FES: CENTER
Dr. Dewald is Chair of the Department of Physical Therapy and Human Movement Sciences and Professor of Physical Therapy and Human Movement Sciences in the Department of Physical Medicine and Rehabilitation at Northwestern University Feinberg School of Medicine. He is also a Professor with the McCormick School of Engineering at Northwestern University and an Adjunct Professor of BME at University of Twente, The Netherlands.
Abstract: The main goal of this presentation is to discuss possible neural mechanisms underlying the loss of independent joint control or limb synergies and stretch reflex hyperactivity (spasticity) in the paretic arm/hand following a unilateral brain injury. Furthermore, novel treatments using a combination of neurophysiological and engineering techniques to reduce the effects of especially the flexor synergy, will be discussed. I will present evidence for the loss of independent joint control in the paretic limb of individuals with stroke during isometric multi-degree of freedom load cell measures and during movements in haptic environments. Furthermore, the relationship between the loss of independent joint control and cortical reorganization using high-resolution EEG, combined with peripheral robot-mediated quantitative measures of a loss of independent joint control. The possibility of increased reliance on bulbospinal pathways, especially the reticulospinal pathway, following the loss of brain injury-induced corticospinal projections will be discussed. Additional research I will briefly discuss involves the study of quantitative computer-driven visual and haptic feedback techniques that seek to improve the ability to produce the necessary torque combinations for reaching and retrieval motions with the paretic arm/hand using novel bio-robotic approaches. We are also working on man-machine interfaces and on pharmacological interventions that aim to alter brain, spinal, and/or brainstem neuronal excitability. Concurrently, we have been studying the impact of time of injury (pre-, peri- versus post- natal brain injuries) on motor impairments in childhood hemiparesis. Up-regulation of reticulospinal motor pathways resulting in an increased neuromodulation of spinal motor neurons is believed to be the source of altered spinal reflex activity (spasticity), and the loss of independent joint control may very well be an important cause for movement discoordination observed in stroke and postnatal childhood hemiparesis.
Dr. Dewald received a Bachelor’s and Master’s degree in Physical Therapy and Motor Rehabilitation from the Vrije Universiteit Brussel, Brussels, Belgium, in 1978 and 1980, respectively, and a PhD in Neurophysiology and Biophysics in 1992 from Loma Linda University, Loma Linda, California. From 1988-2001, Dr. Dewald worked as a pre-doctoral investigator, subsequently as a postdoc, clinical assistant
professor, and finally as a senior clinical research scientist in the Rehabilitation Institute of Chicago (now called the Shirley Ryan AbilityLab). From 2001 to 2005, Dr. Dewald worked as a tenure-track assistant professor in the departments of Physical Therapy & Human Movement Sciences (PTHMS), Biomedical Engineering (BME), and Physical Medicine & Rehabilitation (PM&R) at Northwestern University. He became chair and associate professor in PTHMS and associate professor in BME (core position) and PM&R in 2006. In 2010, Dr. Dewald became a full professor in PTHMS, BME, and PM&R. Dr. Dewald is the director of the neuroimaging and motor control laboratories, and his research is funded by the National Institutes of Health (NIH), the National Science Foundation (NSF), and the American Heart Association (AHA). He has worked for over 30 years in the area of characterizing mechanisms underlying the loss of independent joint control and spasticity following brain injury due to stroke and cerebral palsy, using various engineering techniques.