Correction to: Advanced Robotic Therapy Integrated Centers (ARTIC): an international collaboration facilitating the application of rehabilitation technologies.

The original article [1] contains a small mistake concerning the ARTIC Team members mentioned in the Acknowledgements. The team member, Rocco Salvatore Calabrò had their name presented incorrectly. This has now been corrected in the original article.

Advanced Robotic Therapy Integrated Centers (ARTIC): an international collaboration facilitating the application of rehabilitation technologies.

BACKGROUND: The application of rehabilitation robots has grown during the last decade. While meta-analyses have shown beneficial effects of robotic interventions for some patient groups, the evidence is less in others. We established the Advanced Robotic Therapy Integrated Centers (ARTIC) network with the goal of advancing the science and clinical practice of rehabilitation robotics. The investigators hope to exploit variations in practice to learn about current clinical application and outcomes. The aim of this paper is to introduce the ARTIC network to the clinical and research community, present the initial data set and its characteristics and compare the outcome data collected so far with data from prior studies. METHODS: ARTIC is a pragmatic observational study of clinical care. The database includes patients with various neurological and gait deficits who used the driven gait orthosis Lokomat® as part of their treatment. Patient characteristics, diagnosis-specific information, and indicators of impairment severity are collected. Core clinical assessments include the 10-Meter Walk Test and the Goal Attainment Scaling. Data from each Lokomat® training session are automatically collected. RESULTS: At time of analysis, the database contained data collected from 595 patients (cerebral palsy: n = 208; stroke: n = 129; spinal cord injury: n = 93; traumatic brain injury: n = 39; and various other diagnoses: n = 126). At onset, average walking speeds were slow. The training intensity increased from the first to the final therapy session and most patients achieved their goals. CONCLUSIONS: The characteristics of the patients matched epidemiological data for the target populations. When patient characteristics differed from epidemiological data, this was mainly due to the selection criteria used to assess eligibility for Lokomat® training. While patients included in randomized controlled interventional trials have to fulfill many inclusion and exclusion criteria, the only selection criteria applying to patients in the ARTIC database are those required for use of the Lokomat®. We suggest that the ARTIC network offers an opportunity to investigate the clinical application and effectiveness of rehabilitation technologies for various diagnoses. Due to the standardization of assessments and the use of a common technology, this network could serve as a basis for researchers interested in specific interventional studies expanding beyond the Lokomat®.

The impact of the stimulation frequency on closed-loop control with electrotactile feedback.

BACKGROUND: Electrocutaneous stimulation can restore the missing sensory information to prosthetic users. In electrotactile feedback, the information about the prosthesis state is transmitted in the form of pulse trains. The stimulation frequency is an important parameter since it influences the data transmission rate over the feedback channel as well as the form of the elicited tactile sensations. METHODS: We evaluated the influence of the stimulation frequency on the subject's ability to utilize the feedback information during electrotactile closed-loop control. Ten healthy subjects performed a real-time compensatory tracking (standard test bench) of sinusoids and pseudorandom signals using either visual feedback (benchmark) or electrocutaneous feedback in seven conditions characterized by different combinations of the stimulation frequency (FSTIM) and tracking error sampling rate (FTE). The tracking error was transmitted using two concentric electrodes placed on the forearm. The quality of tracking was assessed using the Squared Pearson Correlation Coefficient (SPCC), the Normalized Root Mean Square Tracking Error (NRMSTE) and the time delay between the reference and generated trajectories (TDIO). RESULTS: The results demonstrated that FSTIM was more important for the control performance than FTE. The quality of tracking deteriorated with a decrease in the stimulation frequency, SPCC and NRMSTE (mean) were 87.5% and 9.4% in the condition 100/100 (FTE/FSTIM), respectively, and deteriorated to 61.1% and 15.3% in 5/5, respectively, while the TDIO increased from 359.8 ms in 100/100 to 1009 ms in 5/5. However, the performance recovered when the tracking error sampled at a low rate was delivered using a high stimulation frequency (SPCC = 83.6%, NRMSTE = 10.3%, TDIO = 415.6 ms, in 5/100). CONCLUSIONS: The likely reason for the performance decrease and recovery was that the stimulation frequency critically influenced the tactile perception quality and thereby the effective rate of information transfer through the feedback channel. The outcome of this study can facilitate the selection of optimal system parameters for somatosensory feedback in upper limb prostheses. The results imply that the feedback variables (e.g., grasping force) should be transmitted at relatively high frequencies of stimulation (>25 Hz), but that they can be sampled at much lower rates (e.g., 5 Hz).

Self-correcting pattern recognition system of surface EMG signals for upper limb prosthesis control.

Pattern recognition methods for classifying user motion intent based on surface electromyography developed by research groups in well-controlled laboratory conditions are not yet clinically viable for upper limb prosthesis control, due to their limited robustness in users' real-life situations. To address this problem, a novel postprocessing algorithm, aiming to detect and remove misclassifications of a pattern recognition system of forearm and hand motions, is proposed. Using the maximum likelihood calculated by a classifier and the mean global muscle activity of the forearm, an artificial neural network was trained to detect potentially erroneous classification decisions. This system was compared to four previously proposed classification postprocessing methods, in both able-bodied and amputee subjects. Various nonstationarities were included in the experimental protocol to account for challenges posed in real-life settings, such as different contraction levels, static and dynamic motion phases, and effects induced by day-to-day transfers, such as electrode shifts, impedance changes, and psychometric user variability. The improvement in classification accuracy with respect to the unprocessed classifier ranged from 4.8% to 31.6%, depending on the scenarios investigated. The system significantly reduced misclassifications to wrong active classes and is thus a promising approach for improving the robustness of hand prosthesis controllability.

