printed by Parkinson’s Disease Rigidity Quantification Kylen Bares, Eddie Cao Vanderbilt University, Department of Biomedical Engineering, Nashville, TN Parkinson’s disease is a neurodegenerative disorder caused by damage or lack of neurons in the substantia nigra which release a neurotransmitter called dopamine. Dopamine is responsible for the stimulation of motor neurons in the basal ganglia. At least a million people in the United States every year are Parkinson’s [1]. The symptoms are all related to the inability to control one’s motor activities. They include tremor or trembling in the hands, arms, legs, jaw, and face as well as rigidity or stiffness of the limbs and trunk. This stiffness has been shown to correlate with the disease severity. Both the prototype arm-frame and control box were fabricated (fig 1) and tested within the guiding parameters of the project. A pressure of 10 PSI was needed to move the arm when it was limp, while 22 PSI was required for a moderately tensed arm. These results are likely skewed by the fact that all of the pivot joints of the device were strait metal-on-metal type joints that have an inherently high friction coefficient and therefore have decreased the discrepancy between states of muscle rigidity. An aluminum prototype was constructed using pneumatic actuators, which served as both the motive source for limb movement and the force transducer for obtaining rigidity information. The “Numatics” actuators (Meredith Air Controls, Nashville TN) were mounted to an arm-frame that translated the linear motion of the cylinders to rotation of the forearm about the elbow. The arm-frame was designed using ProEngineer 3.0 and constructed using 4” C-channel 3030 Aluminum, 0.25” Aluminum sheeting (Metal Supermarket, Nashville TN), and various nuts and bolts obtained from a local hardware store. Testing procedure began with un-attaching the bicep actuator to allow the patient (Eddie Cao) to insert his arm into the arm-frame. The bicep actuator was then re-attached and foam padding was inserted between the patient’s arm and the arm-frame to protect the skin from The Air compressor used for testing was then turned on to allow time to build the necessary pressure. The flow-restrictor on the compressor was barely opened to allow a small amount of air to leak through into the control box for the arm-frame. The joysticks on the controller box were set to force the patient’s arm to flex. The pressure displayed on the gauge cluster was recorded when the arm first began to move with the arm fully relaxed, and then again with the arm held rigid to simulate the rigidity associated with Parkinson’s disease. These pressures were then recorded and the system depressurized to eliminate potential safety hazards CHART or PICTURE This project is declared a success in that it fulfilled the design requirements of the consumer. The device is able to quantitatively decipher between levels of muscle rigidity. LOGO A device to quantitatively measure Parkinson’s symptoms is needed to maximize the benefits of the Deep Brain Stimulation (DBS) surgery, in which the patient’s brain is electrically stimulated in order to decrease the symptoms of the disease. While symptoms range from rigidity and tremors to lack of coordination and balance, we focused primarily on measuring muscle rigidity and tone. Current measures to assess rigidity involve manual manipulation of the arms and hands of patients to qualitatively asses the relative rigidity of the patient during the DBS surgery. Since numerical rigidity information cannot be obtained from this method, it is difficult to determine the most effective location of brain stimulation to alleviate symptoms. The ultimate goal of this project was to create a device that could quantitatively measure the relative rigidity of a patient’s arm during the DBS surgery in order to maximize the effectiveness of this treatment. BACKGROUND PURPOSE AND HYPOTHESIS MATERIALS AND METHODSRESULTS/DISCUSSION CONCLUSIONS/FUTURE WORK BIBLIOGRAPHY LOGO Forearm section of arm- frame Connecting pins Upper arm frame Air cylinder Elbow pivot joint Figure 2: ProE model of arm-frame with bicep cylinder Air cylinder Hand with air cylinder attachment s on the fingertips Figure 3: ProE model of hand-actuator cylinder Figure 1: Photograph of finished prototype in the flexed position Figure 4: Pneumatic circuit diagram (ground = vent to atmosphere) Acknowledgements Special thanks to: Dennis King (Meredith Air Controls) Dr. Galloway (for use of tools and lab space) Phil Davis (for machine shop time) CAFFEINE The Flying Spaghetti Monster (Best Internet Deity Ev3R!!!) CONCLUSIONS/FUTURE WORK - -More adaptability in physical design of the device to accommodate more patients - - Increase the size of the device in order to include more padding for patient comfort and compliance - - After improvements have been made, an assessment of practical application as a diagnostic tool would be in order - - re-build the device with ball-bearing joints to reduce friction and increase the resolution of the device - -Expand the muscles measured by the device (more fingers, wrist…etc)