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.

Transcranial Magnetic Stimulation-Based Machine Learning Prediction of Tumor Grading in Motor-Eloquent Gliomas

BACKGROUND

Navigated transcranial magnetic stimulation (nTMS) is a well-established preoperative mapping tool for motor-eloquent glioma surgery. Machine learning (ML) and nTMS may improve clinical outcome prediction and histological correlation.

METHODS

This was a retrospective cohort study of patients who underwent surgery for motor-eloquent gliomas between 2018 and 2022. Ten healthy subjects were included. Preoperative nTMS-derived variables were collected: resting motor threshold (RMT), interhemispheric RMT ratio (iRMTr)-abnormal if above 10%-and cortical excitability score-number of abnormal iRMTrs. World Health Organization (WHO) grade and molecular profile were collected to characterize each tumor. ML models were fitted to the data after statistical feature selection to predict tumor grade.

RESULTS

A total of 177 patients were recruited: WHO grade 2-32 patients, WHO grade 3-65 patients, and WHO grade 4-80 patients. For the upper limb, abnormal iRMTr were identified in 22.7% of WHO grade 2, 62.5% of WHO grade 3, and 75.4% of WHO grade 4 patients. For the lower limb, iRMTr was abnormal in 23.1% of WHO grade 2, 67.6% of WHO grade 3%, and 63.6% of WHO grade 4 patients. Cortical excitability score (P = .04) was statistically significantly related with WHO grading. Using these variables as predictors, the ML model had an accuracy of 0.57 to predict WHO grade 4 lesions. In subgroup analysis of high-grade gliomas vs low-grade gliomas, the accuracy for high-grade gliomas prediction increased to 0.83. The inclusion of molecular data into the model-IDH mutation and 1p19q codeletion status-increases the accuracy of the model in predicting tumor grading (0.95 and 0.74, respectively).

CONCLUSION

ML algorithms based on nTMS-derived interhemispheric excitability assessment provide accurate predictions of HGGs affecting the motor pathway. Their accuracy is further increased when molecular data are fitted onto the model paving the way for a joint preoperative approach with radiogenomics.

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.

Impact of Preoperative Mapping and Intraoperative Neuromonitoring in Minimally Invasive Parafascicular Surgery for Deep-Seated Lesions

BACKGROUND

Transsulcal tubular retractor-assisted minimally invasive parafascicular surgery changes the surgical strategy for deep-seated lesions by promoting a deficit-sparing approach. When integrated with preoperative brain mapping and intraoperative neuromonitoring (IONM), this approach may potentially improve patient outcomes. In this study, we assessed the impact of preoperative brain mapping and IONM in tubular retractor-assisted neuro-oncological surgery.

METHODS

This retrospective single-center cohort study included patients who underwent transsulcal tubular retractor-assisted minimally invasive parafascicular surgery for resection of deep-seated brain tumors from 2016 to 2022. The cohort was divided into 3 groups: group 1, no preoperative mapping or IONM (17 patients); group 2, IONM only (25 patients); group 3, both preoperative mapping and IONM (38 patients).

RESULTS

We analyzed 80 patients (33 males and 47 females) with a median age of 46.5 years (range: 1-81 years). There was no significant difference in mean tumor volume (26.2 cm3 [range 1.07-97.4 cm3]; P = 0.740) and mean preoperative depth of the tumor (31 mm [range 3-65 mm], P = 0.449) between the groups. A higher proportion of high-grade gliomas and metastases was present within group 3 (P = 0.003). IONM was related to fewer motor (P = 0.041) and language (P = 0.032) deficits at hospital discharge. Preoperative mapping and IONM were also related to shorter length of stay (P = 0.008).

CONCLUSIONS

Preoperative and intraoperative brain mapping and monitoring enhance transsulcal tubular retractor-assisted minimally invasive parafascicular surgery in neuro-oncology. Patients had a reduced length of stay and prolonged overall survival. IONM alone reduces postoperative neurological deficit.

Awake minimally invasive parafascicular approach to a language eloquent brain tumour-surgical video

Deep-seated brain tumours are surgically challenging to access. When planning approaches to these lesions, it is important to take into account eloquent cortical areas, grey matter nuclei, and subcortical white matter tracts. Traditionally, access to deep-seated lesions would require brain retraction; however, this is associated with secondary brain damage, which may impair neurological function. A trans-sulcal minimally invasive parafascicular approach allows gentle splitting of brain fibres and is thought to splay rather than sever white matter tracts. This is particularly important when approaching medially located, language-eloquent tumours, which lack brain surface expression. This video describes a minimally invasive approach to a deep-seated, language-eloquent brain tumour. We utilized preoperative cortical and subcortical planning to define a safe surgical corridor. We then demonstrate using intraoperative neuro-monitoring and mapping of the motor and language functions to define the boundaries of surgical resection. We find trans-sulcal minimally invasive parafascicular approach to be a safe and effective technique when approaching language-eloquent lesions medial to the main language subcortical networks.

Cortical-Subcortical Functional Preservation and Rehabilitation in Neuro-Oncology: Tractography-MIPS-IONM-TMS Proof-of-Concept Study

Surgical management of deep-seated brain tumors requires precise functional navigation and minimally invasive surgery. Preoperative mapping using navigated transcranial magnetic stimulation (nTMS), intraoperative neurophysiological monitoring (IONM), and minimally invasive parafascicular surgery (MIPS) act together in a functional-sparing approach. nTMS also provides a rehabilitation tool to maximize functional recovery. This is a single-center retrospective proof-of-concept cohort study between January 2022 and June 2023 of patients admitted for surgery with motor eloquent deep-seated brain tumors. The study enrolled seven adult patients, five females and two males, with a mean age of 56.28 years old. The lesions were located in the cingulate gyrus (three patients), the central core (two patients), and the basal ganglia (two patients). All patients had preoperative motor deficits. The most common histological diagnosis was metastasis (five patients). The MIPS approach to the mid-cingulate lesions involved a trajectory through the fronto-aslant tract (FAT) and the fronto-striatal tract (FST). No positive nTMS motor responses were resected as part of the outer corridor for MIPS. Direct cortical stimulation produced stable motor-evoked potentials during the surgeries with no warning signs. Gross total resection (GTR) was achieved in three patients and near-total resection (NTR) in four patients. Post-operatively, all patients had a deterioration of motor function with no ischemia in the postoperative imaging (cavity-to-CST distance 0-4 mm). After nTMS with low-frequency stimulation in the contralateral motor cortex, six patients recovered to their preoperative functional status and one patient improved to a better functional condition. A combined Tractography-MIPS-IONM-TMS approach provides a successful functional-sparing approach to deep-seated motor eloquent tumors and a rehabilitation framework for functional recovery after surgery.

