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Neural multicontact cuff electrodes have the potential to activate selectively different groups of muscles and offer more possibilities of electrical configurations compared to whole ring cuffs. Several previous studies explored multicontact electrodes with a limited set of configurations which were sorted using a selectivity index only. The objective of the present study is to classify a larger number of configurations, i.e. the way the current is spread over the 12 contacts of the cuff electrode, using additional criteria such as robustness (i.e. ability to maintain selectivity within a range of current amplitudes) and efficiency (i.e. electrical consumption of the considered multipolar configuration versus the electrical consumption of the reference whole-ring configuration). Experiments were performed on the sciatic nerve of 4 rabbits. Results indicated that the optimal configuration depends on the weights applied to selectivity, robustness and efficiency criteria. Tripolar transverse is the most robust configuration and the less efficient, whereas tripolar longitudinal ring is efficient but not robust. New configurations issued from a previous theoretical study we carried out such as steering current ring appears as good compromise between the 3 criteria., Competing Interests: The authors have read the journal’s policy and the authors of this manuscript have the following competing interests: WT is a paid employee of MxM. There are no patents, products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Following his return to Belgrade, Dejan established many collaborations with clinicians in Belgrade, most notably with the team at the Clinic for Rehabilitation "Dr. Miroslav Zotovi'c" in Belgrade. In 2005, Neurodan was acquired by Otto Bock medical systems, and the portfolio of acquired intellectual property included one of Dejan's patents for the functional electrical therapy system.15 In 2004, Dejan and Milica Piperski, his teaching assistant at the University of Belgrade, designed a system called Gammakey®. Dr. Dejan B. Popovi'c (Figure 1) passed away on October 4, 2021, in Belgrade, Serbia. On the left side is Dr. Laszlo Schwirtlich and in the middle is Dr. Dejan Popovi'c. gl Dejan often used his well-known sarcastic humor to spread the ideas shared by many but not supposed to be shared in public. [Extracted from the article]

This study aims to investigate the effect of a somatosensory cueing on gait disorders in subjects with Parkinson's disease (PD). After having performed stepping in place and timed up and go assessing tasks, 13 participants with PD were equipped with an electrical stimulator and an inertial measurement unit (IMU) located under the lateral malleolus on the sagittal plane. Electrodes were positioned under the arch of the foot and electrical stimulation (ES) parameters (five 500 µs/phase charge-balanced biphasic pulses delivered at 200 Hz, repeated four times at 10 Hz) adjusted to deliver a sensitive signal. Online IMU signal was processed in order to trigger ES at heel off detection. Starting from a quiet standing posture, subjects were asked to walk at their preferred speed on a path including 5 m straight line, u-turn, and walk around tasks. Three situations were considered: no stimulation baseline precondition (C0), ES condition (C1), and no stimulation baseline post-condition (C0bis), for eliminating a learning effect possibility. In ES condition (C1) the time to execute the different tasks was globally decreased in all the subjects ( n = 13). Participants' results were then grouped regarding whether they experienced freezing of gait (FOG) or not during C0 no stimulation baseline precondition. In 'freezer' subjects ( n = 9), the time to complete the entire path was reduced by 19%. FOG episodes occurrence was decreased by 12% compared to baseline conditions. This preliminary work showed a positive global effect on gait and FOG in PD by a somatosensory cueing based on sensitive electrical stimulation. [ABSTRACT FROM AUTHOR]

Most of the studies using functional electrical stimulation (FES) in gait rehabilitation have been focused on correcting the drop foot syndrome. Using FES to control the knee joint in individuals with central nervous system (CNS) disorders could also play a key role in gait recovery: spasticity decrease, higher range of motion, positive effect on balance, limiting hyperextension and flexion in stance phase, reducing joint overload, etc. In stance phase, an accurate timing and a fine tuning of stimulation parameters are however required to provide a proper control of the knee stimulation while ensuring a safe and efficient support. In this study, 11 participants were equipped with inertial measurements units (IMU) and foot pressure insoles after supratentorial ischemic or hemorrhagic stroke, informing on knee angle and gait events used to online adapt FES during a 10 m walking protocol. Asymmetry of stance time and weight bearing were monitored as well as gait quality and physiological cost through a series of relevant markers. Vertical trunk motion has been significantly reduced during gait with FES (p-value = 0.038). Despite no significant improvement of stance phase asymmetry has been found, this preliminary work shows evidence of promising technical and rehabilitative potentials of a sensor-based multichannel FES system to control knee joint in post-stroke gait. [ABSTRACT FROM AUTHOR]

