Based on pathophysiologic mechanisms, animal experiments, and small patient studies, medical treatment may play a role in the treatment of CSDH. There is a lack of level I evidence in the nonsurgical treatment of CSDH. Therefore, randomized controlled trials, currently lacking, are needed to assess which treatment is most effective in each individual patient.

Several recent global traumatic brain injury (TBI) initiatives rely on practice variation in diagnostic and treatment methods to answer effectiveness questions. One of these scientific dilemmas, the surgical management of the traumatic acute subdural hematoma (ASDH) might be variable among countries, among centers within countries, and even among neurosurgeons within a center, and hence be amenable for a comparative effectiveness study. The aim of our questionnaire, therefore, was to explore variations in treatment for ASDH among neurosurgeons in similar centers in a densely populated geographical area. An online questionnaire, involving treatment decisions on six case vignettes of ASDH, was sent to 93 neurosurgeons in The Netherlands and Belgium. Clinical and radiological variables differed per case. Sixty neurosurgeons filled out the questionnaire (response rate 65%). For case vignettes with severe TBI and an ASDH, there was a modest variation in the decision to evacuate the hematoma and a large variation in the decision to combine the evacuation with a decompressive craniectomy. The main reasons for operating were "neurological condition" and "mass effect." For ASDH and mild/moderate TBI, there was large variation in the decision of whether to operate or not, whereas "hematoma size" was the predominant motivation for surgery. Significant inter-center variation for the decision to evacuate the hematoma was observed (p = 0.01). Most pronounced was that 1 out of 7 (14%) neurosurgeons in one region chose a surgical strategy compared with 9 out of 10 (90%) in another region for the same scenario. In conclusion, variation exists in the neurosurgical management of TBI within an otherwise homogeneous setting. This variation supports the methodology of the international Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) initiative, and shaped the Dutch Neurotraumatology Quality Registry (Net-QuRe) initiative.

One of the critical issues in brain-computer interface (BCI) research is how to translate a person's intention into brain signals for controlling computer programs. The motor system is currently the primary focus, where signals are obtained during imagined motor responses. However, cognitive brain systems are also attractive candidates, in that they may be more amenable to conscious control, yielding better regulation of magnitude and duration of localized brain activity. We report on a proof of principle study for the potential use of a higher cognitive system for BCI, namely the working memory (WM) system. We show that mental calculation reliably activates the WM network as measured with functional magnetic resonance imaging (fMRI). Moreover, activity in the dorsolateral prefrontal cortex (DLPFC) indicates that this region is active for the duration of mental processing. This supports the notion that DLPFC can be activated, and remains active, at will. Further confirmation is obtained from a patient with an implanted electrode grid for diagnostic purposes, in that gamma power within DLPFC increases during mental calculation and remains elevated for the duration thereof. These results indicate that cortical regions involved in higher cognitive functions may serve as a readily self-controllable input for BCI applications. It also shows that fMRI is an effective tool for identifying function-specific foci in individual subjects for subsequent placement of cortical electrodes. The fact that electrocorticographic (ECoG) signal confirmed the functional localization of fMRI provides a strong argument for incorporating fMRI in BCI research.

In this group of Dutch pediatric and adolescent patients, residual insular cortex was positively correlated with persistent postoperative seizures. Given the small sample size in this study, however, caution should be used in drawing conclusions about the role of the insular cortex.

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