ArticlePublisher preview available
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Intraoperative mapping and neuromonitoring is an established technique to maximise tumour resection while minimising the risk of inducing permanent postoperative deficit. However, very little is known on how many patients require brain mapping within a general adult neuro-oncology service. A prospective study of all neuro-oncology patients operated over a 12 months’ period (January–December 2017) was performed. All patients were seen in a dedicated neuro-oncology pre-assessment clinic after discussion in a neuro-oncology multidisciplinary team meeting. Inclusion criteria for brain mapping were age more than 18, performance status less than 2, tumour location in an eloquent area. Age, sex, histology, surgical technique, extent of resection and operative complications were analysed. Two hundred thirty-five craniotomies were performed in the study period. Intraoperative mapping was used for 57 (24%) cases. There were 22 females and 35 males; median age was 52 years (22–73).17 (30%) patients were operated awake for speech and 40 (70%) asleep for motor mapping. One hundred fifteen patients had a diagnosis of glioma; of these, 48 (42%) were operated with intraoperative mapping. Age (48.92 ± 2.18versus 58.43 ± 1.63, p = 0.001) and WHO grading were significantly lower in the mapping group and the extent of resection was significantly higher (GTR—81.25% versus 37.3%, p < .001). Within the mapping group, the awake subgroup had a better performance status (p = 0.039), less glioblastomas as histological diagnosis (p < 0.05) and an increased proportion of tumours in both temporal and insular locations (p < 0.05). Intraoperative mapping was employed in almost one quarter of our general adult neuro-oncology population. Four in 10 gliomas were operated with intraoperative mapping. This percentage reflects the need for specialised training in brain mapping and budget allocation within the neuro-oncology department.
This content is subject to copyright. Terms and conditions apply.
How many patients require brain mapping in an adult
neuro-oncology service?
Anastasios Giamouriadis
&Jose Pedro Lavrador
&Ranjeev Bhangoo
&Keyoumars Ashkan
&Francesco Vergani
Received: 11 December 2018 /Revised: 15 April 2019 / Accepted: 6 May 2019
#Springer-Verlag GmbH Germany, part of Springer Nature 2019
Intraoperative mapping and neuromonitoring is an established technique to maximise tumour resection while minimising the risk of
inducing permanent postoperative deficit. However, very little is known on how many patients require brain mapping within a general
adult neuro-oncology service. A prospective study of all neuro-oncology patients operated over a 12 monthsperiod (January
December 2017) was performed. All patients were seen in a dedicated neuro-oncology pre-assessment clinic after discussion in a
neuro-oncology multidisciplinary team meeting. Inclusion criteria for brain mapping were age more than 18, performance status less
than 2, tumour location in an eloquent area. Age, sex, histology, surgical technique, extent of resection and operative complications
were analysed. Two hundred thirty-five craniotomies were performed in the study period. Intraoperative mapping was used for 57
(24%) cases. There were 22 females and 35 males; median age was 52 years (2273).17 (30%) patients were operated awake for
speech and 40 (70%) asleep for motor mapping. One hundred fifteen patients had a diagnosis of glioma; of these, 48 (42%) were
operated with intraoperative mapping. Age (48.92 ± 2.18versus 58.43 ± 1.63, p= 0.001) and WHO grading were significantly lower in
the mapping group and the extent of resection was significantly higher (GTR81.25% versus 37.3%, p< .001). Within the mapping
group, the awake subgroup had a better performance status (p= 0.039), less glioblastomas as histological diagnosis (p< 0.05) and an
increased proportion of tumours in both temporal and insular locations (p< 0.05). Intraoperative mapping was employed in almost one
quarter of our general adult neuro-oncology population. Four in 10 gliomas were operated with intraoperative mapping. This
percentage reflects the need for specialised training in brain mapping and budget allocation within the neuro-oncology department.