• Foot-drop refers to the inability to perform complete ankle dorsiflexion during gait after a stroke. • The data treatment algorithms from inertial measurement units are able to accurately capture kinematic and spatio-temporal gait parameters for post-stroke patients with foot-drop syndrome. • Kinematic and gait parameters obtained from inertial measurement units reflect patient performance. Functional electrical stimulation (FES) can be used for compensation of foot-drop for post-stroke individuals by pre-programmed fixed stimulation; however, this stimulation seems no more effective than mechanical ankle foot orthoses. We evaluated the metrological quality of inertial sensors for movement reconstruction as compared with the gold-standard motion capturing system, to couple FES with inertial sensors to improve dorsiflexion on the paretic side, by using an adaptive stimulation taking into account individuals' performance post-stroke. Adults with ischemic or hemorrhagic stroke presenting foot-drop and able to walk 10 m, were included from May 2016 to June 2017. Those with passive ankle dorsiflexion < 0° with the knee stretched were excluded. Synchronous gait was analyzed with the VICON© system as the gold standard and inertial measurement units (IMUs) worn by participants. The main outcome was the dorsiflexion angle at the heel strike and mid-swing phase obtained from IMUs and the VICON system. Secondary outcomes were: stride length, walking speed, maximal ankle dorsiflexion velocity and fatigue detection. We included 26 participants [18 males; mean age 58 (range 45–84) years]. During heel strike, the dorsiflexion angle measurements demonstrated a root mean square error (RMSE) of 5.5°; a mean average error (MAE) of 3.9°; Bland-Altman bias of − 0.1° with limits of agreement − 10.9° to + 10.7° and good intra-class correlation coefficient (ICC) at 0.87 between the 2 techniques. During the mid-swing phase, the RMSE was 5.6; MAE 3.7°; Bland-Altman bias − 0.9° with limits of agreement − 11.7° to + 9.8° and ICC 0.88. Good agreement was demonstrated for secondary outcomes and fatigue detection. IMU-based reconstruction algorithms were effective in measuring ankle dorsiflexion with small biases and good ICCs in adults with ischemic or hemorrhagic stroke presenting foot-drop. The precision obtained is sufficient to observe the fatigue influence on the dorsiflexion and therefore to use IMUs to adapt FES. [ABSTRACT FROM AUTHOR]

Objective Eighty percent of poststroke patients are temporarily unable to walk without help, often with a dropfoot during the midswing phase. Functional electrical stimulation (FES) induces compensation of dropfoot by preprogrammed fixed stimulation, however they are not more effective than mechanical ankle foot orthesis. FES has the advantage of being able to provoke a physiological muscular contraction and respect the articular amplitude. Our objective is to evaluate the metrological quality of the inertial sensors for movement reconstruction in comparison to the gold standard motion analysis. The aim is to improve the SEF using adaptive triggers for dorsiflexion, in hemiplegic poststroke patients. Material/patients and methods Adults with supratentorial ischaemic or hemorrhagic stroke, presenting a foot-drop, able to walk 10 metres without human help, with or without a walking stick were included from May 2016 to June 2017. Patients with ankle dorsiflexion < 0° in knee extension were excluded. Synchronous gait analysis was performed using the VICON © system, the GAITRITE © walkway system and Fox Hikob inertial measurement unit (IMU). The main outcome is the measurement error for the dorsiflexion angle at the heel strike and midswing phase. Results Eleven patients included so far, 7 right sided hemiplegia, 8 male, mean age 56 years. To compare the IMU with the gold standard VICON, the measurement errors were estimated by Blant Altman analysis. Dorsiflexion angle measurements demonstrated a bias of 0.43° between the two techniques, with the limits of agreement [−13.46°; + 14.32°] during stance phases and a bias of 0.72° with agreement values [−16.19°; + 17.64°] during swing phases. Discussion, conclusion The data treatment algorithms from IMU seem to be effective in measuring ankle dorsiflexion with small biases between techniques. The limits of agreement are too wide from a clinical perspective, probably due to a small sample size, but are narrow enough to warrant further technological research. Analysis of the full sample size will provide further information on the limits of agreement. [ABSTRACT FROM AUTHOR]