Nonenhancing motor eloquent gliomas: navigated transcranial magnetic stimulation oncobiological signature

OBJECTIVE

Preoperative grading of nonenhancing motor eloquent gliomas is hampered by a lack of specific imaging surrogates. Tumor grading is crucial for the informed consent discussion before tumor resection. In this paper, the authors hypothesized that navigated transcranial magnetic stimulation (nTMS)-derived metrics could provide significant information to distinguish between high- and low-grade motor eloquent gliomas that present as nonenhancing tumors and therefore contribute to improving patient counseling, timing of treatment, preoperative planning, and intraoperative strategies.

METHODS

The authors conducted a retrospective single-center cohort study of patients admitted for tumor surgery between January 2018 and April 2022 with a nonenhancing motor eloquent glioma and preoperative bilateral nTMS mapping. nTMS data including resting motor threshold (RMT), interhemispheric RMT ratio (iRMTr), Cortical Excitability Score (CES), area and volume of cortical activation, and motor evoked potential (MEP) characteristics were obtained and integrated with demographic and clinical data.

RESULTS

Thirty patients met the inclusion criteria, and 10 healthy participants were recruited for comparison. Seizures were the most common presenting symptom (25 patients) and WHO grade 3 the most common tumor grade (21 patients). The area and volume of functional cortical activation of both the abductor pollicis brevis and first dorsal interosseous muscles were decreased in healthy participants compared with patients with WHO grade 3 glioma (p < 0.05). An abnormal iRMTr for the lower limbs (16.7% [1/6] WHO grade 2, 76.2% [16/21] WHO grade 3, 100% [3/3] WHO grade 4; p = 0.015) and a higher CES (maximal abnormal CES: 0% [0/6] WHO grade 2, 38% [8/21] WHO grade 3, 66.7% [2/3] WHO grade 4; p = 0.010) were associated with the prediction of high-grade lesions. A total of 7280 MEPs were analyzed. A significant increase in the amplitude and a significant decrease in latency in the MEPs for the first dorsal interosseous and abductor digiti minimi muscles (p < 0.0001) were identified in healthy participants compared with WHO grade 3 glioma patients.

CONCLUSIONS

Nonenhancing motor eloquent gliomas have a different impact on both anatomical and functional reorganization of motor areas according to their WHO grading.

Cortical resting motor threshold difference in asleep-awake craniotomy for motor eloquent gliomas: WHO grading influences motor pathway excitability

Developing neurophysiological tools to predict WHO tumor grade can empower the treating teams for a better surgical decision-making process. A total of 38 patients with supratentorial diffuse gliomas underwent an asleep-awake-sedated craniotomies for tumor removal with intraoperative neuromonitoring. The resting motor threshold was calculated for different train stimulation paradigms during awake and asleep phases. Receiver operating characteristic analysis and Bayesian regression models were performed to analyze the prediction of tumor grading based on the resting motor threshold differences. Significant positive spearman correlations were observed between resting motor threshold excitability difference and WHO tumor grade for train stimulation paradigms of 5 (R = 0.54, P = 0.00063), 4 (R = 0.49, P = 0.002), 3 (R = 0.51, P = 0.001), and 2 pulses (R = 0.54, P = 0.0007). Kruskal-Wallis analysis of the median revealed a positive significant difference between the median of excitability difference and WHO tumor grade in all paradigms. Receiver operating characteristic analysis showed 3 mA difference as the best predictor of high-grade glioma across different patterns of motor pathway stimulation. Bayesian regression found that an excitability difference above 3 mA would indicate a 75.8% probability of a glioma being high grade. Our results suggest that cortical motor excitability difference between the asleep and awake phases in glioma surgery could correlate with tumor grade.

Relationship between guideline adherence and outcomes in severe traumatic brain injury

INTRODUCTION

Traumatic brain injury (TBI) is a leading cause of death and morbidity worldwide. Evidence-based guidelines for managing severe TBI have been available for over 25 years. However, adherence to guidelines remains variable despite evidence highlighting improvement in outcomes with individual recommendations. There is limited evidence to support a superior outcome with compliance to whole sets of recommendations. The aim of this review was to determine whether adherence to TBI guidelines as a package improves outcomes in adults and paediatric patients with severe TBI.

METHODS

A structured literature search was conducted using the MEDLINE®, Embase™, PubMed and CINAHL® (Cumulative Index to Nursing and Allied Health Literature) databases. Studies were considered eligible for inclusion in this review if they were quantitative studies investigating the use of TBI guidelines in relation to one or more of the following outcomes: mortality, functional outcome and length of hospital stay.

