View
9
Download
0
Category
Preview:
Citation preview
Error!
Toronto Rehab Lyndhurst Centre 520 Sutherland Dr.
Toronto, ON Canada, M4G 3V9
Phone: 416-597-3422 ext 6206 Web: www.toronto-fes.ca E-mail: info@toronto-fes.ca
Mus
cle
CNSSensor
Torque
> 80 ms
t 1
t 2 t 3
Reh
abili
tati
on
En
gin
eeri
ng
Lab
ora
tory
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
About the Rehabilitation Engineering Lab
History
The Rehabilitation Engineering Laboratory was established in 2001 at the Lyndhurst
Centre of Toronto Rehab. In 2006, the laboratory underwent a major renovation,
doubling the amount of space available for personnel and experiments.
What We Do
We develop advanced technologies for spinal cord injury (SCI) and stroke
rehabilitation. These include brain/machine interfaces, assessment tools for
determining an individual’s level of function, and rehabilitation techniques for restoring
walking and grasping ability. We also design neuroprosthesis systems to assist
individuals with tasks such as walking, grasping, and balance during standing and
sitting.
Most of our work is based on functional electrical stimulation (FES), which uses
electricity to cause muscles to contract. FES can be used to provide movement to
paralyzed muscles or to re-train weak muscles or the central nervous system.
Accomplishments – 2006 to 2008
• Developed FES therapies for neuro-rehabilitation in stroke and SCI
• Provided FES therapy to more than 50 individuals with SCI or stroke
• Published more than 22 peer-reviewed journal papers
• Obtained more than $2,000,000 in funding for SCI and stroke research
• Trained 8 postdoctoral fellows, and 16 graduate students in SCI and stroke
research, who obtained an additional $1,200,000 in funding
Want to Get Involved?
We’re always looking for participants for our studies, volunteers to help us with the
experiments, students and research collaborators. If you’d like to join us, please feel
free to contact us at 416-597-3422 ext. 6206, or via e-mail at
milos.popovic@utoronto.ca.
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Research at the Rehabilitation Engineering Laboratory Neuroprosthesis for Reaching and Grasping
Our reaching and grasping neuroprosthesis is designed for individuals who cannot
reach and/or grasp voluntarily. These individuals are able to use the system to pick up
and manipulate objects, and can significantly improve their independence in activities
of daily living. People who have SCI at C5-C7 level or stroke have used this system as
a rehabilitation tool to assist in retraining reaching and grasping.
Neuroprosthesis for Walking
The purpose of the neuroprosthesis for walking program is to demonstrate the long-
term benefits of FES therapy on walking function in patients with incomplete SCI and
stroke. Our pilot study showed a significant improvement in walking speed and/or a
reduction in the use of assistive devices for walking after using the neuroprosthesis.
We are currently conducting a randomized treatment-vs-control study to verify that
these benefits truly resulted from FES-assisted therapy.
Neuroprosthesis for Sitting
Trunk instability is a major problem for many people with SCI that affects their
independence and ability to perform activities of daily living. The long-term objective of
this project is to produce a new device that will improve sitting stability by stimulating
paralyzed trunk muscles using FES. This sitting neuroprosthesis will improve the
ability of people with SCI to perform such tasks as reaching and wheeling. We are
currently studying the mechanisms of balance in the trunk and the consequences of
muscle paralysis on these mechanisms. This analysis will form the basis for
developing the FES system for balance during sitting.
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Neuroprosthesis for Standing
The neuroprosthesis for standing and balancing is a device that will allow some
neurologic patients to stand up, perform stable “hands-free” standing, and sit down
again. At least two applications of this technology are envisioned: 1) this device will be
used as an independent system to allow complete SCI patients to stand; and 2) to
retrain standing function and balance control in incomplete SCI, stroke and elderly
patients through active, repetitive, balance training sessions. Besides the obvious
functional benefits, this neuroprosthesis would also help maintain bone density and
prevent pressure sores by allowing people to stand for extended periods of time.
Human-Machine Interfaces
Understanding the relationship between an assistive device and its user is a
fundamental step towards designing better systems. The human-machine interface
project focuses on developing new communication strategies and methodologies to
allow users to have more natural control over an assistive device. One aspect of this
work is our research into brain-machine interfacing, which investigates the relationship
between intended arm movement and electroencephalogram (EEG) signals from the
motor cortex of the brain.
Equipment
The Rehabilitation Engineering Laboratory has a variety of research equipment
including:
• Compex II stimulators
• Body weight support treadmill
• Force plates
• Polhemus motion capture system
• Optotrack dual camera motion capture systems
• Erigo tilt table with motorized leg movement
• Electromagnetically shielded room for EMG and EEG measurements
• Vibration platforms
• REL-PAPPS perturbation system
Rehabilitation Engineering Laboratory – 2008
Our People
Principal Investigators
• Dr. Milos R. Popovic, Head of the Laboratory, Toronto Rehab Chair in Spinal Cord Injury Research, Senior Scientist, and Associate Professor
• Dr. Mary Nagai, Research Scientist and Assistant Professor • Dr. Kei Masani, Research Scientist
Postdoctoral Fellows
• Dr. Judith Hunter (neuroscience), Postdoctoral Fellow • Dr. Richard Preuss (physiotherapy), Postdoctoral Fellow • Dr. Dimitry Sayenko (medical doctor), Postdoctoral Fellow • Dr. Masae Miyatani (exercise physiology), Postdoctoral Fellow • Dr. Dany Gagnon (physiotherapy), Postdoctoral Fellow
Graduate Students
• Cheryl Lynch, PhD student • Cesar Marques Chin, PhD student • Albert Vette, PhD student • José Zariffa, PhD student • Davide Agnello, MASc student • Milad Alizadeh-Meghrazi, MASc student • Rob Babona Pilipos, MASc student • Steve McGie, MASc student • Egor Sanin, MASc student • John Tan, MASc student • Massimo Tarulli, MASc student • Takashi Yoshida, MASc student
Support Staff
• Shaghayegh Bagher, Research Engineer • Zina Bezruk, Administrative Assistant • Abdul Bulsen, Research Engineer • Betty Chan, Grants & Accounts Coordinator • Suzy Iafolla, Physiotherapist • Naaz Kapadia, REL Manager, Research Coordinator and Physiotherapist • Abdulazim Rashidi, Research Engineer • Dr. Vera Zivanovic, Research Coordinator
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Awards Dr. Milos R. Popovic 2008 Professional Engineers Research
and Development Award Professional Engineers of Ontario and Ontario Society of Professional Engineers
2007 Toronto Rehab Chair in Spinal Cord Injury Research
Toronto Rehabilitation Institute
Albert Vette 2008 Norman F. Moody Award in
recognition of academic excellence
Institute of Biomaterials and Biomedical Engineering, University of Toronto
2008 Best Student Paper Award – First Place
3rd National Spinal Cord Injury Conference, Toronto, Canada, November 6-8, 2008.
2008 Best Student Paper Award – Second Place
13th Annual Conference of the International FES Society, Freiburg, Germany, September 21-25, 2008
2007 Engineering Postgraduate Prize for most Outstanding Doctoral Candidate
Natural Sciences and Engineering Research Council of Canada
Jose Zariffa 2007 Best Student Paper Award –
Third Place 30th Canadian Medical and Biological Engineering Conference, FICCDAT, Toronto, Canada, June 16-19, 2007.
