Arthur Wagner

Background: Intraoperative monitoring of motor-evoked potentials (MEPs) during resection of supratentorial brain tumours under general anaesthesia is done either by transcranial electrical stimulation via scalp electrodes (TES) or by direct cortical stimulation via a strip electrode placed on the precentral gyrus (DCS), but evidence favouring one method over the other is lacking.Methods: TRANSEKT was a multicentre, randomised, double-blind, exploratory trial at six neurosurgical centres in Germany and Switzerland. Adults (18–80 years) with supratentorial tumours adjacent to the corticospinal tract and no or only mild preoperative paresis were randomly assigned to surgery under TES-MEP monitoring with a bihemispheric threshold ratio-based criterion or conventional DCS-MEP monitoring. The primary endpoint was deterioration of motor function by at least one Medical Research Council grade at discharge or 7 days after surgery, analysed as complete cases. This trial is registered with DRKS (DRKS00023256).Findings: Between Dec 3, 2020, and March 14, 2024, 137 patients were randomly assigned and 114 were analysed (54 DCS, 60 TES). Motor function deteriorated in 13 of 54 patients (24%) with DCS and 12 of 60 (20%) with TES (OR 0·77, 95% CI 0·30–1·94; p=0·576). TES met the prespecified non-inferiority criterion for negative predictive value (DCS 86% vs TES 93%; one-sided p=0·021); the positive predictive value did not differ (44% vs 29%; p=0·399). Residual tumour was detected in 33% versus 31% (p=0·789). Intraoperative seizures occurred in four (3%) of 137 patients, and nine (6·5%) died during follow-up.Interpretation: TRANSEKT provides the first randomised evidence comparing bihemispheric threshold ratio-based TES-MEP with conventional DCS-MEP during resection of motor-eloquent supratentorial tumours. Neither modality was superior for postoperative motor outcome, predictive performance, or extent of resection. The findings support individualised selection of TES or DCS according to surgical context, technical feasibility, and local expertise.

Purpose: To compare intraoperative screw revision and outcomes of robot-assisted versus navigation-guided percutaneous pedicle screw placement and to explore whether outcomes differed by surgeon experience. Materials and methods: A prospective cohort of 43 consecutive patients undergoing robot-assisted percutaneous pedicle screw fixation between September 2024 and March 2026 was compared with a matched historical cohort of 129 patients treated using navigated conventional percutaneous instrumentation. Propensity score matching included age, sex, ASA physical status, anatomical region, surgical indication, and surgeon expertise. Surgeons were stratified according to prior spondylodesis case volume. Outcomes included screw revision rates (as a measure of screw accuracy), screw placement time, operative time, blood loss, and perioperative complications. Results: Unadjusted screw-level revision proportions were 2.3% with robotic assistance and 3.5% with navigation-guided instrumentation. In adjusted patient-level analysis, greater surgeon experience, but not robotic assistance, was associated with fewer revisions. In the lowest-experience group, the proportions were descriptively 4.3% and 8.2%, but the technique-by-experience interaction was not statistically significant. Median screw-placement time was longer with robotic assistance (7.8 vs. 5.5 min per screw, p < 0.001). No statistically significant between-group differences were detected in blood loss, length of stay, or complication rates. Conclusion: Robot-assisted pedicle screw placement is safe and accurate, with comparable complication rates to conventional navigation. The observed increase in screw placement time may reflect the early adaptation phase of the robotic technique rather than an inherent limitation of the system. The descriptive reduction in revision rates among less experienced surgeons suggests a potential role for robotic assistance in supporting standardization and surgical training; however, this exploratory finding warrants confirmation in larger studies.

Lay Summary: Surgery is the first step in treating patients with the rare brain tumor IDH-mutant grade 4 astrocytoma. In an international study of 266 patients, we examined how the amount of tumor remaining after surgery affects survival. Patients with less remaining contrast-enhancing tumor lived longer. Those who underwent “supramaximal” surgery (tumor removal beyond the visible enhancing portion) had the most favorable outcomes. Loss of the CDKN2A/B gene was linked to worse survival regardless of the extent of surgery. These findings suggest that removing as much enhancing tumor as safely possible may improve outcomes and guide risk stratification in future clinical trials.

Implantable brain-computer interfaces (iBCIs) with single-neuron resolution are showing great promise for restoring mobility and communication in individuals with spinal cord injury or motor neuron disease. Stroke is the most common cause of acquired brain injury and a major contributor to long-term disability, making chronic stroke a highly relevant indication for iBCIs. However, whether stable intracortical recordings can be obtained from the structurally lesioned human brain is unknown. We report recordings from four 64-channel microelectrode arrays implanted in a participant with chronic aphasia after a large left-hemispheric stroke. The arrays targeted right-hemispheric frontoparietal regions homotopic to the damaged left-hemispheric language network. Across 111 sessions spanning 1,240 days, unit yield and signal quality remained stable. Waveform-based tracking reliably identified individual units across sessions, including across extended recording gaps. Short- and long-term unit stability was comparable to previous reports from iBCI participants without structural brain lesions, and tracked units showed consistent spiking properties across sessions. Our findings provide the first evidence that single-neuron recordings can remain stable over the long term in the stroke-lesioned human brain. They establish the feasibility of chronic, cellular-resolution iBCIs after stroke and support the development of neurorestorative applications for deficits caused by structural brain injury.

