Vestibular schwannomas: microsurgery after partial removal and stereoradiosurgery

The aim of this work is a comparison of results in two groups: primary radical removal of vestibular schwannoma (VS) and secondary radical removal following unsuccessful partial surgery and/or gamma knife stereoradiosurgery (GKS) and assessing the favorable one. Between 1997 and 2004, 106 patients with VS were operated on, 8 (7.5%) were after previous subtotal/partial resection and/or unsuccessful GKS. All VS from both groups were microsurgically removed by the same retromastoideal approach using intraoperative nerve monitoring. From primarily treated group 96% ended with good or satisfactory n. VII function and in 7.5% with useful hearing; group with previous subtotal partial resection and/or GKS ended without hearing and only in 25% with satisfactory function n. VII. The worst results of management of VS both microsurgically and by GKS are after previous partial resection. Total removal of VS after subtotal/partial resection and/or stereoradiosurgery is much more difficult. The subtotal/partial resection of VS should be therefore avoided. In all operated patients after GKS a living, biologically active tumour has been proved histologically. Only minimal regressive changes have been observed. This finding unambiguously proves that the stereoradiosurgery did not devitalize tumour as expected. Growing tumours (VS) should be treated by a primary radical microsurgery

Antimicrobial PDMS Surfaces Prepared through Fastand Oxygen-Tolerant SI-SARA-ATRP, Using Na₂SO₃ as a Reducing Agent

[Image: see text] Poly(dimethylsiloxane) (PDMS) is an attractive, versatile, and convenient material for use in biomedical devices that are in direct contact with the user. A crucial component in such a device is its surface in terms of antimicrobial properties preventing infection. Moreover, due to its inherent hydrophobicity, PDMS is rather prone to microbial colonization. Thus, developing an antimicrobial PDMS surface in a simple, large-scale, and applicable manner is an essential step in fully exploiting PDMS in the biomedical device industry. Current chemical modification methods for PDMS surfaces are limited; therefore, we present herein a new method for introducing an atom transfer radical polymerization (ATRP) initiator onto the PDMS surface via the base-catalyzed grafting of [(chloromethyl)phenylethyl]trimethoxysilane to the PDMS. The initiator surface was grafted with poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes via a surface-initiated supplemental activator and reducing agent ATRP (SI-SARA-ATRP). The use of sodium sulfite as a novel reducing agent in SI-SARA-ATRP allowed for polymerization during complete exposure to air. Moreover, a fast and linear growth was observed for the polymer over time, leading to a 400 nm thick polymer layer in a 120 min reaction time. Furthermore, the grafted PDMAEMA was quaternized, using various alkylhalides, in order to study the effect on surface antimicrobial properties. It was shown that antimicrobial activity not only depended highly on the charge density but also on the amphiphilicity of the surface. The fast reaction rate, high oxygen tolerance, increased antimicrobial activity, and the overall robustness and simplicity of the presented method collectively move PDMS closer to its full-scale exploitation in biomedical devices