Dural reconstruction with or without a bone graft of paranasal and anterior skullbase malignancies: retrospective single-center analysis of 11 cases and review of literature

Introduction The reconstruction of frontobasal defects following oncologic resections of paranasal and anterior skull base (ASB) malignancies remains challenging. Ineffective reconstruction could lead to cerebrospinal fluid leak, meningitis, and tension pneumocephalus. Research question Aim of this investigation was to analyse postoperative complication rates with or without bone graft for anterior skull base reconstruction. Material and methods In this retrospective study, we included patients following resection of paranasal and/or anterior skull base malignancies between October 2013 and December 2022. Complications were analysed with regards to the type of skull base reconstruction. Results Eleven patients were identified (2 female, 9 male, age (median, SD) 64 ± 14.1 years (range 38–81). There were nine cases of paranasal sinus and nasal cavity carcinomas and two cases of olfactory neuroblastomas. Overall survival was 22.5 ± 28 months (range: 5–78), progression free survival was 17.0 ± 20.3 months (range: 11–78). Bone skull base reconstruction using a split graft was performed in three cases. Postoperative complications requiring surgical intervention were seen in 33% (one tension pneumocephalus) of cases in the bone reconstruction group and 50% (three patients with cerebrospinal fluid leak, one infection) in the non-bone reconstruction group. Discussion and conclusion The structural reinforcement of structural bone chip grafting might provide additional support of the ASB and prevent CSF leakage or encephalocele. Especially in large (>10 cm2) bone defects of advanced sinonasal malignancies extending into the middle cranial fossa, the full armamentarium of reconstruction possibilities should be considered

Intraoperative radiotherapy after neurosurgical resection of brain metastases as institutional standard treatment – update of the oncological outcome form a single center cohort after 117 procedures

Purpose Stereotactic radiotherapy (SRT) is the predominant method for the irradiation of resection cavities after resection of brain metastases (BM). Intraoperative radiotherapy (IORT) with 50 kV x-rays is an alternative way to irradiate the resection cavity focally. We have already reported the outcome of our frst 40 IORT patients treated until 2020. Since then, IORT has become the predominant cavity treatment in our center due to patients´ choice. Methods We retrospectively analyzed the outcomes of all patients who underwent resection of BM and IORT between 2013 and August 2023 at Augsburg University Medical Center (UKA). Results We identifed 105 patients with 117 resected BM treated with 50 kV x-ray IORT. Median diameter of the resected metastases was 3.1 cm (range 1.3 – 7.0 cm). Median applied dose was 20 Gy. All patients received standardized follow-up (FU) including three-monthly MRI of the brain. Mean FU was 14 months, with a median MRI FU for patients alive of nine months. Median overall survival (OS) of all treated patients was 18.2 months (estimated 1-year OS 57.7%). The observed local control (LC) rate of the resection cavity was 90.5% (estimated 1-year LC 84.2%). Distant brain control (DC) was 61.9% (estimated 1-year DC 47.9%). Only 16.2% of all patients needed WBI in the further course of disease. The observed radio necrosis rate was 2.6%. Conclusion After 117 procedures IORT still appears to be a safe and appealing way to perform cavity RT after neurosurgical resection of BM with low toxicity and excellent LC

Kinematics of Multigrid Monte Carlo

We study the kinematics of multigrid Monte Carlo algorithms by means of acceptance rates for nonlocal Metropolis update proposals. An approximation formula for acceptance rates is derived. We present a comparison of different coarse-to-fine interpolation schemes in free field theory, where the formula is exact. The predictions of the approximation formula for several interacting models are well confirmed by Monte Carlo simulations. The following rule is found: For a critical model with fundamental Hamiltonian H(phi), absence of critical slowing down can only be expected if the expansion of in terms of the shift psi contains no relevant (mass) term. We also introduce a multigrid update procedure for nonabelian lattice gauge theory and study the acceptance rates for gauge group SU(2) in four dimensions.Comment: 28 pages, 8 ps-figures, DESY 92-09

Adaptive Multigrid on Distributed Memory Computers

: A general software package has been developed for solving systems of partial differential equations with adaptive multigrid methods (MLAT) on distributed memory computers. The package supports the dynamic mapping of refinement levels. The general strategy is described and results are reported on computeintensive problems as well as on some simple problems representing worst-case situations from a parallel efficiency point of view. Inherent limitations of the parallel efficiency will be discussed. Keywords: Parallel adaptive multigrid, MLAT, adaptive grids, distributed memory, Euler equations 1 Introduction Generally, adaptive grids are a result of the computation, and dynamically mapping the work load to the processors and achieving load balance are tasks which have to be performed at run time. Careful strategies must be employed in order not to destroy the parallel efficiency through communication overhead. In this paper, we present results obtained for the multi-level adaptive te..

LiSS - An environment for the parallel multigrid solution of partial differential equations on general 2D domains

: L i SS is a very general package for the parallel multigrid solution of nonlinear partial differential equations. This paper gives the reader an impression of what L i SS can do. It includes the description of two important current perspectives, the implementation of adaptive structures and the generalization to 3D. An overview of numerical and parallel results is given. Keywords. Partial differential equations, general domains, multigrid, parallelization, grid partitioning. 1 Introduction The L i SS Package is a package of Fortran programs which provides an environment for the solution of partial differential equations (pdes) on general two-dimensional domains. The distinguishing and unique feature of the package is the core pde solver: it combines the use of fast, efficient multigrid algorithms with the use of block-structured grids; both serial and parallel executable versions are included in a single code. In particular, it is possible to -- execute the code on sequential mac..