Dr. Judith Hunter 2007 Northrop Frye Award University of Toronto
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Recent Research Posters Neuroprosthesis for Grasping
1. “Functional electrical therapy: Retraining reaching and grasping functions in severe hemiplegic patients”
2. “Effect of intensive functional electrical therapy on the upper limb motor recovery after stroke: Single case study of a chronic stroke patient”
3. “FES therapy: Restoring voluntary grasping function”
Neuroprosthesis for Walking
4. “Necessity of successive sensory feedback to update the internal model for walking”
5. “Oxygen uptake during FES treadmill walking: Case study”
Neuroprosthesis for Standing
6. “Frequency response of stimulated knee movement”
7. “Optimal combination of minimum degrees of freedom to be actuated for the facilitation of arm-free paraplegic standing”
8. “Step prediction during perturbed standing using center of pressure measurements”
9. “Control mechanism of ankle muscles during standing”
10. “Motor command of proportional and derivative (PD) controller can match ankle torque modulation during quiet stance”
11. “Stochastic modeling of knee response”
Neuroprosthesis for Sitting
12. “Muscle recruitment patterns in perturbed sitting”
13. “Center of pressure excursion during voluntary trunk movement in sitting”
14. “Posturography measures during quiet sitting”
Rehabilitation Engineering Laboratory – 2008
Contact us:
Lyndhurst Centre Toronto Rehab 520 Sutherland Dr. Toronto, ON M4G 3V9 Canada
416-597-3422 x 6206
www.toronto-fes.ca
info@toronto-fes.ca
Human-Machine Interfaces
15. “Identifying movements from cortical signals”
16. “Localizing active pathways in peripheral nerves“
17. “Control of multiple degree-of-freedom tasks using one-dimensional electroencephalographic signals”
18. “ECoG controlled neuroprosthesis for grasping: Preliminary study”
19. “Influence of the number and location of recording contacts on the selectivity of a nerve cuff electrode”
Other Projects
20. “The relationship between arterial stiffness and body composition in persons with spinal cord injury”
21. “A test-of-principle prototype for a new device to measure a specific pain mechanism: Translating pain neuroscience theory into a clinical/research tool”
22. “Cardiovascular response to FES and passive stepping to improve orthostatic tolerance”
23. “Wave ® vs. Juvent ®: Whole-body vibration assessment: Feasibility & usability for patients with SCI”
24. “A new intramuscular electrode for functional electrical stimulation in the rat”
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
FUNCTIONAL ELECTRICAL THERAPYM.R. Popovic, A.T. Thrasher and V. Zivanovic
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milos.popovic@utoronto.cawww.toronto-fes.ca
Toronto Rehabilitation Institute and University of Toronto
Retraining Reaching and Grasping Functions in Severe Hemiplegic Patients
PARTICIPANTS:Stroke patients with severe unilateral upper extremity paralysis.Chedoke McMaster Stages of Motor Recovery scores 1 or 2 measured at least three weeks after onset of stroke.Participants unable to voluntarily:
• flex, extend, abduct, adduct, or rotate the shoulder; • flex or extend the elbow;• pronate or supinate the forearm; • flex, extend, abduct or adduct the wrist; • move any fingers;
Participants were acute (0 – 6 weeks post stroke) or long-term (12 months after stroke).
Group A - control group had standard physiotherapy and occupational therapy alone.
Group B - treatment group had functional electrical stimulation (FES) therapy administered in addition to conventional physiotherapy and occupational therapy.
FUNCTIONAL TESTS: • Functional Independence Measure (FIM)• Barthel Index (BI)• Chedoke McMaster Stages of Motor Recovery (CMSMR)• Fugl-Meyer Assessment (FMA)• REL Hand Function Test (REL) [1]
FES THERAPY PROTOCOL:Participant was asked to execute a task with the impaired arm (e.g. reaching and grasping a pen) unassisted. The components of the task that the participant was unable to carry out him/herself were assisted by the neuroprosthesis. Compex Motion neuroprosthesis was used for FES therapy [1].In the early stages of the treatment, the arm/hand tasks were performed by the neuroprosthesis alone. As the patient improved, the neuroprosthesis assistance was reduced to the necessary minimum and eventually was removed from the treatment protocol. The patient had three treatment sessions per week, 45 minutes per session, up to 16 weeks.
Materials and Methods
Fig. 1: a) Finger extension performed with the help of neuroprosthesisb) Voluntary finger flexion
b)a)
CONTROL GROUP PROTOCOL:Standard physiotherapy and occupational therapyControl group sessions were equal in length and intensity to the FES therapy sessions.
STATISTICAL ANALYSIS:Wilcoxon rank-sum test
ResultsSUMMARY:
The study was conducted with 24 stroke patients (8 female, 16 male; average age 56):
• 15 participated in FES therapy• 9 were controls
The difference between mean scores obtained on discharge and admission for both Groups A and B are shown in Fig 2. Significant differences were found between Groups A and B in terms of change of the FMA and the torque, force and eccentric load components of the REL Hand Function Test.The statistical analysis suggests that the FES therapy gives rise to greater improvement in arm and hand functions, compared to traditional physiotherapy and occupational therapy alone.
References:[1] Popovic M.R., Thrasher T.A., Zivanovic V., Takaki J., and Hajek
V., Neuroprosthesis for restoring reaching and grasping functions in severe hemiplegic patients. Nauromodulation, 2005. 8(1): p. 60-74.
*
**
**
Fig. 2: Differences between the after and before mean scores for: 1-5) REL Test; 6) FIM; 7) BI; 8) FMA; and 9) CMSMR tests. Statistical significance of the difference is presented as follows: * p < 0.05, and ** p < 0.01.
1
2. MethodsSubject
A 22-year-old woman who had suffered a hemorrhagic stroke 2 years earlier.
Noritaka Kawashima , Vera Zivanovic , Milos R. PopovicInstitute of Biomaterial and Biomedical Engineering, University of Toronto, CanadaLyndhurst Centre,Toronto Rehabilitation Institute, CanadaJapanese Society for Promotion of Science, Japan
123
1,2,3 1,2
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du CanadaCanadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du CanadaNatural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Healthand Long Term CareMinistry of Healthand Long Term Care
Effect of Intensive Functional Electrical Therapyon the Upper Limb Motor Recovery after Stroke
1. Background
What extent of motor recovery can be deliveredby FET for chronic stroke patients?
1. the subject can feel that the proper movement of the paralyzedlimbs and has been acomplished following their appropriate effort
2. sensory signals might be generated by the excitation of afferentpathways in the stimulated peripheral nerves
3. Results
FET is a treatment that integrates electrical stimulation of sensory motorsystems and repetitive functional movement of the paretic arm in hemiplegicpatients.
4. Discussion
FET has a potential to decreaseabnormal spinal motoneuronalexcitability
While motor recovery scored by CMSA scale and MVC level ofupper arm muscles did not show remarkable changes, the patientshowed improvement of upper arm functional motion.
The present results suggest that intensive FET has the capability toimprove upper arm functional movement, specifically by the reduction
of muscle tone for chronic stroke patients.
The improvement of the upper arm functional motion revealed bykinematical tests can attribute not to the motor recovery itself, but tothe reduction of muscle tone and/or spasticity.
1,2
Single Case Study of a Chronic Stroke Patient
Flex
Ext
Flex
Ext
Shoulder
ElbowTB
aDel pDel
BB
Flex
Ext
Flex
Ext
Shoulder
ElbowBB
aDel pDel
TB
Touch nose (or shoulder)
Swing forward
Abduct
Adduct
Flex
Ext
Shoulder
Elbow
aDelpDel
TB
Left side up 23
4
5
6
1
a
b
c
d
ef
aDel
BicepsBrachialis
pDelTricepsBrachialis
Shoulder &Elbow flexor
Shoulder &Elbow extensor
Wrist flexor
Wrist & Finger extensor
B Location of electrodeA FET motion tasks
Touch noseTouch ShoulderSwing forwardLeft side up
FlexionFlexion&Int.rotationExtensionAbduction
FlexionFlexionExtensionExtension
Shoulder & Elbow motion
Wrist & Hand motion
Wrist extension & full finger openWrist flexionTwo finger (Thumb&Index) open
1-4,2-4, & 3-45-61-4
Task Shoulder motion (Electrode) Elbow motion (Electrode)
a-ba-bd-e
a-b & d-e
b-cb-ce-fe-f
Bottle grasping
Small object picking
Task Target motion (Electrode)
While tactile sensation was not severely impaired, motor function of the upper extremity showedthe typical flexor synergy pattern. The patient demonstrated increased resistance to passive stretchin the distal flexor musculature, and did not use her paretic upper limb for functional activities.