Keywords Brain tumour .Brain mapping .Neuromonitoring .Neuro-oncology .Glioma
Tumoursin eloquent areas of the brain represent a challenge to
neurosurgeons due to the risk of inducing permanent neuro-
logical deficits. In glioma patients, postoperative deficits have
also been linked to a decrease in overall survival [6,7,14,21,
22,25,32,39,40,4244]. In order to maximise the extent of
resection while minimising the risk of inducing permanent
deficits, techniques of intraoperative mapping and monitoring
with direct electrical stimulation (DES) have been developed
[35,28,33,38,45,55]. Large series employing intraopera-
tive mapping have been reported in the literature, particularly
by centres with a high volume of low-grade glioma referrals
[5,16,21,26,31,40,51]. It remains to be established what the
percentage of cases is requiring the use of DES out of the total
of cases referred to a general neuro-oncology centre.
In the present paper, we prospectively assessed the number
of patients operated with DES at the Neurosurgical
Department of Kings College Hospital, in order to evaluate
the proportion of patients requiring brain mapping in an unse-
lected neuro-oncology population.
Material and methods
Preoperative evaluation
The neuro-oncology multidisciplinary team (MDT) of Kings
College Hospital covers south-east London and Kent
(England), corresponding to a population of approximately 3
Presentation at a conference
Poster presentation at SBNS/Hellenic Neurosurgical Society Meeting,
Crete, May 2018
Poster presentation at EANS, Brussels, October 2018
*Anastasios Giamouriadis
Department of Neurosurgery, Kings College Hospital NHS
Foundation Trust, Denmark Hill, London SE5 9RS, UK
Neurosurgical Review (2020) 43:729738
/Published online: 19 2019
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... This approach is commonly employed in surgeries where there is a risk to the motor cortex or corticospinal tract and is often conducted with patients under general anesthesia. Bipolar stimulation is frequently used in patients who are required to undergo language testing during awake surgery, which is a practice commonly described as the standard procedure in the existing literature [16,18,35]. In our cohort, bipolar mapping was also mainly employed for language mapping procedures. ...
Full-text available
Background: Patients with eloquently located cerebral lesions require surgery that usually employs mapping and monitoring techniques for the preservation of motor and language function. However, in many cases, mapping only might be sufficient, reducing the need for technical and personnel logistics. Here, we report our experiences using a device that can be operated by the surgeon independently, providing mapping techniques but omitting monitoring techniques. Methods: For monopolar and bipolar cortical/subcortical stimulation, pre-set programs were available and intraoperatively used—two enabling EMG real-time tracking of eight muscles for monopolar (cortical/subcortical) mapping, and two programs for 60 Hz stimulation, one with EMG and one without. Motor mapping was performed under continuous observation of the screened EMG signal and acoustic feedback by the surgeon. For the 60 Hz stimulation, a standard bipolar stimulation probe was connected through a second port. The preoperative application of the subdermal EMG needles, as well as the intraoperative handling of the device, were performed by the surgeons independently. Postoperatively, an evaluation of the autonomous handling and feasibility of the device for the chosen test parameters was conducted. Results: From 04/19–09/21, 136 procedures in patients with eloquently located cerebral lesions were performed by using the “mapping-only” device. Mapping was performed in 82% of the monopolar cases and in 42% of the bipolar cases. Regarding the setup and sufficiency for the cortical/subcortical mapping, the device was evaluated as independently usable for motor and language mapping in 129 procedures (95%). Gross total resection was achieved, or functional limit throughout resection was reached, in 79% of the patients. 13 patients postoperatively suffered from a new neurological deficit. At the 3–6-month follow-up, three patients showed persistent deficit (2%). All of them had language disturbances. The setup time for the device was less than 7 min. Conclusions: The device was evaluated as sufficient in over 90% of cases concerning monopolar and bipolar mapping, and the setup and handling was sufficient in all patients. With the present data we show that in well-selected cases, a very simple system providing mapping only is sufficient to achieve gross total resection with the preservation of functionality.
... Although intracerebral tumors of critical regions, especially gliomas, are the object of many studies in the world literature, the problem of meningiomas of the rolandic region is less debated. Most studies [1, 9, 13-15, 19, 26, 27, 32, 34] include all meningiomas of the brain convexity, parasagittal region and falx without focusing on the rolandic location; others [8,11,16,20] include tumors of the rolandic region of different origin (both intracerebral and extracerebral) without providing separate data on meningiomas. ...