BACKGROUND AND OBJECTIVES: Chronic implantation of brain-computer interface facilitates stable, high-fidelity neuronal recordings over extended periods of time. Planar microelectrode arrays [Utah arrays (UAs)] are commonly used for intracortical signal acquisition. Here, we describe the surgical workflow for chronic implantation of multiple UAs in 2 patients and report safety and signal-quality outcomes. METHODS: Two patients (MB, MM) underwent chronic UA implantation within a translational research program. Preoperative planning included magnetic resonance imaging and navigated transcranial magnetic stimulation mapping for localization of functional targets. MB presented with aphasia after a left hemisphere media territory stroke 6 years before implantation and received 4 UAs in speech-related areas. MM presented with tetraparesis after a high level spinal cord injury and received 4 UAs in areas related to grasping functionality, totaling 256 intracortical electrodes for each patient. RESULTS: The duration of the chronic implantation has currently amounted to 41 months for MB and 4 months for MM. Optimal signal quality has been recorded in MB in 3 of 4 UAs and in MM in all UAs. After 15 months, MB suffered from wound breakdown, necessitating surgical debridement and intravenous antibiotic treatment. Unimpaired signal acquisition resumed after the wound had healed, and no further complications from UA implantation were recorded otherwise. CONCLUSION: Chronic implantation of UAs across distinct cortical areas is safe. A standardized workflow—combining imaging-based functional navigated transcranial magnetic stimulation mapping, intraoperative neuronavigation, and structured postoperative surveillance—supports reliable, long-term intracortical signal acquisition.

Background: In 2022, a nationwide survey revealed heterogeneity and limited standardization in the implementation of molecular tumor boards (MTBs) for neuro-oncology in Germany. This follow-up study aimed to assess recent developments, structural changes, and the integration of digital tools. Methods: An anonymous online questionnaire was distributed to approximately 445 members of the German Neuro-Oncology Working Group (NOA). Items focused on MTB availability, frequency, tumor inclusion, recommendation pathways, implementation, digital infrastructure, and perceived barriers. Results: 35 responses were collected. Respondents were primarily experienced neurosurgeons and neurologists working in certified university centers. Most were based in Bavaria, Baden-Württemberg, North Rhine–Westphalia, and Berlin. The number of in-house MTBs increased, with most boards meeting weekly. A broader range of tumor entities—including lower-grade gliomas—and earlier therapy lines are increasingly discussed. Recommendations were issued in fewer than half of cases, and over 30% of proposed therapies were implemented, though often hindered by lack of reimbursement. Virtual tumor boards (50%) and structured databases (40%) are increasingly used, and around 5% of patients are enrolled into national studies. Follow-up strategies and feedback loops remain inconsistent across centers. Conclusions: MTBs have become more established in neuro-oncology care, reflecting a growing commitment to precision medicine. However, implementation of recommendations remains limited, often constrained by lack of actionable targets, challenges accessing studies or off-label treatments. To fully realize the potential of MTBs, standardized integration pathways, greater harmonization, broader study offerings, and structured evaluation systems are needed.

Human language depends on highly specialized left-hemispheric brain networks. Damage to these networks causes severe language impairments (aphasia), one of the most common, debilitating and costly consequences of left-hemispheric brain injury, especially stroke. The limited recovery of aphasia despite intensive rehabilitation efforts emphasizes the need to understand the basis of residual language abilities at the single-neuron level, which has remained unexplored so far. Here, we report large-scale microelectrode recordings with single-unit resolution over a period of ten months from the right-hemispheric prefrontal and parietal association cortex of an individual with stroke-induced chronic non-fluent aphasia. Single neurons exhibited regionally specific responses during comprehension, retrieval and articulation of words, the core operations of language. Distinct subpopulations encoded linguistic information in a task-specific manner, despite correlated firing patterns across tasks. Both single-neuron activity and temporally coordinated population dynamics were predicted by semantic and phonological embeddings derived from large language models (LLMs), revealing a regional dissociation in which semantic features preferentially accounted for prefrontal activity and phonological features for parietal activity. Our findings suggest that right-hemispheric circuits, homotopic to the left language network, can support language processing through structured, functionally organised activity at the level of single neurons. This study opens an avenue for developing mechanistically specific neurorehabilitation and neurorestorative strategies for aphasia, such as brain-computer interfaces (BCIs), that leverage right-hemispheric language resources.