RESULTS

Nine cohort studies were identified that fulfilled the inclusion criteria and answered the clinical question. A review of these papers was conducted.

CONCLUSIONS

Mortality after severe TBI improves with increasing adherence to evidence-based guidelines in both adults and children. The evidence also suggests that compliance with guideline recommendations results in improved functional outcomes and reduced length of hospital stay.

P11.06.A benefits of carbohydrate loading drinks pre-operatively for patients with a presumed high-grade glioma planned for an awake craniotomy

Background

As part of enhanced recovery after surgery in neuro oncology, carbohydrate loading drinks were reviewed to see if there were any benefits in administering this pre operatively, in particularly for patients for awake craniotomy electively. This method is currently used in colorectal and spinal teams within the trust. Carbohydrate loading drinks are clear, and can be consumed up to 2 hours before induction of anaesthesia. Currently reviewed for patients for awake craniotomy with the vision to implement for all patients planned for craniotomy, both asleep and awake. The concept of this drink, is that it helps with post-operative nausea and vomiting , insulin resistance, helps with energy boost which is helpful during awake craniotomies and potentially during their engagement with therapists post operatively and wound healing (Hausel J et al, 2005). This could essentially lead to safer discharge, reduced risk of wound infection and reduced length of stay.

Material and Methods

In a single centre, data for patients who have undergone awake craniotomies this year were abstracted. Patients planned for an awake surgery were prescribed carb-loading drinks. Due to the start date of this study, there were already a number of patients who have had their awake craniotomies without having carb-loading drinks prescribed. The data for both cohorts enabled comparison on engagement during and after awake craniotomies with therapists and length of stay.

Results

The current data collected has found that the average length of stay in the group who were not prescribed carbohydrate loading drinks pre operatively, had an average length of stay 7.2 days in total, 50% had experienced nausea and vomiting post operatively, which led therapists unable to perform assessments. 66% of patients in this group were found to have some form of difficulties engaging with the therapists during the awake phase of their craniotomies. Compared with patients who were prescribed the carbohydrate loading drink, the average length of stay was 4.6 days, with no post operative nausea and vomiting, no difficulties engaging with therapists post operatively.

Conclusion

Though the current data is of a small volume, carbohydrate loading pre-operatively can help patients for elective awake craniotomies and reduce length of stay in hospital, optimising their recovery in a fast yet safe manner to ensure they are in the best performance status prior to commencing oncology treatment. With further analysis into the use of carb-loading drinks pre-operatively, this can be used widely within neuro-oncology surgeries.

Hausel J, Nygren J, Thorell A et al Randomized clinical trial of the effects of oral preoperative carbohydrates on postoperative nausea and vomiting after laparoscopic cholecystectomy. Br J Surg 2005; : 415-421. [PubMed] [Google Scholar]

Multicellular "hotspots" harbor high-grade potential in lower-grade gliomas

BACKGROUND

Lower-grade gliomas may be indolent for many years before developing malignant behavior. The mechanisms underlying malignant progression remain unclear.

METHODS

We collected blocks of live human brain tissue donated by people undergoing glioma resection. The tissue blocks extended through the peritumoral cortex and into the glioma. The living human brain tissue was cut into ex vivo brain slices and bathed in 5-aminolevulinic acid (5-ALA). High-grade glioma cells avidly take up 5-ALA and accumulate high levels of the fluorescent metabolite, Protoporphyrin IX (PpIX). We exploited the PpIX fluorescence emitted by higher-grade glioma cells to investigate the earliest stages of malignant progression in lower-grade gliomas.

RESULTS

We found sparsely distributed "hot-spots" of PpIX-positive cells in living lower-grade glioma tissue. Glioma cells and endothelial cells formed part of the PpIX hotspots. Glioma cells in PpIX hotspots were IDH1 mutant and expressed nestin suggesting they had acquired stem-like properties. Spatial analysis with 5-ALA-conjugated quantum dots indicated that these glioma cells replicated adjacent to blood vessels. PpIX hotspots were formed in the absence of angiogenesis.

CONCLUSION

Our data show that PpIX hotspots represent microdomains of cells with high-grade potential within lower-grade gliomas and identify locations where malignant progression could start.

Ex vivo ultrasonic samples of human brain tumors in the molecular era

Background

Gliomas are composed of multiple clones of tumor cells. This intratumor heterogeneity contributes to the ability of gliomas to resist treatment. It is vital that gliomas are fully characterized at a molecular level when a diagnosis is made to maximize treatment effectiveness.

