Assistive Exercise Machine for Post Stroke. Rehabilitation. Portland State University Advisor. Portland State University Instructor

Transcription

1 Assistive Exercise Machine for Post Stroke Winter 2014 Rehabilitation Group Members Fahad Aldakheel Chad Knutsen Melanie Ferguson Hamid Tavazoie Evan Topinka Portland State University Advisor Dr. Dave Turcic Portland State University Instructor Dr. Sung Yi Industry Advisors Gregg Meyer, MME Dieterich Steinmetz, M.D. Amy Walker, MPT PORTLAND STATE UNIVERSITY Mechanical Engineering Dept.

2 EXECUTIVE SUMMARY Myoelectric Robotic Orthosis is a device created for Stroke Survivors. It senses the brain signal to a muscle group to power a pulley system connected to the person to assist in therapeutic activities. Our team designated a list of constraints to follow when creating the device, and have since made modifications to that list. From research, interviews, and testing, we have made changes to what our top priorities are. This progress report discusses what our new priorities are, as well as comparing our original goals with our new ones. We will evaluate our progress and delve deeper into our internal and external research. Without a company to fund us or look up to for answers and evaluation, we rely on the consumer to guide us through this process.

3 Contents INTRODUCTION... 4 MISSION STATEMENT... 4 PROJECT PLAN... 5 PRODUCT DESIGN SPECIFICATION SUMMARY... 6 EXTERNAL SEARCH... 7 INTERNAL SEARCH... 8 DESIGN EVALUATION & SELECTION... 8 DETAILED DESIGN PROGRESS CONCLUSION APPENDIX REFERENCES... 24

4 INTRODUCTION According to the National Institute of Neurological Disorders and stroke, there are approximately 4 million Americans living with the effects of stroke (1). Many stroke survivors suffer from weakness (hemiparesis) or paralysis (hemiplegia) on one side of their body affecting the use of their limbs. Therefore, Myoelectric Robotic Orthosis is medical device that will help stroke survivors regain the ability of moving their limbs in a rapid amount of time compared with current physical therapy methods. Basically, this medical device is an exercise machine that uses advanced technology to detect the voltage signals via Biopotential electrode sensors in the Electromyography (EMG) Amplifier. In other words, EMG measures muscle response or electrical activity in response to a nerve s stimulation of the muscle. Most medical researchers use EMG to test if muscles and nerves are working correctly (2). However, in this project it s important to take advantage of the muscle electrical activity and use it as input for the motor. Therefore, electrical signals will be amplified and used to function the device. Figure 1 shows the five main processes in the device. MISSION STATEMENT Designing this medical device will develop the method of integrating technology with physical therapy. It will help stroke survivors relearn skills that are lost when part of the brain is damaged. Also, it will help them to become as independent as possible in a rapid amount of time compared to traditional physical therapy exercises. The ultimate goal is to deliver the final product by the end of Spring 2014.

5 PROJECT PLAN Our project plan was created precisely to keep track of all the work and assignments needed through winter The project plan consists of breaking up the timeline into three different phases. As shown in tables 1, 2 and 3 the team is already done with phase 1 and 2 and still working on the final task in phase 3. However, for spring 2014, our project plan will focus on phase 4, Detailed Design Development. In this phase, a prototype will be built and tested for range of motion, strength, and ease of use for stroke survivors. Table 4 shows all the tasks required in phase 4. - Phase One: Electrical Design Done Electrical Design Phase Due By YES Brainstorming And Ideas 1/30/14 YES Electronic Enclosure Detailed Design 1/30/14 YES Integrating Electronic Components 2/6/14 YES Specify Motor, controller and Voltage regulator 2/6/14 - Phase Two: Programming Done Programming Phase Due By YES Conceptual Brainstorming 2/13/14 YES Configure Microcontroller program 2/13/14 YES Test the program 2/20/14 - Phase Three: Mechanical Components Done Mechanical Prototyping Due By YES Measure Required Torque and speed range for arm 2/26/14 YES Specify Motor Power 2/26/14 YES Specify Gearhead 2/26/14 YES Integrating Programming and Mechanical Phases 3/6/14 Detailed Design Ideas 3/16/14

