Added value of [18F]FDOPA PET to the management of high-grade glioma patients after their initial treatment: a prospective multicentre study.

BACKGROUND: Diagnostic value of 3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine ([18F]FDOPA) PET in patients with suspected recurrent gliomas is recognised. We conducted a multicentre prospective study to assess its added value in the practical management of patients suspected of recurrence of high grade gliomas (HGG). METHODS: Patients with a proven HGG (WHO grade III and IV) were referred to the multidisciplinary neuro-oncology board (MNOB) during their follow-up after initial standard of care treatment and when MRI findings were not fully conclusive. Each case was discussed in 2 steps. For step 1, a diagnosis and a management proposal were made only based on the clinical and the MRI data. For step 2, the same process was repeated taking the [18F]FDOPA PET results into consideration. A level of confidence for the decisions was assigned to each step. Changes in diagnosis and management induced by [18F]FDOPA PET information were measured. When unchanged, the difference in the confidence of the decisions were assessed. The diagnostic performances of each step were measured. RESULTS: 107 patients underwent a total of 138 MNOB assessments. The proposed diagnosis changed between step 1 and step 2 in 37 cases (26.8%) and the proposed management changed in 31 cases (22.5%). When the management did not change, the confidence in the MNOB final decision was increased in 87 cases (81.3%). Step 1 had a sensitivity, specificity and accuracy of 83%, 58% and 66% and step 2, 86%, 64% and 71% respectively. CONCLUSION: [18F]FDOPA PET adds significant information for the follow-up of HGG patients in clinical practice. When MRI findings are not straightforward, it can change the management for more than 20% of the patients and increases the confidence level of the multidisciplinary board decisions.

Free-water correction DTI-based tractography in brain tumor surgery: assessment with functional and electrophysiological mapping of the white matter.

Peritumoral edema prevents fiber tracking from diffusion tensor imaging (DTI). A free-water correction may overcome this drawback, as illustrated in the case of a patient undergoing awake surgery for brain metastasis. The anatomical plausibility and accuracy of tractography with and without free-water correction were assessed with functional mapping and axono-cortical evoked-potentials (ACEPs) as reference methods. The results suggest a potential synergy between corrected DTI-based tractography and ACEPs to reliably identify and preserve white matter tracts during brain tumor surgery.

Towards linking diffusion MRI based macro- and microstructure measures with cortico-cortical transmission in brain tumor patients.

We aimed to link macro- and microstructure measures of brain white matter obtained from diffusion MRI with effective connectivity measures based on a propagation of cortico-cortical evoked potentials induced with intrasurgical direct electrical stimulation. For this, we compared streamline lengths and log-transformed ratios of streamlines computed from presurgical diffusion-weighted images, and the delays and amplitudes of N1 peaks recorded intrasurgically with electrocorticography electrodes in a pilot study of 9 brain tumor patients. Our results showed positive correlation between these two modalities in the vicinity of the stimulation sites (Pearson coefficient 0.54±0.13 for N1 delays, and 0.47±0.23 for N1 amplitudes), which could correspond to the neural propagation via U-fibers. In addition, we reached high sensitivities (0.78±0.07) and very high specificities (0.93±0.03) in a binary variant of our comparison. Finally, we used the structural connectivity measures to predict the effective connectivity using a multiple linear regression model, and showed a significant role of brain microstructure-related indices in this relation.

Transfacet screws using spinal navigation in addition to anterior or oblique lumbar interbody fusion: technical note and preliminary results.

Transfacet screws (TFS) are an alternative to the classic bilateral pedicular screws (BPS) in addition to anterior (ALIF) or oblique (OLIF) lumbar interbody fusion. Spinal navigation could help the surgeon in technically demanding procedures in order to avoid screw malposition. Although spinal navigation is commonly used in BPS, its contribution in TFS remains unclear. Our aim here was to assess the feasibility of TFS using spinal navigation in addition to anterior lumbar fusion. Five patients suffering from lumbar degenerative disc disease were included. During the same general anaesthesia, we performed successively an ALIF or OLIF and then a TFS according to Boucher technique using spinal navigation (O-arm). No peri-operative complication occurred, and all the screws were successfully positioned (n = 10). All clinical scores (ODI, VAS L and VAS R) improved at 6-month follow-up. Segmental lordosis increased from 6° [2.4°-12°] to 13.6° [8°-17°]. Fusion was achieved for the five patients. TFS using O-arm in addition to ALIF/OLIF is feasible. To confirm our early favourable outcomes on clinical and radiological data, this technique must be evaluated on larger samples of patients.

