Transcript Poster - Research - Vanderbilt University

Parkinson’s Disease Rigidity Quantification
LOGO
LOGO
Kylen Bares, Eddie Cao
Vanderbilt University, Department of Biomedical Engineering, Nashville, TN 37235
BACKGROUND
MATERIALS AND METHODS
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.
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.
PURPOSE AND HYPOTHESIS
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.
RESULTS/DISCUSSION
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.
Hand with
air
cylinder
attachment
s on the
fingertips
Forearm
section of armframe
Connecting
pins
Air cylinder
Air
cylinder
Figure 3: ProE model of hand-actuator cylinder
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.
CONCLUSIONS/FUTURE WORK
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.
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)
BIBLIOGRAPHY
1 http://neurologychannel.com/parkinsonsdisease/
Elbow pivot
joint
Upper arm
frame
Acknowledgements
CHART or PICTURE
Figure 2: ProE model of arm-frame with bicep
cylinder
Special thanks to:
Figure 4: Pneumatic circuit diagram (ground = vent to
atmosphere)
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!!!)
Figure 1: Photograph of finished prototype in the flexed position
printed by
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