Covariate shift adaptation in EMG pattern recognition for prosthetic device control.

Ensuring robustness of myocontrol algorithms for prosthetic devices is an important challenge. Robustness needs to be maintained under nonstationarities, e.g. due to electrode shifts after donning and doffing, sweating, additional weight or varying arm positions. Such nonstationary behavior changes the signal distributions - a scenario often referred to as covariate shift. This circumstance causes a significant decrease in classification accuracy in daily life applications. Re-training is possible but it is time consuming since it requires a large number of trials. In this paper, we propose to adapt the EMG classifier by a small calibration set only, which is able to capture the relevant aspects of the nonstationarities, but requires re-training data of only very short duration. We tested this strategy on signals acquired across 5 days in able-bodied individuals. The results showed that an estimator that shrinks the training model parameters towards the calibration set parameters significantly increased the classifier performance across different testing days. Even when using only one trial per class as re-training data for each day, the classification accuracy remained > 92% over five days. These results indicate that the proposed methodology can be a practical means for improving robustness in pattern recognition methods for myocontrol.

Long term stability of surface EMG pattern classification for prosthetic control.

Long-term functioning of a hand prosthesis is crucial for its acceptance by patients with upper limb deficit. In this study the reliability over days of the performance of pattern classification approaches based on surface electromyography (sEMG) signal for the control of upper limb prostheses was investigated. Recordings of sEMG from the forearm muscles were obtained across five consecutive days from five healthy subjects. It was demonstrated that the classification performance decreased monotonically on average by 4.1% per day. It was also found that the accumulated error was confined to three of the eight movement classes investigated. This contribution gives insight on the long term behavior of pattern classification, which is crucial for commercial viability.

Real time simultaneous and proportional control of multiple degrees of freedom from surface EMG: Preliminary results on subjects with limb deficiency.

We present the real time simultaneous and proportional control of two degrees of freedom (DoF), using surface electromyographic signals from the residual limbs of three subject with limb deficiency. Three subjects could control a virtual object in two dimensions using their residual muscle activities to achieve goal-oriented tasks. The subjects indicated that they found the control intuitive and useful. These results show that such a simultaneous and proportional control paradigm is a promising direction for multi-functional prosthetic control.

Current-distance relations for microelectrode stimulation of pyramidal cells.

Microelectrodes placed within the densely packed cortical neuronal region are surrounded by many thin processes. Although dendrites are considered to be functionally different to axons, they also possess voltage sensitive membrane channels. Therefore, dendritic regions are suitable candidates for spike initiation sites when stimulated externally, although they demand two to three times higher thresholds in comparison with thin axons. Simulations based upon recently reported distributions of two types of sodium channels and traced pyramidal cell data accompanied by a simplified model structure enlightened the spike initiation sites for extracellular cortical microstimulation and revealed insights into dendritic excitation patterns. Surprisingly low dendritic threshold values for cathodic stimulation were detected, that is, 3.3 µA for a 0.4-µm diameter fiber excited with a 100-µs pulse in 4-µm distance. However, according to the activating function concept the excited region is calculated by 1414*electrode-distance, therefore a minimum electrode-fiber distance is required as sufficient sodium channels are needed to produce enough intracellular current for spike conduction. The minimum distance for dendritic spike initiation increases with diameter and hinders low current stimulation of thick dendrites. This effect is in contrast to the inverse recruitment order known from functional electrical stimulation. Simulations were performed using NEURON and MATLAB.

A new multiplex PCR assay for the simultaneous detection of vancomycin-resistant enterococci from rectal swabs.

OBJECTIVES: This study describes the diagnostic performance of a recently available multiplex PCR-based kit for the simultaneous detection and identification of Enterococcus faecium, Enterococcus faecalis, vanA, vanB, vanC1 and vanC2/C3 genes, directly from rectal swabs constituting the most complete existing molecular assay currently available. METHODS: The diagnostic performance of this assay was evaluated by a multicenter study involving three independent public hospitals and consisted in the analysis of 187 rectal swabs from patients at high risk for vancomycin-resistant enterococci colonization. RESULTS: When bacteria culture was used as the gold standard, the sensitivity, specificity, positive and negative predicted values for the assay were 96.8%, 76.0%, 67.7% and 97.9%, respectively. When a composite reference standard consisting of culture and DNA sequencing of PCR products was used as the gold standard, the sensitivity, specificity, positive and negative predicted values for the PCR-based assay were 97.8%, 96.9%, 96.7% and 97.9%, respectively. CONCLUSIONS: Based on these results, we conclude that this assay is considerably more sensitive than traditional microbiological methods for detecting vancomycin-resistant enterococci from rectal swabs. It is also much faster than culture. We believe that the implementation of this assay in routine clinical laboratories could help to reduce hospital-acquired vancomycin-resistant enterococci infections.

Anaerobios en sinusitis maxilar aguda / Anaerobios in acute maxillary sinusitis

Se examinó bacteriológicamente 56 muestras de secreción sinusal obtenidas por punción aspirativa de senos maxilares de 39 pacientes adultos con evidencia clínica y radiológica de sinusitis maxilar aguda. Las muestras se cultivaron con técnicas microbiológicas habituales para pesquisa de gérmenes aerobios y anaerobios. La positividad del cultivo de las punciones practicadas fue de un 62,5 por ciento demostrándose la presencia de anaerobios en el 21,4 por ciento de éstas y encontrándose anaerobios puros en el 14,3 por ciento . Los gérmenes anaerobios mas frecuentes aislados fueron el Peptostreptococcus y el Propionibacterium, bacterias habituales de la flora buconasal