Oliver Jansen

Optical control of hard X-ray polarization by electron injection in a laser wakefield accelerator

Laser-plasma particle accelerators could provide more compact sources of high-energy radiation than conventional accelerators. Moreover, because they deliver radiation in femtosecond pulses, they could improve the time resolution of X-ray absorption techniques. Here we show that we can measure and control the polarization of ultra-short, broad-band keV photon pulses emitted from a laser-plasma-based betatron source. The electron trajectories and hence the polarization of the emitted X-rays are experimentally controlled by the pulse-front tilt of the driving laser pulses. Particle-in-cell simulations show that an asymmetric plasma wave can be driven by a tilted pulse front and a non-symmetric intensity distribution of the focal spot. Both lead to a notable off-axis electron injection followed by collective electron–betatron oscillations. We expect that our method for an all-optical steering is not only useful for plasma-based X-ray sources but also has significance for future laser-based particle accelerators.

The Effectiveness and Safety of Exoskeletons as Assistive and Rehabilitation Devices in the Treatment of Neurologic Gait Disorders in Patients with Spinal Cord Injury: A Systematic Review

Study Design Systematic review. Clinical Questions (1) When used as an assistive device, do wearable exoskeletons improve lower extremity function or gait compared with knee-ankle-foot orthoses (KAFOs) in patients with complete or incomplete spinal cord injury? (2) When used as a rehabilitation device, do wearable exoskeletons improve lower extremity function or gait compared with other rehabilitation strategies in patients with complete or incomplete spinal cord injury? (3) When used as an assistive or rehabilitation device, are wearable exoskeletons safe compared with KAFO for assistance or other rehabilitation strategies for rehabilitation in patients with complete or incomplete spinal cord injury? Methods PubMed, Cochrane, and Embase databases and reference lists of key articles were searched from database inception to May 2, 2016, to identify studies evaluating the effectiveness of wearable exoskeletons used as assistive or rehabilitative devices in patients with incomplete or complete spinal cord injury. Results No comparison studies were found evaluating exoskeletons as an assistive device. Nine comparison studies (11 publications) evaluated the use of exoskeletons as a rehabilitative device. The 10-meter walk test velocity and Spinal Cord Independence Measure scores showed no difference in change from baseline among patients undergoing exoskeleton training compared with various comparator therapies. The remaining primary outcome measures of 6-minute walk test distance and Walking Index for Spinal Cord Injury I and II and Functional Independence Measure–Locomotor scores showed mixed results, with some studies indicating no difference in change from baseline between exoskeleton training and comparator therapies, some indicating benefit of exoskeleton over comparator therapies, and some indicating benefit of comparator therapies over exoskeleton. Conclusion There is no data to compare locomotion assistance with exoskeleton versus conventional KAFOs. There is no consistent benefit from rehabilitation using an exoskeleton versus a variety of conventional methods in patients with chronic spinal cord injury. Trials comparing later-generation exoskeletons are needed.

Against the odds: what to expect in rehabilitation of chronic spinal cord injury with a neurologically controlled Hybrid Assistive Limb exoskeleton. A subgroup analysis of 55 patients according to age and lesion level