Intraoperative Neuromonitoring of the Visual Pathway in Asleep Neuro-Oncology Surgery

Brain tumour surgery in visual eloquent areas poses significant challenges to neurosurgeons and has reported inconsistent results. This is a single-centre prospective cohort study of patients admitted for asleep surgery of intra-axial lesions in visual eloquent areas. Demographic and clinical information, data from tractography and visual evoked potentials (VEPs) monitoring were recorded and correlated with visual outcomes. Thirty-nine patients were included (20 females, 19 males; mean age 52.51 ± 14.08 years). Diffuse intrinsic glioma was noted in 61.54% of patients. There was even distribution between the temporal, occipital and parietal lobes, while 55.26% were right hemispheric lesions. Postoperatively, 74.4% remained stable in terms of visual function, 23.1% deteriorated and 2.6% improved. The tumour infiltration of the optic radiation on tractography was significantly related to the visual field deficit after surgery (p = 0.016). Higher N75 (p = 0.036) and P100 (p = 0.023) amplitudes at closure on direct cortical VEP recordings were associated with no new postoperative visual deficit. A threshold of 40% deterioration of the N75 (p = 0.035) and P100 (p = 0.020) amplitudes correlated with a risk of visual field deterioration. To conclude, direct cortical VEP recordings demonstrated a strong correlation with visual outcomes, contrary to transcranial recordings. Invasion of the optic radiation is related to worse visual field outcomes.

MGMT Promoter Methylation: Prognostication beyond Treatment Response

MGMT promoter methylation is related to the increased sensitivity of tumour tissue to chemotherapy with temozolomide (TMZ) and thus to improved patient survival. However, it is unclear how the extent of MGMT promoter methylation affects outcomes. In our study, a single-centre retrospective study, we explore the impact of MGMT promoter methylation in patients with glioblastoma who were operated upon with 5-ALA. Demographic, clinical and histology data, and survival rates were assessed. A total of 69 patients formed the study group (mean age 53.75 ± 15.51 years old). Positive 5-ALA fluorescence was noted in 79.41%. A higher percentage of MGMT promoter methylation was related to lower preoperative tumour volume (p = 0.003), a lower likelihood of 5-ALA positive fluorescence (p = 0.041) and a larger extent of resection EoR (p = 0.041). A higher MGMT promoter methylation rate was also related to improved progression-free survival (PFS) and overall survival (OS) (p = 0.008 and p = 0.006, respectively), even when adjusted for the extent of resection (p = 0.034 and p = 0.042, respectively). A higher number of adjuvant chemotherapy cycles was also related to longer PFS and OS (p = 0.049 and p = 0.030, respectively). Therefore, this study suggests MGMT promoter methylation should be considered as a continuous variable. It is a prognostic factor that goes beyond sensitivity to chemotherapy treatment, as a higher percentage of methylation is related not only to increased EoR and increased PFS and OS, but also to lower tumour volume at presentation and a lower likelihood of 5-ALA fluorescence intraoperatively.

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.

Neurosurgical Management of Central Nervous System Lymphoma: Lessons Learnt from a Neuro-Oncology Multidisciplinary Team Approach

Central nervous system lymphoma (CNSL) represents one of the most aggressive forms of extranodal lymphoma. The gold standard for CNSL diagnosis remains the stereotactic biopsy, with a limited role for cytoreductive surgery that has not been supported by historical data. Our study aims to provide a comprehensive overview of neurosurgery's role in the diagnosis of systemic relapsed and primary CNSL, with an emphasis on the impact on management and survival. This is a single center retrospective cohort study with data collected between August 2012 and August 2020, including patients referred with a potential diagnosis of CNSL to the local Neuro-oncology Multidisciplinary Team (MDT). The concordance between the MDT outcome and histopathological confirmation was assessed using diagnostic statistics. A Cox regression is used for overall survival (OS) risk factor analysis, and Kaplan-Meier statistics are performed for three prognostic models. The diagnosis of lymphoma is confirmed in all cases of relapsed CNSL, and in all but two patients who underwent neurosurgery. For the relapsed CNSL group, the highest positive predictive value (PPV) is found for an MDT outcome when lymphoma had been considered as single or topmost probable diagnosis. Neuro-oncology MDT has an important role in establishing the diagnosis in CNSL, not only to plan tissue diagnosis but also to stratify the surgical candidates. The MDT outcome based on history and imaging has good predictive value for cases where lymphoma is considered the most probable diagnosis, with the best prediction for cases of relapsed CNSL, questioning the need for invasive tissue diagnosis in the latter group.

H3 G34-mutant high-grade gliomas: integrated clinical, imaging and pathological characterisation of a single-centre case series

BACKGROUND

Diffuse hemispheric glioma, H3 G34-mutant, is a novel paediatric tumour type in the fifth edition of the WHO classification of CNS tumours associated with an invariably poor outcome. We present a comprehensive clinical, imaging and pathological review of this entity.

METHODS

Patients with confirmed H3 G34R-mutant high-grade glioma were included in a single-centre retrospective cohort study and examined for clinical, radiological and histo-molecular data.

RESULTS

Twelve patients were enrolled in the study - 7 males/5 females; the mean age was 17.5 years (10-57 years). Most patients presented with signs of raised intracranial pressure (8/12). The frontal lobe (60%) was the prevalent location, with a mixed cystic-nodular appearance (10/12) and presence of vascular flow voids coursing through/being encased by the mass (8/12), and all tumours showed cortical invasion. Nine patients had subtotal resection limited by functional margins, two patients underwent supra-total resection, and one patient had biopsy only. 5-ALA was administered to 6 patients, all of whom showed positive fluorescence. Histologically, the tumours showed a marked heterogeneity and aggressive spread along pre-existing brain structures and leptomeninges. In addition to the diagnostic H3 G34R/V mutation, pathogenic variants in TP53 and ATRX genes were found in most cases. Potential targetable mutations in PDGFRA and PIK3CA genes were detected in five cases. The MGMT promoter was highly methylated in half of the samples. Methylation profiling was a useful diagnostic tool and highlighted recurrent structural chromosome abnormalities, such as PDGFRA amplification, CDKN2A/B deletion, PTEN loss and various copy number changes in the cyclin D-CDK4/Rb pathway. Radiochemotherapy was the most common adjuvant treatment (9/12), and the average survival was 19.3 months.

