Tag: Glioma surgery

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The neuronal reserve in glioma surgery: functional reorganization of the motor network examined by navigated transcranial magnetic stimulation and diffusion tensor imaging tractography

J Neurosurg 143:793–804, 2025

This study demonstrates that glioma-induced reorganization of the motor cortex, measured by navigated transcranial magnetic stimulation and diffusion tensor imaging, is linked to functional recovery. Individual neuronal reserve—reflected in motor area resizing, excitability, and tract integrity—may explain differences in disease progression and surgical outcomes.

• Glioma surgery outcomes vary due to individual differences in motor network compensation and adaptation.

• This study used navigated transcranial magnetic stimulation (nTMS) and diffusion tensor imaging (DTI) tractography to measure motor cortex reorganization in glioma patients.

• Motor area relocation, resizing, and changes in excitability were observed in both affected and unaffected hemispheres, indicating bilateral reorganization.

• Greater preoperative motor area size and excitability were associated with better postoperative motor function and recovery.

• Reduced integrity of the corticospinal tract correlated with motor impairment and limited reorganization capacity.

• Functional recovery was linked to increased motor area size, excitability, and area relocation, supporting the concept of an individual neuronal reserve.

• Reorganization patterns were independent of tumor grade, highlighting the importance of personalized risk stratification and treatment planning.

• The study recommends using nTMS data for tailored preoperative risk assessment and patient counseling in glioma surgery.

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Efficacy and safety of intraoperative MRI in glioma surgery: a systematic review and meta-analysis of prospective randomized controlled trials

J Neurosurg 142:1319–1330, 2025

This meta-analysis of randomized controlled trials found that intraoperative MRI significantly increases gross-total resection rates and progression-free survival in glioma surgery, without increasing neurological deficits or most complications, though it prolongs surgery and may raise infection risk. iMRI is effective and generally safe for maximizing tumor removal.

• Intraoperative MRI (iMRI) significantly increases the rate of gross-total resection (GTR) in glioma surgery compared to conventional neuronavigation.

• Greater extent of resection (EOR) with iMRI leads to improved progression-free survival (PFS), especially in high-grade gliomas.

• No significant difference in overall survival (OS) was observed between iMRI and conventional surgery groups.

• Rates of postoperative neurological deterioration, motor, and language decline are similar between iMRI and control groups.

• iMRI does not increase the risk of postoperative intracranial hemorrhage, but may be associated with higher rates of wound infections in some studies.

• Use of iMRI prolongs surgery time by an average of 42 minutes.

• Only three randomized controlled trials with a total of 384 patients met inclusion criteria for this meta-analysis.

• Combined use of iMRI and 5-ALA may further enhance EOR, but more randomized studies are needed for definitive conclusions.

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Network-level prediction of set-shifting deterioration after lower-grade glioma resection

J Neurosurg 137:1329–1337, 2022

The aim of this study was to predict set-shifting deterioration after resection of low-grade glioma.

METHODS The authors retrospectively analyzed a bicentric series of 102 patients who underwent surgery for low-grade glioma. The difference between the completion times of the Trail Making Test parts B and A (TMT B-A) was evaluated preoperatively and 3–4 months after surgery. High dimensionality of the information related to the surgical cavity topography was reduced to a small set of predictors in four different ways: 1) overlap between surgical cavity and each of the 122 cortical parcels composing Yeo’s 17-network parcellation of the brain; 2) Tractotron: disconnection by the cavity of the major white matter bundles; 3) overlap between the surgical cavity and each of Yeo’s networks; and 4) disconets: signature of structural disconnection by the cavity of each of Yeo’s networks. A random forest algorithm was implemented to predict the postoperative change in the TMT B-A z-score.

RESULTS The last two network-based approaches yielded significant accuracies in left-out subjects (area under the receiver operating characteristic curve [AUC] approximately equal to 0.8, p approximately equal to 0.001) and outperformed the two alternatives. In single tree hierarchical models, the degree of damage to Yeo corticocortical network 12 (CC 12) was a critical node: patients with damage to CC 12 higher than 7.5% (cortical overlap) or 7.2% (disconets) had much higher risk to deteriorate, establishing for the first time a causal link between damage to this network and impaired set-shifting.

CONCLUSIONS The authors’ results give strong support to the idea that network-level approaches are a powerful way to address the lesion-symptom mapping problem, enabling machine learning–powered individual outcome predictions.