Stroke survivors experience significant deficit of sensorimotor functions andhalf of them are left with major functional problems in their hands and armsIf recovery occures it is mostly during the first four weeks after stroke and itis very rare that improvements occur in chronic stroke patients
To investigate the effects of an intensive FET onmotor recovery of a chronic stroke patient.
a potential to restore their upper arm functions, specificallyin chronic stroke patients, is still not fully understoodHowever...
Question:
Purpose:
The results of the drawing test demonstratedan improvement of shoulder and elbow jointcoordination. The subject also showed that aremarkable improvement of dynamic ROM ofshoulder and elbow joints.
Maximal voluntary contraction level of upper arm muscles did not show remarkableimprovements. CMSA scores for arm and hand also showed no changes.
This finding supports the classical concept that muscle tonereduction represents simplistic solutions to the deficit in motorcontrol after stroke.
Functional Electrical Theraphy (FET)
Outcome Measures
FET program
(1) Motor function- CMSA and MVC test
(2) Spasticity assessment- MAS and H-reflex
(3) Kinematical measurements- Drawing test, Dynamic ROM
FET was administrated twotimes per day (one hour ineach session) and carried outfor 12 weeks. The patient hadcompleted all training sessions(in total 108 sessions)
A remarkable reduction of the armspasticity was observed as indicatedby the decrease of MAS and thereduction of H-reflex in the wrist flexormuscle (82.09% to 45.04% in theHmax/Mmax).
At the end of training, the patient was capable of picking up a thin object andtouched her nose which could not be done perior to the training.
Spasticity Assessment
Kinematical measurements
Motor Function
Acknowledgement:The authors acknowledge the support of Toronto Rehabilitation Institute who receives funding under theProvincial Rehabilitation Research Program from the Ministry of Health and Long-Term Care in Ontario.
Muscle activation level (stimulus intensity) which dealt with FET was not enoughto increase muscle strength in chronic stroke
The therapy consisted of two components:
During FET...
Recent studies reported a significant effect of the FET on recovery of upperextremity functions in stroke patients.
Pre-programmed, coordinate muscular stimulation that coincided with the phaseand type of arm motions that patient is trying to move. Stimulus intensity was 2times larger than motor thresholdManual assisted (externally generated) passive motion in order to establishphysiologically correct movement
(1)
(2)
2
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milos.popovic@utoronto.cawww.toronto-fes.ca
FES Therapy for Individuals with Complete and Incomplete SCI
FES Therapy: Restoring Voluntary Grasping FunctionM.R. Popovic, N. Kawashima, M.E. Adams, R. Yee and V. Zivanovic
Lyndhurst Centre, Toronto RehabInstitute of Biomaterials and Biomedical Engineering, University of Toronto
MethodsSubjects:
• 23 individuals with acute C4 to C7 SCI• 8 complete
• 3 FES therapy and 5 controls• 15 incomplete
• 7 FES therapy and 8 controls• On admission no active movement in the
wrists and/or fingers - up to less than half the normal active range
Assessments: • Assessments performed before and after the
treatment period • Hand function assessed using the REL
Hand Function Test• ADL assessed using FIM and SCIM• Assessments made without FES
Therapy:• Controls received two “doses” of regular OT
and PT (2h per day), which may have included electrical stimulation for muscle strengthening without the functional component
• Treatment group received one “dose” of conventional therapy (1h per day) plus one “dose” individualized FES programs (1h per day) in which the neuroprosthesis was used to help the patients complete only those movements they were unable to produce on their own
• Treatment was 5 times per week, for up to 8 weeks
Novelty• Programmable transcutaneous FES
system used to deliver short-term therapy
• Goal was to restore voluntary grasping function
• Both individuals with complete and incomplete SCI participated
• FES was not used as a permanent assistive device to facilitate grasping
Conclusions• Repetitive daily FES therapy facilitated the carryover in hand function in all
SCI individuals• ASIA A, B, C and D participants in the treatment group showed larger
improvements as compared to controls• Frequently small improvements in the hand function resulted in
considerable gains as measured by FIM
Results
Popovic et al, Med. Eng. & Physics 2005 Popovic et al, Spinal Cord 2006
3
2. Gait Experiment
In order to evaluate such an interesting phenomena quantitatively, wehave conducted the following very easy and simple gait experiment.
According to self-contemplation, H.O. strongly relies on visual informationduring walking. He told us the following interesting experiences;
Experiments consisted of three consecutive sets of walking at their comfortable speed. Stridetime interval was evaluated from the data obtained from accelerometer (AS-10G, Kyowa Inc.,Japan) placed on the lumber portion of the subjects (see below picture). The data was digitized(1 kHz) and stored in the memory of the data logging system (EDS-400, Kyowa Inc., Japan).
MethodsSubjects
He cannot walk with his eyes closed and is scared to walk in darkness.Interestingly, he needs several tens of seconds after the beginning ofwalking untill he feels "walking is stable."
0.9
1
1.1
1.2
1.3
1.5
1.7
0.9
1
1.1
1st 5 min walk 2nd 5 min walk 3rd 5 min walk
1minbreak
1minbreak
Patient H.O. (sensory loss)
Patient S.N. (hemiplegic stroke)
Normal M.A.
AccelerometerAS-10G, Kyowa Inc.
Sensor
(64yrs, Stroke patient who has complete sensory loss)(61yrs, Stroke patient who has lacks both sensory and motor function)(34yrs, Able-bodied person)
Results
cf. Similar description was partly provided by Rothwell et al. (1982)
Stride interval had larger variability, but kept within a certain range. Averaged stride time interval( gait speed) of patient H.O. was longer (slower) than that of M.A., but shorter (faster) than thatof S.N.
1"12 1"08 "58
The subjects walked on track field with their confortable speed (left picture). The right panel shows time-series stride timeinterval calculated from acceleration data. Triangle markers indicate the timing when O.H. felt "walking was stable".
Kawashima N ,Popovic MRNational Rehabilitation Institute for the Persons with Disability, JapanInstitute of Biomaterial and Biomedical Engineering, University of Toronto, CanadaLyndhurst Centre,Toronto Rehabilitation Institute, CanadaJapanese Society for Promotion of Science, Japan
1
2
3
4
1,2,3,4 2,3
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du CanadaCanadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du CanadaNatural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Healthand Long Term CareMinistry of Healthand Long Term Care
Necessity of Successive Sensory Feedbackto Update the Internal Model for Walking
1. BackgroundWalking is a highly sophisticated movement
in human behaviorEven when we walk on an unstable surface, we can unconsciouslyaccomplish stable walking within a few steps.
Given the previous finding about the internal model,two major mechanisms have been hypothesized tounderlie the above phenomenon of walking:
1. A predictive process according to previousexperiences (i.e., using the internal model)
2. A modifying process that detects a mismatchbetween the planned and actual movement(i.e., updating the internal model).
(Kawato et al. 1987)
3. Patient's InformationH.O. is a 64 year old stroke patient. While he has complete sensory lossin the right side of the body, his motor function is very well preserved.
The results of the electrophysiological testshowed that there are no somatosensoryevoked potentials elicited by the electricalstimulation from paretic side of the ulnar nerve(A), but larger motor evoked potentials in thefirst dorsal interosseous (FDI) muscle elicitedby transcranial magnetic stimulation on themotor cortex (B). Comparable EMG level duringmaximal voluntary contraction was observed inFDI of both side (C).