Anesthesia management for low-grade glioma awake surgery: a European Low-Grade Glioma Network survey.

BACKGROUND: Awake surgery has become a key treatment of diffuse low-grade gliomas (DLGG) and is divided in three main phases: opening, tumor resection - during which the patient needs to be fully awake - and closure. The anesthetic management of awake neurosurgery is a challenge, and there are currently no guidelines. OBJECTIVE: The objective of the survey was to explore differences and commonalities regarding the anesthetic management of awake DLGG surgery within the European Low-Grade Glioma Network (ELGGN) centers. METHODS: A form that contained 14 questions about the anesthetic management was sent to 28 centers in May 2015. RESULTS: Twenty centers responded. During the opening and closing non-awake periods, 56% of teams chose general anesthesia with mechanical ventilation for at least one period (asleep-awake-asleep, SAS protocol), and 44% monitored anesthesia care including sedation without mechanical ventilation (MAC protocol). In case of SAS, all the teams chose intravenous anesthesia, 82% used laryngeal mask instead of endotracheal intubation during the opening sequence, and 71% during closure. Local and regional anesthesia was practiced by all the teams. The most frequently reported cause of pain was dural and cerebral vessels manipulation (77%). Pain management was mostly based on paracetamol (70%) and remifentanil (55%). CONCLUSION: Our survey showed that there was an equivalent proportion of centers using SAS or MAC protocols in the anesthetic management of awake surgery in ELGGN centers. The advantages and disadvantages of each anesthesia protocol were reviewed.

Correction to: 18F-DOPA PET/CT in brain tumors: impact on multidisciplinary brain tumor board decisions.

Jérôme Barriere was inadvertently missing in the original version of this article. He has participated to the study design, protocol writing and inclusion of a significant number of patients.

18F-DOPA PET/CT in brain tumors: impact on multidisciplinary brain tumor board decisions.

PURPOSE: This study aimed to assess the therapeutic impact and diagnostic accuracy of 18F-DOPA PET/CT in patients with glioblastoma or brain metastases. METHODS: Patients with histologically proven glioblastoma or brain metastases were prospectively included in this monocentric clinical trial (IMOTEP). Patients were included either due to a clinical suspicion of relapse or to assess residual tumor infiltration after treatment. Multimodality brain MRI and 18F-DOPA PET were performed. Patients' data were discussed during a Multidisciplinary Neuro-oncology Tumor Board (MNTB) meeting. The discussion was first based on clinical and MRI data, and an initial diagnosis and treatment plan were proposed. Secondly, a new discussion was conducted based on the overall imaging results, including 18F-DOPA PET. A second diagnosis and therapeutic plan were proposed. A retrospective and definitive diagnosis was obtained after a 3-month follow-up and considered as the reference standard. RESULTS: One hundred six cases were prospectively investigated by the MNTB. All patients with brain metastases (N = 41) had a clinical suspicion of recurrence. The addition of 18F-DOPA PET data changed the diagnosis and treatment plan in 39.0% and 17.1% of patients' cases, respectively. Concerning patients with a suspicion of recurrent glioblastoma (N = 12), the implementation of 18F-DOPA PET changed the diagnosis and treatment plan in 33.3% of cases. In patients evaluated to assess residual glioblastoma infiltration after treatment (N = 53), 18F-DOPA PET data had a lower impact with only 5.7% (3/53) of diagnostic changes and 3.8% (2/53) of therapeutic plan changes. The definitive reference diagnosis was available in 98/106 patients. For patients with tumor recurrence suspicion, the adjunction of 18F-DOPA PET increased the Younden's index from 0.44 to 0.53 in brain metastases and from 0.2 to 1.0 in glioblastoma, reflecting an increase in diagnostic accuracy. CONCLUSION: 18F-DOPA PET has a significant impact on the management of patients with a suspicion of brain tumor recurrence, either glioblastoma or brain metastases, but a low impact when used to evaluate the residual glioblastoma infiltration after a first-line radio-chemotherapy or second-line bevacizumab.

Functional compensation of the left inferior longitudinal fasciculus for picture naming.