Objective Age and lesion level are believed to represent outcome predictors in rehabilitation of patients with chronic spinal cord injury (SCI). The Hybrid Assistive Limb (HAL) exoskeleton enables patients to perform a voluntary controlled gait pattern via an electromyography-triggered neuromuscular feedback system, and has been introduced as a temporary gait training tool in patients with SCI. The aim of this prospective pre- and postintervention study was to examine functional outcomes as a function of age and lesion level in patients with chronic incomplete SCI (iSCI) or chronic complete SCI (cSCI) with zones of partial preservation (ZPP) by using the HAL as a temporary training tool. Methods Fifty-five participants with chronic iSCI or cSCI (mean time since injury 6.85 ± 5.12 years) were classified according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS) and divided by age (< 50 or ≥ 50 years), independent of lesion level, and also into 4 homogeneous groups according to lesion level. The subgroups were as follows: Subgroup 1, tetraplegic iSCI (n = 13) (C2-8, AIS C [n = 8] and AIS D [n = 5]); Subgroup 2, paraplegic iSCI with spastic motor behavior (n = 15) (T2-12, AIS C [n = 8] and AIS D [n = 7]); Subgroup 3, paraplegic cSCI with complete motor paraplegia and absence of spastic motor behavior (n = 18) (T11-L4 [AIS A], and ZPP from L-3 to S-1); and Subgroup 4, paraplegic iSCI with absence of spastic motor behavior (n = 9) (T12-L3, AIS C [n = 8] and AIS D [n = 1]). The training paradigm consisted of 12 weeks of HAL-assisted treadmill training (5 times/week). Baseline status was documented prior to intervention by using the AIS grade, Walking Index for SCI II (WISCI II) score, the 10-meter walk test (10MWT), and the 6-minute walk test (6MinWT). Training effects were assessed after 6 and 12 weeks of therapy, without HAL assistance. Results Overall, a time reduction of 47% in the 10MWT, self-selected speed (10MWTsss) (< 50 years = 56% vs ≥ 50 years = 37%) and an increase of 50% in the 6MinWT were documented. The WISCI II scores showed a mean gain of 1.69 levels. At the end of the study, 24 of 55 patients (43.6%) were less dependent on walking aids. Age had a nonsignificant negative influence on the 10MWTsss. Despite a few nonsignificant subgroup differences, participants improved across all tests. Namely, patients with iSCI who had spastic motor behavior improved to a nonsignificant, lesser extent in the 6MinWT. Conclusions The HAL-assisted treadmill training leads to functional improvements in chronic iSCI or cSCI, both in and out of the exoskeleton. An improvement of approximately 50% in the 10MWTsss and in gait endurance (6MinWT) can be expected from such training. The influences of SCI lesion level and age on functional outcome were nonsignificant in the present study. Older age (≥ 50 years) may be associated with smaller improvements in the 10MWTsss. An iSCI in paraplegic patients with spastic motor behavior may be a nonsignificant negative predictor in gait endurance improvements. Clinical trial registration no.: DRKS00010250 ( https://drks-neu.uniklinik-freiburg.de/drks_web/setLocale_DE.do ).

Treadmill Training with HAL Exoskeleton—A Novel Approach for Symptomatic Therapy in Patients with Limb-Girdle Muscular Dystrophy—Preliminary Study

Purpose: Exoskeletons have been developed for rehabilitation of patients with walking impairment due to neurological disorders. Recent studies have shown that the voluntary-driven exoskeleton HAL® (hybrid assistive limb) can improve walking functions in spinal cord injury and stroke. The aim of this study was to assess safety and effects on walking function of HAL® supported treadmill therapy in patients with limb-girdle muscular dystrophy (LGMD). Materials and Methods: Three LGMD patients received 8 weeks of treadmill training with HAL® 3 times a week. Outcome parameters were 10-meter walk test (10 MWT), 6-minute walk test, and timed-up-and-go test (TUG). Parameters were assessed pre and post training and 6 weeks later (follow-up). Results: All patients completed the therapy without adverse reactions and reported about improvement in endurance. Improvements in outcome parameters after 8 weeks could be demonstrated. Persisting effects were observed after 6 weeks for the 10 MWT and TUG test (follow-up). Conclusions: HAL® treadmill training in LGMD patients can be performed safely and enables an intensive highly repetitive locomotor training. All patients benefitted from this innovative method. Upcoming controlled studies with larger cohorts should prove its effects in different types of LGMD and other myopathies.

Hybrid Assistive Limb Exoskeleton HAL in the Rehabilitation of Chronic Spinal Cord Injury: Proof of Concept; the Results in 21 Patients.

