Monitoring Functional Arm Movement for HomeBased Therapy after Stroke

1
Monitoring Functional Arm Movement for Home-Based
Therapy after Stroke

• R.Sanchez1, D.Reinkensmeyer1, P.Shah1, J.Liu1, S.
  Rao1,
• R. Smith1, S. Cramer2, T. Rahman3, J. Bobrow1
• 1Department of Mechanical and Aerospace
  Engineering, University of California, Irvine,
  USA
• 2Department of Neurology, University of
  California, Irvine, USA
• 3A. I. DuPont Hospital for Children, Delaware, USA

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OUTLINE

• Background
• Methodology
• T-WREX Design
• Java Therapy Software Enhancements
• Device Testing
• Results

3
Background

• 50 of Stroke survivors have chronic arm/hand
  motor impairment.
• In 1999, more than 1.1 million American adults
  reported functional limitations (difficulties
  with activities of daily living) resulting from
  stroke.
• Stroke costs the United States 30 to 40 billion
  per year (American Stroke Assoc.).

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The Stroke Rehabilitation Paradox

• There is increasing evidence that intensive
  sensory motor training can improve functional
  recovery.
• However, stroke patients are getting less therapy
  and going home sooner due to economic pressures.
• There is little technology available to continue
  therapy at home in order to maintain, improve, or
  monitor recovery.

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T-WREX Mechanical Design

• Training- Wilmington Robotic Exoskeleton
  (modified from WREX, T. Rahman) designed for use
  in arm movement training by weakened Stroke
  Survivors at home.
• T-WREX is a 5-DOF, backdriveable, passive
  anti-gravity position tracking system.
• Utilizes elastic bands, wrapped around two four
  bar mechanisms, to counterbalance the arm.

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T-WREX Sensorized

• 5 potentiometers encased in protective housings
  measure arm movement.
• Measurement accuracy is measured within 0.50cm.
• Potentiometers do not require homing, only an
  initial calibration.
• Arm position is calculated from the matrix
  exponentials formation.

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Java Therapy 2.0

• Java Therapy 2.0 allows the user to
• perform organized and monitored rehabilitative
  video game prompted exercises from the home.
• keep track of usage and progress .

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Java therapy 2.0 cont

• Uploads subject data to a main server on the web.
• Communicates with T-WREX through a custom dll
  (dynamic link library).
• The doctor / therapist can
• monitor patient progress and activity.
• assign games / exercises based on performance.

9
Device Testing

• Five volunteers with a history of chronic stroke
  ( gt 3 months prior) and persistent motor
  deficits, but absence of cognitive deficits,
  neglect, and shoulder pain participated in the
  study.
• Three types of movement tests were performed with
  and without gravity balance, with the order of
  presentation of the two conditions randomized.

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Movement Tests

• Functional Test A sub section of the arm motor
  Fugl-Meyer Motor Score consisting of 14 tasks
  that could be performed while in the orthosis
  (Score range 0-28).
• Reaching Movements The subject reached to soft
  targets located at the boundary of the arms
  passive workspace eight times.
• One target was placed in the workspace
  contralateral to the impaired arm and one
  ipsilateral.
• The subjects also reached upwards from the lap to
  the highest point possible eight times.
• Drawing movement test The subject traced circle
  patterns (Ø18cm) presented on a transparent
  plastic disc in the vertical plane, centered in
  front of them, 4-5 fist lengths from the front of
  the shoulder.

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Functional Test Results

• The score on the subset of arm motor Fugl-Meyer
  testing without gravity-balance was 9.0 (/- 6.2
  SD) and with gravity-balance was 10.4 (/- 6.5
  SD), out of a possible score of 28.
• The change in Fugl-Meyer was marginally
  significant (p .054) for a one-sided, paired
  t-test comparing the change to zero.

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Reaching Results

• Effect of gravity balance on reaching movements.
  
• (A) Average reaching range of motion across
  subjects to targets with and with out gravity
  balance (distance traveled to target / total
  distance to target).
• Gravity balance significantly improved reaching
  to the contralateral target.
• (B) Average height reached above lap, with and
  without gravity balance. No short-term learning
  was observed across eight movement attempts.
• Gravity balance significantly improves vertical
  reach.
• ? p lt .05, paired t-test.

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Tracing Movement Results

• Effect of gravity balance on tracing movement for
  one subject.
• The subject attempted to trace a circle 30 times,
  without gravity balance (top four panels) and
  with gravity balance (bottom four panels).
• The panels show example trials throughout the 30
  trials.
• Tracing circles with gravity balance improved
  over time and shows an obvious masked motor
  function capability.

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Discussion

• T-WREXs gravity balance function improved
• a clinical measure for arm movement.
• range of motion for reaching.
• accuracy of drawing movements.
• These results highlight the threshold nature of
  gravity
• a threshold amount of strength is required to
  move against gravity.
• gravity balance appeared to unmask a latent motor
  learning capability that was not apparent with
  gravitational loading.
• All subjects were pleased with their experience
  and asked to participate in future studies.

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Conclusion

• Our initial test with T-WREX showed that the
  device will provide a means to measure and safely
  assist in naturalistic arm movement.
• We envision using T-WREX to provide
• gradable levels of assistance by adding or
  removing rubber bands.
• the ability to perform software guided home
  based therapy (telerehabilitation).
• quantitative feedback of progress at home and at
  the clinic.
• We hope to increase access to and improve
  functional outcomes of arm therapy after stroke.

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Acknowledgements

• Supported by the Department of Education
  National Institute on Disability and
  Rehabilitation Research (NIDRR), H133E020732, as
  part of the Machines Assisting Recovery from
  Stroke (MARS) Rehabilitation Engineering Research
  Center (RERC) on Rehabilitation Robotics and
  Telemanipulation and NIH N01-HD-3-3352.
• University of California Irvine, Biomechatronics
  Laboratory.