Category: Awake craniotomy

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Predicting the Extent of Resection in Low-Grade Glioma by Using Intratumoral Tractography to Detect Eloquent FasciclesWithin the Tumor

Neurosurgery 88(2) 2021: E190–E202

An early maximal safe surgical resection is the current treatment paradigm for low-grade glioma (LGG). Nevertheless, there are no reliable methods to accurately predict the axonal intratumoral eloquent areas and, consequently, to predict the extent of resection.

OBJECTIVE: To describe the functional predictive value of eloquent white matter tracts within the tumor by using a pre- and postoperative intratumoral diffusion tensor imaging (DTI) tractography protocol in patients with LGG.

METHODS: A preoperative intratumoral DTI-based tractography protocol, using the tumor segmented volume as the only seed region, was used to assess the tracts within the tumor boundaries in 22 consecutive patients with LGG. The reconstructed tracts were correlated with intraoperative electrical stimulation (IES)-based language and motor subcortical mapping findings and the extent of resection was assessed by tumor volumetrics.

RESULTS: Identification of intratumoral language and motor tracts significantly predicted eloquent areas within the tumor during the IES mapping: the positive predictive value for the pyramidal tract, the inferior fronto-occipital fasciculus, the arcuate fasciculus and the inferior longitudinal fasciculus positive was 100%, 100%, 33%, and 80%, respectively, whereas negative predictive value was 100% for all of them. The reconstruction of at least one of these tracts within the tumor was significantly associated with a lower extent of resection (67%) as opposed to the extent of resection in the cases with a negative intratumoral tractography (100%) (P< .0001).

CONCLUSION: Intratumoral DTI-based tractography is a simple and reliable method, useful in assessing glioma resectability based on the analysis of intratumoral eloquent areas associated with motor and language tracts within the tumor.

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Cognitive functioning in patients with low-grade glioma: effects of hemispheric tumor location and surgical procedure

J Neurosurg 133:1671–1682, 2020

The authors evaluated the cognitive performance of patients with low-grade glioma (LGG) before and after surgery, and specifically investigated 1) the effects of hemispheric tumor location and 2) the type of surgery (either with or without intraoperative stimulation mapping [ISM]).

METHODS Patients underwent neuropsychological assessment 1 day before (T0) and 3 months after (T3) surgery. ISM targeted motor and/or language functions, but no other cognitive functions. Using 2-way mixed ANOVAs, differences between groups (i.e., for patients with right- vs left-sided lesions and normative controls [NCs], and also for patients operated on with vs without ISM and NCs), effects over time (T0–T3), and interaction effects in cognitive functioning were explored. Individual changes over time were assessed with reliable change indices for each neuropsychological test.

RESULTS In total, 77 patients with LGG were included (38 and 39 patients with right- and left-sided lesions, respectively; and 42 patients with and 35 patients without ISM). The majority of patients who were operated on with ISM had left-sided lesions. Patients with right- and left-sided lesions scored significantly lower on 6 and 3 out of 8 tests, respectively, compared to NCs. No significant differences between hemispheric groups were found at T0 or at T3. Patients with left-sided lesions showed significant deterioration of performance on verbal memory and sustained attention over time. Patients who underwent operation with versus without ISM scored significantly lower on 6 and 3 out of 8 tests, respectively, compared to NCs. Patients in the ISM group scored significantly lower on the Stroop test, shifting attention test, and verbal fluency test than patients without ISM. Also, the ISM group showed a significant decline in mean cognitive flexibility and sustained attention performance over time.

CONCLUSIONS Cognitive impairments were found in patients irrespective of hemispheric tumor location, whereby patients who were operated on with ISM performed slightly worse after surgery than patients without ISM. The authors conclude that there is room for improvement of cognitive functioning in surgically treated patients with LGG. The use of specific tests for higher cognitive functions during surgery may potentially improve functional outcome, but that is to be determined in future studies and balanced against oncological outcome. Implementation of neuropsychological assessments into the clinical management of patients with LGG should be encouraged, to inform and alert patients and clinicians on the status of cognitive functioning.

 

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Experience with awake throughout craniotomy in tumour surgery

Acta Neurochirurgica (2020) 162:3055–3065

Awake craniotomy is the standard of care in surgery of tumours located in eloquent parts of the brain. However, high variability is recorded in multiple parameters, including anaesthetic techniques, mapping paradigms and technology adjuncts. The current study is focused primarily on patients’ level of consciousness, surgical technique, and experience based on a cohort of 50 consecutive cases undergoing awake throughout craniotomy (ATC).

