BACKGROUND.A long-held dream of scientists is to transfer information directly to the visual cortex of blind individuals, thereby restoring a rudimentary form of sight. However, no clinically available cortical visual prosthesis yet exists. METHODS.We implanted an intracortical microelectrode array consisting of 96 electrodes in the visual cortex of a 57-year-old person with complete blindness for a sixmonth period. We measured thresholds and the characteristics of the visual percepts elicited by intracortical microstimulation. RESULTS.Implantation and subsequent explantation of intracortical microelectrodes were carried out without complications. The mean stimulation threshold for single electrodes was 66.8  36.5 A. We consistently obtained high-quality recordings from visually deprived neurons and the stimulation parameters remained stable over time. Simultaneous stimulation via multiple electrodes were associated with a significant reduction in thresholds (p<0.001, ANOVA test) and evoked discriminable phosphene percepts, allowing the blind participant to identify some letters and recognize object boundaries. CONCLUSIONS.Our results demonstrate the safety and efficacy of chronic intracortical microstimulation via a large number of electrodes in human visual cortex, showing its high potential for restoring functional vision in the blind. TRIAL REGISTRATION. ClinicalTrials.gov identifier NCT02983370.

Object Nowadays the role of microsurgical management of intrinsic brain tumors is to maximize the volumetric resection of the tumoral tissue, minimizing the postoperative morbidity. The purpose of this paper was to study the benefits of an original protocol developed for the microsurgical treatment of tumors located in eloquent motor areas where the navigation and electrical stimulation of motor subcortical pathways have been implemented. Methods A total of 17 patients who underwent resection of cortical or subcortical tumors in motor areas have been included in the series. The preoperative planning for multimodal navigation was done by integrating anatomical studies, motor functional MR (fMR) imaging, and subcortical pathway volumes generated by diffusion tensor (DT) imaging. Intraoperative neuromonitoring included motor mapping by direct cortical stimulation (CS) and subcortical stimulation (sCS), and localization of the central sulcus by using cortical multipolar electrodes and the N20 wave inversion technique. The location of all cortically and subcortically stimulated points with positive motor response was stored in the navigator and correlated with the cortical and subcortical motor functional structures defined preoperatively. Results The mean tumoral volumetric resection was 89.1 ± 14.2% of the preoperative volume, with a total resection (≥ 100%) in 8 patients. Preoperatively a total of 58.8% of the patients had some kind of motor neurological deficit, increasing 24 hours after surgery to 70.6% and decreasing to 47.1% at 1 month later. There was a great correlation between anatomical and functional data, both cortically and subcortically. A total of 52 cortical points submitted to CS had positive motor response, with a positive correlation of 83.7%. Also, a total of 55 subcortical points had positive motor response; in these cases the mean distance from the stimulated point to the subcortical tract was 7.3 ± 3.1 mm. Conclusions The integration of anatomical and functional studies allows a safe functional resection of the brain tumors located in eloquent areas. Multimodal navigation allows integration and correlation among preoperative and intraoperative anatomical and functional data. Cortical motor functional areas are anatomically and functionally located preoperatively thanks to MR and fMR imaging and subcortical motor pathways with DT imaging and tractography. Intraoperative confirmation is done with CS and N20 inversion wave for cortical structures and with sCS for subcortical pathways. With this protocol the authors achieved a good volumetric resection in cortical and subcortical tumors located in eloquent motor areas, with an increase in the incidence of neurological deficits in the immediate postoperative period that significantly decreased 1 month later. Ongoing studies must define the safe limits for functional resection, taking into account the intraoperative brain shift. Finally, it must be demonstrated whether this protocol has any long-term benefit for patients by prolonging the disease-free interval, the time to recurrence, or the survival time.

A 3-D reconstruction of the cortical surface can be easily created with free OsiriX software. This technique helps the surgeon perfect the mentally created 3-D picture of the tumor location to carry out cleaner, safer surgeries.

OBJECTIVEThe coronavirus disease 2019 (COVID-19) pandemic has caused dramatic changes in medical education. Social distancing policies have resulted in the rapid adoption of virtual learning (VL) by neurosurgeons as a method to exchange knowledge, but it has been met with variable acceptance. The authors surveyed neurosurgeons from around the world regarding their opinions about VL and how they see the future of neurosurgical conferences.METHODSThe authors conducted a global online survey assessing the experience of neurosurgeons and trainees with VL activities. They also questioned respondents about how they see the future of on-site conferences and scientific meetings. They analyzed responses against demographic data, regions in which the respondents practice, and socioeconomic factors by using frequency histograms and multivariate logistic regression models.RESULTSEight hundred ninety-one responses from 96 countries were received. There has been an increase in VL activities since the start of the COVID-19 pandemic. Most respondents perceive this type of learning as positive. Respondents from lower-income nations and regions such as Europe and Central Asia were more receptive to these changes and wanted to see further movement of educational activities (conferences and scientific meetings) into a VL format. The latter desire may be driven by financial savings from not traveling. Most queried neurosurgeons indicated that virtual events are likely to partially replace on-site events.CONCLUSIONSThe pandemic has improved perceptions of VL, and despite its limitations, VL has been well received by the majority of neurosurgeons. Lower-income nations in particular are embracing this technology. VL is still evolving, but its integration with traditional in-person meetings seems inevitable.