Full-text available
Objective Meningiomas of the rolandic region are associated to high risk of postoperative motor deficits. This study discusses the factors affecting motor outcome and recurrences from the analysis of a monoinstitutional case series and eight studies from a literature review. Methods Data of 75 patients who underwent surgery for meningioma of the rolandic region were retrospectively reviewed. The analyzed factors included tumor location and size, clinical presentation, magnetic resonance imaging (MRI) and surgical findings, brain-tumor interface, extent of resection, postoperative outcome and recurrence. Eight studies from literature on rolandic meningiomas treated with or without intraoperative monitoring (IOM) were reviewed with the aim to define the impact of IOM on the extent of resection and motor outcome. Results Among the 75 patients of the personal series, the meningioma was on the brain convexity in 34 (46%), at the parasagittal region in 28 (37%) and at the falx in 13 (17%). The brain-tumor interface was preserved in 53 cases (71%) at MRI and in 56 (75%) at surgical exploration. Simpson grade I resection was obtained in 43% of patients, grade II in 33%, grade III in 15% and grade IV in 9%. The motor function worsened postoperatively in 9 among 32 cases with preoperative deficit (28%) and in 5 among 43 with no preoperative deficit (11.5%); definitive motor deficit was evidenced in overall series at follow-up in 7 (9.3%). Patients with meningioma with lost arachnoid interface had significant higher rates of worsened postoperative motor deficit (p = 0.01) and seizures (p = 0.033). Recurrence occurred in 8 patients (11%). The analysis of the 8 reviewed studies (4 with and 4 without IOM) shows in the group without IOM higher rates of Simpson grades I and II resection (p = 0.02) and lower rates of grades IV resection (p = 0.002); no significant differences in postoperative immediate and long-term motor deficits were evidenced between the two groups. Conclusions Data from literature review show that the use of IOM does not affect the postoperative motor deficit Therefore, its role in rolandic meningiomas resection remains to be determined and will be defined in further studies.
... Intraoperative neurophysiological monitoring (IOM) remains across time in the first line and have gotten the title of the golden standard procedure for lesion located in functional areas, even though we are witnessing a high development of functional imaging techniques especially 3D diffusion tractography and functional magnetic resonance imaging [1,9,11]. ...
Introduction: Intraoperative neurophysiological monitoring is the golden standard for lesions located in eloquent areas of the brain. On the one hand, positive mapping offers a view of the relationship between the anatomo-functional cortical organisation of the patient and the lesion, facilitating the choice of the cerebrotomy entry point and the resection until the functional borders are found. On the other hand, negative mapping does not offer certainty that the absence of the motor response, from the operative field, is the real feedback or is the result of the false-negative response. In such a situation, a differentiation between those two must be done. Materials and methods: We evaluated the results of direct cortical stimulation of lesion located in or near the primary motor area, which were diagnosticated with contrast-enhancement head MRI and admitted to the Third Department of Neurosurgery, "Prof. Dr N. Oblu” Emergency Clinical Hospital, Iasi, Romania, between January 2014 and July 2018. Special attention was given especially to the negative mapping cases, regarding the histological type, imagistic localisation, symptoms and neurological outcome immediate postoperative, at 6 months and one-year follow-up. Results: From all 66 patients meeting the inclusion and exclusion criteria in 9,09% (6 cases) we did not obtain any motor response after direct cortical stimulation. The imagistic localisations of those cases were: 3 – Rolandic, 2 – pre-Rolandic and one retro-Rolandic. Tumors histological types were: glioblastoma, anaplastic astrocytoma, oligoastrocytoma and oligodendroglioma each one case and two cases of fibrillary astrocytoma. The intensity range was between 6 – 18mA, the mode – 12mA and the median – 10mA. Postoperatively the neurological condition of 3 patients worsened (4,54% from all the cases), while 3 had a favourable evolution with symptom remission. At 6monts and one-year follow-up in one case (1,51%), we observed no improvement in contrast with the other two, where dysfunction remission was highlighted. Conclusion: The possible technical, surgical and anesthesiologic causes of false-negative motor response must be eliminated to be able to differentiate from the real absence of the functional area from the operative field. In the first scenario, the resection may be associated with permanent postoperative neurologic deficit and major life quality alteration while in the second one the patient presents no motor dysfunction after surgery and the resection may be extensive with multiple oncological benefits.