Methods Data was collected prospectively for 46 patients undergoing 50 operations over 14-month period, by the senior author, including demographics, extent of resection (EOR), adverse intraoperative events, surgical morbidity, surgery duration, levels of O2 saturation and brain oedema. A prospective, patient experience questionnaire was delivered to 38 patients.

Results The ATC technique was well tolerated in all patients. Once TCI stopped, all patients were immediately assessable for mapping. Despite > 75% of cases being considered inoperable/high risk, gross total resection (GTR) was achieved in 68% patients and subtotal resection in 20%. The average duration of surgery was 220 min with no episodes of hypoxia. Early and late severe deficits recorded in 12% and 2%, respectively. No stimulation-induced seizures or failed ATCs were recorded. Patient-recorded data showed absent/minimal pain during (1) clamp placement in 95.6% of patients; (2) drilling in 94.7% of patients; (3) surgery in 78.9% of patients. Post-operatively, 92.3% of patients reported willingness to repeat the ATC, if necessary.

Conclusions The current ATC paradigm allows immediate brain mapping, maximising patient comfort during selfpositioning. Despite the cohort of challenging tumour location, satisfactory EOR was achieved with acceptable morbidity and no adverse intraoperative events.

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Impact of facility type and volume in low-grade glioma outcomes

J Neurosurg 133:1313–1323, 2020

The object of this study was to investigate the impact of facility type (academic center [AC] vs non-AC) and facility volume (high-volume facility [HVF] vs low-volume facility [LVF]) on low-grade glioma (LGG) outcomes.

METHODS This retrospective cohort study included 5539 LGG patients (2004–2014) from the National Cancer Database. Patients were categorized by facility type and volume (non-AC vs AC, HVF vs LVF). An HVF was defined as the top 1% of facilities according to the number of annual cases. Outcomes included overall survival, treatment receipt, and postoperative outcomes. Kaplan-Meier and Cox proportional-hazards models were applied. The Heller explained relative risk was computed to assess the relative importance of each survival predictor.

RESULTS Significant survival advantages were observed at HVFs (HR 0.67, 95% CI 0.55–0.82, p < 0.001) and ACs (HR 0.84, 95% CI 0.73–0.97, p = 0.015), both prior to and after adjusting for all covariates. Tumor resection was 41% and 26% more likely to be performed at HVFs vs LVFs and ACs vs non-ACs, respectively. Chemotherapy was 40% and 88% more frequently to be utilized at HVFs vs LVFs and ACs vs non-ACs, respectively. Prolonged length of stay (LOS) was decreased by 42% and 24% at HVFs and ACs, respectively. After tumor histology, tumor pattern, and codeletion of 1p19q, facility type and surgical procedure were the most important contributors to survival variance. The main findings remained consistent using propensity score matching and multiple imputation.

CONCLUSIONS This study provides evidence of survival benefits among LGG patients treated at HVFs and ACs. An increased likelihood of undergoing resections, receiving adjuvant therapies, having shorter LOSs, and the multidisciplinary environment typically found at ACs and HVFs are important contributors to the authors’ finding.

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Pure Apraxia of Speech After Resection Based in the Posterior Middle Frontal Gyrus

Neurosurgery DOI:10.1093/neuros/nyaa002

Apraxia of speech is a disorder of articulatory coordination and planning in speech sound production. Its diagnosis is based on deficits in articulation, prosody, and fluency. It is often described concurrent with aphasia or dysarthria, while pure apraxia of speech is a rare entity.

CLINICAL PRESENTATION: A right-handed man underwent focal surgical resection of a recurrent grade III astrocytoma in the left hemisphere dorsal premotor cortex located in the posterior middle frontal gyrus. After the procedure, he experienced significant longterm speech production difficulties. A battery of standard and custom language and articulatory assessments were administered, revealing intact comprehension and naming abilities, and preserved strength in orofacial articulators, but considerable deficits in articulatory coordination, fluency, and prosody—consistent with diagnosis of pure apraxia of speech. Tractography and resection volumes compared with publicly available imaging data from the Human Connectome Project suggest possible overlap with area 55b, an under-recognized language area in the dorsal premotor cortex and has white matter connectivity with the superior longitudinal fasciculus.

CONCLUSION: The case reported here details a rare clinical entity, pure apraxia of speech resulting from resection of posterior middle frontal gyrus. While not a classical language area, emerging literature supports the role of this area in the production of fluent speech, and has implications for surgical planning and the general neurobiology of language.

