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10:30   Neuromechanics II Chair: Herman van der Kooij 10:30 15 mins FEASIBILITY AND EFFICACY OF A NEW LASER-BASED CUEING DEVICE, PATH FINDER, FOR FREEZING OF GAIT IN PARKINSON’S DISEASE Murielle Ferraye, Claudia Barthel, Nonnekes Jorik, Renée Haan, Arno Janssen, Vivian Weerdesteyn, Bettina Debû, Richard van Wezel, Bastiaan Bloem Abstract: Background Freezing of gait (FoG) in Parkinson’s disease (PD) is defined as a general inability to produce effective steps (1). FoG remains a great treatment challenge in clinical practice (2). Non-pharmaceutical approaches such as cueing are generating a growing interest for the management of FoG. Cueing encompasses a large range of means to increase perceptual sensations in a patient in the aim to trigger movement through compensatory cerebral pathways. Visual cueing could be the preferred cueing modality for FoG. However, thus far, it has proven difficult to translate visual cueing observations to the patients’ own real-life environment, and in particular to deliver cueing continuously as an ambulatory intervention that can assist patients regardless of where they are. Here, we introduce Path Finder, a new cueing device with practical applicability for use in daily life (3). Methods We tested the feasibility and efficacy of Path Finder in 22 PD patients with FoG, both in the lab (OFF and ON medication) and in-home. In the lab, we measured the number of FoG episodes and the percent time frozen occurring while walking under FoG provoking circumstances. The home measurement involved 3 one-week periods consisting of walking with Path Finder switched OFF (week 1, Passive control), with Path Finder switched ON (week 2, Path Finder), and after withdrawal of Path Finder (week 3, Carry-over). The New Freezing of Gait Questionnaire (NFOGQ) was administered following the three in-home measurements. Results The percent time frozen significantly reduced with Path Finder ON, both OFF (33.8 %) and ON medication (32.1 %). There was a significant difference in the total NFOGQ score between the Control and Path Finder conditions (15.3 % reduction) and between the Control and Carry-over periods, while the Path Finder period did not significantly differ from the Carry-over period. Conclusions Taken together, these findings suggest a promising potential for Path Finder to provide patients with FoG with in-home successful cueing. 10:45 15 mins CUEING VIA SMART GLASSES TO REDUCE FREEZING OF GAIT IN PATIENTS WITH PARKINSON’S DISEASE Sabine Janssen, Jorik Nonnekes, Benjamin Bolte, Marian Bittner, Anja van Gestel, Erwin van Wegen, Lucille Dorresteijn, Agnes Wertenbroek, Henk Willem Nijmeijer, Jeroen van Vugt, Marleen Tjepkema-Cloostermans, Bastiaan Bloem, Richard van Wezel, Yan Zhao Abstract: Part of the people with Parkinson’s Disease (PD) experience freezing of gait (FOG): a disabling phenomenon in which sudden paroxysmal gait arrests prevent effective forward movement, described ‘as if the feet are glued to the floor’. In between episodes of FOG, patients with PD and FOG (PD-FOG) display gait abnormalities such as increased step timing variability and reduced stride length, suggesting a more continuous timing and scaling deficit. External cues like a metronome or transverse lines on the floor can facilitate gait initiation and continuation, and reduce FOG. However, current (especially visual) cueing strategies are difficult to apply in daily life, pointing out a need for portable visual cues. Smart glasses carry the potential to offer personalized, portable cues and have been welcomed as an assistive technology to facilitate daily living by a majority of respondents in an user requirement survey amongst patients with PD(1). We study the effect of cues delivered through smart glasses on FOG and gait. In our first smart glasses study, 12 patients with PD-FOG walked along a FOG-provoking trajectory whilst wearing a Google Glass providing three different external cues (metronome, flashing light, and optic flow) or ‘no cue'. The presence of FOG episodes was scored using video recordings; motion data from inertial sensors was used for gait analysis(2). In our second, ongoing study, patients with PD-FOG walk along a similar trajectory whilst receiving augmented three-dimensional (3D) visual cues in the central visual field via custom-made smart glasses. Again, video recordings and motion data are used for analysis of FOG and kinematics. In our Google Glass study, 41 episodes of FOG were elicited in 8 out of 12 participants. Fewer FOG episodes occurred when the metronome was applied during 360˚ turns. Otherwise, the number and duration of FOG episodes did not significantly differ amongst cueing conditions(2). All cues reduced stride length variability and deviation in cadence from the cueing frequency. The results of the ongoing study with custom-made smart glasses are expected early 2017. The low number of FOG episodes in the Google Glass study has likely reduced the power to find a significant effect of cues on FOG. FOG is notorious for being difficult to provoke in a laboratory, underscoring the importance to study cueing devices in the home situation. The reduction in stride length and cadence variability suggests a more stable walking pattern when cues are applied. In conclusion, cues delivered through smart glasses have a varying effect on FOG and gait parameters. Our current study is expected to answer the question whether augmented 3D visual cues in the lower to central visual field improve FOG and walking parameters in a laboratory setting. 1. Zhao Y, Heida T, van Wegen EE, Bloem BR, van Wezel RJ. E-health Support in People with Parkinson's Disease with Smart Glasses: A Survey of User Requirements and Expectations in the Netherlands. Journal of Parkinson's disease. 2015. 2. Zhao Y, Nonnekes J, Storcken EJ, Janssen S, van Wegen EE, Bloem BR, et al. Feasibility of external rhythmic cueing with the Google Glass for improving gait in people with Parkinson's disease. Journal of neurology. 2016;263(6):1156-65. 11:00 15 mins TREADMILL PERTURBATIONS TO EVOKE STRETCH REFLEXES DURING GAIT IN CHILDREN WITH CEREBRAL PALSY Lizeth Sloot, Laurien van Capelleveen, Janne van der Heijden, Annemieke Buizer, Jaap Harlaar, Marjolein van der Krogt Abstract: Spasticity, i.e. exaggerated velocity-dependent stretch reflex activity, is one of the key impairments in neurological diseases, but its effect on gait is unclear [1]. To quantify spastic reflexes during gait, ankle rotations have been applied by mechanical devices [2], but a feasible technical solution that can be integrated into current clinical gait analysis is warranted for treatment selection. Our aim was to investigate whether treadmill perturbations can be used to quantify stretch reflexes during gait in typically developing (TD) children and children with cerebral palsy (CP), as previously shown for healthy adults [3]. 14 TD children (10.8±3.1y) and 4 children with CP (9.8±1.3y / GMFCSI-II, data collection ongoing) walked on a split-belt instrumented treadmill at fixed walking speed, for 6 minutes. Treadmill belt accelerations and decelerations of three different intensities (change in belt speed of 0.13, 0.26 and 0.37 m/s respectively within 20 ms) were applied just after initial contact, 10 times each in random order. 3D kinematics and EMG of eight main leg muscles were analyzed [3]. In TD, perturbations resulted in increased ankle dorsiflexion, which increased with intensity up to 3.7±1.7° (p<.001). This caused an increasing stretch velocity of gastrocnemius and soleus, and bursts of increased muscle activity in these muscles up to twice the normal value (p<0.001). Reactions in CP were more variable, with 3 out of 4 subjects showing enhanced activity in either gastrocnemius, soleus and/or peroneus muscles compared with TD. These results indicate that stretch reflexes can be evoked using treadmill perturbations in both TD and CP. The enhanced reflex activity in CP indicates that treadmill perturbations are a promising method for assessing spasticity during gait in a clinically applicable manner. Future study will include the analysis of ankle joint stiffness using ground reaction forces, to unravel the passive and active contributions to joint hyper-resistance during gait in patients with spasticity. 