6 - Phase four: Detailed Design Development Done Final Mechanical Assembly Due By Detailed design Discussion 4/3/14 CAD Model/Solidworks 4/10/14 Generating G-Code 4/17/14 CNC Machining of electronics enclosure 4/24/14 3D print and laser cutting 4/24/14 Machining Rigid Support Frame 5/2/12 Design thermoform mold 5/9/14 Sewing 5/16/14 3D Print thermoform mold 5/16/14 Thermoforming of cuffs 5/23/14 Assembly 5/30/14 Test Prototype 6/1/14 - Refer to Appendix-A for the detailed descriptions of all the tasks and the approximate amount of time that is associated for each task. PRODUCT DESIGN SPECIFICATION SUMMARY A Product Design Specification layout was created to act as a guide to design this product. Electrical and programming designs is complete, therefore the mechanical design components are the main focus of the updated PDS. From the research and interviews conducted since the original PDS document, the following summary of the updated design specifications was created. REQUIREMENTS Survivor - Comfort is a luxury, but should be integrated if possible. - There should be no safety concerns that distract the patient from their mental focus. - Ease of use will also allow mental focus on the task at hand. Therapist - Target multiple muscle groups. - Device needs to work as good, or better than current technology. - It will save time and money by allowing patients to use it without assistance. - The machine needs to be adjustable to perform multiple exercises.

7 - A wall-mounted design is of preference. - Exercises should target extension muscles, as well as contraction muscles. - Level-plane motion (perpendicular to force of gravity) is of importance. - Exercises should mimic everyday tasks. - Repetition is a major component of success. These are all things that are necessary for this product to function in a matter that will be accepted by and purchased by the therapeutic industry. EXTERNAL SEARCH There are many methods, devices, and machines being used in post stroke rehabilitation. The devices and machines that appeared to be affective were too expensive and the affordable options were already being offered to my grandma. The existing devices are passive. Passive rehabilitation included devices and methods that assist the patient through a task or motion without the patient initiating or controlling the movement. An example of this is a simple range of motion exercise where the therapist holds the patients arm and physically assists them. Another example is the parallel beams. These are used to assist the patient in relearning how to walk. After doing neurological research on the physiology of a stroke, and reading case studies relating to stroke therapy, the idea for an active therapy device came about. An overview of the findings from this research can be found in appendix A. An active therapy device means that the patient initiates the movement and the machine or device assists. The case studies supported this approach and confirmed that it is more effective in restoring function and greatly reduces overall recovery time. The next step was to search for existing active therapy devices. The mpower was discovered. It is a wearable robotic orthosis developed by MIT. This was the only active therapy device found.

8 INTERNAL SEARCH After the arm brace style device was found to be unviable due to patent protection, the capstone team began brainstorming to generate alternative methods of limb actuation. Three main concepts were initially explored for the actuation. The first concept involved moving affected limbs in a similar manner to an adjustable hospital bed. The second was to initiate movement on a Cartesian plane much like a CNC table. The third movement method was a device comparable to an exercise machine, where instead of using weights to supply resistance to movement a motor would be used to assist movement. In addition to the general concept of movement, system layout was explored. The layout of the machine is crucial in generating a detailed design. This led to the discovery of four possible design layouts: wall mounted, table mounted, stationary free standing, and movable free standing. Another topic for brainstorming was the components and set up of the electrical system. The ideas generated for powering the DC motor included an H-bridge and a linear amplifier. It was found that both would power the motor with less of a delay. To track the movement of the motor, both potentiometers and encoders were discussed. After extensive brainstorming, it was necessary to evaluate the ideas produced and make a selection based on the needs of the system. DESIGN EVALUATION & SELECTION To evaluate the ideas produced during brainstorming, seven main criteria were used: versatility, low weight and volume, simplicity, ease of use, low cost, low visibility, and safety. First, the system needs to be versatile in order to be most useful for patients. If the machine can perform more exercises and function with more degrees of freedom, then it can help patients to regain the use of more limbs and joints.