Normal side Paretic side
A Somatosensory evoked potential
20msecStim
Stim
B Motor evoked potential
20msec
1mV
100msec
C Maximal voluntary contraction
References:Hodgson et al. Can the mammalian lumber spinal cord kean a motor task? Med Sci Sports Exerc 26: 1491-1497, 1994Kawato M et al. A hierarchical neural-network model for control and lerning of voluntary movement. Biol Cybern 57: 169-185, 1987.Lam T et al. Contribution of feedback and feedforward strategies to locomotor adaptations. J Neurophysiol 95: 766-773, 2006Rothwell JC et al. Manual motor performance in a deafferented man. Brain 105: 515-542, 1982Timoszyk WK et al. The rat lumbosacral spinal cord adapts to robotic loading applied during stance. J Neurophysiol 88: 3108-3117, 2002Wolpart D and Ghahremani Z Comptational principle of movement neuroscience. Nature Neurosci 3: 1212-1217, 2000
Some evidences for the involvement of an internal model in the control of gaitwere suggested (Hodgson et al. 1994, Timoszyk et al. 2002, Lam et al. 2006)
4. Discussion
H.O. can seemingly walk well, but it takes several tens of seconds afterthe beginning of walking until the subject's stride reaches a steady level.(Such adaptive changes were not observed in S.N.)
Because H.O. is six years post injury, his walking performance hasalready been well established. Therefore, H.O. could presumably planand accomplish the task of walking by using the internal model.
Such adaptive changes might reflect the process which compensates forthe lack of sensory feedback using the visual information.
Once H.O. stops walking and resumes walking after one minute of break,it takes much time again to reestablish stable walking.
Main Results and Discussion
The present results strongly suggest that successive sensory feedbackis an essential factor for updating the internal model of walking.
Does H.O. have internal model for walking?
H.O. cannot detect a mismatch betweenplanned and accomplished movementbecause of his loss of sensory feedback.
Compensatory process accomplished by the visual information can beused only temporally. This process significantly differs from updatingthe internal model in able bodied individuals.
"The difference between the predicted and actualsensory feedback can be used as an error signalto update a predictive model"
(Wolpert and Ghahramani 2000)
As a result, H.O. needs visually inducedcompensation for the sensory loss ineach walk initiation.
Proposed Model
MotionError
FeedbackController
ControlledObject
ActualMovement
PredictedMovement
FeedbackMotor
Command
MotorCommand
Inverse Model FeedforwardMotor
Command
MotionError
FeedbackController
ControlledObject
ActualMovement
PredictedMovement
FeedbackMotor
Command
MotorCommand
Inverse Model FeedforwardMotor
Command
(A) The general feedback-error-learning model
(B) H.O.'s case
Somatosensory Feedback
MotorCommand
Error
MotorCommand
Error
ormmm
Mmmmam
Visuo-motorCenter
ory Feedbosensotosensoory Feo
Somatosensory Feedback
Compensatory process accomplishedby the visual information cannot bepreserved as an internal model.
Visuo-motorcommand
4
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
•Measurements- Measured Parameters: Oxygen Uptake (VO2 ), Telemetric breath respirationmesurement system (K4b2, Cosmed, Italy)- Calculated Parameter: Metabolic Equivalent (Index of exercise intensity):METs) (1MET = 3.5 ml/kg/m VO2 )- Stride length: Two-dimensional motion-analysis, the distance of the toe marker between two consecutive gate cycle (only participant A)
Methods•Participants: Two adults with incomplete SCI (participants A and B) and two able-bodied individuals (participants C and D) participated. The individuals with SCI completed 4 months of FES-assisted gait training prior to this study.
List of subjects
•Experimental Protocol- Walking Speed : 2.1km/h (participant A, C, D) and 2.5km/h (participant B) - Protocol
•FES System- Equipment: Compex Motion stimulators (Compex SA, Switzerland). Biphasic asymmetrical pulses (frequency 35Hz and pulse duration 0-300 s) were delivered to the body via eight self-adhesive gel electrodes. - Target Muscle: quadriceps, hamstrings, gastrocnemius /soleus and tibialisanterior- Pulse Amplitude: Participant A, B: 75% of the maximum FES induced contraction, Participant C, D: 20-25mA- FES Program: Feed-forward stimulation pattern triggered using two pushbuttons. For more details consult (Thrasher et al. 2005).
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: miyatani.masae@torontorehab.on.cawww.toronto-fes.ca
Oxygen Uptake during FES Treadmill Walking: Case StudyM. Miyatani1,2, N. Kawashima1,2, T.A. Thrasher3, M.Ranjan1,
K. Masani1,2 and M.R. Popovic1,2
Introduction•People with spinal cord injury (SCI) need to exercise on a regular basis to prevent secondary complications, such as cardiovascular diseases, osteoporosis and obesity. •To achieve the required fitness level is a challenging task for SCI patients because they have difficulty increasing their exercise intensity by on their own.•Functional electrical stimulation (FES) can restore movements by artificially contracting paralyzed or paretic muscles. Our previous study suggests that FES-assisted gait training has a positive effect on SCI patients (Thrasher et al. 2005). •It is likely that FES-assisted gait training can provide the required cardiopulmonary exercise in SCI patients by increasing their leg muscle activity and energy consumption. •However, to date, the physiological intensity of FES-assisted gait training has not been investigated.
PurposeTo examine the oxygen uptake and exercise intensity of FES-assisted gait training in patients with the motor-incomplete SCI.
1 Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2 Lyndhurst Centre, Toronto Rehab; & 3 Health & Human Performance, University of Houston
Results and Discussion
Non-FESWalking
FESWalking
Non-FESWalking
1min
Rest
4min 4min 4min
Rest
1min
Oxygen consumption was increased in FES walking in all four participants. The intensities of FES walking in the SCI participants were 4.0 and 5.3 METs. Thus, FES walking can be used to increase the exercise intensity for individuals with SCI who in general have difficulty increasing their exercise intensity on their own.
Conclusion
Oxygen Uptake during Rest, Non-FES Walking and FES Walking
VO2 was increased during FES walking compared to the initial Non-FES walking, and then decreased again during the second Non-FES walking in all four participants. The VO2 increments in FES walking from the initial Non-FES walking were 9.0, 5.0, 10.6 and 20.8% in participant A, B, C and D respectively.
METs value of rest, Non-FES Walking and FES Walking
METs values increased in FES walking in all four participants. MET values in participants A and B during FES walking (4-5 METs) corresponded to the level of moderate walking, which is the recommended daily physical exercise intensity by American college of sports medicine.
Subject Age (years) Height (cm) Weight (kg) SCI level ASIA score Yearspostinjury
Participant A 45 175.0 77.0 C4 C 2
Participant B 39 173.0 58.0 T6 Notapplocable 9
Participant C 30 169.0 63.0 - - -
Participant D 39 174.0 75.7 - - - Subject Rest Non-FES Walking(1st ) FES Walking Non-FES Walking
(2nd) Rest
Participant A 1.0 3.7 4.0 3.7 2.5
Participant B 2.2 5.1 5.3 5.0 0.0
Participant C 1.7 3.1 3.5 2.7 1.5
Participant D 1.1 2.4 2.9 2.4 1.0
Stimulation program for a single leg. The stimulation begins from initial state representing late stance phase, and pushbutton triggers open-loop sequence beginning with swing phase (Thrasher et al. 2005).