INTRODUCTION The use of mobile exoskeletons is becoming more and more common in the field of spinal cord injury (SCI) rehabilitation. The hybrid assistive limb (HAL) exoskeleton provides a tailored support depending on the patients voluntary drive. MATERIALS AND METHODS After a pilot study in 2014 that included 8 patients with chronic SCI, this study of 21 patients with chronic SCI serves as a proof of concept. It was conducted to provide further evidence regarding the efficacy of exoskeletal-based rehabilitation. Functional assessment included walking speed, distance, and time on a treadmill, with additional analysis of functional mobility using the following tests: 10-meter walk test (10MWT), timed up and go (TUG) test, 6-minute walk test (6MWT), and the walking index for SCI II (WISCI-II) score. RESULTS After a training period of 90 days, all 21 patients significantly improved their functional and ambulatory mobility without the exoskeleton. Patients were assessed by the 6MWT, the TUG test, and the 10MWT, which also indicated an increase in the WISCI-II score along with significant improvements in HAL-associated walking speed, distance, and time. CONCLUSION Although, exoskeletons are not yet an established treatment in the rehabilitation of spinal cord injuries, the devices will play a more important role in the future. The HAL exoskeleton training enables effective, body weight-supported treadmill training and is capable of improving ambulatory mobility. Future controlled studies are required to enable a comparison of the new advances in the field of SCI rehabilitation with traditional over-ground training.

Functional Outcome of Neurologic-Controlled HAL-Exoskeletal Neurorehabilitation in Chronic Spinal Cord Injury: A Pilot With One Year Treatment and Variable Treatment Frequency

Study Design: Longitudinal prospective study. Objectives: Whether 1-year HAL-BWSTT of chronic spinal cord injured patients can improve independent ambulated mobility further as a function of training frequency, after an initial 3-month training period. Methods: Eight patients with chronic SCI were enrolled. They initially received full standard physical therapy and neurorehabilitation in the acute/subacute posttrauma phase. During this trial, all patients first underwent a daily (5 per week) HAL-BWSTT for 12 weeks. Subsequently, these patients performed a 40-week HAL-BWSTT with a training session frequency of either 1 or 3 to 5 sessions per week. The patients’ functional status including HAL-associated treadmill-walking time, -distance, and -speed with additional analysis of gait pattern, and their independent (without wearing the robot suit) functional mobility improvements, were assessed using the 10-Meter-Walk Test (10MWT), Timed-Up-and-Go Test (TUG) and 6-Minute-Walk Test (6MinWT) on admission, at 6 weeks, 12 weeks, and 1 year after enrollment. The data were analyzed separately for the 2 training frequency subgroups after the initial 12-week training period, which was identical in both groups. Results: During the 1-year follow-up, HAL-associated walking parameters and independent functional improvements were maintained in all the patients. This result held irrespective of the training frequency. Conclusions: Long-term 1-year maintenance of HAL-associated treadmill walking parameters and of improved independent walking abilities after initial 12 weeks of daily HAL-BWSTT is possible and depends mainly on the patients’ ambulatory status accomplished after initial training period. Subsequent regular weekly training, but not higher frequency training, seems to be sufficient to preserve the improvements accomplished.

Evaluating the microbial pattern of periprosthetic joint infections of the hip and knee

Purpose. Periprosthetic joint infection (PJI) is a devastating complication that leads to enormous economic and health care complaints from affected patients. The aim of this study is to identify the causative pathogens responsible for PJI, evaluate temporal trends concerning the pathogen pattern and identify potential risk factors for PJI. Methodology. This was a retrospective study analysing a total of 937 patients suffering PJI of the hip or knee joint between 2003 and 2011. Results. In total, 394 patients (42.0 %) with total knee arthroplasty (TKA), 477 patients (50.9 %) with total hip arthroplasty (THA) and 64 patients (6.8 %) receiving a dual‐head prosthesis had to be hospitalised due to PJI. In two cases (0.2 %), a simultaneous infection of TKA and THA occurred. The mean age of the study cohort was 70.85±11.68 years. The mean body mass index (BMI) was 28.53±5.7. According to the Charlson comorbidity index, 2.99 % of the patients were classified as severity Grade 1, 13.98 % Grade 2, 40.02 % Grade 3 and 43.0 % Grade 4. Staphylococcus aureus (MSSA), methicillin‐resistant Staphylococcus epidermidis (MRSE), methicillin‐resistant Staphylococcus aureus (MRSA), coagulase‐negative Staphylococcus (CoNS), Streptococcus, and Enterococcus were the pathogens mainly responsible. An increase in high‐resistance pathogens, such as MRSE, extended‐spectrum beta‐lactamase bacteria (ESBL), ampicillin‐resistant Enterococcus, Acinetobacter spp. and vancomycin‐resistant Enterococcus (VRE), was found during the study period. Only MRSA showed a declining tendency in a regression model. Conclusion. Patients suffering PJI present a certain risk profile with many comorbidities, e.g. high age and obesity. The observed microbiological pattern demonstrates the rise of high‐resistance pathogens.