9 Second, the machine should not be excessively heavy or large. The more compact and maneuverable the machine is, the more likely it is to appeal to rehabilitation facilities. Third, the design for the machine should be relatively simple. If the design or manufacture of the system is too complex, the machine will be less likely to be finished on time for this project, more likely to have problems, and will probably be more expensive. Fourth, the ease of use of the machine is crucial. Since the idea is to sell the device to physical therapy and rehabilitation facilities, the machine will need to be intuitive and easy to use, or the physical therapists will not want to use it for treatment. Customer satisfaction will also increase sales. Therefore, this criterion reflects the opinion of the group on ease of use, as well as some feedback from physical therapists and customers. Fifth, the device must be low cost. This is important both for the feasibility of completion for this Capstone project, and for the future manufacture and sale of these machines. The device must be comparable to or less expensive than existing products, or it will not be useful for customers. Sixth, the machine should not be too visible or bulky. The user should not feel that they are hooked to a machine, but rather that they are simply going through the motions themselves. This is important for the stroke survivors to restore their neurological pathways through the concept or neuroplasticity. Finally, safety is imperative. The exercise machine must be safe to use, including the ability to contain programming and mechanical stops to keep the device from overextending limbs or otherwise harming the patients. Safety is a high priority and must be addressed in any concept that is chosen. Each concept generated during brainstorming was rated in each of these seven criteria. The rating is weighted and each concept is given a score out of the highest score possible for each criteria. The total of the rating values was calculated for each concept. The concept with the highest total was deemed to be most appropriate for the project and was selected. See Table 1 for the ratings and totals.

10 Table 1: Concept Evaluation Criteria and Ratings After applying the evaluation criteria, a decision was made for each category based on the totals for each concept. The final decision was to develop a pulley exercise machine that can be mounted on a wall or stationary freestanding. Using these components, the detailed design process could begin. DETAILED DESIGN PROGRESS Detailed design encompasses three fundamental areas: electrical, programming, and mechanical. The initial electrical system prototype used voltage sensors placed on the forearm, a differential amplifier, an arduino microcontroller and a transistor circuit to drive a servo motor. A power supply was used to power both the controller and the servo motor. This system proved the possibility of controlling a motor by sensing muscle voltage changes. However, when the servo motor was replaced with a DC motor that had sufficient power to move a limb, there was a perceivable delay between sensory input to motor output. This problem was resolved by using an H-bridge circuit to drive the motor. The H-bridge and motor are powered by a separate supply from the Arduino microprocessor, due to electromagnetic interference (noise) issues. Currently the prototype electrical system drives a geared DC motor without perceptible delay.

11 Another consideration in the electrical system was position sensing and feedback. The design options considered were to use an optical encoder to sense the rotational position of the armature or using a potentiometer attached to either the output shaft of the actuating pulley, or on the patient s arm itself. Using a potentiometer to sense motor output shaft position was selected mainly due to lower cost and simpler design. Using an encoder would add more complex code and a lot of processing time to the circuit. Since the goal is to minimize the patients perceivable delay, the potentiometer was the best option. Using a potentiometer, changes in position will change the resistance, which can be measured as a voltage change in the circuit proportional to angular position. The microcontroller program currently receives voltage input and converts this signal to voltage output normalized to the 24VDC input of the motor. Subsequent programming steps will incorporate a calibration program that will set the resting muscle voltage to zero and set the limits of motion for the motor. A graphic display will also be used to streamline the interface between the user and the machine. The mechanical system is supplied motive power from a 24V brushed DC gear motor. Body segment mass data and limb movement speed were researched to determine the torque and angular velocity specifications of the motor. While stepper motors and brushless motors were initially considered, the brushed motor was selected due to price, simplicity of control, and no need for fine angular positioning due to the reduction in angular speed through a gearbox. The purchased motor provides a rated torque and rotational velocity of 31 in-lb and 167 rpm, respectively, with a keyed shaft for pulley attachment. Detailed design of the entire assembly which includes an adjustable frame structure, components, and interface is in progress. The frame consists of a vertical square tube with attachments points on the top and bottom that can accommodate free standing and wall mount operation. A housing containing the motor and part of the electronics package will be attached to the tube allowing for vertical adjustment for patient build and differing exercises. A counterweight system will be employed to preclude the housing unit from falling to the floor if unclamped. Design of the