... Nowadays tumors located in functional areas of the brain, brainstem and medullary lesions still represents a challenge for many neurosurgeons because of the high risk of postoperatively permanent neurological deficits, but the technological development comes in our aid and the golden standard of maximal resection with minimal neurological disfunction can be reached more often using functional technique perioperatively [12,34,35,41,46]. ...
Full-text available
Intraoperative neurophysiological monitoring (IOM) and especially motor evoked potentials represents an important tool in the evaluation of the nervous system integrity and particularly of the motor tracts. A real and correct registration of the potentials with a proper interpretation of the modification is mandatory for an optimal outcome in eloquent areas, tumours, brainstem and medullary lesions. For all this to happen a suitable anaesthetic protocol must be used. Even though there is a large spectrum of anaesthetic agents at our disposal it is imperative to know their effect on the IOM signals recordings and the fact that some of them are dose-dependent. Drugs effects and physiological changes produced intraoperatively must be corrected before a shift in the direction of the surgical lesion resection it is taken. We present an overview of the action of the anaesthetic agents, most used protocols and the physiological alteration encountered in the operative theatre.
Full-text available
We read with great enthusiasm the paper by Peabody et al 1 discussing the challenges of the informed consent for clinical research in the context of intraoperative brain research. This is a crucial ethical challenge requiring deep reflexion in the current environment within the neurosurgical practice. The authors highlight the heterogeneous impact and retention of the information provided during the consent process as well the unique place occupied by the relational dimension between the surgeon and the patient during this process. They suggest the involvement of a patient's advocate and reconsent during awake craniotomy (if applied) to overcome some of the abovementioned limitations. At our center, we have established a dedicated neuro-oncology preoperative assessment clinic for discussing the diagnosis and the treatment plan with both patients and their relatives. 2 We strongly agree that patient's relatives should be involved in the decision-making process from very early stages to support the patient to take the best informed decisions for himself. The introduction to potential research programs is performed by the responsible neurosurgeon although the research consent process is independent and performed by the research team. Nevertheless, the responsible neurosurgeon is at the center of the consent process given the personalized relational dimension outlined by Peabody et al 1 and unique relationship between the surgeon and the patient , particularly in the setting of the awake craniotomy. A point that is worthwhile mentioning is how the research-derived information can help the clinical consent process. At our institution, we performed extensive preoperative mapping that is explained to the patients as part of their consent process. 3,4 This significantly improves their understanding about the procedure, particularly the benefits and risks involved. 5 Therefore, there is an active interaction between the clinical and research consent processes. Although they are independent in their nature, the information provided by one can facilitate the understanding of the other and promote a more informed decision and potential involvement in both treatment and research processes. Patient information for patients with cancer is a vital part to personalized informed consent 6 and forms a national measure to hold UK oncology centers accountable. According to the National Cancer Patient Experience Survey in the United Kingdom, 7 89.4% of patients, who underwent surgery for cancer, said that before their treatment started, they had the information they needed in a way they could understand. It demonstrated that although the experience was good, we still had more room for improvement and innovation in the way we educate patients and make them understand regarding their disease process. Different strategies have been used to improve the consent form process, such as personalized 2-dimensional and 3-dimensional imaging available during consent process 8 which is aligned with the General Medical Council in UK recommendations in their principles of decision making and consent. 9 Thus, pushing the boundaries with innovative technology that is patient friendly promoting positive patient experience would act as an important process in the armamentarium for the current and future neurosurgeons. The increase utilization 10 and recent advances in intraoperative neuromonitoring and mapping paved the way to a better understanding of the mechanisms underlying the brain function. Despite being independent processes, clinical treatment and research have a dynamic interaction where the neurosurgical team has a pivotal role in integrating the information provided. We could not agree more that the patient is at the center of all the decisions made even at the time of surgery during awake procedures. 1 The challenge to the surgical teams is to provide constantly updated information to allow the best decision-making process to the patients and their advocates before surgery and to the patient himself during the awake procedure. Funding This study did not receive any funding or financial support.