 

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A 360° electronic device for recording high-resolution intraoperative electrocorticography of the brain during awake craniotomy

J Neurosurg 133:443–450, 2020

Epilepsy is common among patients with supratentorial brain tumors; approximately 40%–70% of patients with glioma develop brain tumor–related epilepsy (BTRE). Intraoperative localization of the epileptogenic zone during surgical tumor resection (real-time data) may improve intervention techniques in patients with lesional epilepsy, including BTRE. Accurate localization of the epileptogenic signals requires electrodes with high-density spatial organization that must be placed on the cortical surface during surgery. The authors investigated a 360° high-density ring-shaped cortical electrode assembly device, called the “circular grid,” that allows for simultaneous tumor resection and real-time electrophysiology data recording from the brain surface.

METHODS The authors collected data from 99 patients who underwent awake craniotomy from January 2008 to December 2018 (29 patients with the circular grid and 70 patients with strip electrodes), of whom 50 patients were matchedpair analyzed (25 patients with the circular grid and 25 patients with strip electrodes). Multiple variables were then retrospectively assessed to determine if utilization of this device provides more accurate real-time data and improves patient outcomes.

RESULTS Matched-pair analysis showed higher extent of resection (p = 0.03) and a shorter transient motor recovery period during the hospitalization course (by approximately 6.6 days, p ≤ 0.05) in the circular grid patients. Postoperative versus preoperative Karnofsky Performance Scale (KPS) score difference/drop was greater for the strip electrode patients (p = 0.007). No significant difference in postoperative seizures between the 2 groups was present (p = 0.80).

CONCLUSIONS The circular grid is a safe, feasible tool that grants direct access to the cortical surgical surface for tissue resection while simultaneously monitoring electrical activity. Application of the circular grid to different brain pathologies may improve intraoperative epileptogenic detection accuracy and functional outcomes, while decreasing postoperative complications.

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Awake vs. asleep motor mapping for glioma resection: a systematic review and meta-analysis

Acta Neurochirurgica (2020) 162:1709–1720

Intraoperative stimulation (IS) mapping has become the preferred standard treatment for eloquent tumors as it permits a more accurate identification of functional areas, allowing surgeons to achieve higher extents of resection (EOR) and decrease postoperative morbidity. For lesions adjacent to the perirolandic area and descending motor tracts, mapping can be done with both awake craniotomy (AC) and under general anesthesia (GA). Objective We aimed to determine which anesthetic protocol—AC vs. GA—provides better patient outcomes by comparing EOR and postoperative morbidity for surgeries using IS mapping in gliomas located near or in motor areas of the brain.

Methods A systematic literature search was carried out to identify relevant studies from 1983 to 2019. Seven databases were screened. A total of 2351 glioma patients from 17 studies were analyzed.

Results A random-effects meta-analysis revealed a trend towards a higher mean EOR in AC [90.1% (95% C.I. 85.8–93.8)] than with GA [81.7% (95% C.I. 72.4–89.7)] (p = 0.06). Neurological deficits were divided by timing and severity for analysis. There was no significant difference in early neurological deficits [20.9% (95% C.I. 4.1–45.0) vs. 25.4% (95% C.I. 13.6–39.2)] (p = 0.74), late neurological deficits [17.1% (95% C.I. 0.0–50.0) vs. 3.8% (95% C.I. 1.1–7.6)] (p = 0.06), or in non-severe [28.4% (95% C.I. 0.0–88.5) vs. 20.1% (95% C.I. 7.1–32.2)] (p = 0.72), and severe morbidity [2.6% (95% C.I. 0.0–15.5) vs. 4.5% (95% C.I. 1.1–9.6)] (p = 0.89) between patients who underwent AC versus GA, respectively.

Conclusion Mapping during resection of gliomas located in or near the perirolandic area and descending motor tracts can be safely carried out with both AC and GA.

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Awake craniotomy with transcortical motor evoked potential monitoring for resection of gliomas in the precentral gyrus

J Neurosurg 132:987–997, 2020

Resection of gliomas in the precentral gyrus carries a risk of severe motor dysfunction. To prevent permanent, severe postoperative motor dysfunction, reliable intraoperative predictors of postoperative function are required. Since 2005, the authors have removed gliomas in the precentral gyrus with combined functional mapping and estimation of intraoperative voluntary movement (IVM) during awake craniotomy and transcortical motor evoked potentials (MEPs). The purpose of the current study was to evaluate whether intraoperative findings of combined monitoring of IVM during awake craniotomy and transcortical MEP monitoring were useful for predicting postoperative motor function of patients with gliomas in the precentral gyrus.