Methods

We collected ultrasonic tissue fragments during glioma surgery. Large tissue fragments were separated in the operating theater and bathed continuously in oxygenated artificial cerebrospinal fluid to keep them alive. The ex vivo tissue fragments were transferred to a laboratory and incubated in 5-aminolevulinic acid (5-ALA). 5-ALA is metabolized to Protoporphyrin IX (PpIX), which accumulates in glioma cells and makes them fluorescent. The molecular and neuropathological features of the PpIX fluorescent ultrasonic tissue fragments were studied.

Results

We show that PpIX fluorescence can rapidly identify tissue fragments infiltrated by glioma in the laboratory. Ultrasonic tissue fragments from the tumor core provided molecular and neuropathological information about the glioma that was comparable to the surgical biopsy. We characterized the heterogeneity within individual gliomas by studying ultrasonic tissue fragments from different parts of the tumor. We found that gliomas exhibit a power relationship between cellular proliferation and tumor infiltration. Tissue fragments that deviate from this relationship may contain foci of more malignant glioma. The methylation status of the O ⁶-methylguanine DNA methyltransferase gene promoter varied within each glioma.

Conclusions

Ex vivo ultrasonic tissue fragments can be rapidly screened for glioma infiltration. They offer a viable platform to characterize heterogeneity within individual gliomas, thereby enhancing their diagnosis and treatment.

P11.49 An electrophysiological signature of glioma infiltration in the ex vivo human brain

BACKGROUND

Invading glioma cells affect the physiological function of the peritumoural cortex. This may manifest clinically as seizures. Here, we investigate the effect the invading glioma cells on the electrophysiological signalling of the peritumoral cortex using living human brain tissue donated by people having a craniotomy for glioma resection (REC approval, 18/SW/002).

MATERIAL AND METHODS

The brain tissue was cut into thin slices, which preserved the architecture of the glioma and the adjacent healthy brain. The brain slices were incubated in 5-aminolevulinic acid to make the glioma cells fluorescent. We observed 5-ALA induced fluorescence in both low-grade and high-grade gliomas. This enabled us to make electrophysiological recordings of brain activity across the boundary between glioma and brain.

RESULTS

We recorded from brain slices of 5 participants with glioblastoma and 4 participants with oligodendroglioma (WHO grade II - III). Spontaneous “seizure-like” discharges were recorded in brain slices from 5/8 participants (3 GBM, 2 oligodendroglioma) who reported seizures and from one participant (GBM) who had not had any clinical seizures. Further analysis of the electrical discharges revealed that they could be subdivided into two distinct types based on the major frequencies in the discharge.

CONCLUSION

We concluded that human brain slices from people with either a low-grade or a high-grade glioma can generate spontaneous seizure-like discharges. This electrophysiological signature will be compared to infiltration and grade of the glioma cells in the donated sample. The living human brain tissue preparation gives us a platform to study the mechanisms of tumour-associated seizures and how abnormal neural activity affects glioma growth.

P6 The use of 5-ALA fluorescence in excision of supratentorial endodermal cyst

Objectives

The first documented use of 5-ALA in the excision of an intraparenchymal endodermal cyst.

Design

Case review.

Subjects

52 year old female presented with headaches, progressive right sided hemiparesis and anomic aphasia. She had a large cystic frontal lesion, adjacent of the frontal horn of the lateral ventricles cyst which did not show any nodular or solid component, and did not enhance with gadolinium.

Methods

Case report and review of the literature.

Results

5-ALA assisted, image guided fenestration of the cystic lesion and insertion of a ventricular catheter connected to an Ommaya reservoir was performed. The cyst wall was observed under the microscope and it fluoresced with 5-ALA. Multiple biopsies were obtained from this tissue, which confirmed diagnosis of endodermal cyst. The patient had improvement in clinical symptoms and size of the cyst radiologically in both the immediate post-operative period and the 6 months follow up.

Conclusions

Previous reports described the use of 5-ALA to identify tumour cells within the solid component of cystic haemangioblastomas as well as in cystic ependymomas where the cystic component does not fluoresce. In our patient, the homogeneous fluorescence of the wall suggested that this was indeed a different entity from a haemangioblastoma or an ependymoma because of the different pattern of fluorescence observed. 5-ALA-assisted resection of cystic lesions should be considered when a tumoral origin is uncertain.

P10 Traumatic brain injury outcomes in older adults: is there an age-dependent cut off?

Objectives

To assess the outcomes in patients>60 years with traumatic brain injury (TBI) and determine if there is an age cut-off for worse prognosis.

Design

Single centre retrospective study. Data collected as part of TrIBAL study.