2468
101214161820
Rest Non-FESWalking
(1st )
FES Walking Non-FESWalking
(2nd)
Rest
Participant AParticipant BParticipant CParticipant D
A
Stride length during Non-FES Walking and FES Walking
2025303540455055606570
1st Non-FESWalking
FES Walking 2nd Non-FESWalking
Strid
e le
ngth
(cm
)
P<0.05 P<0.05 Stride length during FES walking was significantly larger than that of 1st Non-FES walking. Stride length during 2nd Non-FES Walking was smaller than that of FES Walking, but there was no significant difference between two sessions. This preliminary result might suggest that the VO2 increment in FES walking is due to the increment of stride length.
5
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: cheryl.card@utoronto.cawww.toronto-fes.ca
FREQUENCY RESPONSE OF STIMULATED KNEE MOVEMENTC. L. Lynch1,2, L. Mourra1 and M. R. Popovic1,2
What can the Bode plot tell us about electrical stimulation in SCI individuals?
Introduction
1Institute of Biomaterials & Biomedical Engineering, University of Toronto 2Toronto Rehabilitation Institute
Results
Discussion
References[1] Phillips CL & Harbor RD. Feedback Control Systems, 3rd edition. Prentice Hall, Upper Saddle River, NJ, USA. 1996.
• Functional electrical stimulation (FES) can be used to restore motor function to paralyzed muscles in individuals with spinal cord injuries (SCI). FES uses electricity to generate muscle contractions.
• New FES applications, such as balance while standing and torso control while sitting, require closed-loop control of stimulated muscle contractions.
• A system’s frequency response provides information about the system’sdynamics, and is useful when developing closed-loop control systems [1].
• We determined the frequency response of electrically stimulated knee movements in an individual with complete SCI:
• Input sinusoid – amplitude of stimulation delivered to muscle,
• Output sinusoid – resulting knee angle.
Hypotheses• The magnitude and phase responses will decrease with increasing fatigue
• The phase response will decrease with increasing frequency.
Methods
Figure 1 – Experimental Apparatus
• The magnitude and phase responses decreased with increasing fatigue.
• The phase response decreased with increasing frequency.
• Future work:
• Investigate the phase decrease at higher frequencies.
• Extend this study to multiple subjects, multiple sessions.
• Use results to describe system, then design closed-loop FES controller.
Knee Trajectory
Gonio-meter
Electrodes
Padded Bench
Figure 3 – Magnitude Response of Stimulated Knee Movements
Figure 2 – Phase Response of Stimulated Knee Movements• The quantities calculated for each trial: average phase shift, attenuation between stimulation waveform and knee angle.
• Figures 2 and 3 show the Bode plot of the stimulated knee movements.
• The quadriceps muscle was stimulated to contract (stim. frequency = 25 Hz, pulse width = 250 s), and resulting knee angle was recorded (see Fig. 1).
• The knee angle was made to follow a sinusoid by varying the stimulation amplitude sinusoidally between x and y mA:
• x – minimum amplitude at which knee began to extend,
• y – amplitude corresponding to maximum knee extension.
• Trials were conducted at different frequencies of stimulation sinusoid.
6
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated Foundation
Methods3D Dynamic ModelThe 3D dynamic model, which represents the human body during double-support stance, is shown in Fig. 1 [Kim et al., 2006].
Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: a.vette@utoronto.cawww.toronto-fes.ca
Optimal Combination of Minimum Degrees of Freedom to be Actuated for the Facilitation of Arm-Free Paraplegic Standing
Joon-Young Kim1,2, Albert H. Vette2,3, and Milos R. Popovic2,3
1 Department of Mechanical and Industrial Engineering, University of Toronto2 Lyndhurst Centre, Toronto Rehabilitation Institute
3 Institute of Biomaterials and Biomedical Engineering, University of Toronto
Inverse Dynamics SolutionApplication of a computationally efficient inverse dynamics method [Nakamura et al., 1989]:
• driven by kinematic data from four healthy subjects;• torque estimation for eight perturbation directions (D1 to D8 in Fig. 1);• torque estimation for six combinations of six active DOF (Cases I to
VI in Fig. 2) as identified in [Kim et al., 2006].
Fig. 1: Dynamic model of quiet standing with twelve DOF and eight perturbation directions (D1 to D8).
Results and Discussion
Conclusions
BackgroundArm-free paraplegic standing by means of functional electrical stimulation (FES) has the potential to allow individuals with paraplegia to stand and at the same time use both arms to perform activities of daily living such as cooking and ironing. In this context, we have recently shown that only six of the existing twelve degrees of freedom (DOF) in the lower limbs need to be actuated to facilitate stable standing in the presence of external perturbations [Kim et al., 2006].
Introduction
After identifying the various combinations of six DOF that allow stability during perturbed arm-free standing, the purpose of the present study was to determine the optimal DOF combination, i.e., the combination that requires the minimum total torque to regulate balance.
• HAT: – Head-Arms-Trunk– rigid body with constant mass and moment of inertia
• Legs: – six DOF each– sufficient number of DOF for a reasonable approximation
of the double-support characteristics of human standing
Fig. 2: Six cases of six DOF that need to be actuated in order to facilitate stable standing when external perturbations are present.
Fig. 3: Torque sums of the joint torques (5 s) at all active DOF, shown for each of the six cases and all directions of perturbation (D1 to D8).
The torque sums for each case (Case I to VI) and each perturbation direction (D1 to D8) are shown in Fig. 3. The torque sums were calculated for a duration of 5 s after the perturbation.
• Cases V and VI (Fig. 2) exhibited the smallest torque sums (Fig. 3) for all subjects and perturbations.
• Due to the symmetry of the legs, this results in four combinations of six active DOF that are optimal with respect to the joint torque sums.
D1 D2 D3 D4 D5 D6 D7 D80
200
400
600
Torq
ue S
um (N
m*s
)
D1 D2 D3 D4 D5 D6 D7 D80
400
800
1200
D1 D2 D3 D4 D5 D6 D7 D80
500
1000
1500
Perturbation Direction
Torq
ue S
um (N
m*s
)
D1 D2 D3 D4 D5 D6 D7 D80
200
400
600
Perturbation Direction
Case I Case II Case III Case IV Case V Case VI
Subject S1
Subject S3
Subject S2
Subject S4
Hip rotation (l)
Hip ab-/adduction (r)Hip flexion/extension (l)
Ankle dorsi-/plantarflexion (l)Ankle in-/eversion (r)
Knee flexion/extension (r)
• Cases V and VI of six active DOF can achieve paraplegic arm-free standing while requiring minimum joint torques.
• The required joint torques can be generated by contemporary FES technology.
• FES-assisted arm-free standing is feasible even in the case where only six DOF in the lower limbs of a paraplegic can be actuated.
7
8
PU
RP
OS
EPU
RPO
SE
CO
NC
LUSI
ON
CO
NC
LUSI
ON
Par
tner
s:
9
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated Foundation
Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: a.vette@utoronto.cawww.toronto-fes.ca
Motor Command of Proportional and Derivative (PD) Controller Can Match Ankle Torque Modulation during Quiet Stance
Albert H. Vette, Kei Masani, and Milos R. PopovicLyndhurst Centre, Toronto Rehab
Institute of Biomaterials and Biomedical Engineering, University of Toronto
The PD controller can not only regulate balance, but also mimic the sensory-motor control task during quiet stance. Future work will implement the PD control strategy as part of a closed-loop system to test the feasibility of developing a neuroprosthesis for standing.
Discussion and Conclusion• PD controller can match ankle torque modulation during quiet standing – even for a large sensory-motor time delay (> 180 ms).• Optimized PD gains agree with previous findings [Masani et al.,2006], and optimized twitch contraction time is physiologically valid.
Quiet Standing Experiments (12 healthy subjects)• Measurements:
– Ground reaction forces (Kistler force plate)– Body angle (Keyence laser sensor)
Fig. 3: Example of torque matching for eyes open condition (validation data for one subject).