12 EMG sensors and integrated limb attachment point are currently underway and will be the final step of detailed design. CONCLUSION The progress of the design is congruent with the goals set in place. A prototype of the Myoelectric Robotic Orthosis device is complete, but is lacking full functional potential. Goals were set based on three categories: Electrical, Programming, and Mechanical, and further design will be addressed Spring The electrical system currently consists of many discrete and disconnected parts. The next step in detailed design is to consolidate these separate elements into an unobtrusive electronic package, and to create versatility in the exercises of the machine. Although the mechanism works in the simplest form, the functionality of the system needs to be altered to meet design requirements based on consumer feedback. An adjustable pulley system will be integrated that allows patients to mimic everyday tasks. The last portion of the mechanical design is refining the sensor attachment and being more specific about placement of the electrode pads. A detailed CAD model will be complete by April 10. The final step of the programming is adding ROM and baseline voltage calibration sequence into the program and integrating a graphic interface. Furthermore, there have been three major stopping points in this design process that called for creative decision-making. The necessary decisions made at these crossroads were the following: Creating a machine that targets multiple body parts and body motions as opposed to an arm brace, switching from a servo motor to a DC motor with an H- bridge to facilitate power, and to have a wall-mounted machine to harness leverage without compromising floor space. With all these design components in place, the greatest compromise made is in the optimization of time and money versus functionality. Instead of creating a machine with a complex system that can do all intended exercises, time and money constraints lead to a more simple and efficient machine that does most intended exercises.

13 APPENDIX Appendix-A [Timeline Schedule] - This table shows the detailed descriptions of all the tasks, and the approximate amount of time that is associated to each one. *Number inside boxes indicate number of team members for each task Task Name Duration January February March April May June W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 W17 W18 W19 W20 W21 W22 Electrical Procurement Lead Time 20 days Conceptual Brainstorming and Selection 16 hrs Group Integrating Electronic Components 10 hrs 2 Electronic Enclosure Detailed Design 12 hrs Group Specify motor controller and voltage regulato6 hrs 1 Total Work 44 hrs Programming Conceptual Brainstorming and Selection 10 hrs Group Configure Microcontroller Program 6 hrs 1 Test the program 1 hr 1 Total Work 17 hrs Mechanical Prototyping Procurement Lead Time 15 days Conceptual Brainstorming and Selection 20 hrs Group Detailed design 20 hrs Group Measure required torque range to assist arm30 min 2 Measure required speed range to assist arm 5 min 2 Specify motor power 3 hrs 1 Specify gearhead 3 hrs 1 CAD Model 10 hrs 1 3D print and laser cutting time 36 hrs 1 Assembley 5 hrs Group Test 2 hrs Group Design Refinement 10 hrs Group Total Work 83 hrs Final Mechanical Assembley Procurement Lead Time 15 days Detailed design 10 hrs Group CAD Model 10 hrs 1 Generating G-Code 3 hrs 1 CNC Machining of electronics enclosure 12 hrs 1 Machining Rigid Support Frame 5 hrs 2 Design thermoform mold 2 hrs Group Sewing 5 hrs 2 3D Print thermoform mold 10 hrs 1 Thermoforming of cuffs 1 hr 2 Assembley 10 hrs Group Total Work 41 hrs

