Tag: Brain surgery

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Mapping the Functional Boundaries of the Speech Articulation Network Using Positive and Negative Direct Electrical Stimulation With Resting-State Functional MRI

Neurosurgery 98:577–587, 2026

This clinical research integrates positive and negative direct electrical stimulation (DES) with presurgical resting-state fMRI to refine the speech articulation network (SAN) atlas in glioma patients. Analyzing 25 patients, the study maps DES-positive and DES-negative seed-based connectivity, compares anticorrelated networks, and evaluates sensitivity and specificity across group-frequency thresholds.

Key findings show DES-positive sites robustly identify bilateral SAN regions (rolandic operculum, inferior frontal and superior temporal gyri), while DES-negative points delineate functional borders and improve atlas specificity; a 41% SAN-positive threshold yields approximately 80% sensitivity and specificity for clinical use.

Resting-state fMRI and DES: Resting-state functional MRI (rs-fMRI) is a noninvasive tool for mapping brain networks, while direct electrical stimulation (DES) during awake surgery (AwS) is the gold standard for causally identifying functional brain regions, especially for speech articulation mapping in glioma patients.

Inclusion of DES-negative points: Incorporating both DES-positive (eliciting function) and DES-negative (no function elicited) points enables more precise mapping of the speech articulation network (SAN) and its functional borders, improving specificity and sensitivity compared to using only positive points.

Comprehensive SAN atlas: A new SAN atlas was created from 25 glioma patients using 32 DES-positive and 42 DES-negative points, with presurgical rs-fMRI seed-based connectivity analysis, providing a more accurate and clinically relevant definition of the SAN.

Distinct connectivity patterns: DES-positive points consistently mapped the SAN to bilateral rolandic operculum, inferior frontal gyrus, and superior temporal gyrus, while DES-negative points revealed distinct, only partially overlapping connectivity patterns, helping delineate the SAN’s functional borders.

Threshold for clinical use: A 41% frequency threshold for the SAN-positive network achieves approximately 80% sensitivity and specificity, offering a practical balance for clinical application in presurgical planning.

Functional borders and overlap: Minimal overlap between SAN-positive and SAN-negative networks identifies functional borders, especially in the precentral sulcus and inferior frontal gyrus, aiding neurosurgeons in distinguishing critical from non-critical areas during mapping.

Clinical implications: Defining precise SAN borders improves intraoperative decision-making, reduces irrelevant stimulation, shortens mapping time, and enhances safety in both awake and asleep brain surgeries.

Limitations and future directions: The study’s limitations include sample size, heterogeneity, and MRI field strength; future research should use larger, more homogeneous cohorts and higher-resolution imaging to further refine SAN mapping.

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Minimally Invasive Hematoma Evacuation Using the MindsEye Expandable Tubular Retractor

World Neurosurg. (2023) 176:162-167

Recent advances in intraoperative neuronavigation and cranial access devices have facilitated an increasing interest in the use of minimally invasive techniques (minimally invasive surgery) to safely treat
subcortical lesions via a parafascicular approach.

Newly developed expandable retractors, such as the MindsEye system further optimize such approaches. In this technical report, we describe the nuances in minimally invasive surgery parenchymal hematoma evacuation using the MindsEye device.

METHODS: After placement of the device, the inner stylet and inner obturator are removed, and the expandable sheath is left in place and secured into place with a Greenberg refractor. The sheath easily dilates to the surgeon’s preference with a dial, and the walls of the sheath
are composed of a thin, clear, membrane to allow easy visualization of the lesion. We additionally retrospectively reviewed clinical characteristics and outcomes across three patients treated at our facility with spontaneous multicompartment intracranial hematoma using the Mind-sEye system.

RESULTS: We provide a video case demonstrating the use of the MindsEye retractor in a transfrontal parenchymal hematoma evacuation. Successful evacuation with achieved in less than 90 minutes with near total clot removal and resolution of mass effect for all reviewed cases with no patients experiencing procedure-related postoperative decline.

CONCLUSIONS: Minimally invasive catheter-based and parafascicular approaches using tubular retractors are increasingly recognized as a viable option in the treatment of subcortical lesions. The MindsEye is the first expandable brain access port designed for removal of deep
intracranial lesions. We believe it represents a recent addition in the armament of cranial surgeons.

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The perspectives of mapping and monitoring of the sense of self in neurosurgical patients

Acta Neurochirurgica (2021) 163:1213–1226

Surgical treatment of tumors, epileptic foci or of vascular origin, requires a detailed individual pre-surgical workup and intraoperative surveillance of brain functions to minimize the risk of post-surgical neurological deficits and decline of quality of life. Most attention is attributed to language, motor functions, and perception. However, higher cognitive functions such as social cognition, personality, and the sense of self may be affected by brain surgery. To date, the precise localization and the network patterns of brain regions involved in such functions are not yet fully understood, making the assessment of risks of related postsurgical deficits difficult. It is in the interest of neurosurgeons to understand with which neural systems related to selfhood and personality they are interfering during surgery.