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Incidence and linguistic quality of speech errors: a comparison of preoperative transcranial magnetic stimulation and intraoperative direct cortex stimulation

J Neurosurg 134:1409–1418, 2021

Given the interindividual variance of functional language anatomy, risk prediction based merely on anatomical data is insufficient in language area–related brain tumor surgery, suggesting the need for direct cortical and subcortical mapping during awake surgery. Reliable, noninvasive preoperative methods of language localization hold the potential for reducing the necessity for awake procedures and may improve patient counseling and surgical planning. Repetitive navigated transcranial magnetic stimulation (rnTMS) is an evolving tool for localizing language-eloquent areas. The aim of this study was to investigate the reliability of rnTMS in locating cortical language sites.

METHODS Twenty-five patients with brain tumors in speech-related areas were prospectively evaluated with preoperative rnTMS (5 Hz, train of five, average 105% resting motor threshold) and navigated direct cortical stimulation (DCS; bipolar, 50 Hz, 6–8 mA, 200-μsec pulse width) during awake surgeries employing a picture-naming task. Positive and negative stimulation spots within the craniotomy were documented in the same MRI data set. TMS and DCS languagepositive areas were compared with regard to their spatial overlap, their allocation in a cortical parcellation system, and their linguistic qualities.

RESULTS There were over twofold more positive language spots within the exposed area on rnTMS than on DCS. The comparison of positive rnTMS and DCS (ground truth) overlaps revealed low sensitivity (35%) and low positive predictive value (16%) but high specificity (90%) and high negative predictive value (96%). Within the overlaps, there was no correlation in error quality. On DCS, 73% of language-positive spots were located in the pars opercularis and pars triangularis of the frontal operculum and 24% within the supramarginal gyrus and dorsal portion of the superior temporal gyrus, while on rnTMS language positivity was distributed more evenly over a large number of gyri.

CONCLUSIONS The current protocol for rnTMS for language mapping identified language-negative sites with good dependability but was unable to reliably detect language-positive spots. Further refinements of the technique will be needed to establish rnTMS language mapping as a useful clinical tool.

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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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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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Intraoperative monitoring of threshold level in transcranial MEP

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J Neurosurg 125:795–802, 2016

Warning criteria for monitoring of motor evoked potentials (MEP) after direct cortical stimulation during surgery for supratentorial tumors have been well described. However, little is known about the value of MEP after transcranial electrical stimulation (TES) in predicting postoperative motor deficit when monitoring threshold level. The authors aimed to evaluate the feasibility and value of this method in glioma surgery by using a new approach for interpreting changes in threshold level involving contra- and ipsilateral MEP.

Methods Between November 2013 and December 2014, 93 patients underwent TES-MEP monitoring during resection of gliomas located close to central motor pathways but not involving the primary motor cortex. The MEP were elicited by transcranial repetitive anodal train stimulation. Bilateral MEP were continuously evaluated to assess percentage increase of threshold level (minimum voltage needed to evoke a stable motor response from each of the muscles being monitored) from the baseline set before dural opening. An increase in threshold level on the contralateral side (facial, arm, or leg muscles contralateral to the affected hemisphere) of more than 20% beyond the percentage increase on the ipsilateral side (facial, arm, or leg muscles ipsilateral to the affected hemisphere) was considered a significant alteration. Recorded alterations were subsequently correlated with postoperative neurological deterioration and MRI findings.

Results TES-MEP could be elicited in all patients, including those with recurrent glioma (31 patients) and preoperative paresis (20 patients). Five of 73 patients without preoperative paresis showed a significant increase in threshold level, and all of them developed new paresis postoperatively (transient in 4 patients and permanent in 1 patient). Eight of 20 patients with preoperative paresis showed a significant increase in threshold level, and all of them developed postoperative neurological deterioration (transient in 4 patients and permanent in 4 patients). In 80 patients no significant change in threshold level was detected, and none of them showed postoperative neurological deterioration. The specificity and sensitivity in this series were estimated at 100%. Postoperative MRI revealed gross-total tumor resection in 56 of 82 patients (68%) in whom complete tumor resection was attainable; territorial ischemia was detected in 4 patients.

Conclusions The novel threshold criterion has made TES-MEP a useful method for predicting postoperative motor deficit in patients who undergo glioma surgery, and has been feasible in patients with preoperative paresis as well as in patients with recurrent glioma. Including contra- and ipsilateral changes in threshold level has led to a high sensitivity and specificity.