11:15 15 mins PRESSURE INSOLES FOR GAIT AND BALANCE ESTIMATION Mohamed Irfan Mohamed Refai, Bert-Jan van Beijnum, Peter Veltink Abstract: Stroke leads to impairment in motor ability, gait, and balance, due to brain tissue damage [1]. Clinical therapy following stroke aims at improving mobility and functional capacity. However, there is lack of objective information about subject’s performance once they are transferred home [2]. A wearable, unobtrusive system is needed to describe and compare clinical capacity and performance in a home setting. Systems have been designed to provide holistic information about the subject’s gait and balance [2], [3]. They have shown differences in the capacity and performance of the subject by using a range of measures to estimate gait and balance. However, these systems are obtrusive and require a long time to set up. This project addresses the need for a wearable and minimal sensing system with an unobtrusive set up. Pressure insoles are inconspicuous, and when coupled with an Inertial Measurement Unit (IMU), several gait and balance measures can be estimated. In this study, a 1-D pressure insole system (MEDILOGIC®) is coupled with an IMU (Xsens) to obtain qualitative gait and balance measures, including Step length and width, Centre of Pressure, Extended Centre of Mass, and compared against a 3-D system, the Force Shoes™ (Xsens) [4], [5]. The results will be used to validate the use of a 1-D system for gait and balance measures. The results will also be used in designing a wearable in-shoe system that can be used in daily life monitoring for stroke subjects. The study is a part of project 7 of NeuroCIMT, funded by the Dutch National foundation STW. REFERENCES [1] S. F. Tyson, M. Hanley, J. Chillala, A. Selley, and R. C. Tallis, “Balance disability after stroke.,” Phys. Ther., vol. 86, no. 1, pp. 30–38, 2006. [2] B. Klaassen, B.-J. F. van Beijnum, M. Weusthof, D. Hof, F. B. van Meulen, Ed Droog, H. Luinge, L. Slot, A. Tognetti, F. Lorussi, R. Paradiso, J. Held, A. Luft, J. Reenalda, C. Nikamp, J. H. Buurke, H. J. Hermens, and P. H. Veltink, “A Full Body Sensing System for Monitoring Stroke Patients in a Home Environment,” Commun. Comput. Inf. Sci., vol. 511, pp. 378–393, 2016. [3] S. J. M. Bamberg, A. Y. Benbasat, D. M. Scarborough, D. E. Krebs, and J. A. Paradiso, “Gait analysis using a shoe-integrated wireless sensor system.,” IEEE Trans. Inf. Technol. Biomed., vol. 12, no. 4, pp. 413–23, 2008. [4] A. L. Hof, M. G. J. Gazendam, and W. E. Sinke, “The condition for dynamic stability,” J. Biomech., vol. 38, no. 1, pp. 1–8, 2005. [5] F. B. Van Meulen, D. Weenk, E. H. F. Van Asseldonk, and H. M. Schepers, “Analysis of dynamic balance during functional walking in stroke survivors,” PLoS One, pp. 1–29. 11:30 15 mins MODELLING AND SIMULATING HUMAN SENSORIMOTOR CONTROL DURING STANCE: A NEUROROBOTICS APPROACH Jantsje Pasma, Lorenz Asslander, Joost van Kordelaar, Digna de Kam, Thomas Mergner, Alfred Schouten Abstract: Balance control models are often used to describe human balance behaviour identified in the frequency domain using system identification. A good balance control model helps to get more insight in the underlying mechanisms and therefore to improve diagnosis of impaired balance and apply targeted interventions to reduce falling. We validated a commonly used balance control model, the independent channel (IC) model [1], using human experiments, computer simulations and real world situations simulated with a humanoid robot in the time domain. This will provide insight in the robustness of the model under real world conditions. Seven healthy young participants were included. Balance behaviour was measured by applying pseudorandom continuous support surface rotations with maximum amplitudes of 0.5 and 1 degrees peak-to-peak with eyes open and eyes closed, while the participants kept their balance on the support surface, and recording the body sway. System identification and parameter estimation were used to describe the balance behaviour by Frequency Response Functions (FRFs) and estimated model parameters. The IC model with the estimated parameters from human experiments was implemented in Simulink for both computer simulations and robot experiments, in which the PostuRob II [2] was used. The balance behaviour simulated by the computer and the robot was again described using system identification and parameter estimation. The body sway, FRFs and estimated parameters from experiments and simulations were compared to investigate the validity of the IC model. The