A Non Linear Model to explain persons with StrokePresentation Transcript
A Non Linear Model to explain persons with Stroke K Hari ohm Professor in PT MSAJ college of PT The Indian Centre for Evidence Based Neuro-Rehabilitation
Introduction• Humans like many natural systems are complex• How do we commonly study complex systems
Reductionism• Reductionism - understanding the nature of complex things by reducing them to simpler or more fundamental things• Philosophical position that a complex system is the sum of its parts, and that an account of it can be reduced to accounts of individual constituents• Reductionism is the belief that human behavior can be explained by breaking it down into smaller component parts. Reductionism and Holism in Psychology by Saul McLeod
What is linearity• Linearity• Linear systems satisfy the properties of superposition and homogeneity.• Add them up• Starting state- predictability of complex system• Point to point relation
Applying reductionism inunderstanding and managing stroke
Why is not my patient walking? • Spasticity Impairments • weakness • Inability to walk Disability • unable to eat • Unable to go to work • Unable to go to handicap marriage
Paraphrasing Esther Thelen questionWHAT IS THE DIFFERENCE BETWEEN APATIENT WHO HAS LEARNED TO WALKAND WHO HAS NOT?•IS BIOLOGICAL FACTORS ENOUGH ?•CAN HUMAN SYSTEM BE SUBJECTED TOREDUCTIONISM ?
• Will be true if it is a Simple system or Static1. Human systems are dynamic and complex2. Variable
Understanding variations• In human biology – variation is normality• Behavioural variability• Movement variability – Throw darts- for example, we are unable to hit the ‘bull’s eye’ on every attempt. – When we walk, our footprints never repeat themselves exactly. – When we stand quietly, we continuously sway around a central equilibrium point without ever remaining exactly still
Example of Increased Stride Time Variability in Elderly FallersQuantification of Stride-to-Stride Fluctuations Time (min) Time (min)
Variability or noise• James Clerk Maxwell (1879), Henri Poincare (1912), Edward Lorenz 1961
Non linearity• This paradigm has no single name but has been described in terms of1. Chaos2. Nonlinear dynamics (sometimes called nonlinear dynamical systems theory),3. Complexity theory4. Self-organization. Scott Barton January 1994 • American Psychologist Chaos, Self-Organization, and Psychology
What is Non linearity ?• “Nonlinear dynamics,” can be defined as a system whose output is not proportional to its input.• Nonlinear systems are more complex
Nonlinear• Nonlinear equations are not additive; therefore, they are often difficult to solve.• Sometimes a single solution can be obtained, but often the answer involves a pattern of solutions.• Nonlinear systems tend to settle down over time.
• Human beings are nonlinear because a small change in input can lead to a huge and unpredictable change in output.• A minor change in initial conditions may lead to a significant, abrupt change of behavior
Some properties of non-linear dynamic systems are:• They do not follow the principle of superposition (linearity and homogeneity)
• Timing and form of such changes are not fully predictable due to the complexity of the system• They may have multiple isolated equilibrium points (linear systems can have only one)• They may exhibit properties such as bifurcation, chaos, self organization emergence etc.
Complex system• Fundamentally a system is complex, if its behavior cannot be easily described.• System consists of many components,• Numerous relationships and interactions between these components.• This is a nonlinear system because the input does not lead to a linear change in output. Balance control in hemiparetic stroke patients: Main tools for evaluation Clarissa Barros de Oliveira et al J Rehabil Res Dev. 2008;45(8):1215-26.
Non linearity• One of the fundamental principles of complex systems is non linearity• Complex systems are dynamical systems they change over time• Difficult to determine the boundaries of a complex system
• interdependence of variables in a nonlinear system, along with sensitivity to initial conditions, lead to the implication that studying each factor in isolation may not lead to useful knowledge about the behavior of the system as a whole
IMPLICATION FOR STROKEMANAGEMENT
Model of aperson withstroke in nonlinear complexsystem From Stroke rehabilitation : a functional activity based approach K Hari ohm R Vasanthan
Implication for stroke management• Non linear systems are hard to solve – They cannot be broken into parts