An accuracy approach to robotic microsurgery in the ear

Concerns of rising healthcare costs and the ever increasing desire to improve surgical outcome have motivated the development of a new robotic assisted surgical procedure for the implantation of artificial hearing devices (AHDs). This paper describes our efforts to enable minimally invasive, cost effective surgery for the implantation of AHDs. We approach this problem with a fundamental goal to reduce errors from every component of the surgical workflow from imaging and trajectory planning to patient tracking and robot development. These efforts were successful in reducing overall system error to a previously unattained level.

Oncology nurses' perceptions about involving patients in the prevention of chemotherapy administration errors

To explore oncology nurses' perceptions and experiences with patient involvement in chemotherapy error prevention.

Combining 3D tracking and surgical instrumentation to determine the stiffness of spinal motion segments: a validation study

The spine is a complex structure that provides motion in three directions: flexion and extension, lateral bending and axial rotation. So far, the investigation of the mechanical and kinematic behavior of the basic unit of the spine, a motion segment, is predominantly a domain of in vitro experiments on spinal loading simulators. Most existing approaches to measure spinal stiffness intraoperatively in an in vivo environment use a distractor. However, these concepts usually assume a planar loading and motion. The objective of our study was to develop and validate an apparatus, that allows to perform intraoperative in vivo measurements to determine both the applied force and the resulting motion in three dimensional space. The proposed setup combines force measurement with an instrumented distractor and motion tracking with an optoelectronic system. As the orientation of the applied force and the three dimensional motion is known, not only force-displacement, but also moment-angle relations could be determined. The validation was performed using three cadaveric lumbar ovine spines. The lateral bending stiffness of two motion segments per specimen was determined with the proposed concept and compared with the stiffness acquired on a spinal loading simulator which was considered to be gold standard. The mean values of the stiffness computed with the proposed concept were within a range of ±15% compared to data obtained with the spinal loading simulator under applied loads of less than 5 Nm.

Tracking the transcriptional host response from the acute to the regenerative phase of experimental pneumococcal meningitis

Despite the availability of effective antibiotic therapies, pneumococcal meningitis (PM) has a case fatality rate of up to 30% and causes neurological sequelae in up to half of the surviving patients. The underlying brain damage includes apoptosis of neurons in the hippocampus and necrosis in the cortex. Therapeutic options to reduce acute injury and to improve outcome from PM are severely limited.With the aim to develop new therapies a number of pharmacologic interventions have been evaluated. However, the often unpredictable outcome of interventional studies suggests that the current concept of the pathophysiologic events during bacterial meningitis is fragmentary. The aim of this work is to describe the transcriptomic changes underlying the complex mechanisms of the host response to pneumococcal meningitis in a temporal and spatial context using a well characterized infant rat model.

Localization of primary language areas by arcuate fascicle fiber tracking

To reduce the risk of disabling postoperative functional deficit in patients with lesions in the dominant hemisphere, information about the localization of eloquent language areas is mandatory.

The link between visual exploration and neuronal activity: A multi-modal study combining eye tracking, functional magnetic resonance imaging and transcranial magnetic stimulation

In the present multi-modal study we aimed to investigate the role of visual exploration in relation to the neuronal activity and performance during visuospatial processing. To this end, event related functional magnetic resonance imaging er-fMRI was combined with simultaneous eye tracking recording and transcranial magnetic stimulation (TMS). Two groups of twenty healthy subjects each performed an angle discrimination task with different levels of difficulty during er-fMRI. The number of fixations as a measure of visual exploration effort was chosen to predict blood oxygen level-dependent (BOLD) signal changes using the general linear model (GLM). Without TMS, a positive linear relationship between the visual exploration effort and the BOLD signal was found in a bilateral fronto-parietal cortical network, indicating that these regions reflect the increased number of fixations and the higher brain activity due to higher task demands. Furthermore, the relationship found between the number of fixations and the performance demonstrates the relevance of visual exploration for visuospatial task solving. In the TMS group, offline theta bursts TMS (TBS) was applied over the right posterior parietal cortex (PPC) before the fMRI experiment started. Compared to controls, TBS led to a reduced correlation between visual exploration and BOLD signal change in regions of the fronto-parietal network of the right hemisphere, indicating a disruption of the network. In contrast, an increased correlation was found in regions of the left hemisphere, suggesting an intent to compensate functionality of the disturbed areas. TBS led to fewer fixations and faster response time while keeping accuracy at the same level, indicating that subjects explored more than actually needed.

Eliminating Adhesion Errors in Nanoindentation of Compliant Polymers and Hydrogels

Nanoindentation is a valuable tool for characterization of biomaterials due to its ability to measure local properties in heterogeneous, small or irregularly shaped samples. However, applying nanoindentation to compliant, hydrated biomaterials leads to many challenges including adhesion between the nanoindenter tip and the sample. Although adhesion leads to overestimation of the modulus of compliant samples when analyzing nanoindentation data using traditional analysis techniques, most studies of biomaterials have ignored its effects. This paper demonstrates two methods for managing adhesion in nanoindentation analysis, the nano-JKR force curve method and the surfactant method, through application to two biomedically-relevant compliant materials, poly(dimethyl siloxane) (PDMS) elastomers and poly(ethylene glycol) (PEG) hydrogels. The nano-JKR force curve method accounts for adhesion during data analysis using equations based on the Johnson-Kendall-Roberts (JKR) adhesion model, while the surfactant method eliminates adhesion during data collection, allowing data analysis using traditional techniques. In this study, indents performed in air or water resulted in adhesion between the tip and the sample, while testing the same materials submerged in Optifree Express() contact lens solution eliminated tip-sample adhesion in most samples. Modulus values from the two methods were within 7% of each other, despite different hydration conditions and evidence of adhesion. Using surfactant also did not significantly alter the properties of the tested material, allowed accurate modulus measurements using commercial software, and facilitated nanoindentation testing in fluids. This technique shows promise for more accurate and faster determination of modulus values from nanoindentation of compliant, hydrated biological samples. Copyright 2013 Elsevier Ltd. All rights reserved.