14 Item # Relative Importance(1-5) Appendix-B [Product Design Specifications] - This table shows the House Of Quality used in the Product Design Specification Phase. House of Quality Customer Requirements Design Criteria Microcontroller Selection Motor Torque Motor Speed Gear Reduction Brace Material Selection Length of moment arm Friction reduction Gear ratio Mechanical Function with user Performance 1 Relatively Silent operation Level of Correlation 2 Brace weight None 3 moving an average person's arm unassisted Low 4 range of motion Moderate 5 Calibration setup time High 6 ambidextrous operation Intuitive User Interface 4 + Cost 10 parts <$ Design Life 10 NA Quality 11 Withstand small impacts Operate at full capacity Safety 14 Does not cause injury

15 - This table consists of all the original Product Design Specifications such as: Performance, Safety, Environment, Ergonomics, Manufacturing and Installation.

16 Appendix-C [External Search Information] - An overview of the physiology of a stroke and background on case studies supporting active therapy. Physiology of a stroke Stroke victims suffering from hemiplegia or hemiparesis show functional deficits in voluntary motor control. All voluntary motor control originates in the brain and the motor cortex is the area of the brain most involved with voluntary movement. Even the simplest tasks require many complex sequential and concurrent processes. When you take a drink of water from a glass, it involves reaching out towards the glass and positioning your hand so it can grab the glass. Your prefrontal cortex immediately begins preparation for this movement and transmits the information through a large number of axons projecting from the parietal cortex, a region involved with spatial perception. Its analysis of the position of your body and limbs relative to the glass is essential in preparing for the movement. The basal ganglia are another set of brain structures involved in this part of the process. The premotor cortex and supplementary motor area work with the cerebellum to specify the precise sequence of contractions of the various muscles that will be required to carry out the selected motor action, in this case, raising your arm and extending it forward to grab the glass. To do this your brain will need to convert the glasses location in the external environment into a set of intrinsic coordinates allowing precise adjustment of the angles of the joints involved in the movement. The primary motor cortex, the brain stem, and the spinal cord produce the contractions of all the muscles needed for the chosen movement. The primary motor cortex determines how much force each muscle group must exert, and then sends this information to the spinal motor neurons and interneurons that generate the movement itself, as well as the postural adjustments that accompany it.

17 Neuroplasticity Neuroplasticity refers to the brains ability to change in response to stimuli from the external and internal environments. The changes involve individual neurons for example, synthesis of different proteins or sprouting of new dendrites as well as changes in the strengths of synaptic connections including the neuromuscular junction. The areas of the brain known to have this capability include the association areas of the frontal, parietal, occipital, and temporal lobes, and the primary somatosensory and primary motor areas in the brain. If a particular body part is used more intensively or in a newly learned activity, such as reading Braille, the cortical areas of the brain devoted to that body part gradually expand. Memory occurs in stages over a period of time. Immediate memory is the ability to recall ongoing experiences for a few seconds. It provides a perspective to the present time that allows us to know where we are and what we are doing it is related to. Short-term memory is the temporary ability to recall a few pieces of information for seconds to minutes. One example is when you look up an unfamiliar telephone number, cross the room to the phone, and then dial the new number. If the number has no special significance, it is usually forgotten within a few seconds. Brain areas involved in immediate and short-term memory include the two nuclei of the thalamus (anterior and medial nuclei). Some evidence supports the notion that short-term memory depends more on electrical and chemical events in the brain than on structural changes, such as the formation of new synapses. Information in short-term memory may later be transformed into a more permanent type of memory, called long-term memory, which lasts from days to years. If you use that new telephone number often enough, it becomes part of long-term memory. Information in long-term memory usually can be retrieved for use whenever needed. The reinforcement that results from the frequent retrieval of a piece a piece of information is called memory consolidation. Long-term memories for information that can be expressed by language, such as a telephone number, apparently are stored in wide regions of the cerebral cortex.