CONCLUSIONS

H3 G34R-mutant hemispheric glioma is a distinct entity with characteristic imaging and pathological features. Genomic landscaping of individual tumours can offer an opportunity to adapt individual therapies and improve patient management.

Tractography-Enhanced Biopsy of Central Core Motor Eloquent Tumours: A Simulation-Based Study

Safe Trajectory planning for navigation guided biopsy (nBx) of motor eloquent tumours (METs) is important to minimise neurological morbidity. Preliminary clinical data suggest that visualisation of the corticospinal tract (CST) and its relation to the tumour may aid in planning a safe trajectory. In this article we assess the impact of tractography in nBx planning in a simulation-based exercise. This single centre cross-sectional study was performed in March 2021 including 10 patients with METs divided into 2 groups: (1) tractography enhanced group (T-nBx; n = 5; CST merged with volumetric MRI); (2) anatomy-based group (A-nBx; n = 5; volumetric MRI only). A biopsy target was chosen on each tumour. Volunteer neurosurgical trainees had to plan a suitable biopsy trajectory on a Stealth S8® workstation for all patients in a single session. A trajectory safety index (TSI) was devised for each trajectory. Data collection and analysis included a comparison of trajectory planning time, trajectory/lobe changes and TSI. A total of 190 trajectories were analysed based on participation from 19 trainees. Mean trajectory planning time for the entire cohort was 225.1 ± 21.97 s. T-nBx required shorter time for planning (p = 0.01). Mean trajectory changes and lobe changes made per biopsy were 3.28 ± 0.29 and 0.45 ± 0.08, respectively. T-nBx required fewer trajectory/lobe changes (p = 0.01). TSI was better in the presence of tractography than A-nBx (p = 0.04). Neurosurgical experience of trainees had no significant impact on the measured parameters despite adjusted analysis. Irrespective of the level of neurosurgical training, surgical planning of navigation guided biopsy for METs may be achieved in less time with a safer trajectory if tractography imaging is available.

Therapeutic Strategies and Challenges in the Management of Craniospinal Tumors in Pregnancy: A Ten-Year Retrospective Tertiary-Center Study, Systematic Review, and Proposal of Treatment Algorithms

OBJECTIVE

This study aims to review therapeutic strategies in the management of craniospinal tumors in pregnant patients and the factors that may influence the management along with their influence on maternal and fetal outcomes.

METHODS

A retrospective single-center cohort study was performed at a tertiary neurosurgical referral center. Pregnant patients referred to the neuro-oncology multidisciplinary meeting (MDM) with craniospinal tumor were included. Ten-year patient data were collected from hospital records and neuro-oncology MDM outcomes. A systematic review was performed of the available literature as per PRISMA guidelines.

RESULTS

Twenty-five patients were identified, with a mean age of 31 years. Of these patients, 88% (n = 22) had cranial lesions and 12% (n = 3) had spinal lesions. Most of the patients had World Health Organization grade I/II tumors. Of the patients, 44% underwent surgery when pregnant, whereas in 40%, this was deferred until after the due date. Of patients, 16% did not require surgical intervention and were followed up with serial imaging in the MDM. The left lateral/park bench position was the preferred position for the spinal and posterior fossa lesions. Systematic review and retrospective data led to proposal of treatment algorithms addressing the therapeutic strategy for management of craniospinal tumors during pregnancy. Factors that may influence maternal and fetal outcomes during management of these tumors were identified, including aggressiveness of the tumor and stage of pregnancy.

CONCLUSIONS

Craniospinal tumors presenting in pregnancy are challenging. The surgical management needs to be tailored individually and as part of a multidisciplinary team approach. Factors influencing maternal and fetal outcomes are to be considered during management and patient counseling.

On Natural History and Management of Colloid Cysts: Time to Rethink?

BACKGROUND

Colloid cysts, although benign, may occasionally cause obstructive hydrocephalus and sudden death. Reliable prognostic factors for symptomatic progression have been sought, with heterogenous results.

METHODS

We conducted a retrospective review of all cases of colloid cysts of the third ventricle managed at our center between 2009 and 2019. Clinical and neuroimaging characteristics were analyzed using logistic regression in relation to symptomatic status and hydrocephalus. The cutoff values for outcome prediction were calculated using the receiver operating characteristic curve analysis.

RESULTS

There were 82 patients with colloid cysts, of whom 60 were asymptomatic and 22 symptomatic. None of the asymptomatic patients experienced acute neurologic decline or hydrocephalus during follow-up, whereas half (n = 11) of the symptomatic patients presented with hydrocephalus, 8 of whom had acute hydrocephalus. We found 3 putative candidate risk factors for symptomatic colloid cysts: T1-weighted magnetic resonance imaging hyperintense/mixed signal appearance (P = 0.004), location in risk zone I (P = 0.007), and a volume >236.49 mm³ (P = 0.007). Cyst diameter and volume/foramen of Monro diameter ratios had a decreasing trend over time among asymptomatic patients, providing new insights into the natural history of the disease.

CONCLUSIONS

Only a few asymptomatic colloid cysts showed progression requiring surgery, with no acute deterioration or fatal events, whereas the rest remained stable over time, thus supporting a more conservative approach for this group of patients. Higher risk for developing symptomatic colloid cyst was defined by a risk score that included T1-weighted magnetic resonance imaging appearance, risk zone, and colloid cyst volume, aiding the detection of patients at risk of clinical deterioration.

Case report: 'Photodynamics of Subependymal Giant Cell Astrocytoma with 5-Aminolevulinic acid'

Subependymal Giant Cell Astrocytoma (SEGA) is a common diagnosis in patients with Tuberous Sclerosis. Although surgical treatment is often required, resection may entail a significant risk for cognitive function given the anatomical relation with critical structures such as the fornices and subgenual area. Therefore, target subtotal resections using minimal invasive approaches focused in the higher metabolic areas are valuable options to preserve quality of life while addressing specific problems caused by the tumor, such as hydrocephalus or progressive growth of a specific component of the tumor. In this report, the authors explore the potential role of 5-ALA in the identification of highly metabolic areas during SEGA resection in the context of minimal invasive approaches.

