The utilization of fluorescein-guided biopsies has recently been discussed to improve and expedite operative techniques in the detection of tumor-positive tissue, as well as to avoid making sampling errors. In this study, we aimed to report our experience with fluorescein-guided biopsies and elucidate distribution patterns in different histopathological diagnoses in order to develop strategies to increase the efficiency and accuracy of this technique. We report on 45 fluorescence-guided stereotactic biopsies in 44 patients (15 female, 29 male) at our institution from March 2016 to March 2021, including 25 frame-based stereotactic biopsies and 20 frameless image-guided biopsies using VarioGuide^®. A total number of 347 biopsy samples with a median of 8 samples (range: 4–18) per patient were evaluated for intraoperative fluorescein uptake and correlated to definitive histopathology. The median age at surgery was 63 years (range: 18–87). Of the acquired specimens, 63% were fluorescein positive. Final histopathology included glioblastoma (n = 16), B-cell non-Hodgkin lymphoma (n = 10), astrocytoma, IDH-mutant WHO grade III (n = 6), astrocytoma, IDH-mutant WHO grade II (n = 1), oligodendroglioma, IDH-mutant and 1p/19q-codeleted WHO grade II (n = 2), reactive CNS tissue/inflammation (n = 4), post-transplantation lymphoproliferative disorder (PTLD; n = 2), ependymoma (n = 1), infection (toxoplasmosis; n = 1), multiple sclerosis (n = 1), and metastasis (n = 1). The sensitivity for high-grade gliomas was 85%, and the specificity was 70%. For contrast-enhancing lesions, the specificity of fluorescein was 84%. The number needed to sample for contrast-enhancing lesions was three, and the overall number needed to sample for final histopathological diagnosis was five. Interestingly, in the astrocytoma, IDH-mutant WHO grade III group, 22/46 (48%) demonstrated fluorescein uptake despite no evidence for gadolinium uptake, and 73% of these were tumor-positive. In our patient series, fluorescein-guided stereotactic biopsy increases the likelihood of definitive neuropathological diagnosis, and the number needed to sample can be reduced by 50% in contrast-enhancing lesions.

Aneurysmal subarachnoid hemorrhage (aSAH) from a ruptured intracranial aneurysm is a severe, life-threatening condition with high morbidity and mortality. The current treatment often involves surgical clipping or endovascular treatment within the first 24-48 hours. While there is ample evidence on complications of treating unruptured aneurysms, smiliar data in patients with acutly ruptured aneurysms is limited. The Earlydrain trial showed improved neurological results from lumbar-drainage after aneurysm treatment in patients with aSAH. Using this dataset, we aim to study frequency and effects of complications and identify associated risk factors. This is a sub-study of the prospective multicenter randomized controlled Earlydrain trial. We analyzed treatment associated complications (bleeding and/or infarctions) detected on a CT-scan on day 1 after aneurysm occlusion. Outcomes were the occurrence of postprocedural-complications, secondary infarctions in the acute phase and the modified-Ranking-Scale after 6 months. The Earlydrain-trial recruited 287 patients in 19 centers. 56 (19.5%) of these suffered from a treatment complication. 25(8.7%) patients experienced postprocedural intracranial hemorrhage and 34(11.8%) patients suffered from a treatment associated infarction. Patients suffering from a complication show more secondary infarctions(p=0.049) and worse neurological outcome after 180 days (p=0.025) compared to patients with no complication. Aneurysm location, rebleeding before the treatment, number of patients recruited per center and the day of the treatment were independent risk factors for the occurrence of complications. The present study reveals that patients with aSAH frequently experience intervention associated complications associated with aneurysm occlusion required to prevent recurrent hemorrhage. Consequently, aSAH patients with treatment related complications fare more often a worse clinical course and poor outcome.