Objective: The integration of multidisciplinary team meetings (MDTMs) for neurosurgical care has been accepted worldwide. Our objective was to review the literature for the limiting factors to MDTMs that may introduce bias to patient care. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) was used to perform a literature review of MDTMs for neuro-oncology, pituitary oncology, cerebrovascular surgery, and spine surgery and spine oncology. Limiting factors to productive MDTMs and factors that introduce bias were identified as well as determining whether MDTMs led to improved patient outcomes. Results: 1264 manuscripts were identified from a Pubmed and Ovid Medline search of which 27 of 500 neuro-oncology, 4 of 279 pituitary, and 11 of 260 spine surgery articles met our inclusion criteria above. Of 224 cerebrovascular manuscripts, none met criteria. Factors for productive MDTMs included quaternary/tertiary referral centers, non-hierarchical environment, regularly scheduled meetings, concise inclusion of non-medical factors at the same level of importance as patient clinical information, inclusion of nonclinical participants, and use of clinical guidelines and institutional protocols to provide recommendations. Our review did not identify literature that described the use of artificial intelligence to reduce bias and guide clinical care. Conclusions: The continued implementation of MDTMs in neurosurgery should be recommended but cautioned by limiting bias.
Full-text available
Maximal safe resection is the mainstay of treatment in the neurosurgical management of gliomas, and preserving functional integrity is linked to favorable outcomes. How these modalities differ in their effectiveness on the extent of resection (EOR), survival, and complications remains unknown. A systematic literature search was performed with the following inclusion criteria: published between 2005 and 2022, involving brain glioma surgery, and including one or a combination of intraoperative modalities: intraoperative magnetic resonance imaging (iMRI), awake/general anesthesia craniotomy mapping (AC/GA), fluorescence-guided imaging, or combined modalities. Of 525 articles, 464 were excluded and 61 articles were included, involving 5221 glioma patients, 7(11.4%) articles used iMRI, 21(36.8%) used cortical mapping, 15(24.5%) used 5-aminolevulinic acid (5-ALA) or fluorescein sodium, and 18(29.5%) used combined modalities. The heterogeneity in reporting the amount of surgical resection prevented further analysis. Progression-free survival/overall survival (PFS/OS) were reported in 18/61(29.5%) articles, while complications and permanent disability were reported in 38/61(62.2%) articles. The reviewed studies demonstrate that intraoperative adjuncts such as iMRI, AC/GA mapping, fluorescence-guided imaging, and a combination of these modalities improve EOR. However, PFS/OS were underreported. Combining multiple intraoperative modalities seems to have the highest effect compared to each adjunct alone.
Background Low-grade gliomas (LGG) are a heterogeneous group with significant changes in their management during the last decade. Objective To assess how our multidisciplinary team approach to the management of LGG has evolved over the past 10 years and its implications for outcomes. Methods Retrospective single-center cohort study of adult patients with a pathologically confirmed diagnosis of WHO grade II glioma between 2009-2018. Demographic, clinical and pathological data were collected. Results 95 patients were included. There was a statistically significant difference in the surgical approach with a higher number of patients having gross total resection - 45.7% versus 18.4% - and fewer patients having a biopsy - 21.8% versus 49.0% (p=0.002) after 2014. There was a significantly better overall survival after 2014 (<2014 – 16.3%; ≥2014 – 0 deaths, p=0.010) measured at the mean time of follow-up. The use of adjuvant chemotherapy (p=0.045) and radiotherapy (p=0.001) significantly decreased after 2014. A subgroup analysis showed the impact of extent of surgical resection was the greatest for survival in the 1p19q non co-deleted tumors (p=0.029) and for seizure outcomes in the 1p19q co-deleted group (p=0.018). There was no statistically significant increase in neurological disability with more radical surgery, incorporating intra-operative neuro-monitoring, as measured by modified Rankin Score (p>0.05). Conclusions More radical surgery was associated with increased survival, less need for post-operative adjuvant therapy and better seizure control, without significant morbidity. Molecular markers are useful tools for stratification of benefits following such surgery.