QLTI-03. AN INNOVATIVE APPROACH TO ACCESSIBLE INFORMATION FOR BRAIN TUMOUR PATIENTS AND THEIR LOVED ONES

Patient information for cancer patients is acknowledged for its vital contribution to informed consent and a positive patient experience. It forms a measure to which UK oncology centres are held to account in the national cancer patient experience survey. It could be argued that this has driven the production of such information rather than it being designed to best meet the need of the neuro-oncology patient. With this in mind a YouTube channel was set up after consulting current High Grade Glioma patients on their preferred medium. Patients wanted short clips in a conversational style explaining aspects of their treatment and the pathway. They wanted it to be available in a medium that they were familiar with either s a podcast or YouTube shorts. The CNS team requested patients choose the name of the channel and began making short videos with patients and professionals on subjects suggested by patients. In twelve weeks, we have produced 23 videos, which have had 2282 views and 105 hours of watch time. The average person watches for two hours and forty-six minutes. It is possible to extrapolate from this that people are engaging with the content. The availability of information in this form has reduced the length of conversations and emails with the CNS’s pre-operatively. Patients have reported a greater sense of comfort from hearing other patient’s stories. The authors acknowledge there is not enough data available yet to formerly support this. In conclusion patient information should be designed to meet the needs of the patient not the guidance. It needs to be accessible to patients who have neurological impairments including changes in vision and concentration and provided in a medium that is current, visual and easily accessible.

Combined extradural and intradural approach to a trigeminal nerve hemangiopericytoma with cranial nerve monitoring: a technical note of a rare case

Hemangiopericytoma (HPC) of the trigeminal nerve is extremely rare. We present a case of a large cystic HPC of the mandibular division of the trigeminal nerve, only the third case described in the literature, with both intradural and extradural components. We describe the surgical approach, assisted by neurophysiological techniques of mapping and monitoring including blink reflex and triggered electromyography. Additionally, we report a method of monitoring of the sensory branches of the trigeminal nerve, poorly described in the literature, through peripheral and direct nerve stimulation and recording of transcranial somatosensory evoked potentials.

Photodynamics of Subependymal Giant Cell Astrocytoma (SEGA) with 5-Aminolevulinic Acid (5-ALA/Gliolan©)

AIMS

5-ALA (Gliolan©) is a valuable surgical tool used predominantly in high grade tumours, which utilises tissue fluorescence to improve the visualisation of the brain-tumour interface. This ensures safe maximal resection, while preserving healthy brain. While Gliolan© use in low grade tumours has previously been reported with variable results, reports of its use and success in the context of SEGA are extremely rare. This report highlights the use of Gliolan© in a patient presenting with a Subependymal Giant Cell Astrocytoma (in a background of tuberous sclerosis), facilitating maximal safe resection and preserving eloquent tissue.

METHOD

Tumour resection was performed with pre-operative DTI-fiber tracking and mapping. A transsulcal minimal invasive parafascicular approach (tsMIPS) was carried out with assistance of NICO BrainPath© tubular retractor system (60x13.5), neuronaviagtion, Gliolan©, intra-operative neuro monitoring (IONM), and ultrasound guidance

RESULTS

The tumour was found to have both bright and pale fluorescence in the cystic and solid components respectively. Resection was limited to the soft cystic component only, as the solid tumour component showed anatomical attachment to the subgenual area and the fornix. No fluorescence was perceived at the end of resection. The patient made a good recovery with no post-operative deficits. Histopathology confirmed subependymal giant cell astrocytoma (SEGA, WHO grade I). No adjuvant treatment was required

CONCLUSION

This reports suggests 5-ALA may be beneficial in the safe resection of SEGAs. Further studies and technological advances in the area of photodynamics, imaging, and intra-operative mapping may be helpful to fully evaluate the efficacy of 5-ALA in SEGAs and other low-grade tumours.

Exploring the Role of Specialist Physiotherapy in Awake Craniotomy Surgery for the Neuro-Oncology Patient

AIMS

To describe the methods used to assess and monitor motor function during awake craniotomy surgery for tumour resection.

METHOD

A service review was carried out over 10 months. Patients with highly motor eloquent lesions – invasion of primary motor cortex or fronto-parietal connections involved in motor cognition – were included. Clinical notes were reviewed and summarised using descriptive analysis. Dexterity and grip strength were measured using 9-hole peg test and handheld dynameter pre/intra and post-operatively. Patient occupation/interests were reported to guide bespoke assessments to trial intra-operatively.

RESULTS

From April 2021 to January 2022, 13 patients (mean age 39.7 years, 4 female:10 male, 9 low grade:5 high grade gliomas) were included. Mean score 9-hole peg test 22.2sec pre-operatively, 30.6sec post-operatively; handheld dynameter 26.7kg pre-operatively, 18.4kg post-operatively. At discharge 5 of 7 impaired patients demonstrated motor improvement. For motor coordination, motor tasks used frequently included repetitive finger tapping, open/closed hand. Bespoke tasks included texting/writing, playing instruments, and computer games. Movement was closely monitored and verbal feedback given to the neurosurgeons throughout. With video analysis movement comparisons were made.

CONCLUSION

The role of physiotherapy in awake surgery is evolving to provide movement analysis for complex motor tasks such as upper limb sequencing and dexterity. A combination of standard and bespoke assessments have been trialled and their feasibility within surgery tested. A post-operative deterioration of motor function (power and cognition) is expected after surgery for highly eloquent motor gliomas. However, intraoperative motor assessment for motor cognition allows function preservation and potentiates its recovery.

Impact of Tubular Retractor-Assisted Transsulcal Minimal Invasive Parafascicular Approach for Deep-Seated Lesions in Cortical Vascularization

AIMS

Assess the impact of tubular retractor-assisted transsulcal minimal invasive parafascicular approaches(tsMIPS) in the cortical vascularization using indocianin green angiography(ICGA) during removal of deep-seated cerebral tumours.

METHOD

Single-centre prospective cohort study of patients with deep-seated lesions – distance to nearest sulcus &gt; 10mm - where ICGA was performed. Zeiss FLOW800 Software was used to analyse the following variables - delay time, speed, time to peak and rise time - before and after insertion of the tubular retractor (NICO BrainPath).

RESULTS

13 patients were enrolled. 60 regions-of-interest were analysed. The most common pathology was high grade glioma (69%). The average depth of tumours was 34,2mm (23– 45mm) and the time-under-retraction 166mins (45-280 mins). The most common vascular pattern before-after tubular retractor was: increase on the delay time, time to peak and rising time (present in 8 patients) and a decrease on the speed (present in 7 patients). Two patients had a mayor neurological deficit after the surgery. Both had the same flow pattern with an increase on the speed and decrease on the time to peak and rise time, the delay was indifference.