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Glioma surgery in eloquent areas: can we preserve cognition?

Surgery for low-grade glioma infiltrating the central cerebral region

Acta Neurochir (2016) 158:35–50

Cognitive preservation is crucial in glioma surgery, as it is an important aspect of daily life functioning. Several studies claimed that surgery in eloquent areas is possible without causing severe cognitive damage. However, this conclusion was relatively ungrounded due to the lack of extensive neuropsychological testing in homogenous patient groups. In this study, we aimed to elucidate the short-term and long-term effects of glioma surgery on cognition by identifying all studies who conducted neuropsychological tests preoperatively and postoperatively in glioma patients.

Methods We systematically searched the electronical databases Embase, Medline OvidSP, Web of Science, PsychINFO OvidSP, PubMed, Cochrane, Google Scholar, Scirius and Proquest aimed at cognitive performance in glioma patients preoperatively and postoperatively.

Results We included 17 studies with tests assessing the cognitive domains: language, memory, attention, executive functions and/or visuospatial abilities. Language was the domain most frequently examined. Immediately postoperatively, all studies except one, found deterioration in one or more cognitive domains. In the longer term (3–6/6–12 months postoperatively), the following tests showed both recovery and deterioration compared with the preoperative level: naming and verbal fluency (language), verbal word learning (memory) and Trailmaking B (executive functions).

Conclusions Cognitive recovery to the preoperative level after surgery is possible to a certain extent; however, the results are too arbitrary to draw definite conclusions and not all studies investigated all cognitive domains. More studies with longer postoperative follow-up with tests for cognitive change are necessary for a better understanding of the conclusive effects of glioma surgery on cognition.

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Combination of Intraoperative Magnetic Resonance Imaging and Intraoperative Fluorescence to Enhance the Resection of Contrast Enhancing Gliomas

Combination of Intraoperative Magnetic Resonance Imaging and Intraoperative Fluorescence to Enhance the Resection of Contrast Enhancing Gliomaspdf

Neurosurgery 77:16–22, 2015

Evidence suggests that extent of resection (EOR) is a prognostic factor for patients harboring gliomas. Recent studies have displayed the importance of intraoperative magnetic resonance imaging (iMRI) with 5-aminolevulinic acid (5-ALA) fluorescence-guidance in order to maximize EOR.

OBJECTIVE: To compare iMRI and 5-ALA fluorescence-guidance and the impact on patient survival.

METHODS: Thirty-two patients with contrast-enhancing gliomas undergoing intended gross total resection (GTR) were included in a prospective study. Surgeries were started under white-light conditions. When GTR was thought to be achieved, an iMRI scan was performed and a blue light turned on to search for unintentionally remaining tumor tissue. iMRI findings were compared with intraoperative fluorescence findings. Histological examination of tumor bulk and any additionally resected tissue was performed. All patients underwent early postoperative high-field MRI to determine EOR.

RESULTS: In 13 patients (40.6%), iMRI and fluorescence unequivocally did not show residual tumor intraoperatively. In 19 patients (59.4%), resection was continued due to iMRI or fluorescence findings. In 9 of these (47.4%), iMRI and fluorescence findings were inconsistent regarding residual tumor. GTR according to postoperative MRI was achieved in all but 1 patient. Histological examination ruled out false positive findings in all additionally resected specimens. Sensitivity and specificity to detect residual tumor tissue were 75% and 100%, respectively, for iMRI and 70% and 100% for 5-ALA fluorescence.

CONCLUSION: Use of iMRI as well as fluorescence-guidance are appropriate methods to improve the extent of resection in surgery of contrast-enhancing gliomas. Best results can be achieved by complementary use of both modalities.

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Impact of intraoperative magnetic resonance imaging and functional neuronavigation on surgical outcome in patients with gliomas involving language areas

Impact of intraoperative magnetic resonance imaging and functional neuronavigation on surgical outcome in patients with gliomas involving language areas

Neurosurg Rev (2015) 38:319–330

Balancing the benefit of extensive tumor resection with the consequence of potential postoperative language deficits remains a challenge in glioma surgery involving language areas. This study is designed to evaluate the impact of intraoperative magnetic resonance imaging (iMRI) and functional neuronavigation on surgical outcome in patients with gliomas involving language areas.