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.
Full-text available
Objective: We assessed the impact of surgery on postoperative cognitive function and ability to work in adult patients harboring a diffuse low-grade glioma involving eloquent brain regions and having a functional-based maximal surgical resection using intraoperative corticosubcortical mapping under awake conditions. Methods: We prospectively included 39 consecutive diffuse IDH-mutant low-grade glioma patients without preoperative and adjuvant oncological treatment and assessed preoperative (mean 24.1±21.2 days before surgery) and postoperative (mean 14.6±13.2 months following surgery) cognitive evaluations and ability to work together with clinical, imaging, therapeutic, and follow-up characteristics before tumor progression. Results: None of the 3 patients without preoperative cognitive deficit had postoperative worsening. We observed a significant inverse interaction between worsened postoperative cognitive function and extent of resection: 80.0%, 18.8%, and 16.7% of worsening following partial, subtotal, and total resection, respectively (p=0.020). We observed an independent interaction between improved postoperative cognitive function and extent of resection: 20.0%, 43.7%, and 44.4% of improvement following partial, subtotal, and total resection, respectively (p=0.022). 61.8% of the employed patients were unable to work preoperatively, 82.4% of them resumed their employment postoperatively (mean, 6.9±5.5 months). We observed an independent interaction between postoperative ability to work, similar or superior to preoperative work capacity and extent of resection (p<0.001): 20.0%, 87.5%, and 100% ability to work following partial, subtotal resection, and total resection. Conclusions: The extent of the functional-based surgical resection and the residual tumor for diffuse low-grade gliomas involving eloquent brain regions correlate with postoperative cognitive outcomes and return to work rates.
Introduction: Radical glioma resection improves overall survival, both in low-grade and high-grade glial tumors. However, preservation of the quality of life is also crucial. Areas covered: Due to the diffuse feature of gliomas, which invade the central nervous system, and due to considerable variations of brain organization among patients, an individual cerebral mapping is mandatory to solve the classical dilemma between the oncological and functional issues. Because functional neuroimaging is not reliable enough, intraoperative electrical stimulation, especially in awake patients benefiting from a real-time cognitive monitoring, is the best way to increase the extent of resection while sparing eloquent neural networks. Expert commentary: Here, we propose a paradigmatic shift from image-guided resection to functional mapping-guided resection, based on the study of the dynamic distribution of delocalized cortico-subcortical circuits at the individual level, i.e., the investigation of brain connectomics and neuroplastic potential. This surgical philosophy results in an improvement of both oncological outcomes and quality of life. This highlights the need to reinforce the link between glioma surgery and cognitive neurosciences.
OBJECTIVE Apraxia is a cognitive-motor deficit affecting the execution of skilled movements, termed praxis gestures, in the absence of primary sensory or motor disorders. In patients affected by stroke, apraxia is associated with lesions of the lateral parietofrontal stream, connecting the posterior parietal areas with the ventrolateral premotor area and subserving sensory-motor integration for the hand movements. In the neurosurgical literature to date, there are few reports regarding the incidence of apraxia after glioma surgery. A retrospective analysis of patients who harbored a glioma around the central sulcus and close to the parietofrontal circuits in depth showed a high incidence of long-term postoperative hand apraxia, impairing the patients’ quality of life. To avoid the occurrence of postoperative apraxia, the authors sought to develop an innovative intraoperative hand manipulation task (HMt) that can be used in association with the brain mapping technique to identify and preserve the cortical and subcortical structures belonging to the praxis network. METHODS The intraoperative efficacy of the HMt was investigated by comparing the incidence of postoperative ideomotor apraxia between patients undergoing mapping with (n = 79) and without (n = 41) the HMt. Patient groups were balanced for all demographic and clinical features. RESULTS In patients with lesions in the dominant hemisphere, the HMt dramatically reduced the incidence of apraxia, with a higher sensitivity for the ideomotor than for the constructional abilities; patients with lesions in the nondominant hemisphere benefitted from the HMt for both ideomotor and constructional abilities. The administration of the test did not reduce the extent of resection. CONCLUSIONS The HMt is a safe and feasible intraoperative tool that allowed surgeons to prevent the occurrence of long-term hand apraxia while attaining resection goals for the surgical treatment of glioma.