CONCLUSION

This is the first study assessing the impact of tubular retractor-assisted tsMIPS in cortical vascularization during deep-seated lesion resection. The most common cortical vascular pattern is: an increase on the delay time, time to peak and rising time and a decrease on the speed. The two patients who presented vascular injury shared the same pattern (increase on the speed, decrease on the time to peak and rise time, with indifference delay).

How Can Clinical Teams Support Patients With a Brain Tumour Diagnosis With Sex Relationships and Intimacy?

AIMS

There is a gap in supporting patients with sexual relationships and intimacy. The aim of this study is to establish if patients with a brain tumour feel they are able to ask questions and concerns about sex, relationships and intimacy following diagnosis; is there an unmet need and how can this be addressed.

METHOD

An anonymous survey was sent to patients known to a neuro-oncology team. Questions were in relation to their experiences of sex relationships and intimacy. Patients were asked if they had concerns about changes in their relationships since their diagnosis. They were also asked for their comments on the subject so we can better understand how as a service we can improve to ensure holistic care.

RESULTS

There are 40 responses. The majority of respondents had concerns about their relationship since diagnosis and that their relationships have changed. 57% were concerned about a physical relationship with a partner/ future partners. 50% agreed their physical relationship had changed. 45% of people agreeing their emotional relationships have changed. 38 out of the 40 people questioned, had not asked their clinical team for advice about sex and relationships. 46% suggested clinicians initiating these conversations.

CONCLUSION

Sex relationships and intimacy are significant for most adult populations, encompassing connection with their loved ones, self esteem and psychological and emotional well-being. With brain tumour diagnosis this part of people’s lives can hugely impacted. Historically clinicians have found this a difficult subject to discuss. Further work is required to understand the barriers initiating this subject

Simultaneous Motor and Visual Intraoperative Neuromonitoring in Asleep Parietal Lobe Surgery: Dual Strip Technique

Background: The role played by the non-dominant parietal lobe in motor cognition, attention and spatial awareness networks has potentiated the use of awake surgery. When this is not feasible, asleep monitoring and mapping techniques should be used to achieve an onco-functional balance. Objective: This study aims to assess the feasibility of a dual-strip method to obtain direct cortical stimulation for continuous real-time cortical monitoring and subcortical mapping of motor and visual pathways simultaneously in parietal lobe tumour surgery. Methods: Single-centre prospective study between 19 May−20 November of patients with intrinsic non-dominant parietal-lobe tumours. Two subdural strips were used to simultaneously map and monitor motor and visual pathways. Results: Fifteen patients were included. With regards to motor function, a large proportion of patients had abnormal interhemispheric resting motor threshold ratio (iRMTr) (71.4%), abnormal Cortical Excitability Score (CES) (85.7%), close distance to the corticospinal tract—Lesion-To-Tract Distance (LTD)—4.2 mm, Cavity-To-Tract Distance (CTD)—7 mm and intraoperative subcortical distance—6.4 mm. Concerning visual function, the LTD and CTD for optic radiations (OR) were 0.5 mm and 3.4 mm, respectively; the mean intensity for positive subcortical stimulation of OR was 12 mA ± 2.3 mA and 5/6 patients with deterioration of VEPs > 50% had persistent hemianopia and transgression of ORs. Twelve patients remained stable, one patient had a de-novo transitory hemiparesis, and two showed improvements in motor symptoms. A higher iRMTr for lower limbs was related with a worse motor outcome (p = 0.013) and a longer CTD to OR was directly related with a better visual outcome (p = 0.041). At 2 weeks after hospital discharge, all patients were ambulatory at home, and all proceeded to have oncological treatment. Conclusion: We propose motor and visual function boundaries for asleep surgery of intrinsic non-dominant parietal tumours. Pre-operative abnormal cortical excitability of the motor cortex, deterioration of the VEP recordings and CTD < 2 mm from the OR were related to poorer outcomes.

P16.03.A Epithelioid gliobastoma requires rapid treatment and BRAF inhibitors should be made readily available for their treatment

Background

Epithelioid glioblastoma is a rare subtype of Glioblastoma. We examine two cases who presented acutely with symptoms of headache, neck stiffness and an eye squint. The purpose of this case review is to look at their management, the spread of the disease and propose the availability of BRAF inhibiting agents be made readily available for this subtype.

Material and Methods

The clinical records including pathology and surgical reports, multi-disciplinary team meeting documents, oncology plans and inpatient notes have all been reviewed alongside the literature on epithelioid GBM and BRAF V600e mutations and inhibitors.

Results

Patients were females aged 25 and 32 presenting with acute onset headache and neck stiffness to emergency Department. The 25 year old had developed a right eye squint within seven days of the other symptoms, her tumour was right frontal with midline shift. The 32 year old had symptoms for 10 days prior to presentation, the tumour was right temporal. They both underwent craniotomies. The frontal tumour was totally resected, while the temporal lobe tumour was haemorrhagic in nature and minimally de-bulked. Pre-operative stealth imaging showed that there had been an increase in the size of the temporal lesion in the fourteen days since presentation. Histology proved these to be epithelioid GBM’s with BRAF V600e mutations, IDH wild-type and TERT promoter mutant. Full pathology reports with molecular markers were available within ten days. The frontal lobe patient began chemo-radiation sixteen days from her surgical date. On day two she was admitted with severe headache and nausea. She became agitated, confused, and transferred back to the neurosurgery unit for management of hydrocephalus. She was diagnosed with PRES and simultaneously treated for this and hydrocephalus. Clinically she suffered storming, passing away exactly eight weeks from presentation. Seven days after surgery the temporal lobe tumour patient suffered a seizure and admitted for symptom management and expedite oncology treatment. She passed away six days later suffering continual neurological deterioration and the tumour progression with leptomeningeal spread. This was exactly four weeks from initial presentation.

Conclusion

The prognosis for epithelioid Glioblastoma is limited to weeks to short months. Extent of resection in these case studies demonstrates benefit in delaying progression though it is clear that time is of the essence from presentation, to surgery, to adjuvant treatment. Neither of these tumours were methylated meaning the standard treatment for glioblastoma is likely to lack efficacy. BRAF inhibitors should be made readily available for this rare sub-type to commence treatment expediently. Both patients suffered distressing neurological symptoms in their final days which require expert management and are best managed in a neurosurgical centre.

