourable prognostic marker and are a new molecular marker for disease diagnosis. Its role in determining response to chemotherapy is still controversial but with further study, IDH1 mutations may prove to be an invaluable marker in the management of gliomas.

Progressive tension pneumocephalus as a delayed postoperative complication in the absence of any obvious CSF leak

Tension pneumocephalus is a rare neurosurgical emergency usually causing rapid deterioration. Slowly-progressive postoperative tension pneumocephalus is very rare. We present a case that came to our attention 5 weeks after a craniotomy with gradual development of symptoms, and in the absence of any obvious CSF leak. A dural defect causing a one-way valve system was found at explorative craniotomy.

The high-frequency description of scatter of a plane compressional wave by an elliptic crack

High-frequency approximations that can be interpreted in terms of the Uniform Geometrical Theory of Diffraction (UGTD) and Uniform Kirchhoff Approximation (UKA) are used to develop a code for modeling ultrasonic scatter of a plane compressional wave by an elliptic crack in the radiating near field. The approximations are intercompared and partially validated against a direct numerical code based on an FD (Finite-Difference) scheme. At present, in many realistic situations the approximate codes of the type described here offer the only viable simulation tool; purely numeric codes are not only much slower, they still require too much computer memory to simulate the complex structure of the radiating near fields.

Functional and structural changes in the memory network associated with left temporal lobe epilepsy

Understanding functional plasticity in memory networks associated with temporal lobe epilepsy (TLE) is central to predicting memory decline following surgery. However, the extent of functional reorganization within memory networks remains unclear. In this preliminary study, we used novel analysis methods assessing network-level changes across the brain during memory task performance in patients with TLE to test the hypothesis that hippocampal functions may not readily shift between hemispheres, but instead may show altered intra-hemispheric organization with unilateral damage. In addition, we wished to relate functional differences to structural changes along specific fibre pathways associated with memory function. Nine pre-operative patients with intractable left TLE and 10 healthy controls underwent functional MRI during complex scene encoding. Diffusion tensor imaging was additionally performed in the same patients. In our study, we found no evidence of inter-hemispheric shifts in memory-related activity in TLE using standard general linear model analysis. However, tensor independent component analysis revealed significant reductions in functional connectivity between bilateral MTL, occipital and left orbitofrontal regions among others in left TLE. This altered orbitofrontal activity was directly related to measures of fornix tract coherence in patients (P < 0.05). Our results suggest that specific fibre pathways, potentially affected by MTL neurodegeneration, may play a central role in functional plasticity in TLE and highlight the importance of network-based analysis approaches. Relative to standard model-based methods, novel objective functional connectivity analyses may offer improved sensitivity to subtle changes in the distribution of memory functions relevant for surgical planning in TLE.

51-year-old woman with double vision

A 51-year-old woman presented with a 2-month history of double vision and numbness around her left ear. She subsequently became unsteady on her feet and developed further cranial nerve abnormalities, before complaining of headache, nausea and vomiting. Imaging revealed features suggestive of two intracranial lesions; one non-contrast-enhancing high-signal area in the cerebellum with associated calcification, and a second contrast-enhancing low-signal area in association with the fourth ventricle, and at surgery there were two apparent components to the tumor. The histopathological features were those of a low-grade, focally calcified tumor comprising atypical ganglion and glial cells with interspersed Rosenthal fibres. Mitotic figures were not seen, and there was no necrosis. An infiltrate of small reactive lymphocytes was interspersed among the neoplastic cells. Immunohistochemistry revealed expression of synaptophysin by many of the dysplastic ganglion cells, with some co-expressing neurofilament protein and occasionally glial fibrillary acidic protein (GFAP). Several of the dysplastic ganglion cells also expressed CD34. The glial cell population was highlighted by GFAP. Ki-67 (MIB-1) activity was not noted among the neoplastic populations--the few positive nuclei in these areas were those of interspersed reactive CD3-positive T lymphocytes. In addition, at the edge of one of the biopsies was a dense infiltrate of mitotically-active large atypical CD 20-positive B lymphocytes, among which the Ki-67 (MIB-1) labeling index reached 80%. The final diagnosis was diffuse large B cell lymphoma arising within a ganglioglioma of the cerebellum, and this is believed to be the first reported case.

Transcallosal resection of hypothalamic hamartoma for gelastic epilepsy

INTRODUCTION

Hypothalamic hamartomas (HHs) are commonly associated with severe epilepsy resistant to anticonvulsant therapy. Historically, surgical resection of HHs resulted in considerable morbidity.