Recent neuroscience research using virtual reality and clinical observations suggest that the insular cortex, medial prefrontal cortex, and temporo-parietal junction are important components of a neural system dedicated to self-consciousness based on multisensory bodily processing, including exteroceptive and interoceptive cues (bodily self-consciousness (BSC)).

Here, we argue that combined extra- and intra-operative approaches using targeted cognitive testing, functional imaging and EEG, virtual reality, combined with multisensory stimulations, may contribute to the assessment of the BSC and related cognitive aspects. Although the usefulness of particular biomarkers, such as cardiac and respiratory signals linked to virtual reality, and of heartbeat evoked potentials as a surrogate marker for intactness of multisensory integration for intra-operative monitoring has to be proved, systemic and automatized testing of BSC in neurosurgical patients will improve future surgical outcome.

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Ultrasound-guided brain surgery: echographic visibility of different pathologies and surgical applications in neurosurgical routine

Acta Neurochirurgica (2018) 160:1175–1185

The use of intraoperative ultrasound (iUS) has increased in the last 15 years becoming a standard tool in many neurosurgical centers. Our aim was to assess the utility of routine use of iUS during various types of intracranial surgery. We reviewed our series to assess ultrasound visibility of different pathologies and iUS applications during the course of surgery.

Materials and methods This is a retrospective review of 162 patients who underwent intracranial surgery with assistance of the iUS guidance system (SonoWand). Pathologic categories were neoplastic (135), vascular (20), infectious (2), and CSF related (5). Ultrasound visibility was assessed using the Mair classification, a four-tiered grading system that considers the echogenicity of the lesion and its border visibility (from 0 to 3; grade 0, pathology not visible; grade 3, visible with clear border with normal tissue). iUS applications included lesion localization, approach planning to deep-seated lesions, and lesion removal.

Results All pathologies were visible on iUS except one aneurysm. On average, extra-axial tumors were identified more easily and had clearer limits compared to intra-axial tumors (extra-axial 17%grade 2, 83%grade 3; intra-axial 5.5% grade 1, 46.5%grade 2, 48% grade 3). iUS provided precise and safe transcortical trajectories to deep-seated lesions (71 patients; tumors, hemangiomas, ICHs); iUS was judged to be less useful to approach skull base tumors and aneurysms. iUS was used to judge extent of resection in 152 cases; surgical artifacts reduced sonographic visibility in 25 cases: extent of resection was correctly checked in 127 patients (53 gliomas, 15 metastases, 39 meningiomas, 4 schwannomas, 4 sellar region tumors, 6 hemangiomas, 3 AVMs, 2 abscesses).

Conclusions iUS was highly sensitive in detecting all types of pathology, was safe and precise in planning trajectories to intraparenchymal lesions (including minimally mini-invasive approaches), and was accurate in checking extent of resection in more than 80% of cases. iUS is a versatile and feasible tool; it could improve safety and its use may be considered in routine intracranial surgery.

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Application of Novel Response/Progression Measures for Surgically Delivered Therapies for Gliomas: Response Assessment in Neuro-Oncology (RANO) Working Group

Neurosurgery 70:234–244, 2012 DOI: 10.1227/NEU.0b013e318223f5

The Response Assessment in Neuro-Oncology (RANO) Working Group is an international, multidisciplinary effort to develop new standardized response criteria for clinical trials in brain tumors. The RANO group identified knowledge gaps relating to the definitions of tumor response and progression after the use of surgical or surgically based treatments.

OBJECTIVE: To outline a proposal for new response and progression criteria for the assessment of the effects of surgery and surgically delivered therapies for patients with gliomas.

METHODS: The Surgery Working Group of RANO identified surgically related end-point evaluation problems that were not addressed in the original Macdonald criteria, performed an extensive literature review, and used a consensus-building process to develop recommendations for how to address these issues in the setting of clinical trials.

RESULTS: Recommendations were formulated for surgically related issues, including imaging changes associated with surgical resection or surgically mediated adjuvant local therapies, the determination of progression in the setting where all enhancing tumor has been removed, and how new enhancement should be interpreted in the setting where local therapies that are known to produce nonspecific enhancement have been used. Additionally, the terminology used to describe the completeness of surgical resections has been recognized to be inconsistently applied to enhancing vs nonenhancing tumors, and a new set of descriptors is proposed.

CONCLUSION: The RANO process is intended to produce end-point criteria for clinical trials that take into account the effects of prior and ongoing therapies. The RANO criteria will continue to evolve as new therapies and technologies are introduced into clinical trial and/or practice.

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