Two hundred seventeen patients were prospectively enrolled, 124 in the study group underwent iMRI and functional neuronavigationguided microsurgery and 93 in the control group underwent conventional navigation-guided microsurgery. Extent of tumor volume resection (EoR) and rate of gross total resection (rGTR) were calculated perioperatively. Aphasia quotient (AQ) was assessed to evaluate the change of language function perioperatively and at 6-month follow-up. Survival outcome for glioblastoma, including progression-free survival (PFS) and overall survival (OS), were recorded.

In 198 glioma patients (112 in the study group and 86 in the control group), EoR (95.50 versus 89.85 %, p<0.001) and rGTR (69.60 versus 47.70 %, p=0.002) were significantly higher in the study group, and language functions were also better at 6-month follow-up in the study group (87.47 versus 78.73, p=0.001). Furthermore, postoperative new aphasia occurred in 34.8 % of the control group, whereas it occurred only in 2.3 % of the study group (p<0.001). In addition, PFS (12.5 versus 6.6 m, p=0.003) and OS (19.6 versus 13.0 m, p<0.001) for patients with glioblastomas were dramatically prolonged in the study group than in the control group.

These results indicated that iMRI and functional neuronavigation may help maximize tumor resection, minimize language deficits in patients with gliomas involving language areas, and improve survival time for patients with glioblastomas.

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Awake craniotomy in intraoperative MRI

Awake craniotomy for gliomas in a high-field intraoperative magnetic resonance imaging suite

J Neurosurg 121:810–817, 2014

The object of this study was to describe the experience of combining awake craniotomy techniques with high-field (1.5 T) intraoperative MRI (iMRI) for tumors adjacent to eloquent cortex.

Methods. From a prospective database the authors obtained and evaluated the records of all patients who had undergone awake craniotomy procedures with cortical and subcortical mapping in the iMRI suite. The integration of these two modalities was assessed with respect to safety, operative times, workflow, extent of resection (EOR), and neurological outcome.

Results. Between February 2010 and December 2011, 42 awake craniotomy procedures using iMRI were performed in 41 patients for the removal of intraaxial tumors. There were 31 left-sided and 11 right-sided tumors. In half of the cases (21 [50%] of 42), the patient was kept awake for both motor and speech mapping. The mean duration of surgery overall was 7.3 hours (range 4.0–13.9 hours). The median EOR overall was 90%, and gross-total resection (EOR ≥ 95%) was achieved in 17 cases (40.5%). After viewing the first MR images after initial resection, further resection was performed in 17 cases (40.5%); the mean EOR in these cases increased from 56% to 67% after further resection. No deficits were observed preoperatively in 33 cases (78.5%), and worsening neurological deficits were noted immediately after surgery in 11 cases (26.2%). At 1 month after surgery, however, worsened neurological function was observed in only 1 case (2.3%).

Conclusions. There was a learning curve with regard to patient positioning and setup times, although it did not adversely affect patient outcomes. Awake craniotomy can be safely performed in a high-field (1.5 T) iMRI suite to maximize tumor resection in eloquent brain areas with an acceptable morbidity profile at 1 month.

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Real-Time Atlas-Based Stereotactic Neuronavigation

Real-Time Atlas-Based Stereotactic Neuronavigation

Neurosurgery 74:128–134, 2014

Surgery for tumors in eloquent brain faces immense challenges when attempting to maximize resection and avoid neurological deficits.

OBJECTIVE: In order to give the surgeon real-time atlas-based anatomic information linked to the patient’s anatomy, we developed a software-based interface between deformable anatomic templates (DATs) and an intraoperative navigation system.

METHODS: Magnetic resonance imaging (MRI), diffusion tensor imaging, and/or functional MRI were performed on 3 patients preoperatively for the purposes of tumor resection by the use of neuronavigation. The DAT was registered to the patients’ navigation coordinate system and utilized coordinates from the navigation system during surgery. This provided the surgeon with a list of proximal anatomic and functional structures and a real-time image of the atlas at that location fused to the patient’s MRI. The clinical feasibility of this approach was evaluated during the resection of 3 eloquent tumors (right postcentral gyrus, left inferior frontal gyrus, and left occipital cuneus gyrus).

RESULTS: Tumor resection was performed successfully in all 3 patients. With the use of the coordinates from the navigation system, anatomic and functional structures and their distances were visualized interactively during tumor resection by using the DAT.