DISCUSSION

Two series of patients who successfully underwent resection using a transcallosal approach have now been published; we report the first UK experience of this technique in a series of five patients with HHs and gelastic epilepsy resistant to anticonvulsant therapy. Patients were assessed pre- and postoperatively for seizure activity, endocrine function, ophthalmology, and neurocognitive function. Two patients had precocious puberty and all had evidence of developmental delay and behavioral problems. Postoperatively, all children experienced at least a 50% reduction in seizure frequency with abolition of major seizure types; one child remains seizure-free. One child developed a mild postoperative right hemiparesis and one developed transient diabetes insipidus.

CONCLUSION

There were no adverse developmental effects of surgery. Transcallosal resection of HHs ameliorates resistant epilepsy syndromes associated with HH.

Long term survival in a patient with variant Creutzfeldt-Jakob disease treated with intraventricular pentosan polysulphate

Variant Creutzfeldt-Jakob disease (vCJD) is a neurodegenerative disease that principally affects young people and has a median duration of illness of 13 (range 6-39) months. vCJD is incurable and there are currently no treatments that conclusively slow the rate of disease progression. However, recent animal studies and isolated case reports have suggested that treatment with intraventricular pentosan polysulphate (PPS) may be beneficial in the treatment of patients with vCJD. We report a case of a 22-year-old male with vCJD treated 19 months after the onset of clinical symptoms with continuous intraventricular PPS (32 microg/kg/day) over a period of 31 months. Treatment with PPS appeared to be safe and well tolerated and was associated with prolonged survival (51 months) when compared to natural history studies. However, PPS treatment did not appear to arrest the progression of the disease.

Characterization and removal of DNAPL from sand and clay layered media

Important characterization and remediation techniques (e.g. partitioning tracer tests (PTT), cosolvent and surfactant flushing) have been developed over the years to deal with dense nonaqueous phase liquid (DNAPL) sources in the saturated zone. Unfortunately, subsurface media layering and heterogeneity pose a major challenge to the efficiency of these and other techniques that rely on flushing fluids through porous media. Using laboratory column experiments with both single media and layered-media columns and computer modeling of tracer breakthrough results, we examined the difficulty that layering poses to subsurface remediation and characterization techniques. Quantifying tetrachloroethylene (PCE) saturation in layered media was determined using PTT and effluent mass determinations. Conservative tracer breakthrough curves were used to determine permeability and the flow through layers before and after PCE contamination. The removal efficiency of alcohol flushing in the layered systems was also determined. Results showed that even a relatively simple layering with less than an order magnitude difference in permeability leads to difficulty in characterization and remediation using flushing technologies. These results suggest that much greater volumes of flushing solutions will be needed in heterogeneous environments to ensure adequate flushing of lower permeable lenses and layers.

Distinct right frontal lobe activation in language processing following left hemisphere injury

Right hemisphere activation during functional imaging studies of language has frequently been reported following left hemisphere injury. Few studies have anatomically characterized the specific right hemisphere structures engaged. We used functional MRI (fMRI) with verbal fluency tasks in 12 right-handed patients with left temporal lobe epilepsy (LTLE) and 12 right-handed healthy controls to localize language-related activity in the right inferior frontal gyrus (RIFG). During the phonemic task, LTLE patients activated a significantly more posterior region of the right anterior insula/frontal operculum than healthy controls (P = 0.02). Activation of the left inferior frontal gyrus (LIFG) did not differ significantly between the two groups. This suggests that, following left hemisphere injury, language-related processing in the right hemisphere differs from that with a functionally normal left hemisphere. The localization of activation in the left and right inferior frontal gyri was determined with respect to the anatomical sub-regions pars opercularis (Pop), pars triangularis (Ptr) and pars orbitalis (Por). In the LIFG, both healthy controls (8 out of 12) and LTLE patients (9 out of 12) engaged primarily Pop during phonemic fluency. Activations in the RIFG, however, were located mostly in the anterior insula/frontal operculum in both healthy controls (8 out of 12) and LTLE patients (8 out of 12), albeit in distinct regions. Mapping the locations of peak voxels in relation to previously obtained cytoarchitectonic maps of Broca's area confirmed lack of homology between activation regions in the left and right IFG. Verbal fluency-related activation in the RIFG was not anatomically homologous to LIFG activation in either patients or controls. To test more directly whether RIFG activation shifts in a potentially adaptive manner after left hemisphere injury, fMRI studies were performed in a patient prior to and following anatomical left hemispherectomy for the treatment of Rasmussen's encephalitis. An increase in activation magnitude and posterior shift in location were found in the RIFG after hemispherectomy for both phonemic and semantic tasks. Together, these results suggest that left temporal lobe injury is associated with potentially adaptive changes in right inferior frontal lobe functions in processing related to expressive language.

Secondary contamination in organophosphate poisoning: analysis of an incident

BACKGROUND

Acute organophosphate poisoning is rare in the UK, and the risks to attending staff are seldom appreciated.