relative mean absolute difference in body sway between the human experiments and the simulations was in the range of 11.15-23.22% and the range of 45.51-62.14% for the robot experiments. The FRFs of the human experiments, simulations and robot experiments showed small differences, except around the resonance peak for the robot experiments. The differences in parameters between the simulations and the human experiments ranged from 10.71-16.89% and from 13.60-27.28% for the robot experiments. In conclusion, the IC model is able to mimic human balance behaviour in the time and frequency domain, both in computer simulations and robot experiments, and is able to keep the robot in an upright position. Therefore, the IC model is valid and robust in a real world situation to control the humanoid robot, despite the descriptive nature of the model. [1] R.J. Peterka, “Sensorimotor integration in human postural control”, J Neurophysiol, 88(3): p. 1097-118, (2002). [2] G. Hettich, L. Asslander, A. Gollhofer, and Mergner, T, “Human hip-ankle coordination emerging from multisensory feedback control”, Hum Mov Sci, 37: p. 123-146, (2014). 11:45 15 mins DYNAMIC ULTRASOUND IMAGING OF TISSUE DEFORMATION OF THE TIBIALIS ANTERIOR IN FACIOSCAPULOHUMERAL DYSTROPHY Kaj Gijsbertse, André Sprengers, Maartje Nillesen, Nico Verdonschot, Chris de Korte Abstract: ABSTRACT: Ultrasound imaging can be used as either a screening tool for the presence of neuromuscular disease or as a focused examination looking for patterns found in a specific neuromuscular disorder. Ultrasound imaging of muscle typically focuses on the assessment of anatomical features (e.g., muscle thickness, fascicle length and pennation angle) and echogenicity of the muscle. Facioscapulohumeral dystrophy (FSHD) is the third most common inherited muscular dystrophy after Duchenne dystrophy and myotonic dystrophy. Ultrasound has been used to evaluate the pathological condition of these patients using quantitative grey-scale analysis [1]. An increase of echo intensity reflects increasing dystrophic muscle. Although currently the progression of the disease can be monitored measuring the echo intensity of the muscle, the exact change in functional behaviour is not understood. The goal of this study was to investigate the m. tibialis anterior tissue displacement patterns in FSHD patients. This information might provide complementary insights into the progression of FSHD. Two-dimensional ultrasound data were acquired in the longitudinal direction at the centre of the m. tibialis anterior in six FSHD patients during maximum voluntary isometric contraction. All patients were scored using a 10-grade clinical severity scale (CSS), and fat infiltration was assessed by the mean echogenicity level of the muscle tissue. Subsequently a cross-correlation based algorithm was used to track muscle tissue displacement locally throughout the contraction [2]. The results show a different displacement pattern for mildly affected patients than for severely affected patients with muscles with high infiltration of fat. For mildly affected patients non-uniform tissue displacement patterns were observed, with the central aponeurosis consistently exhibiting larger displacements than the superficial and deeper layers of the muscle (average of 1.8 times larger). Patients with severely affected muscle tissue showed a more homogeneous displacement pattern, where the superficial and deeper layers of the muscle exhibited almost equal displacement as the central aponeurosis. The results indicate a strong relation between the severity of muscle dystrophy and muscle tissue displacement patterns. Therefore, dynamic ultrasound imaging might be a promising technique to help understand the pathophysiological mechanisms in neuromuscular diseases such as FSHD. REFERENCES: [1] B. H. Janssen, S. Pillen, N. B. Voet, A. Heerschap, B. G. van Engelen, and N. van Alfen, "Quantitative muscle ultrasound versus quantitative magnetic resonance imaging in facioscapulohumeral dystrophy," Muscle Nerve, vol. 50, pp. 968-75, Dec 2014. [2] R. G. Lopata, J. P. van Dijk, S. Pillen, M. M. Nillesen, H. Maas, J. M. Thijssen, et al., "Dynamic imaging of skeletal muscle contraction in three orthogonal directions," J Appl Physiol (1985), vol. 109, pp. 906-15, Sep 2010.