METHODS The current study included 30 patients who underwent resection of precentral gyrus gliomas during awake craniotomy from April 2000 to January 2018. All tumors were removed with monitoring of IVM during awake craniotomy and transcortical MEPs. Postoperative motor function was classified as stable or declined, with the extent of decline categorized as mild, moderate, or severe. We defined moderate and severe deficits were those that hindered daily life.

RESULTS In 28 of 30 cases, available waveforms were obtained with transcortical MEPs. The mean extent of resection (EOR) was 93%. Relative to preoperative status, motor function 6 months after surgery was considered stable in 20 patients and was considered to show mild decline in 7, moderate decline in 2, and severe decline in 1. Motor function 6 months after surgery was significantly correlated with IVM (p = 0.0096), changes in transcortical MEPs (decline ≤ or > 50%) (p = 0.0163), EOR, and ischemic lesions on postoperative MRI. Six patients with no change in IVM showed stable motor function 6 months after surgery. Only 2 patients with a decline in IVM and a decline in MEPs ≤ 50% had a decline in motor function 6 months after surgery (18%; 2/11 patients), whereas 11 patients with a decline in IVM and a decline in MEPs > 50% had such a decline in motor function (73%; 8/11 patients) including 2 patients with moderate and 1 with severe deficits. Three patients with moderate or severe motor deficits showed the lowest MEP values (< 100 μV).

CONCLUSIONS Combined judgment from monitoring of IVM during awake craniotomy and transcortical MEPs is useful for predicting postoperative motor function during removal of gliomas in the precentral gyrus. Maximum resection was achieved with an acceptable morbidity rate. Thus, these tumors should not be considered unresectable.

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Eliciting Smiles and Laughter During Intraoperative Electric Stimulation of the Cingulum: Surgical Scenario

World Neurosurg. (2020) 133:55.

Laughter has a major role in daily social interactions; consequently, its biologic bases have been previously studied. Nevertheless, its cerebral representation remains unclear. The most accepted hypothesis has postulated that laughter has 2 components: mirth, related to the temporal and frontal neocortical areas, and motor aspect, related to the limbic system and brainstem. Furthermore, in prior studies, laughter has been elicited during electric stimulation with depth electrodes in the supplementary motor area and the cingulum.

This Video 1 reports resection of a right superior frontal gyrus diffuse astrocytoma (isocitrate dehydrogenase mutant, World Health Organization grade II) with awake intraoperative electric cortical and subcortical stimulation mapping. Diffusion tensor imaging (DTI) tractography, including all the tracts in relation to the tumor, was obtained preoperatively and postoperatively. Stimulation of the cingulum medially and inferiorly to the tumor elicited a patient’s smile and laugh without mirth or merriment. Also, this point correlated with the reconstructed cingulum in the intraoperatively navigated DTI tractography.

In conclusion, these findings support the anatomic subdivision of the laughter’s mechanism and the role of the cingulum in its motor component. Furthermore, smiles and laughter could be useful functional landmarks to identify the cingulum during subcortical mapping. Although it remains unclear whether pursuing resection beyond this point would have caused permanent postoperative deficits, considering laughter’s role in social interaction and other emotion-processing functions associated with the cingulum, in the future it could be potentially considered a functional limit of the resection of intrinsic tumors.

1-s2.0-S187887501932532X-mmc1.mp4

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Resection of gliomas deemed inoperable by neurosurgeons based on preoperative imaging studies

J Neurosurg 129:567–575, 2018

Maximal safe resection is a primary objective in the management of gliomas. Despite this objective, surgeons and referring physicians may, on the basis of radiological studies alone, assume a glioma to be unresectable. Because imaging studies, including functional MRI, may not localize brain functions (such as language) with high fidelity, this simplistic approach may exclude some patients from what could be a safe resection. Intraoperative direct electrical stimulation (DES) allows for the accurate localization of functional areas, thereby enabling maximal resection of tumors, including those that may appear inoperable based solely on radiological studies. In this paper the authors describe the extent of resection (EOR) and functional outcomes following resections of tumors deemed inoperable by referring physicians and neurosurgeons.

METHODS The authors retrospectively examined the cases of 58 adult patients who underwent glioma resection within 6 months of undergoing a brain biopsy of the same lesion at an outside hospital. All patients exhibited unifocal supratentorial disease and preoperative Karnofsky Performance Scale scores ≥ 70. The EOR and 6-month functional outcomes for this population were characterized.