Objective: Little is known about the functional role of the white matter connections running within and around the right inferior parietal lobule (IPL). We used direct electrostimulation during awake surgery to investigate this connectivity and to avoid permanent deficit following resection for right IPL gliomas. Methods: We reviewed patients who underwent awake mapping for a glioma involving the right IPL. Resection was achieved up to functional cortico-subcortical boundaries detected by electrostimulation. Results of the intraoperative mapping were confronted to pre and postoperative MRI to perform anatomo-functional correlations. Results: Fourteen consecutive patients were enrolled (9 men, mean age: 44 years). Cortically, the resection was limited anteriorly by the retrocentral somatosensory area (11 cases) or by the precentral motor cortex (3 cases). Subcortically, the thalamocortical pathways were identified anteriorly in all patients. Articulatory disturbances were elicited anteriorly and laterally (6 cases) corresponding to the superior longitudinal fascicle (SLF) part III. Deeper and superiorly, stimulating the SLF part II or the arcuate fasciculus induced spatial disorders (6 cases). More laterally and posteriorly, disrupting the inferior fronto-occipital fasciculus induced non-verbal semantic disorders (7 cases). Six patients had visual deficits while stimulating the optic radiations. A total or subtotal resection was achieved in all patients but one. There were no permanent impairments, except an expected left superior quadrantanopia in 4 cases. Conclusions: This is the first surgical series focusing on right IPL gliomas. The complex functional connectivity detected within and around this region fully supports the use of intraoperative multimodal functional mapping for optimizing outcomes.
Objective: Brain tumors involving the primary motor cortex are often deemed unresectable due to the potential neurological consequences that result from injury to this region. Nevertheless, we have challenged this dogma for many years and used asleep, as well as awake, intraoperative stimulation mapping to maximize extent of resection. It remains unclear whether these tumors can be resected with acceptable morbidity, whether performing the surgery with the patient awake or asleep impacts extent of resection, and how stimulation mapping influences outcomes. Methods: A retrospective chart review was performed on the senior author's cohort to identify patients treated between 1998 and 2016 who underwent resection of tumors that were located within the primary motor cortex. Clinical notes, operative reports, and radiographic images were reviewed to identify intraoperative stimulation mapping findings and functional outcomes following tumor resection. Extent of resection was quantified volumetrically. Characteristics of patients were analyzed to identify factors associated with postoperative motor deficits. Results: Forty-nine patients underwent 53 resections of tumors located primarily within the motor cortex. Stimulation mapping was performed in all cases. Positive cortical sites for motor response were identified in 91% of cases, and subcortical sites in 74%. Awake craniotomy was performed in 65% of cases, while 35% were done under general anesthesia. The mean extent of resection was 91%. There was no statistically significant difference in extent of resection in cases done awake compared with those done under general anesthesia. New or worsened postoperative motor deficits occurred in 32 patients (60%), and 20 patients (38%) had a permanent deficit. Of the permanent deficits, 14 were mild, 4 were moderate, and 2 were severe (3.8% of cases). Decreased intraoperative motor response and diffusion restriction on postoperative MRI were associated with permanent deficit. Awake motor mapping surgery was associated with increased diffusion signal on postoperative MRI. Conclusions: Resection of tumors from the primary motor cortex is associated with an increased risk of motor deficit, but most of these deficits are transient or mild and have little functional impact. Excellent extent of resection can be achieved with intraoperative stimulation mapping, suggesting that these tumors are indeed amenable to resection and should not be labeled unresectable. Injury to small perforating or en passage blood vessels was the most common cause of infarction that led to moderate or severe deficits. Awake motor mapping was not superior to mapping done under general anesthesia with regard to long-term functional outcome.