18 Anatomical changes occur in neurons when they are stimulated. For example, electron micrographs of neurons subjected to prolonged, intense activity reveal an increase in the number of presynaptic terminals and enlargement of synaptic end bulbs in presynaptic neurons, as well as an increase in the number of dendritic branches in postsynaptic neurons. Moreover, neurons grow new synaptic end bulbs with increasing age, presumably because of increased use. Mirror Neurons Scientists studying Area F5 in the ventral premotor cortex of monkeys found that certain neurons in this area sent out action potentials not only when the monkeys were moving their hands or mouths, but also when they were simply watching another animal or a human being who was making such a gesture. These neurons were dubbed mirror neurons because of the way that a visually observed movement seemed to be reflected in the motor representation of the same movement in the observer. In addition to mirror neurons, which are activated both when you perform an action yourself and when you see someone else performing it, another kind of neurons, called canonical neurons, become activated when you merely see an object that can be grasped by the prehensile movement of the hand whose movements they encode as if your brain were foreseeing a possible interaction with this object and preparing itself accordingly. What these two types of neurons have in common is that they are both activated by an action regardless of whether you are carrying that action out, anticipating carrying it out, or watching someone else carrying it out. Many subsequent studies have tended to confirm that mirror neurons exist in the human brain as well. For example, in a study published in the December 2004 on-line edition of Cerebral Cortex, a group of professional ballet dancers and a group of dancers of capoeira (a Brazilian dance/martial arts form) were asked to watch short videos of dancers performing brief ballet and capoeira moves, while a functional magnetic resonance imaging (fmri) scanner detected changes in their brain activity. A control group of non-dancers also participated.

19 The fmri results showed that the areas of the dancers brains associated with this mirror neuron system were more active when they were watching movements of the kind that they were trained in than when they were watching the other kind. The non-dancers in the control group showed even less mirror-neuron activity than the ballet dancers watching capoeira or the capoeira dancers watching ballet, and this lower level of activity was the same regardless of which of the two types of dance they were watching. This study thus not only supports the idea that there is a mirror neuron system in the human brain, but also shows that this system s activity level increases with the degree of training that the individual has in certain particular types of movements. And, it should be stressed, this increased activity occurs not in the visual centers of the occipital cortex, but in the motor area where the brain plans complex movements, as well as in the intraparietal sulcus, a brain area responsible for visual-motor integration. Action Potential Action potential is the technical term used to describe a nerve impulse. It consists of a brief, reversible polarization that propagates along an axon. It differs from a receptor potential (synaptic potential) in several respects. First of all, an action potential does not propagate passively, but actively, by means of special voltage-sensitive ion channels in the axon. In addition, mammals have a particular mechanism that accelerates the propagation of the action potential. This process also requires energy from the neuron, which must maintain the activity of the ion pumps that rebalance the charges on either side of the membrane after an action potential has passed. Action potentials do not vary in amplitude or intensity. If the intensity of a stimulus falls below the neuron s excitation threshold, nothing happens. If the intensity of this stimulus exceeds this threshold, it does not matter whether it does so by a small or a large amount. Either way, an action potential will be triggered, and its amplitude and frequency will always be the same for

20 any given cell. Consequently, the only way a neuron can transmit information is by varying the frequency of its action potentials. The action potential creates a voltage potential that is proportional to the force of the contraction and this voltage potential can be measure at the surface of the skin above the muscle and observed used an EMG. Evidence Based Rehabilitation Studies There are several types of post stroke rehabilitation that can be divided into three categories; pharmacological, behavioral, and cognitive. Behavioral and cognitive are shown to have the greatest impact in facilitating neuroplasticity. Behavioral Therapy: Exercise is one of the best behavioral therapies because it has one of the most significant effects on neuroplasticity. Studies have shown that exercise can have substantial benefits for brain reorganization, because it stimulates the connections in the central nervous system. Rehabilitating exercise improves motor skills after a stroke which helps the brain forge new neural pathways and connections. This facilitates the processes involved in neural plasticity. Cognitive Therapy: Cognitive rehabilitation focuses on the recovery of functions such as memory, attention, motor skills, as well as other functions. Depending on the patients care needs, it can be the most important. It s the most effective form of therapy for stimulating the neuroplasticity processes in post-stroke patients due to its direct effects on the cognitive areas in the brain.