CONCLUSION: This is a proof of concept that an interactive atlas-based navigation can provide detailed anatomic and functional information that supplements MRI, diffusion tensor imaging, and functional MRI. The atlas-based navigation generated distances to important anatomic structures from the navigation probe tip. It can be used to guide direct electrical stimulation and highlight areas to avoid during tumor resection.

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Deformable Anatomic Templates Improve Analysis of Gliomas With Minimal Mass Effect in Eloquent Areas

Deformable Anatomic Templates Improve Analysis of Gliomas With Minimal Mass Effect in Eloquent Areas

Neurosurgery 73:534–542, 2013

Despite improvements in advanced magnetic resonance imaging and intraoperative mapping, cases remain in which it is difficult to determine whether viable eloquent structures are involved by a glioma. A novel software program, deformable anatomic templates (DAT), rapidly embeds the normal location of eloquent cortex and functional tracts in the magnetic resonance images of glioma-bearing brain.

OBJECTIVE: To investigate the feasibility of the DAT technique in patients with gliomas related to eloquent brain.

METHODS: Forty cases of gliomas (grade II-IV) with minimal mass effect were referred for a prospective preoperative and postoperative DAT analysis. The DAT results were compared with the patient’s functional magnetic resonance imaging, diffusion tensor imaging, operative stimulation, and new postoperative clinical deficits.

RESULTS: Fifteen of the 40 glioma patients had overlap between tumor and eloquent structures. Immediate postoperative neurological deficits were seen in 9 cases in which the DAT showed the eloquent area both within the tumor and within or at the edge of the resection cavity. In 6 cases with no deficits, DAT placed the eloquent area in the tumor but outside the resection cavity.

CONCLUSION: This is proof of concept that DAT can improve the analysis of diffuse gliomas of any grade by efficiently alerting the surgeon to the possibility of eloquent area invasion. The technique is especially helpful in diffuse glioma because these tumors tend to infiltrate rather than displace eloquent structures. DAT is limited by tract displacement in gliomas that produces moderate to severe mass effect.

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Postoperative ischemic changes following resection of newly diagnosed and recurrent gliomas and their clinical relevance

Postoperative ischemic changes following resection of newly diagnosed and recurrent gliomas and their clinical relevance

J Neurosurg 118:801–808, 2013

The aim of surgical treatment of glioma is the complete resection of tumor tissue with preservation of neurological function. Inclusion of diffusion-weighted imaging (DWI) in the postoperative MRI protocol could improve the delineation of ischemia-associated postoperative neurological deficits. The present study aims to assess the incidence of infarctions following resection of newly diagnosed gliomas in comparison with recurrent gliomas and the influence on neurological function.

Methods. Patients who underwent glioma resection for newly diagnosed or recurrent gliomas had early postoperative MRI, including DWI and apparent diffusion coefficient (ADC) maps. Postoperative areas of restricted diffusion were classified as arterial territorial infarctions, terminal branch infarctions, or venous infarctions. Tumor entity, location, and neurological function were recorded.

Results. New postoperative ischemic lesions were identified in 26 (31%) of 84 patients with newly diagnosed gliomas and 20 (80%) of 25 patients with recurrent gliomas (p < 0.01). New permanent and transient neurological deficits were more frequent in patients with recurrent gliomas than in patients with newly diagnosed tumors. Patients with neurological deficits had a significantly higher rate of ischemic lesions.

Conclusions. Postoperative infarctions occur frequently in patients with newly diagnosed and recurrent gliomas and do have an impact on postoperative neurological function. In this patient cohort there was a higher risk for ischemic lesions and for deterioration of neurological function after resection of recurrent tumors. Radiogenic and postoperative tissue changes could contribute to the higher risk of an ischemic infarction in patients with recurrent tumors.