Background: Biological approaches to intervertebral disc (IVD) restoration and/or regeneration have become of increasing interest. However, the IVD comprises a viscoelastic system whose biological replacement remains challenging. The present study sought to design load-sharing two-component model systems of circular, nested, concentric elements reflecting the nucleus pulposus and annulus fibrosus. Specifically, we wanted to investigate the effect of architectural design variations on (1) model system failure loads when testing the individual materials either separately or homogeneously mixed, and (2) also evaluate the potential of modulating other mechanical properties of the model systems. Methods: Two sets of softer and harder biomaterials, 0.5% and 5% agarose vs. 0.5% agarose and gelatin, were used for fabrication. Architectural design variations were realized by varying ring geometries and amounts while keeping the material composition across designs comparable. Results: Variations in the architectural design, such as lamellar width, number, and order, combined with choosing specific biomaterial properties, strongly influenced the biomechanical performance of IVD constructs. Biomechanical characterization revealed that the single most important parameter, in which the model systems vastly exceeded those of the individual materials, was failure load. The model system failure loads were 32.21- and 84.11-fold higher than those of the agarose materials and 55.03- and 2.14-fold higher than those of the agarose and gelatin materials used for system fabrication. The compressive strength, dynamic stiffness, and viscoelasticity of the model systems were always in the range of the individual materials. Conclusions: Relevant architecture-promoted biomechanical performance-tuning of tissue-engineered constructs for biological IVD replacement can be realized by slight modifications in the design of constructs while preserving the materials’ compositions. Minimal variations in the architectural design can be used to precisely control structure–function relations for IVD constructs rather than choosing different materials. These fundamental findings have important implications for efficient tissue-engineering of IVDs and other load-bearing tissues, as potential implants need to withstand high in situ loads.

Bone tissue engineering (BTE) is an interdisciplinary discipline that focuses on bone structure–function relationships for improving the replacement and/or regeneration of bone tissues. Thereby, the architecture and load-bearing capacity of embedded scaffolds play an important role in the generation of artificial tissues. The aim of this study was to develop a parametric numerical model and the accompanying fabrication of polycaprolactone (PCL) scaffolds for BTE applications. Therefore, we manufactured layered PCL-based constructs using three-dimensional (3D) printing. The material properties of PCL and constructs were determined by mechanical testing, and numerical models based on Beam188 Timoshenko elements were developed in the software environment ANSYS. PCL constructs were coated with collagen and seeded with osteoblasts, mesenchymal stem cells (MSCs), MLO-Y4 and MG63 cell types. We demonstrated the successful production of PCL constructs with 3D interconnected pores suitable for BTE applications. Furthermore, we provided for the first time geometrical parametric numerical models that determined the mechanical behavior of layered PCL scaffolds consisting of interconnected compartments for strains up to 3%. The parametric structures of the model allowed us to flexibly study new geometries in silico, which demonstrated its role as an important tool for supporting the fabrication of customized PCL constructs in planning and performing suitable mechanical characterizations for BTE applications.

Purpose: This study evaluated whether standardized proximal translaminar spinal tethering at the upper instrumented vertebra (UIV) + 1 and UIV + 2 reduces the incidence of proximal junctional kyphosis (PJK) and the need for revision surgery in patients undergoing thoraco-lumbar deformity correction for adult spinal deformity (ASD). Methods: A retrospective cohort study was conducted on 59 adult patients who underwent thoraco-lumbar deformity correction surgery between October 2019 and August 2023. Patients were categorized into tethered (T) and non-tethered (NT) groups. Radiographic measurements were performed preoperatively, early postoperatively (≤ 3 months), and late postoperatively (> 3 months) to assess PJK, defined as a proximal junctional angle (PJA) ≥ 10° and ≥ 10° greater than the corresponding preoperative measurement. Results: Overall, 18 patients (30.5%) developed PJK, with no significant difference between tethered (12%) and non-tethered (20.5%) patients within the first 3 months (p = 0.384). However, at late follow-up, the PJK rate was significantly higher in non-tethered (41.1%) compared to tethered (16%) patients (p = 0.037), with non-tethered patients being 3.67 times more likely to develop PJK (95% CI = 1.03–13.07). Kaplan–Meier analysis showed a significant reduction in time-dependent PJK development for tethered patients (p = 0.027). Revision surgery was required in 11.8% of non-tethered patients compared to 4% of tethered patients (p = 0.289). Conclusion: Proximal translaminar tethering at UIV + 1 and UIV + 2 effectively reduces the incidence of PJK in patients undergoing thoraco-lumbar deformity correction. However, the effect on surgical revision rates due to PJK remains unclear, warranting further long-term prospective studies.