The role of the left inferior longitudinal fasciculus (ILF) in language processing has been called into question by recent studies showing that disruption of this tract in glioma patients did not necessarily lead to detrimental effects on spoken language, especially on picture naming. Here we show that disruption of the left ILF with axonal stimulation in patients undergoing an "awake" surgery for a slow-growing tumour systematically induces pure anomia, but only when the temporal pole (TP) is not infiltrated by the tumour. This finding not only confirms that the ILF plays a role in lexical retrieval in normal circumstances but also suggests that the information conveyed by this tract can be rerouted to alternative pathways when the TP is widely lesioned and abandons its function. This conclusion is further supported by the case of a patient who developed a long-lasting anomic aphasia after a surgically preplanned interruption of the ILF.

Dural and pial pain-sensitive structures in humans: new inputs from awake craniotomies.

Our knowledge on intracranial pain-sensitive structures in humans comes essentially from observations during neurosurgical procedures performed in awake patients. It is currently accepted that intracranial pain-sensitive structures are limited to the dura mater and its feeding vessels and that small cerebral vessels and pia mater are insensitive to pain, which is inconsistent with some neurosurgical observations during awake craniotomy procedures. We prospectively collected observations of painful events evoked by mechanical stimulation (touching, stretching, pressure, or aspiration) of intracranial structures during awake craniotomies, routinely performed for intraoperative functional mapping to tailor brain tumour resection in the eloquent area. Intraoperatively, data concerning the locations of pain-sensitive structures were drawn by the surgeon on a template and their corresponding referred pain was indicated by the patient by drawing a cross on a diagram representing the head. Ninety-three painful events were observed and collected in 53 different patients (mean age 41.2 years, 25 males) operated on awake craniotomy for left (44 cases) or right (nine cases) supra-tentorial tumour resection in eloquent areas. On average, 1.8 painful events were observed per patient (range 1-5). All the painful events were referred ipsilaterally to the stimulus. In all cases, the evoked pain was sharp, intense and brief, stopped immediately after termination of the causing action, and did not interfere with the continuation of the surgery. In 30 events, pain was induced by stimulation of the dura mater of the skull base (23 events) or of the falx (seven events) and was referred predominantly in the V1 territory and in the temporal region. In 61 cases, pain was elicited by mechanical stimulation of the pia mater or small cerebral vessels of the temporal (19 events), frontal (25 events), parietal (four events) lobes and/or the peri-sylvian region, including the insular lobe (13 events), and referred in the V1 territory. In this observational study, we confirmed that dura of the skull base and dura of the falx cerebri are sensitive to pain and that their mechanical stimulation induced pain mainly referred in the sensory territories of the V1 and V3 divisions of the trigeminal nerve. Unlike earlier studies, we observed that the pia and the small cerebral vessels were also pain-sensitive, as their mechanical stimulation induced pain referred mainly in the V1 territory. These observations suggest that small pial cerebral vessels may also be involved in the pathophysiology of primary and secondary headaches.awy005media15756834882001.

Quality of Randomized Controlled Trials Reporting in the Treatment of Adult Patients with High-Grade Gliomas.

BACKGROUND: The randomized controlled trial (RCT) is the gold standard to objectively assess the effect of treatments. To help improve the quality of RCTs, experts established a list of recommendations, the CONsolidated Standards of Reporting Trials (CONSORT) Statement. In this study, we evaluated the implementation of the CONSORT Statement in the field of high-grade gliomas in adult patients and looked for criteria associated with higher quality of RCTs. MATERIALS AND METHODS: We searched all high-grade gliomas RCTs published in PubMed between January 1990 and December 2016. The quality of these RCTs was assessed by completing a modified CONSORT Score (CS). RESULTS: Ninety-six published RCTs were identified. The median CS was 19.5 on a scale of 0-33. Items were not equally reported. Items regarding the method of randomization or the blinding were reported in less than 25% of RCTs. However, the CS has constantly improved over the years. Before the implementation of the CONSORT Statement in 1996, the median CS was 13, whereas it was 17 for the period 1996-2004 and 22 after 2005. A higher CS was observed when RCTs were published in a journal with an impact factor above 10 (p < .001) or after 2010 (p = .001), when the primary outcome was clearly defined (p < .001) and for RCTs that enrolled more than 200 patients (p = .004). CONCLUSION: Although there has been a steady improvement in the CS over the years in the field of high-grade gliomas, a major effort must be made in the reporting methods for randomization and blinding. IMPLICATIONS FOR PRACTICE: This study showed that the quality of reporting of randomized control trials (RCTs) concerning the treatment of high-grade gliomas is poor. Factors associated with a better quality of reports were identified and should be incorporated into the design of future RCTs. When clinicians read the results of RCTs, they should be aware of the possible inadequate reporting from these trials and take it into account for the management of their patients. This study identifies how RCTs can be improved in their reporting but also in their design, in order to advance care for patients with high-grade gliomas in the future.