Results
Fig. 4: Overall torque error (A) and matching percentage (B).
PD Controlled Feedback ModelThe modeled PD controller utilizes experimental body angle data to generate a motor command that is translated into ankle torque by a 2nd
order muscle model of the plantar flexors [Tani et al., 1996] (Fig. 2).
Materials and Methods
Fig. 2: Schematic diagram of the PD controlled feedback model.
Closed-Loop Time Delay to be Considered (Fig. 1A):– Feedback time delay (TauF = 40 ms)– Motor command time delay (TauM = 40 ms)– Torque generation delay (TauE > 100 ms)
= closed-loop time delay of more than 180 ms that needs to be compensated for by the neural PD controller
IntroductionBackground of StudyOur simulation studies have demonstrated that a proportional andderivative (PD) feedback controller can compensate for the sensory-motor time delay (Fig. 1A) and stabilize the body during uprightstance. The required phase advance is generated by a large derivative gain Kd (Fig. 1B), resulting in a physiological motor command that precedes body sway by 100 to 200 ms [Masani et al., 2006].
After verifying experimentally that the PD controller can regulate balance during quiet stance [Vette et al., 2007], the purpose of the present study was to investigate whether the modulation of the PD controlled ankle torque can match the experimentally identified ankle torque modulation during quiet standing.
Fig. 1: Sensory-motor time delay (A) and PD phase advance (B).
( ) ( ) ( )PD P DdM t K t K tdt
Kp Channel
MPD
Kd
Cha
nnel
Phase Advance
B
COM
A
Experimental Body Angle
M
F
Kp
Kd
+ PD Controlled Ankle Torque2 2
1T s +2Ts+1
CNS Experimental Ankle Torque
Feedbacktime delay
Motortime delay
Torque generation delay
E
Muscle
> 180 ms
Hypothesis: Despite the closed-loop time delay, the PD controlled ankle torque modulation (model output) can match the experimental ankle torque modulation during quiet standing.
The authors acknowledge the support of the Toronto Rehabilitation Institute which receives funding under the Provincial Rehabilitation Research Program from the Ministry of Health and Long-Term Care in Ontario. The views expressed do not necessarily reflect those of the Ministry.
• Tasks:– Quiet standing with eyes open (2 60 s)– Quiet standing with eyes closed (2 60 s)
Optimization Procedure (DIRECT algorithm)• Optimized Parameters (gray boxes in Fig. 2):
– PD gains: Kp [Nm/rad] and Kd [Nm s/rad]– Twitch contraction time T of muscle model [ms]
• For each trial: 30 s of optimization & 30 s of validation• Analysis: Identification of error torque and matching percentage
0 10 20 3050
60
70 [Kp,Kd,T] = [746,250,73]
Experimental torquePD controlled torque
EO EC0
1
2
Erro
r Tor
que
[Nm
]
EO EC94
96
98
100
Mat
chin
g
Pe
rcen
tage
[%]
Ank
le T
orqu
e [N
m]
Time [s]
BA
10
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milos.popovic@utoronto.cawww.toronto-fes.ca
A Model of Electrically Stimulated Knee Response for Use in FES Systems
•Functional electrical stimulation (FES) is a promising rehabilitation modality for individuals with spinal cord injuries (SCI) that involves electrically stimulating the neuromuscular system to generate skeletal muscle contractions. FES has been used for gait training [1] and grasp rehabilitation [2], among other applications. Currently, such systems require a significant amount of intervention by the user or the therapist.
•We are developing FES rehabilitation systems that work semi-autonomously, freeing the therapist and patient to concentrate on the rehabilitation, instead of concentrating on the technology. Such FES systems require closed-loop control, which is not currently available for clinical FES systems.
•One of the reasons that closed-loop control is not currently used in clinical FES systems is the lack of a model of the body’s response to electrical stimulation that captures the variability of the response.
•We propose a new stochastic model that will capture the day-to-day variation in the body’s response to stimulation.
Introduction
Fig 2 – Raw Data and Envelope of 100 Stochastic Best-Fit Models
References[1] TA Thrasher, HM Flett, & MR Popovic. Spinal Cord. 44(6):1-5. 2006.
[2] MR Popovic, TA Thrasher, ME Adams, V Takes, V Zivanovic, MI Tonack. Spinal Cord. 44(3):143-151. 2006.
[3] WH Press, BP Flannery, SA Teukolsky, WT Vetterling. Numerical Recipes in C, 2nd ed. Cambridge University Press, Cambridge, UK, 1999.
STOCHASTIC MODELING OF KNEE RESPONSEC. L. Lynch1,2 and M. R. Popovic1,2
1Institute of Biomaterials & Biomedical Engineering, University of Toronto 2Toronto Rehabilitation Institute
•We hypothesize that a nonlinear model with a stochastic term will capture the day-to-day variation in response to electrical stimulation that is seen in individuals with SCI.
Hypotheses
•We randomly stimulated the quadriceps and hamstrings of a seatedindividual with a complete SCI at T3, and recorded the resulting knee angle with an electrogoniometer.
•We collected data during 24 hour-long sessions over the course of 8 weeks. We processed the data to de-noise and normalize all trials to the same initial knee angle, and grouped the trials by stimulation level.
•For each set of quadriceps and hamstrings stimulation parameters, we found the best-fit stochastic model of the form
•The deterministic portion of the model was a linear combination of M nonlinear basis functions, gi(t), which were chosen to represent parts of typical response curves. The coefficients, ai, were found by using singular value decomposition and were chosen to minimize a Chi-square metric.
•The stochastic portion of the model, X(t), is a function whose value at each time point is a normally distributed random variable. The standard deviation of the random variable is the same as the standard deviation of the recorded knee responses at that time point, for a particular set of stimulation parameters.
Methods
•Fig 1 and 2 show the results of modeling the knee response to 86 mA quadriceps and 24 mA hamstrings stimulation. Fig 1 shows the mean of all trials at this stimulation level and the stochastic best-fit model. For this stimulation level, the best-fit model used 7 basis functions. Fig 2 shows the raw data as well as the envelope of 100 stochastic best-fit models.
Results
•The raw data and stochastic best-fit models show similar statistical properties, and the stochastic model encompasses the variation seen in the knee response.
•This stochastic modeling method captures the day-to-day variation in response to electrical stimulation that can be seen in individuals with spinal cord injuries. Such models will facilitate the development of a closed-loop system that is sufficiently robust to be used in real-world FES rehabilitation applications.
Conclusions
Fig 1 – Stochastic Best-Fit Model
tXtgatf M
i ii1
11
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: v.sin@utoronto.cawww.toronto-fes.ca
Muscle Recruitment Patterns in Perturbed SittingV. Sin1,2, K. Masani1,2, A. H. Vette1,2, T. A. Thrasher3, A. Morris2, N. Kawashima2,
B.C. Craven2, and M. R. Popovic1,2
• People with spinal cord injury (SCI) have trouble maintaining trunk stability during sitting
• Functional electrical stimulation (FES) applies bursts of short electric pulses to groups of muscles to generate functional muscle contractions
• FES could be used to increase trunk stability during sitting for people with SCI
• Information about which trunk muscles are essential during sitting, and how these muscles respond to external perturbations are needed to develop a practical neuroprosthesis for sitting
1Institute of Biomaterials and Biomedical Engineering, University of Toronto2Toronto Rehab, Lyndhurst Centre, 3University of Houston
• Directional dependencies could be seen for RA, EO, IO, T9 and L3 (Fig. A)• No directional dependencies found for SM and SC • EMG responses of RA, EO, IO, T9 and L3 were curve fitted using Gaussian (Fig. B):
Results
• The present study was the first to characterize the muscle responses mathematically to loads from different perturbation directions
• The direction and range of activation in which each muscle was maximally activated could be identified using these formula
• These formulas could be used in implementing a FES system for trunk muscles to stabilize sitting posture for people with SCI
This project was funded by CIHR
Conclusion
• Subjects: 12 healthy, right-handed male, age 21 to 39 years
• Protocol:• Surface electrodes were placed on trunk and neck muscles on both sides of the body to measure muscle activities (EMG)
• Subject sat on a custom seating apparatus, with the arms crossed in front of their chest, eyes-closed in a relaxed and natural position. Subject wore headphones and listened to asynchronous nature sounds. He also counted numbers aloud to prevent anticipation.