RESULTS Intraoperative DES mapping was performed on 96.6% (56 of 58) of patients. Nearly half of the patients (46.6%, 27 of 58) underwent an awake surgical procedure with DES. Overall, the mean EOR was 87.6% ± 13.6% (range 39.0%–100%). Gross-total resection (resection of more than 99% of the preoperative tumor volume) was achieved in 29.3% (17 of 58) of patients. Subtotal resection (95%–99% resection) and partial resection (PR; < 95% resection) were achieved in 12.1% (7 of 58) and 58.6% (34 of 58) of patients, respectively. Of the cases that involved PR, the mean EOR was 79.4% ± 12.2%. Six months after surgery, no patient was found to have a new postoperative neurological deficit. The majority of patients (89.7%, 52 of 58) were free of neurological deficits both pre- and postoperatively. The remainder of patients exhibited either residual but stable deficits (5.2%, 3 of 58) or complete correction of preoperative deficits (5.2%, 3 of 58).

CONCLUSIONS The use of DES enabled maximal safe resections of gliomas deemed inoperable by referring neurosurgeons. With rare exceptions, tumor resectability cannot be determined solely by radiological studies.

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Resection of highly language-eloquent brain lesions based purely on rTMS language mapping without awake surgery

resection-of-highly-language-eloquent-brain-lesions-based-purely-on-rtms-language-mapping-without-awake-surgery

Acta Neurochir (2016) 158:2265–2275

The resection of left-sided perisylvian brain lesions harbours the risk of postoperative language impairment. Therefore the individual patient’s language distribution is investigated by intraoperative direct cortical stimulation (DCS) during awake surgery. Yet, not all patients qualify for awake surgery. Non-invasive language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) has frequently shown a high correlation in comparison with the results of DCS language mapping in terms of language-negative brain regions. The present study analyses the extent of resection (EOR) and functional outcome of patients who underwent left-sided perisylvian resection of brain lesions based purely on rTMS language mapping.

Methods Four patients with left-sided perisylvian brain lesions (two gliomas WHO III, one glioblastoma, one cavernous angioma) underwent rTMS language mapping prior to surgery. Data from rTMS language mapping and rTMS-based diffusion tensor imaging fibre tracking (DTI-FT) were transferred to the intraoperative neuronavigation system. Preoperatively, 5 days after surgery (POD5), and 3 months after surgery (POM3) clinical follow-up examinations were performed.

Results No patient suffered from a new surgery-related aphasia at POM3. Three patients underwent complete resection immediately, while one patient required a second rTMSbased resection some days later to achieve the final, complete resection.

Conclusions The present study shows for the first time the feasibility of successfully resecting language-eloquent brain lesions based purely on the results of negative language maps provided by rTMS language mapping and rTMS-based DTI-FT. In very select cases, this technique can provide a rescue strategy with an optimal functional outcome and EOR when awake surgery is not feasible.

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A novel tablet computer platform for advanced language mapping during awake craniotomy procedures

a novel platform

J Neurosurg 124:938–944, 2016

A computerized platform has been developed to enhance behavioral testing during intraoperative language mapping in awake craniotomy procedures. The system is uniquely compatible with the environmental demands of both the operating room and preoperative functional MRI (fMRI), thus providing standardized testing toward improving spatial agreement between the 2 brain mapping techniques. Details of the platform architecture, its advantages over traditional testing methods, and its use for language mapping are described.

Four illustrative cases demonstrate the efficacy of using the testing platform to administer sophisticated language paradigms, and the spatial agreement between intraoperative mapping and preoperative fMRI results. The testing platform substantially improved the ability of the surgeon to detect and characterize language deficits. Use of a written word generation task to assess language production helped confirm areas of speech apraxia and speech arrest that were inadequately characterized or missed with the use of traditional paradigms, respectively. Preoperative fMRI of the analogous writing task was also assistive, displaying excellent spatial agreement with intraoperative mapping in all 4 cases.

Sole use of traditional testing paradigms can be limiting during awake craniotomy procedures. Comprehensive assessment of language function will require additional use of more sophisticated and ecologically valid testing paradigms. The platform presented here provides a means to do so.

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Plastic relocation of motor cortex in a patient with LGG (low grade glioma) confirmed by NBS (navigated brain stimulation)

Acta Neurochir (2012) 154:2003–2008

We report on a patient with LGG, in whom NBS mapping confirmed relocation of the primary motor cortex (M1) concurrent with multistage surgery. Comparing the NBS results at 18 months with the initial results revealed that the M1 representation had shifted from the precentral to the postcentral gyrus. The patient underwent a third surgical intervention. Intraoperative direct cortical stimulation (DCS) confirmed the shift of the M1. Plastic changes in M1 localization permitted complete tumour removal without neurological sequela. To our knowledge, this is the first report on a LGG patient where induced brain plasticity has been confirmed by NBS mapping.

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