Cervical Spinal Cord Injury Shows Markedly Lower than Predicted Mortality (>72 Hours After Multiple Trauma) From Sepsis and Multiple Organ Failure

Background: Sepsis and multiple organ failure (MOF) remain one of the main causes of death after multiple trauma. Trauma- and infection-associated immune reactions play an important role in the pathomechanism of MOF, but the exact pathways remain unknown. Spinal cord injury (SCI) may lead to an altered immune response, and some studies suggest a prognostic advantage for such patients having sepsis or multiple trauma. Yet these findings need to be evaluated in larger cohorts of trauma patients. Methods: Retrospective, multicenter study, using the data of the TraumaRegister DGU. Patients with and without SCI surviving the initial first 72 hours after trauma were matched according to injury pattern and age. Comparative analysis considered morbidity (sepsis, MOF) and hospital mortality. Results: The study population included 800 matched pairs. As intended by the matching process, patients with cervical SCI had an otherwise comparable injury pattern but a higher severity of trauma (mean Injury Severity Score: 36 vs 29, mean number of diagnosis: 5.6 vs 4.4). They had a higher rate of sepsis (15.9% vs 10.9%, P = .005) and MOF (35.9% vs 24.1%, P < .001) while mortality revealed no significant difference (9.5% vs 9.9%, P = .866). Conclusions: Cervical SCI leads to an increased rate of sepsis and MOF but appears to be favorable with respect to outcome of sepsis and MOF following multiple trauma. Further research should focus on the pathomechanisms and the possible arising therapeutic options.

Percutaneous Dilatational Tracheostomy in Ankylosing Spondylitis (Bechterew Disease) Is Feasible and Not Associated With Higher Complication Rates.

Background: Ankylosing spondylitis (AS) is a common disease with an incidence of approximately 0.5% in Europe, causing severe limitations of axial spine mobility and cervical kyphosis. Deformities of the cervical spine and the temporomandibular joints could increase the risk of complications while performing an intubation or tracheostomy. The percutaneous dilatational tracheostomy (PDT) is a standard procedure in intensive care medicine. However, the combination of cervical kyphosis and osteoporosis makes patient positioning challenging. Therefore, one could conclude that patients with AS are not candidates for PDT, but neither studies nor case reports yet reported about feasibility of this procedure in AS. Methods: Retrospective analysis at a level 1 trauma center of patient records from 2002 to 2016, assessing all patients with AS and PDT. Results: A total of 31 patients with AS have been subjected to PDT. All PDTs were performed using the modified Ciaglia single-step dilatational technique. Neither cardiopulmonary nor surgical complications occurred during the procedure. One patient received a change of the existing airway prior to the procedure; a small nasal tube was changed for a laryngeal mask. Conclusion: Although head positioning may be challenging, PDT should be taken into consideration for patients with AS. In the hands of an experienced doctor, it is safe and feasible.

Extracorporeal membrane oxygenation in spina bifida and (H1N1)-induced acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized as an acute hypoxemic and/or hypercapnic respiratory failure seen in critically ill patients and is still, although decreased over the past few years, associated with high mortality. Furthermore, ARDS may be a life-threatening complication of H1N1 pneumonia. We report on a 45-year-old spina bifida patient with confirmed H1N1 influenza virus infection causing acute respiratory failure, who was successfully weaned from 42-day veno-venous extracorporeal membrane oxygenation (vv-ECMO) treatment with an excellent outcome. Due to the physical constitution of spina bifida patients, we experienced challenges concerning cannula positioning and mechanical ventilation settings during weaning.