• 40 perturbation trials (8 directions, 5 trials each) were applied to the subject at chest level manually
Methods
• To determine the directional dependencies of trunk muscle responses, and the amount of muscle activities to perturbations applied from different directions during sitting of able-bodied subjects
Goals
)))/)(((10
232exp ccxccy
1 - rectus abdominis (RA)2 - external obliques (EO)3 – internal obliques (IO)4 – thoracic erector spinae (T9)5 – lumbar erector spinae (L3)6 – latissimus dorsi (LD)7 – sternocleidomastoid (SM)8 – splenius capitis (SC)9 - reference
12
3
45
6
7
8
3Back
4
5
6
8
12
79
Front
Fig. A
Fig. B
Introduction
12
Toro
nto
Re
ha
bEv
eryt
hing
Hum
anl
yPo
ssib
le
ib
bm
eIn
sti
tute
of
Bio
ma
teri
als
an
dB
iom
ed
ica
lE
ng
ine
eri
ng
Rehabilit
ati
on
Engin
eerin
gLaborato
ry
Canada
Foundatio
nfo
rIn
nova
tion
Fondatio
nC
anadie
nne
pour
l’innova
tion
Min
istr
yo
f
Hea
lth
and
Lon
g-T
erm
Car
e
Onta
rio
CIH
RC
ana
dia
nIn
stitute
so
fH
ea
lth
Re
sea
rch
IRSC
Inst
ituts
de
rec
he
rche
en
santé
du
Ca
nd
a
RE
PA
RFR
SQ
CR
SN
G
NS
ER
C
Na
tura
lS
cie
nce
sa
nd
En
gin
ee
rin
gR
ese
arc
hC
ou
ncil
of
Ca
na
da
Co
nse
ild
ere
ch
erc
he
an
dscie
nce
sn
atu
relle
se
te
ng
én
ied
uC
an
ad
aN
atu
ralS
cie
nce
sa
nd
En
gin
ee
rin
gR
ese
arc
hC
ou
ncil
of
Ca
na
da
Co
nse
ild
ere
ch
erc
he
an
dscie
nce
sn
atu
relle
se
te
ng
én
ied
uC
an
ad
a
Part
ners
:T
he
vie
ws
expre
ssed
inth
isposte
rdo
notnecessarily
reflectth
ose
ofany
ofth
egra
nting
agencie
s
Reh
ab
ilit
ati
on
En
gin
eeri
ng
Lab
ora
tory
Insti
tute
of
Bio
mate
rials
an
dB
iom
ed
icalE
ng
ineeri
ng
,U
niv
ers
ity
of
To
ron
toTo
ron
toR
eh
ab
ilit
ati
on
Insti
tute
Co
nta
ct:
ww
w.t
oro
nto
-fes.c
am
ilos.p
opovic
@uto
ronto
.ca
MadeinCanada
We
als
oth
an
kD
r.Jo
yce
Fu
ng
,a
nd
the
JR
H-C
RIR
,fo
rth
eu
se
of
eq
uip
me
nt
an
dla
bo
rato
ryspa
ce
for
the
acq
uis
itio
no
fth
ese
da
ta.
Ap
pro
ach
:a
)C
OP
po
sitio
nd
urin
gta
rge
t-d
ire
cte
dtr
un
km
ove
me
nts
(11
su
bje
cts
)
b)
Ma
rgin
of
sta
bili
ty=
min
imu
md
ista
nce
fro
mC
OP
tolim
its
of
sta
bili
ty
Re
su
lts:
Th
em
arg
ino
fsta
bili
tysig
nific
an
tly
de
cre
ase
dw
ith
:a
)M
ove
me
nt
inth
efr
on
talp
lan
e
b)
Incre
ase
dta
rge
td
ista
nce
c)
Incre
ase
dm
ove
me
nt
sp
ee
d
Sig
nific
an
tin
tera
ctio
ne
ffe
cts
we
refo
un
db
etw
ee
n:
a)
Ta
rge
td
ista
nce
an
dm
ove
me
nt
sp
ee
db
)Ta
rge
td
ista
nce
an
dm
ove
me
nt
dire
ctio
n
2)
Po
stu
ralsw
ay:
qu
iet
up
rig
ht
sit
tin
g
Main
Fin
din
gs:
a)
Covers
atare
a<
0.0
2%
ofB
oS
b)
Elli
ptical,
with
majo
raxis
offsetfr
om
sagitta
lpla
ne
c)
Cente
red
inth
ebase
ofsupport
(slig
htly
left
&a
nte
rio
r)
CE
NT
ER
OF
PR
ES
SU
RE
EX
CU
RS
ION
DU
RIN
GV
OL
UN
TA
RY
TR
UN
KM
OV
EM
EN
TIN
SIT
TIN
G
Ric
hard
A.P
reu
ss
Ph
DP
Tan
dM
ilo
sR
.P
op
ovic
Ph
DP.E
ng
.
1)
Lim
its
of
sta
bilit
y
Main
Fin
din
gs:
a)
Covers
an
are
a~
33%
ofth
ebase
ofsupport
b)
Elli
ptical,
with
the
majo
raxis
inth
esagitta
lpla
ne
c)
Cente
red
inth
ebase
ofsupport
(slig
htly
left
&a
nte
rio
r)
Ap
pro
ach
:a
)M
axim
um
vo
lun
tary
lea
nin
8d
ire
ctio
ns
(11
su
bje
cts
)
b)
Le
ast-
sq
ua
ree
llipse
fit
tom
axim
um
CO
Pe
xcu
rsio
n
Re
su
lts:
Elli
ptica
llim
its
of
sta
bili
ty-
me
an
(sd
)
Are
a:
32
.7%
(0.4
%)
Bo
S
Ce
nte
r:5
4.9
%(4
.5%
)B
oS
len
gth
45
.5%
(1.5
%)
Bo
Sw
idth
Ma
jor
Axis
:3
5.7
%(3
.4%
)B
oS
len
gth
26
.9%
(3.9
%)
Bo
Sw
idth
Ecce
ntr
icity:
0.6
6
Orie
nta
tio
n:
-2.0
(5.3
)o
o
Ap
pro
ach
:a
)C
OP
po
sitio
no
ve
r4
min
ute
so
fq
uie
tsittin
g(9
su
bje
cts
)
b)
Le
ast
sq
ua
ree
llipse
fit
(axis
len
gth
do
ub
led
)
c)
Elli
pse
sfit
toe
ach
1m
inu
tep
erio
d(a
xis
len
gth
do
ub
led
)
Re
su
lts:
Fo
ur
Min
ute
s:
On
eM
inu
teIn
terv
als
:A
rea
:0
.01
55
%(0
.00
36
%)
Bo
SA
rea
:0
.00
47
%to
0.0
09
2%
Bo
SC
en
ter:
53
.3%
(4.1
%)
Bo
Sle
ng
thC
en
ter:
52
.5%
to5
2.1
%B
oS
len
gth
48
.1%
(1.1
%)
Bo
Sw
idth
48
.3%
to4
8.0
%B
oS
wid
thM
ajo
rA
xis
:1
.02
%(0
.54
%)
Bo
Sle
ng
thM
ajo
rA
xis
:0
.66
%to
0.4
2%
Bo
Sle
ng
thM
ino
rA
xis
:0
.45
%(0
.19
%)
Bo
Sle
ng
thM
ino
rA
xis
:0
.41
%to
0.3
3%
Bo
Sle
ng
thE
cce
ntr
icity:
0.9
0E
cce
ntr
icity:
0.4
2to
0.7
8O
rie
nta
tio
n:
-6.7
(21
.4)
Orie
nta
tio
n:
-11
.2to
6.7
oo
oo
3)
Targ
et-
dir
ecte
dtr
un
km
ovem
en
t
Main
Fin
din
gs:
Sig
nific
antdecre
ase
inth
em
arg
inofsta
bili
tyw
ith:
a)
Movem
entin
the
fronta
lpla
ne
vs.sagitta
lpla
ne
b)
Incre
ased
targ
etdis
tance
c)
Incre
ased
speed
ofm
ovem
ent
Un
ify
ing
Co
nc
lus
ion
:T
he
se
limits
of
sta
bili
typ
rovid
ea
va
lidm
ea
ns
toq
ua
ntita
tive
lyin
terp
ret
the
ch
alle
ng
eto
sta
bili
typ
ose
db
yva
rio
us
tasks
pe
rfo
rme
din
sittin
g.