Imaging practice in low-grade gliomas among European specialized centers and proposal for a minimum core of imaging.

OBJECTIVE: Imaging studies in diffuse low-grade gliomas (DLGG) vary across centers. In order to establish a minimal core of imaging necessary for further investigations and clinical trials in the field of DLGG, we aimed to establish the status quo within specialized European centers. METHODS: An online survey composed of 46 items was sent out to members of the European Low-Grade Glioma Network, the European Association of Neurosurgical Societies, the German Society of Neurosurgery and the Austrian Society of Neurosurgery. RESULTS: A total of 128 fully completed surveys were received and analyzed. Most centers (n = 96, 75%) were academic and half of the centers (n = 64, 50%) adhered to a dedicated treatment program for DLGG. There were national differences regarding the sequences enclosed in MRI imaging and use of PET, however most included T1 (without and with contrast, 100%), T2 (100%) and TIRM or FLAIR (20, 98%). DWI is performed by 80% of centers and 61% of centers regularly performed PWI. CONCLUSION: A minimal core of imaging composed of T1 (w/wo contrast), T2, TIRM/FLAIR, PWI and DWI could be identified. All morphologic images should be obtained in a slice thickness of ≤ 3 mm. No common standard could be obtained regarding advanced MRI protocols and PET. IMPORTANCE OF THE STUDY: We believe that our study makes a significant contribution to the literature because we were able to determine similarities in numerous aspects of LGG imaging. Using the proposed "minimal core of imaging" in clinical routine will facilitate future cooperative studies.

A Positive Feed-forward Loop Associating EGR1 and PDGFA Promotes Proliferation and Self-renewal in Glioblastoma Stem Cells.

Glioblastomas are the most common primary brain tumors, highly vascularized, infiltrating, and resistant to current therapies. This cancer leads to a fatal outcome in less than 18 months. The aggressive behavior of glioblastomas, including resistance to current treatments and tumor recurrence, has been attributed to glioma stemlike/progenitor cells. The transcription factor EGR1 (early growth response 1), a member of a zinc finger transcription factor family, has been described as tumor suppressor in gliomas when ectopically overexpressed. Although EGR1 expression in human glioblastomas has been associated with patient survival, its precise location in tumor territories as well as its contribution to glioblastoma progression remain elusive. In the present study, we show that EGR1-expressing cells are more frequent in high grade gliomas where the nuclear expression of EGR1 is restricted to proliferating/progenitor cells. We show in primary cultures of glioma stemlike cells that EGR1 contributes to stemness marker expression and proliferation by orchestrating a PDGFA-dependent growth-stimulatory loop. In addition, we demonstrate that EGR1 acts as a positive regulator of several important genes, including SHH, GLI1, GLI2, and PDGFA, previously linked to the maintenance and proliferation of glioma stemlike cells.

Brain tumors in eloquent areas: A European multicenter survey of intraoperative mapping techniques, intraoperative seizures occurrence, and antiepileptic drug prophylaxis.

Intraoperative mapping and monitoring techniques for eloquent area tumors are routinely used world wide. Very few data are available regarding mapping and monitoring methods and preferences, intraoperative seizures occurrence and perioperative antiepileptic drug management. A questionnaire was sent to 20 European centers with experience in intraoperative mapping or neurophysiological monitoring for the treatment of eloquent area tumors. Fifteen centers returned the completed questionnaires. Data was available on 2098 patients. 863 patients (41.1%) were operated on through awake surgery and intraoperative mapping, while 1235 patients (58.8%) received asleep surgery and intraoperative electrophysiological monitoring or mapping. There was great heterogeneity between centers with some totally AW oriented (up to 100%) and other almost totally ASL oriented (up to 92%) (31% SD). For awake surgery, 79.9% centers preferred an asleep-awake-asleep anesthesia protocol. Only 53.3% of the centers used ECoG or transcutaneous EEG. The incidence of intraoperative seizures varied significantly between centers, ranging from 2.5% to 54% (p < 0.001). It there appears to be a statistically significant link between the mastery of mapping technique and the risk of intraoperative seizures. Moreover, history of preoperative seizures can significantly increase the risk of intraoperative seizures (p < 0.001). Intraoperative seizures occurrence was similar in patients with or without perioperative drugs (12% vs. 12%, p = 0.2). This is the first European survey to assess intraoperative functional mapping and monitoring protocols and the management of peri- and intraoperative seizures. This data can help identify specific aspects that need to be investigated in prospective and controlled studies.