STUDY DESIGN

Report of an incident.

RESULTS

In May 2001, a 45-year-old man attempted suicide by drinking organophosphate insecticide, and was brought to an urban general hospital in a collapsed state. Twenty-five hospital workers and paramedics sought medical advice after coming into contact with the poisoned patient, of whom ten complained of symptoms related to toxin exposure. Provision of emergency services by the hospital was compromised, and the emergency department was closed until the area was decontaminated and staffing levels could be restored.

DISCUSSION

Ingestion of OP compounds can present a significant risk to health professionals as well as patients. Problems with the management of this patient included late recognition of the need for decontamination, large numbers of non-essential staff coming into contact with the patient, and the difficulty of carrying out medical procedures while wearing protective equipment. Decontamination should always be considered early, and the possibility of an ingested poison being vomited and causing a chemical spill should not be overlooked.

Posterior spinal ligament rupture associated with laryngeal mask insertion in a patient with undisclosed unstable cervical spine

A case of posterior spinal ligament rupture associated with a general anaesthetic for a laparoscopic cholecystectomy is reported. The role of the general anaesthetic in this case is discussed and a review of the literature is presented.

3-Anilino-4-arylmaleimides: potent and selective inhibitors of glycogen synthase kinase-3 (GSK-3)

Potent 3-anilino-4-arylmaleimide glycogen synthase kinase-3 (GSK-3) inhibitors have been prepared using automated array methodology. A number of these are highly selective, having little inhibitory potency against more than 20 other protein kinases.

High-dose intrathecal diamorphine for analgesia after Caesarean section

Forty women undergoing elective Caesarean section under spinal anaesthesia using hyperbaric 0.5% bupivacaine were randomly allocated to receive either 0.5 mg or 1 mg intrathecal diamorphine. All women received diclofenac 100 mg at the end of surgery and morphine via a patient-controlled analgesia system. Oral analgesics were not used. Postoperative analgesia was more prolonged and more reliable in the 1-mg group. Mean time to first analgesia was 10.2 h in the 1-mg group and 6.9 h in the 0.5-mg group, and 45% in the 1-mg group used no morphine, compared with 10% in the 0.5-mg group. Mean morphine consumption over 24 h was 5.2 mg in the 1-mg group and 10.6 mg in the 0.5-mg group. Pain scores all tended to be lower in the 1-mg group but this was only significant at 4 h. There were no serious side-effects. Minor side-effects were common but well tolerated, and the incidence did not differ between the groups. If intrathecal diamorphine is used in combination with rectal diclofenac and without oral analgesia, then 1 mg provides superior analgesia to 0.5 mg without any worsening of the side-effects.

The inhibition of human cytomegalovirus (hCMV) protease by hydroxylamine derivatives

Aryl hydroxylamine derivatives have been synthesised that are some of the most potent inhibitors of hCMV protease prepared to date (IC50 14-60 nM). Mass spectrometry studies indicate that oxazinone derived hydroxylamines inhibit the enzyme by acylation of Ser132 whereas non-oxazinone derived hydroxylamines appear to inhibit via formation of a sulfinanilide at Cys138.

Artefact on MRA following aneurysm clipping: an in vitro study and prospective comparison with conventional angiography

Using both an experimental model and clinical cases, we looked at the artefact produced by Aesculap titanium-alloy aneurysm clips on MRA. Experimentally, the volume affected by artefact was 50 % less when the clip was imaged lying parallel to the main ferromagnetic field than when lying perpendicular to it. Clinically, MRA was prospectively compared with digital subtraction angiography (DSA) in nine patients who had undergone aneurysm clipping. One patient with a non-diagnostic MRA due to movement artefact was excluded. In all other cases there was an area of signal loss surrounding the clips, obscuring the immediately adjacent vessel segments. There was good demonstration of the adjacent bifurcations in five cases and the contralateral circulation was seen well in all patients. In three cases in which the adjacent bifurcations were not seen, considerable vasospasm was suggested by MRA and confirmed with DSA. In one patient an unclipped contralateral ophthalmic artery aneurysm was identified using both modalities. In this series there were no adverse events relating to clips in either static or time-varying magnetic fields.

Fused aminotetralins: novel antagonists with high selectivity for the dopamine D3 receptor

Starting from a series of 2-aminotetralins 1, a novel series of N-[4-(4-phenylbenzoylamino)butyl]-octahydrobenzoquinolines and hexahydrobenzoindoles with high potency and selectivity for the dopamine D3 receptor has been designed. The effect of ligand chirality on binding affinity has been established. Selected derivatives (e.g. 2o, 2p) show high functional selectivity and enhanced in vivo properties compared to 1.