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]

Continuous Microdebrider-Based Dynamic Subcortical Motor Mapping: A Technical Advance in Tubular Retractor-Assisted Surgery

BACKGROUND

Transsulcal minimally invasive parafasicular (TsMIP) approaches to brain tumor resection use tubular retractors to minimize iatrogenic brain injury. Dynamic cortical and subcortical continuous neurophysiological mapping facilitates safer resection of motor-eloquent tumors.

OBJECTIVE

To describe a new technique to address the challenge of combining TsMIP with tubular retractors and dynamic subcortical mapping using a single electrified stimulating microdebrider instrument.

METHODS

We adapted the NICO Myriad microdebrider with continuous monopolar stimulation electrification using high-frequency stimulation with the train-of-5 technique. We performed continuous subcortical mapping using this device and compared it with standard dynamic monopolar subcortical mapping using a suction stimulation device. We found no significant difference in recorded stimulation response.

RESULTS

Using a single operating instrument that provides synchronous tumor resection and monopolar subcortical mapping with the NICO Brainpath tubular retractor, we observed increased degrees of movement, faster surgical resection times with an enlarged working channel down the retractor, and improved safety because the stimulating probe sits 2 mm deep to the resection window.

CONCLUSION

We show that the adapted device is reliable and provides similar stimulation response as conventional subcortical mapping. We advocate the use of our adapted microdebrider in TsMIP tubular retractor approaches.

First Human In Vivo Neuroelectrophysiology Recordings of Uncrossed Dentatothalamocortical White Matter Connections: On the Fast Tract

OBJECTIVES

We aim to demonstrate intraoperative recording of cerebellar to cortical pathways that have not been previously recorded in humans, though imaged.

METHODS

We report two cases with intraoperative neurophysiological mapping of cerebello-cortical tracts. Direct electrical stimulation of subcortical cerebellum along with recordings of cortical evoked potential and motor muscle recordings were performed during surgery. MR tractography data from healthy subjects were used to further illustrate the pathways.

RESULTS

Neurophysiological recordings showed large waveforms of evoked potentials in bilateral electrodes over premotor/motor cortices on stimulation of the dentate nucleus. EMG recordings showed responses in face and neck muscles on stimulation of dentate nucleus at motor threshold. We thus demonstrated first-in-human in vivo neurophysiological evidence of cerebellum to cortex responses through an uncrossed dentato-thalamo-cortical tract to the motor/premotor cortices.

DISCUSSION

This technique provides a methodology for the direct mapping of the cerebellum and cerebello-cerebral connections. We hypothesize a direct structural connection from the dentate nucleus to the premotor and motor cortices, as well as to ipsilateral hemibody muscles, acting as a fast route of cerebellar output and 'back up' for immediate motor responses. This will further help explain the modulatory effects of the cerebellum on motor, language and cognitive functions.

Commissural Inter-M1 Cortico-cortical Evoked Potential: A Proof of Concept Report

BACKGROUND

Intraoperative neuromonitoring of motor functions experienced a dramatical revolution in the last years thanks to significant advances in anesthesiology procedures and both preoperative and intraoperative mapping techniques. Asleep, awake, and combined intraoperative mapping techniques were responsible for an improvement in the functional outcomes in neurosurgery, providing reliable and reproducible mapping of both projection and association fibers involved in motor control.

METHODS

We report inter-M1 cortico-cortical evoked potential (CCEP) recording during asleep resection of a bilateral parasagittal meningioma with intraoperative neuromonitoring and motor mapping.

RESULTS

CCEPs were recorded between both M1 cortices with bipolar stimulations of both supplementary motor areas (10.5-11.5 μV).

CONCLUSIONS

Here, we provide evidence of intraoperative mapping of commissural fibres involved in motor control in a patient with asleep technique as well as a review of the potential tracts involved in the connectivity underlying the motor function.

5-Aminolevulinic Acid-Guided Resection in Grade III Tumors-A Comparative Cohort Study

BACKGROUND

The benefits of using 5-aminolevulinic acid (5-ALA) in resection of grade IV tumors have been extensively researched. However, few studies have investigated the use of 5-ALA in grade III gliomas.

OBJECTIVE

To discover whether 5-ALA provides significant benefit in assisting resection of grade III gliomas.

METHODS

A single-center, retrospective cohort study between January 2013 and January 2019 of adult patients with grade III gliomas. Patients were separated into a 5-ALA-guided surgery group (5-ALA-GS) and non-5-ALA-guided surgery group (non-5-ALA-GS). Primary outcome was overall survival (OS); secondary outcomes were both postoperative and 6-month performance status (PS6m), and extent of resection (EoR).

RESULTS

Sixty-nine patients with grade III gliomas were included (39 and 30 patients in the 5-ALA-GS group and non-5-ALA-GS group, respectively). There was no significant difference in tumor characteristics between the groups. No significant difference was observed in OS (P = .072) and EoR (P = .609) between both the groups. In a subgroup of the 5-ALA-GS where gross total resection (GTR) was achieved, there was a better OS (P = .043). Significantly worse outcomes were seen postoperatively (P = .044) and at PS6m (P = .041) in the 5-ALA-GS group, mainly because of the poorer outcome in the subtotal resection subgroup.

CONCLUSION

Despite the benefits of 5-ALA in grade IV glioma surgery, these benefits are limited to a smaller group of patients with grade III tumors where there is sufficient fluorescence to allow GTR. In this cohort of patients, 5-ALA use may result in worse neurological outcomes particularly when GTR is not feasible and therefore caution is warranted.

Minimally invasive approach to a deep-seated motor eloquent brain tumour: a technical note

Deep-seated brain tumours represent a unique neurosurgical challenge as they are often surrounded by eloquent structures. We describe a minimally invasive technique using tubular retractors and intraoperative neurophysiology monitoring for open biopsy of a deep-seated lesion surrounded by the corticospinal tract. We used preoperative functional mapping with diffusion tensor imaging tractography and navigated transcranial magnetic stimulation to identify a safe surgical corridor. We also used 5-Aminolevulinic Acid induced fluorescence to identify the lesion intraoperatively and optimize tissue samples obtained for histopathological diagnosis. We found the use of these tools improved the safety of surgery and reduced the risk of surgical morbidity.

Intraoperative ultrasound to aid resection of a peritorcular meningioma: a technical note

Surgery for meningiomas involving dural venous sinuses is challenging. We describe a case of a peritorcular meningioma involving major venous sinuses, which was removed using a venous sparing approach with the aid of intraoperative ultrasound. We found ultrasound to be a useful adjunct as it enabled us to get real-time information about the location of venous structures, their function and demonstrate dynamic changes in blood flow during surgery.