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Spontaneous speech of patients with gliomas in eloquent areas before and early after surgery

Aphasia induced by gliomas

Acta Neurochir Volume 155, Issue 4, April 2013, 685-692

Glioma patients often complain about problems in daily conversation. A detailed spontaneous speech analysis could provide more insight in these communicative problems; no previous studies are reported.
Objective
To select sensitive parameters in spontaneous speech pre- and post-operatively in patients with gliomas in eloquent areas.
Methods
We included 27 patients and 21 healthy controls. In addition to a naming and category fluency test, spontaneous speech was collected 1 month pre-operatively and 3 months post-operatively, and analysed with the variables: Self-corrections, Repetitions, Lexical Diversity, Incomplete Sentences and Mean Length of Utterance (MLUw). A correlation analysis was performed between the linguistic variables and tumour characteristics (grade, localisation and volume), treatment related factors, and between the linguistic variables and the language tasks.
Results
Pre-operatively, patients produced more Incomplete Sentences than the controls (p < 0.001). Post-operatively, patients’ utterance length (MLUw) (p < 0.05) was also deviant. The quality of the spontaneous speech was influenced by tumour grade and localisation. There was no influence of tumour volume or treatment-related factors. Pre- and post-operatively, patients’ performance on the naming and the fluency task deviated from normal (p < 0.001). The majority of the linguistic variables did not correlate with the language tasks, pointing to a measurement of distinct linguistic aspects.
Conclusion
Pre- and post-operatively there was a disorder in naming, category fluency and spontaneous speech, partly influenced by tumour characteristics. A spontaneous speech analysis appeared to be a valuable addition to standardised language tasks. Both measurements are important tools to obtain a complete linguistic profile.
Keywords

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Predictive Value and Safety of Intraoperative Neurophysiological Monitoring With Motor Evoked Potentials in Glioma Surgery

Neurosurgery 70:1060–1071, 2012 DOI: 10.1227/NEU.0b013e31823f5ade

Resection of gliomas in or adjacent to the motor system is widely performed with intraoperative neuromonitoring (IOM). Despite the fact that data on the safety of IOM are available, the significance and predictive value of the procedure are still under discussion. Moreover, cases of false-negative monitoring affect the surgeon’s confidence in IOM.

OBJECTIVE: To examine cases of false-negative IOM to reveal structural explanations.

METHODS: Between 2007 and 2010, we resected 115 consecutive supratentorial gliomas in or close to eloquent motor areas using direct cortical stimulation for monitoring of motor evoked potentials (MEPs). The monitoring data were reviewed and related to new postoperative motor deficit and postoperative imaging. Clinical outcomes were assessed during follow-up.

RESULTS: Monitoring of MEPs was successful in 112 cases (97.4%). Postoperatively, 30.3% of patients had a new motor deficit, which remained permanent in 12.5%. Progression- free follow-up was 9.7 months (range, 2 weeks-40.6 months). In 65.2% of all cases, MEPs were stable throughout the operation, but 8.9% showed a new temporary motor deficit, whereas 4.5% (5 patients) presented with permanently deteriorated motor function representing false-negative monitoring at first glance. However, these cases were caused by secondary hemorrhage, ischemia, or resection of the supplementary motor area.

CONCLUSION: Continuous MEP monitoring provides reliable monitoring of the motor system, influences the course of operation in some cases, and has to be regarded as the standard for IOM of the motor system. In our series, we found no false-negative MEP results.

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Utility of diffusion tensor-imaged (DTI) motor fiber tracking for the resection of intracranial tumors near the corticospinal tract

Acta Neurochir. DOI 10.1007/s00701-010-0817-0

Treatment of intracranial tumors near the corticospinal tract remains a surgical challenge. Several technical tools to map and monitor the motor tract have been implemented. The present study aimed to assess the utility of diffusion tensor imaging (DTI) fiber tracking in the surgical treatment of motor eloquent tumors at our institution.

Methods Patients operated for intracranial tumors close to the motor tract with the use of intraoperative image guidance including DTI fiber tracking of the corticospinal tract and intraoperative motor evoked potential (MEP) monitoring were analyzed. The intraoperative utility of fiber tracking data was analyzed. Furthermore, preoperative MRI scans with and without motor fiber tracking were reevaluated post hoc for tumor relation to the motor tract, estimated resectability, and best approach. Thereby, the utility of fiber tracking in surgical planning was assessed.

Results Nineteen patients were analyzed. The estimation of tumor localization in relation to the motor tract and of resectability was not influenced by fiber tracking in any of the cases. Only in one single case did evaluating surgeons change their surgical approach after the addition of the fiber tracking data. In all cases, fiber tracking included in image guidance did not change the intraoperative strategy, while MEP monitoring did.

Conclusions DTI fiber tracking did not influence the surgical planning or the intraoperative course. However, it is still used at our institution due to its ease in acquisition and its potential impact in a larger series. Furthermore, more experience with this technique is required to lead to a technical improvement.

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