Tumorigenic potential of miR-18A* in glioma initiating cells requires NOTCH-1 signaling.

Stem cell-like properties of glioma initiating cells (GiCs) fuel glioblastoma (GBM) development by providing the different cell types that comprise the tumor. It is therefore likely that the molecular circuitries that regulate their decision to self-renew or commit to a more differentiated state may offer targets for future innovative therapies. In previous micro-RNA profiling studies to search for regulators of stem cell plasticity, we identified miR-18a* as a potential candidate and its expression correlated with the stemness state. Here, using human GiCs we found that miR-18a* expression promotes clonal proliferation in vitro and tumorigenicity in vivo. Mechanistically, ERK-dependent induction of miR-18a* directly represses expression of DLL3, an autocrine inhibitor of NOTCH, thus enhancing the level of activated NOTCH-1. Activated NOTCH-1 in turn is required for sustained ERK activation. This feed-forward loop, driven by miR-18a*, is required to turn on the SHH-GLI-NANOG network, essential for GiC self-renewal. Hence, by tightly regulating expression of DLL3, miR-18a* constitutes an important signaling mediator for fine tuning the level of GiC self-renewal.

Parietal network underlying movement control: disturbances during subcortical electrostimulation.

Our understanding of brain movement control has changed over the last two decades. Recent findings in the monkey and in humans have led to a parallel and interconnected network. Nevertheless, little is known about these networks. Here, we present two cases of patients with a parietal low-grade glioma. They underwent surgery under local anesthesia with cortical and subcortical mapping. For patient 1, subcortical electrostimulation immediately posterior to thalamocortical fibers induced movement disorders, with an inhibition of leg and arm movements medially and, more laterally, an acceleration of arm movement. For patient 2, electrostimulation of white matter immediately posterior to thalamocortical fibers induced an inhibition of both arm movement. It means that the detected fibers in the parietal lobe may be involved in the motor control modulation. They are distributed veil-like immediately posterior to thalamocortical pathways and could correspond to a fronto-parietal movement control subnetwork. These two cases highlight the major role of the subcortical connectivity in movement regulation, involving parietal lobe, thus the necessity to be identified and preserved during brain surgery.

Improvement of diffusion tensor imaging-based tractography by free-water correction in nonedematous gliomas: assessment with brain mapping.

OBJECTIVE: The free-water correction algorithm (Freewater Estimator Using Interpolated Initialization [FERNET]) can be applied to standard diffusion tensor imaging (DTI) tractography to improve visualization of subcortical bundles in the peritumoral area of highly edematous brain tumors. Interest in its use for presurgical planning in purely infiltrative gliomas without peritumoral edema has never been evaluated. Using subcortical maps obtained with direct electrostimulation (DES) in awake surgery as a reference standard, the authors sought to 1) assess the accuracy of preoperative DTI-based tractography with FERNET in a series of nonedematous glioma patients, and 2) determine its potential usefulness in presurgical planning. METHODS: Based on DES-induced functional disturbances and tumor topography, the authors retrospectively reconstructed the putatively stimulated bundles and the peritumoral tracts of interest (various associative and projection pathways) of 12 patients. The tractography data obtained with and without FERNET were compared. RESULTS: The authors identified 21 putative tracts from 24 stimulation sites and reconstituted 49 tracts of interest. The number of streamlines of the putative tracts crossing the DES area was 26.8% higher (96.04 vs 75.75, p = 0.016) and their volume 20.4% higher (13.99 cm3 vs 11.62 cm3, p < 0.0001) with FERNET than with standard DTI. Additionally, the volume of the tracts of interest was 22.1% higher (9.69 cm3 vs 7.93 cm3, p < 0.0001). CONCLUSIONS: Free-water correction significantly increased the anatomical plausibility of the stimulated fascicles and the volume of tracts of interest in the peritumoral area of purely infiltrative nonedematous gliomas. Because of the functional importance of the peritumoral zone, applying FERNET to DTI could have potential implications on surgical planning and the safety of glioma resection.

Cluster-like headache secondary to parasagittal hemangiopericytoma.

We describe an original case of cluster-like headache CLH) revealing a parasagittal tumor invading the superior sagittal sinus (SSS). Resection of the tumor (hemangiopericytoma) allowed the re-permeabilization of the SSS and was followed by the complete disappearance of CLH. Several mechanisms including obstruction of the SSS, hypervascularization with arterio-veinous shunt, and overflow in the cavernous sinus might explain the symptoms.