Functional neurological disorders in patients with brain tumours

Aims

Signs and symptoms that develop in people with brain tumours are often attributed to their tumour. The prevalence and management of functional neurological symptoms in brain tumour patients have received little attention. This is surprising because functional neurological symptoms complicate management greatly and misdiagnosis can lead to inappropriate treatment and iatrogenic side-effects. Therefore, we investigated the presentation, diagnosis and management of functional neurological disorders (FND) in patients who had a brain or meningeal tumour.

Method

A retrospective case review was performed from 2017 - 2021 to identify adult brain tumour patients who developed a functional neurological disorder that caused significant disability necessitating expedited investigations. All patients attended a regional neuro-oncology centre. We recorded type of brain tumour and diagnostic investigations. The onset of functional symptoms was divided into three time windows: before tumour diagnosis, after diagnosis and before treatment or after tumour treatment. A neuropsychological review looked for evidence of previous adverse life events. Therapeutic interventions for functional neurological disorder and their outcomes were documented. The case review was combined with a systematic review of the literature to identify the published presentations of functional neurological disorder in the adult brain tumour population. MEDLINE, EMBASE and PsycINFO databases were searched for studies published between January 1980 and February 2021.

Results

Six patients (5 female, 1 male) were identified from the case review with a median age of 41 (range 29 - 56) years old. Four patients had non-epileptic attack disorder, which was diagnosed with videotelemetry of habitual attacks. One patient had a functional hemiparesis with normal central motor conduction time. One patient had a functional speech disorder with normal EEG. Half of these patients had functional neurological symptoms prior to surgery/oncological treatment. Five patients (83%) were referred for further neuropsychiatric or psychological evaluation. A history of significant psychological trauma prior to the brain tumour diagnosis was elicited in four (66%) patients.

Conclusion

Patients with either a brain or meningeal tumour may develop functional neurological symptoms. Our findings suggest the possibility that diagnosis of a brain tumour may precipitate a debilitating functional neurological disorder. The neurobiological basis for functional neurological disorders is being actively investigated. There are suggestions in the literature that some brain diseases increase the risk of developing a functional neurological disorder. Further work is needed to determine whether this is true for patients with brain tumours. Increased awareness of functional neurological disorders will improve management. Withdrawal of unnecessary treatment, such as anticonvulsant drugs, reduces the risk of iatrogenic side effects. Initiation of multi-disciplinary care pathways, e.g. physiotherapy, speech and language therapy and psychological treatments, promotes recovery. Collectively, these interventions improve our patients’ quality of life.

An audit on the diagnosis of primary CNS lymphoma

Aims

Primary central nervous system lymphoma (PCNSL) is a rare form of non–Hodgkin lymphoma with exclusive manifestations in the central nervous system, leptomeninges and eyes. It forms around 5% of all primary brain tumours. It is an aggressive tumour which has a poor prognosis if left untreated. It is imperative that diagnosis is made timely so treatment can be started promptly. Therefore, we performed an audit looking into the speed of diagnostic process of PCNSL in our tertiary Neuro–oncology Unit.

Method

Single-centre retrospective review of PCNSL cases referred to a tertiary Neuro–Oncology Unit over a six month period from June to November 2020.

Results

A total of 1309 cases were discussed in the Neuro–oncology MDT meeting over the study period. Fourteen cases (6 male, 8 female; median age [range] 66 [59–83] years) were identified as highly likely PCNSL. Neuroimaging suggested PCNSL as the likely diagnosis in twelve patients. Twelve patients were started on steroids after CT or MRI brain scans. Nine patients had a surgical target and proceeded to have diagnostic brain biopsy. Two patients had different working diagnoses and three patients were deemed unsuitable for brain surgery. One patient required repeat brain biopsy. A tissue diagnosis was made in twelve patients. One patient deteriorated rapidly and one patient had a brain lesion that was deemed too high risk for surgery. The median time between neuroimaging and biopsy was 25 days. The median time taken from first investigation to the pathological confirmation of PCNSL was 36 days (range 6–86 days).

Conclusion

The chief reason for delay in diagnosis of PCNSL was that patients were started on steroids before diagnostic investigations were completed. Steroids caused the brain lesions to become smaller or disappear. Accordingly, time was needed to allow withdrawal of steroids before diagnostic investigations could be repeated. Diagnostic delays may have been exacerbated by logistical issues associated with COVID–19. We propose that there needs to be greater awareness of how early introduction of steroids can markedly delay the diagnosis of PCNSL.

Electromagnetic Navigation Systems and Intraoperative Neuromonitoring: Reliability and Feasibility Study

BACKGROUND

A recent influx of intraoperative technology is being used in neurosurgery, but few reports investigate the accuracy and safety of these technologies when used simultaneously.

OBJECTIVE

To assess the ability to use an electromagnetic navigation system alongside multimodal intraoperative neurophysiological monitoring (IONM).

METHODS

Single-institution prospective cohort study of patients requiring craniotomy for brain tumor resection operated using an electromagnetic navigation system (AxiEM, Medtronic®). motor evoked potentials, somatosensory evoked potentials (SSEPs), electroencephalography, and electromyography were recorded and analyzed with AxiEM on (with/without filters) and off. The neurological outcomes of the patients were recorded.

RESULTS

A total of 15 patients were included (8 males/7 females, mean age 52.13 yr). Even though the raw acquisition is affected by the electromagnetic field (particularly SSEPs), no significant difference was detected in the morphology, amplitude, and latency of the different monitoring modalities (AxiEM off vs on) after the appropriate software filter application. Adjustments to the frequency of SSEP stimulation and number of averages, and reductions to the low-pass filters were applied. Notch filters were used appropriately and changes to the physical setup of the IONM and electromagnetic navigation system equipment reduced noise. Postoperatively, none of the patients developed new focal deficits; 7 patients showed improvement in their motor deficit (4 recovered fully).

CONCLUSION

The information provided by the IONM in intracranial neurosurgery patients whilst also using electromagnetic navigation systems is reliable for monitoring, mapping, and detecting intraoperative complications, provided that the appropriate software filters and tools are applied.