21 Mental practice is the term given to practicing activities and movements in the mind, and it has been used in athletes. Recent studies have shown that it can also be used on stroke patients, who visualize motor movements through mental imagery, alongside other cognitive-based treatments. It has been suggested that patients should visualize and practice an activity mentally in conjunction with other conventional treatments in order to improve motor functions, especially arm movement. Virtual reality has also been used to improve motor movements alongside balance. With regards to fine motor skills, repetition of the same activities every day such as putting on make-up, picking up and putting down a coin helps to produce new neural pathways in order to compensate for the damaged pathways, and these exercises can help promote neuroplasticity in post-stroke patients. With more strenuous motor movements such as with arm movement, studies have shown that it s more beneficial to conduct bimanual exercises opposed to merely exercising the affected arm alone. Bimanual exercises have also been shown to have a direct effect on promoting cortical neural plasticity in various ways: motor cortex disinhibition that allows increased use of the spared pathways of the damaged hemisphere, increased recruitment of the ipsilateral pathways from the contralateral hemisphere supplementing the damaged corticospinal pathways, and up regulation of descending premotor neuron commands onto propriospinal neurons. Conclusion from Research Analysis Not all of the research data was presented in this report. The following conclusions are presented in the same order as the sections of data presented. In some cases, conclusions will be made based on correlations found between sections with an emphasis on neuroplasticity. The specific functional deficits observed in someone who has suffered a stroke can be correlated with the functions of the cortical regions damaged by the stroke. The interdependencies that exist between the areas of the brain responsible for the initiating, coordinating, learning, and remembering voluntary movement in conjunction with neuroplasticity mean that stimulation of at any point in the loop is an effective way to innervate new neural growth resulting in healthy brain function in stroke victims.

22 The cerebellum uses visual signals associated with movement of limbs to store information that will improve the coordination of muscle tension and relaxation resulting in more precise and accurate voluntary movement of that limb. The brain releases dopamine during a rewarding experience. The motor cortex contains dopamine receptors which can form positive associative memories that reinforce the neuro connections used in the corresponding movement. Neuroplasticity is the most important process that should be stimulated in the affected areas of the brain. Visualizing a movement associated with an affected limb is an effective way to stimulate the areas affected by the stroke thereby initiating the reparative effects of neuroplasticity. Cognitive therapy is the most effective form of therapy because it stimulates the activation of neuroplasticity. Neuroplasticity can heal the neural connections damaged by a stroke and restore lost functionality. When the patient initiates a voluntary movement, an action potential in the form of a voltage differential is created across the appropriate muscle. This voltage change only exists when the patient initiates movement. The voltage potential is created by sodium and potassium ions and can be measured quantitatively. The threshold of an action potential is dynamic and influenced by the brains interpretation of visual, tactile, pressure, and force signals from sensory receptors associated with the movement. Recommendations It is our recommendation that the use of EMG activated motorized exercise machine be implemented and used during all cognitive therapy sessions. When used on the affected limb it will have a direct impact on the corresponding areas of the cortical region affected by the stroke. The machine works by sensing the intent to move by measuring and monitoring the action potential created during a muscle contraction. An EMG amplifier and sensors are used to take these measurements in real time. At the instant the action potential is sensed, the motor which is located on the exercise machine above the joint of the affected limb begins to rotate. The motor spools a cable with an appropriate handle or strap that connects to the affected

23 limb. The assisted motion can be incremental or continuous through the range of motion. The visual feedback will stimulate the cerebellum reinforcing the creation of new neuro pathways for the motion. The result is an increase in restored function compared to passive rehabilitation. This versatility of this device makes it appropriate for use on the upper and lower extremities of all stroke victims. The cost of the device is relatively low compared to passive therapy devices such as electrical stimulation.

24 REFERENCES [1] Stroke rehabilitation information. (2013, June 19). Retrieved from [2] Rash, G. (n.d.). Electromyography fundamentals. Retrieved from Lab/EMGfundamentals.pdf [3]