Intraventricular fibrinolysis for severe aneurysmal intraventricular hemorrhage: a randomized controlled trial and meta-analysis.

UNLABELLED: The aim of this study was to assess the safety and efficacy of intraventricular fibrinolysis (IVF) for aneurysmal subarachnoid hemorrhage (aSAH) with severe intraventricular hemorrhage (IVH). In this randomized controlled trial, between 2005 and 2009, patients with aSAH and severe IVH were randomly assigned into two groups: one treated with external ventricular drainage (EVD) combined with intraventricular recombinant tissue plasminogen activator (rt-PA) and the second with EVD alone. The primary end-point was mortality rate within the first 30 days. We performed meta-analysis including all published articles that compared IVF + EVD to EVD alone in patients with aSAH IVH. Eleven patients were included in the rt-PA group, eight in the control group. At 30 days, mortality rate was lower in the rt-PA group (45.5 vs. 62.5%), but results were not statistically significant (p = 0.65). Clearance of third and fourth ventricles was obtained previously in the rt-PA group (4.25 days) compared to the control group (10.67 days) (p = 0.001). There was no statistically significant difference concerning the occurrence of complications. The meta-analysis showed a better survival rate with IVF without raised statistical significance (odds ratio = 0.32 [95% confidence interval, 0.10-1.03]). This study shows that IVF is as safe as EVD alone for aSAH with severe IVH. It accelerates blood clot resolution in the ventricular system. Mortality rate could be improved by IVF but without significant results. Because of the severity and rarity of this pathology, a multicenter study is required. CLINICAL TRIAL REGISTRATION INFORMATION: www.clinicaltrials.gov (NCT00823485).

A New Noninvasive Frameless Registration System for Stereotactic Cranial Biopsy: A Technical Note.

BACKGROUND: Although frame-based stereotactic biopsy is still considered the gold standard for brain biopsies, frameless robot-assisted stereotactic systems are now able to provide an equal level of safety and accuracy. However, both systems suffer from a lack of efficiency of the operative workflow. OBJECTIVE: To describe the technique of a new frameless and noninvasive registration tool Neurolocate (Renishaw). This tool, combined with an intraoperative cone-beam computed tomography imaging system like O-ARM (Medtronic), might facilitate the achievement and workflow of robot-assisted stereotactic intracranial biopsies. METHODS: Neurolocate is a 3-dimensional fiducial tool fixed directly on the Neuromate (Renishaw) robot arm. It consists of 5 radio-opaque spherical fiducials, whose geometry is constant. This tool made it possible to carry out the coregistration then the biopsy in the same operating time, following a five-step procedure described here. We retrospectively extracted selected preliminary results from our initial experience. RESULTS: Over 1 year, 23 consecutive adult patients were biopsied with Neurolocate in our center. The mean overall operative time, from patient's installation to skin closure, was 97 minutes ± 27 (SD). The entire procedure took place in a single location unit (operating room), which facilitated workflow and surgical planning. No invasive gesture was performed outside of the operating time. CONCLUSION: Neurolocate is a new frameless and noninvasive registration tool that could improve workflow and flexibility for operating room management and surgical planning. It may also increase the comfort of patients undergoing robot-assisted intracranial stereotactic biopsies. The accuracy and safety profile should be addressed in specific studies.

Application accuracy of Neuromate robot-guided deep brain stimulation procedures using the non-invasive frameless Neurolocate registration system.

OBJECTIVE: to measure the in vivo application accuracy of Neuromate robot-assisted deep brain stimulation procedures (DBS) using the new, non-invasive, frameless Neurolocate registration method. METHODS: Neurolocate accuracy was measured in 17 patients undergoing DBS (32 leads). The registration was obtained by automatic recognition of the spatial location of the Neurolocate fiducials, fixed on the robot arm, on 3D intraoperative computerized tomography (CT) images relative to the patient's skull contours. Application accuracy was measured as the Euclidian distance between the points theoretically targeted on preoperative magnetic resonance imagingand the tip of the guiding tube visible on intraoperative CT images after merging images. RESULTS: Mean robot inaccuracy was 0.72 mm (SD 0.40; range 0.2-1.7 mm). Inaccuracies ≥1.5 mm were observed in 2/32 cases. CONCLUSION: Our study confirms in vivo that the accuracy of the Neurolocate registration is compatible with the accuracy required for DBS procedures.