Surveillance for subsequent neoplasms of the CNS for childhood, adolescent, and young adult cancer survivors: a systematic review and recommendations from the International Late Effects of Childhood Cancer Guideline Harmonization Group

Exposure to cranial radiotherapy is associated with an increased risk of subsequent CNS neoplasms among childhood, adolescent, and young adult (CAYA) cancer survivors. Surveillance for subsequent neoplasms can translate into early diagnoses and interventions that could improve cancer survivors' health and quality of life. The practice guideline presented here by the International Late Effects of Childhood Cancer Guideline Harmonization Group was developed with an evidence-based method that entailed the gathering and appraisal of published evidence associated with subsequent CNS neoplasms among CAYA cancer survivors. The preparation of these guidelines showed a paucity of high-quality evidence and highlighted the need for additional research to inform survivorship care. The recommendations are based on careful consideration of the evidence supporting the benefits, risks, and harms of the surveillance interventions, clinical judgment regarding individual patient circumstances, and the need to maintain flexibility of application across different health-care systems. Currently, there is insufficient evidence to establish whether early detection of subsequent CNS neoplasms reduces morbidity and mortality, and therefore no recommendation can be formulated for or against routine MRI surveillance. The decision to start surveillance should be made by the CAYA cancer survivor and health-care provider after careful consideration of the potential harms and benefits of surveillance for CNS neoplasms, including meningioma.

5-Aminolevulinic acid-guided resection improves the overall survival of patients with glioblastoma-a comparative cohort study of 343 patients

Background

5-Aminolevulic acid-guided surgery (5-ALA-GS) improves the extent of resection (EoR) and progression-free survival in patients with glioblastoma multiforme (GBM).

Methods

A single-center retrospective cohort study of adult patients with GBM who had surgical resection between 2013 and 2019, 5-ALA guided versus a non-5-ALA cohort. The primary outcome was the overall survival (OS). Secondary outcomes were EoR, performance status (PS), and new focal neurological deficit.

Results

Three hundred and forty-three patients were included: 253 patients in 5-ALA-GS group and 90 patients in the non-5-ALA-GS group. The OS (17.47 vs 10.63 months, P < .0001), postoperative PS (P < .0001), PS at 6 months (P = .002), new focal neurological deficit (23.3% vs 44.9%, P < .0001), and radiological EoR (gross total resection [GTR]-47.4% vs 22.9%, P < .0001) were significantly better in the 5-ALA-GS group compared to non-5-ALA-GS group. In multivariate analysis, use of 5-ALA (P = .003) and MGMT promoter methylation (P = .001) were significantly related with a better OS. In patients with radiological GTR, OS was also significantly better (P < .0001) in the 5-ALA-GS group compared to the non-5-ALA-GS group.

Conclusions

5-ALA-GS is associated with a significant improvement in the OS, PS after surgery and at 6 months, larger EoR, and fewer new motor deficits in patients with GBM.

Altered Motor Excitability in Patients With Diffuse Gliomas Involving Motor Eloquent Areas: The Impact of Tumor Grading

BACKGROUND

Diffuse gliomas have an increased biological aggressiveness across the World Health Organization (WHO) grading system. The implications of glioma grading on the primary motor cortex (M1)-corticospinal tract (CST) excitability is unknown.

OBJECTIVE

To assess the excitability of the motor pathway with navigated transcranial magnetic stimulation (nTMS).

METHODS

Retrospective cohort study of patients admitted for surgery with diffuse gliomas within motor eloquent areas. Demographic, clinical, and nTMS-related variables were collected. The Cortical Excitability Score (CES 0 to 2 according to the number of abnormal interhemispheric resting motor threshold (RMT) ratios) was calculated for patients where bilateral upper and lower limb mapping was performed.

RESULTS

A total of 45 patients were included: 9 patients had a low-grade glioma and 36 patients had a high-grade glioma. The unadjusted analysis revealed an increase in the latency of the motor evoked potential of the lower limb with an increase of the WHO grade (P = .038). The adjusted analysis confirmed this finding (P = .013) and showed a relation between the increase in the WHO and a decreased RMT (P = .037) of the motor evoked responses in the lower limb. When CES was calculated, an increase in the score was related with an increase in the WHO grade (unadjusted analysis-P = .0001; adjusted analysis-P = .001) and in isocitrate dehydrogenase (IDH) wild-type tumors (unadjusted analysis-P = .020).

CONCLUSION

An increase in the WHO grading system and IDH wild-type tumors are associated with an abnormal excitability of the motor eloquent areas in patients with diffuse gliomas.

Middle Frontal Gyrus and Area 55b: Perioperative Mapping and Language Outcomes

Background: The simplistic approaches to language circuits are continuously challenged by new findings in brain structure and connectivity. The posterior middle frontal gyrus and area 55b (pFMG/area55b), in particular, has gained a renewed interest in the overall language network.

Methods: This is a retrospective single-center cohort study of patients who have undergone awake craniotomy for tumor resection. Navigated transcranial magnetic simulation (nTMS), tractography, and intraoperative findings were correlated with language outcomes.

Results: Sixty-five awake craniotomies were performed between 2012 and 2020, and 24 patients were included. nTMS elicited 42 positive responses, 76.2% in the inferior frontal gyrus (IFG), and hesitation was the most common error (71.4%). In the pMFG/area55b, there were seven positive errors (five hesitations and two phonemic errors). This area had the highest positive predictive value (43.0%), negative predictive value (98.3%), sensitivity (50.0%), and specificity (99.0%) among all the frontal gyri. Intraoperatively, there were 33 cortical positive responses—two (6.0%) in the superior frontal gyrus (SFG), 15 (45.5%) in the MFG, and 16 (48.5%) in the IFG. A total of 29 subcortical positive responses were elicited−21 in the deep IFG–MFG gyri and eight in the deep SFG–MFG gyri. The most common errors identified were speech arrest at the cortical level (20 responses−13 in the IFG and seven in the MFG) and anomia at the subcortical level (nine patients—eight in the deep IFG–MFG and one in the deep MFG–SFG). Moreover, 83.3% of patients had a transitory deterioration of language after surgery, mainly in the expressive component (p = 0.03). An increased number of gyri with intraoperative positive responses were related with better preoperative (p = 0.037) and worse postoperative (p = 0.029) outcomes. The involvement of the SFG–MFG subcortical area was related with worse language outcomes (p = 0.037). Positive nTMS mapping in the IFG was associated with a better preoperative language outcome (p = 0.017), relating to a better performance in the expressive component, while positive mapping in the MFG was related to a worse preoperative receptive component of language (p = 0.031).

Conclusion: This case series suggests that the posterior middle frontal gyrus, including area 55b, is an important integration cortical hub for both dorsal and ventral streams of language.