Subjects

All patients with TBI admitted to our hospital over a 4 month period.

Methods

Patients were divided into 6 groups based on their age; group 0 included patients<60 years, 60≤Group 1<65, 65≤Group 2<70, 70≤Group 3<75, 75≤Group 4<80 and Group 5>80. Data was collected on various factors that influence outcomes in TBI patients including presenting GCS, hypotension, hypoxia, antithrombotic therapy and Marshall CT score. Glasgow outcome score (GOS) at discharge from hospital was used. A multinomial logistic regression analysis was performed.

Results

Over the 4 month period 144 patients with TBI were admitted. There were no significant differences in baseline characteristics including presenting GCS and Marshall CT scores between the groups. The GOS at discharge was significantly worse only in Group 5 when Group 0 was considered as the base outcome (p<0.001). Groups 1 to 5 had a significant increased number of patients on antithrombotic therapy when compared with Group 0 (p<0.05). The adjusted analysis for GOS at discharge revealed the use of antithrombotic therapy in Group 5 was the only factor that influenced outcome (p=0.014).

Conclusions

In this cohort, age >80 years was the cut off for worse prognosis. In this age group anticoagulation was the only factor we found that influenced outcome.

WP1-18 Risk factors and patterns of recurrence of low grade glioma: a systematic review

Objectives

To review the risk factors and patterns of progression/recurrence of low grade glioma (LGG).

Design

Systematic review of the published literature.

Subjects

Inclusion criteria were peer reviewed publications of cohort studies of recurrent/progressive LGG. Studies of wider populations were included if relevant LGG data could be analysed separately.

Methods

Medline and Cochrane databases were searched using MeSH and non-MeSH terms, including ‘glioma’, ‘astrocytoma’, ‘oligoastrocytoma’, ‘diffuse glioma’, ‘oligodendroglioma’, ‘low grade’ and ‘disease recurrence’ by two independent reviewers.

Results

Overall, 917 studies were screened, of which 57 studies met the inclusion criteria. The most frequently described risk factor for recurrent LGG was suboptimal extent of resection (EOR) of the initial tumour (in 20 studies); recurrence was also associated with the patient’s age (2), tumour location (4), neurological status (3), tumour volume (6), bihemispherical tumour (3) and astrocytic histology (6). IDH mutation was associated with recurrence in 1 out of 3 studies, but TP53 mutation (2 of 4) and MGMT methylation status (4) were not. Malignant transformation was associated with TP53 mutations (3), IDH mutation (1) and EOR (1). Favourable progression free survival (PFS) and/or overall survival (OS) were associated with greater EOR (16), oligodendroglioma histology (2 of 4), initial KPS (3) and the use of adjuvant therapies (9 of 14). IDH mutation was associated with improved PFS and OS (3 of 4). TP53 mutation improved PFS in 1 of 3 studies. MGMT methylation and 1 p/19q codeletion may predict treatment response but their effects on survival are unclear.

Conclusions

Astrocytoma histology, IDH and TP53 mutation statuses and surgical treatment (EOR) are essential in determining the time to recurrence or progression in LGG.

P11 Which factors influence the decision to transfer patients with traumatic brain injury to a neurosurgery unit in a major trauma network?

Objectives

To identify factors that influence the decision to transfer patients with traumatic brain injury (TBI) to a neurosurgical centre.

Design

Retrospective data collected as part of TrIBAL study.

Subjects

All patients with TBI referred to our neurosurgery unit from regional acute hospitals over a 4 month period.

Methods

Our primary outcome was transfer to a neurosurgical centre. We identified the following factors that may predict decision to transfer: patient demographics, transfer distance, anticoagulation therapy and severity of TBI (initial GCS and Marshall score). A multivariable logistic regression analysis was performed.

Results

A total of 347 patients were referred from regional hospitals with TBI and of these, 53 (15%) were transferred. The mean age of patients referred was 69.6 years, 62.5% were men and 43% on antiplatelets or anticoagulated. Similar number of patients were referred from hospitals within 30 miles (54%) and those more than 30miles away (46%). Eighty-four percent of patients had mild TBI (GCS 13–15) on initial assessment and 67% had a Marshall CT score of 2. After regression analysis, younger age, male gender and higher Marshall score predicted transfer to our neurosurgical centre (p<0.05).

Conclusions

Many patients with TBI have relatively ‘minor’ injuries and remain at their local hospital. In our cohort higher Marshall score, younger age and male gender predicted transfer to a neurosurgicial centre. Transfer distance, anticoagulation therapy and initial GCS did not influence decision to transfer.