Surgery remains the mainstay treatment of gliomas, with maximal resection of the tumour being central to achieving long-term disease control; growing evidence supports efforts to undertake more-extensive 'supratotal' resection The real clinical benefit of glioma surgery depends, however, on the balance between the extent of cytoreduction and neurological morbidity; novel surgical techniques and technologies can be leveraged to improve both of these determinants of patient outcomes Advanced intraoperative imaging methods (such as intraoperative neuronavigation, MRI, and ultrasonography), fluorescence-based tumour biomarkers, and real-time mutational analyses can be exploited to maximize tumour resection In parallel, the risk of perioperative morbidity can be minimized through the combined use of corticospinal tract imaging (MRI-based diffusion tensor imaging tractography and transcranial magnetic stimulation), stimulation mapping, and/or somatosensory-evoked potential techniques Together, these technological advances and modern principles of neurosurgical oncology have dramatically altered the approach to the treatment of patients with glioma and have enabled improvements in clinical outcomes
Introduction: Intraoperative application of electrical current to the brain is a standard technique during brain surgery for inferring the function of the underlying brain. The purpose of intraoperative functional mapping is to reliably identify cortical areas and subcortical pathways involved in eloquent functions, especially motor, sensory, language and cognitive functions. Material and methods: The aim of this article is to review the rationale and the electrophysiological principles of the use of direct bipolar electrostimulation for cortical and subcortical mapping under awake conditions. Results: Direct electrical stimulation is a window into the whole functional network that sustains a particular function. It is an accurate (spatial resolution of about 5mm) and a reproducible technique particularly adapted to clinical practice for brain resection in eloquent areas. If the procedure is rigorously applied, the sensitivity of direct electrical stimulation for the detection of cortical and subcortical eloquent areas is nearly 100%. The main disadvantage of this technique is its suboptimal specificity. Another limitation is the identification of eloquent areas during surgery, which, however, could have been functionally compensated postoperatively if removed surgically. Conclusion: Direct electrical stimulation is an easy, accurate, reliable and safe invasive technique for the intraoperative detection of both cortical and subcortical functional brain connectivity for clinical purpose. In our opinion, it is the optimal technique for minimizing the risk of neurological sequelae when resecting in eloquent brain areas.
For a long time, the right hemisphere (RH) was considered as "non-dominant", especially in right-handers. In neurosurgical practice, this dogma resulted in the selection of awake procedure with language mapping only for lesions of the left "dominant" hemisphere. Conversely, surgery under general anesthesia (possibly with motor mapping) was usually proposed for right lesions. However, when objective neuropsychological assessments were performed, they frequently revealed cognitive and behavioral deficits following brain surgery, even in the RH. Therefore, to preserve an optimal quality of life, especially in patients with a long survival expectancy (as in low-grade gliomas), awake surgery with cortical and axonal electrostimulation mapping has recently been proposed for right tumors resection. Here, we review new insights gained from intraoperative stimulation into the pivotal role of the RH in movement execution and control, visual processes and spatial cognition, language and non-verbal semantic processing, executive functions (e.g. attention), and social cognition (mentalizing and emotion recognition). Such original findings, that break with the myth of a "non-dominant" RH, may have important implications in cognitive neurosciences, by improving our knowledge of the functional connectivity of the RH, as well as for the clinical management of patients with a right lesion. Indeed, in brain surgery, awake mapping should be considered more systematically in the RH. Moreover, neuropsychological examination must be achieved in a more systematic manner before and after surgery within the RH, to optimize the care by predicting the likelihood of functional recovery and by elaborating specific programs of rehabilitation.