0
0
0.2
0.2
0.2
0.4
0.4
0.4
0.6
0.6
0.6
0.8
0.8
0.8
1
1
0
0
0.2
0.2
0.2
0.4
0.4
0.4
0.6
0.6
0.6
0.8
0.8
0.8
1
1
0.7
5
L
AL
A
AR
R
Dire
ctio
ns
12
3
15
o
Dis
tan
ce
s
20
15
10 5
25
L
L
L
AL
AL
AL
A
A
A
AR
AR
AR
R
R
R
Sp
eed
1S
peed
2S
peed
3
Margin(%lengthofBoS)
Dis
tance
1
20
15
10 5
25
L
L
L
AL
AL
AL
A
A
A
AR
AR
AR
R
R
R
Sp
eed
1S
peed
2S
peed
3
Margin(%lengthofBoS)
Dis
tance
2
20
15
10 5
25
L
L
L
AL
AL
AL
A
A
A
AR
AR
AR
R
R
R
Sp
eed
1S
peed
2S
peed
3
Margin(%lengthofBoS)
Dis
tance
3
Metronome-PacedMovements
0.4
75
0.4
7
0.4
75
0.4
8
0.4
85
0.4
80
.48
50
.49
a)
0.4
75
0.4
7
0.4
75
0.4
8
0.4
85
0.4
80
.48
50
.49
b)
0.4
75
0.4
7
0.4
75
0.4
8
0.4
85
0.4
80
.48
50
.49
Min
ute
1M
inu
te2
Min
ute
3M
inu
te4
c)
Sp
ee
ds
10/so
20/so
30/so
Self-P
aced
Me
tro
no
me
Pa
ce
d
12
3
Self-PacedMovements
Margin(%lengthofBoS)
20
15
10 5
25
L
L
L
AL
AL
AL
A
A
A
AR
AR
AR
R
R
R
Dis
tan
ce
1D
ista
nc
e2
Dis
tan
ce
3
0.4
75
0.5
15
0.5
2
0.5
3
0.4
80.4
85
0.4
9
0.5
25
0
0
0.2
0.2
0.2
0.4
0.4
0.4
0.6
0.6
0.6
0.8
0.8
0.8
1
1
Lim
its
of
Sta
bili
ty
Qu
iet
Sittin
g(4
min
ute
s)
0.4
75
0.5
15
0.5
2
0.5
3
0.4
80.4
85
0.4
9
0.5
25
Min
ute
1M
inu
te2
Min
ute
3M
inu
te4
Qu
iet
Sittin
g(1
min
ute
inte
rva
ls)
13
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milos.popovic@utoronto.cawww.toronto-fes.ca
Posturography Measures during Quiet Sitting
• Sitting balance is an important factor for the activity of daily life of individuals with SCI
• Previous studies have shown that the centre of pressure (COP) displacement recorded during quiet standing reflects the overallpostural control system
• Postural steadiness (posturography) is commonly used for balance assessment but has not been applied to the study of sitting balance
Introduction
Fig1 – (A) Experimental setup and (B) an example of COP time series (only 30 s of data presented) in a planar plot (left), and time series of AP (top) and ML (bottom)
Table 1: Stabilogram Diffusion Function Measures
References1. C. Maurer, R.J. Peterka, Journal of Neurophysiology 93 (2005)
189 - 200.2. T.E. Prieto, et al., IEEE Transactions on Biomedical Engineering
43 (1996) 956-966.3. J.J. Collins, C.J. de Luca, Experimental Brain Research 95
(1993) 308-318.
• Differences in time-domain measures, and frequency-domain measures between quiet sitting and quiet standing could be attributed to the differences in the size of the free moving part (i.e., the whole body versus trunk, arms and head)
• Quiet sitting utilizes open-loop and closed-loop postural control schemes similar to standing, but the exact control schemes are different between sitting and standing
Conclusions
• Thirteen healthy male individuals with no history of neurological disorders participated
•Age 21-39 years•Height 178.0 ± 4.7cm•Weight 70.3 ± 10.0kg
• Individuals were asked to sit quietly on a force plate for 140 seconds, as shown in Fig1
• The force plate data was used to calculate the net COP in the anterior-posterior (AP) and medio-lateral (ML) directions, and resultant distance (RD)
• Signals were collected using a 64-channel, 12-bit analog-to-digital converter at a sampling frequency of 2000Hz
Methods
1Institute of Biomaterials and Biomedical Engineering, University of Toronto2Toronto Rehab, Lyndhurst Centre, 3University of Houston,
4Japan Society for the Promotion of Science
V. Sin1,2, K. Masani1,2, A. H. Vette1,2, T. A. Thrasher3, N. Kawashima4,A. Morris2 and M. R. Popovic1,2
• The time-domain measure values during quiet sitting were smaller than the corresponding values during quiet standing (Fig2)
• Mean frequency was two to three times higher for quiet sitting as compared to quiet standing (Fig2)
• Stabilogram diffusion analyses measures (Table 1): Hurst exponent for the short-term and long-term intervals for sitting were larger and shorter, respectively, as compared to standing. The critical time interval was shorter during sitting as compared tostanding
Results
• Time-domain, frequency-domain and stabilogram diffusion analyses were applied to the COP time series as described in thestudy by Maurer et al. [1]
• Time-domain, frequency-domain results were compared to those described in the quiet standing study by Prieto et al. [2]
• Stabilogram diffusion analyses results were compared to those described in the quiet standing study by Collins and DeLuca [3]
Analysis
Quiet Sitting Quiet Standing [2] Ratio*
RD 0.45 ± 0.24 0.92 ± 0.29 0.49 AP 0.53 ± 0.36 0.97 ± 0.46 0.55
tc (s)
ML 0.49 ± 0.23 1.06 ± 0.42 0.47 RD 0.86 ± 0.03 0.76 ± 0.04 1.13 AP 0.86 ± 0.03 0.77 ± 0.04 1.12
HS
ML 0.89 ± 0.05 0.74 ± 0.05 1.20 RD 0.12 ± 0.14 0.34 ± 0.08 0.31 AP 0.10 ± 0.18 0.38 ± 0.10 0.28
HL
ML 0.20 ± 0.12 0.23 ± 0.05 0.89 *ratio = quiet sitting / quiet standing
Fig2 – Comparison of time-domain and frequency-domain measures
• To investigate how posturography during quiet sitting in healthy young male individuals differs from that of quiet standing
• To provide a benchmark for evaluating balance capacity during quiet sitting within different patient populations
Purpose of study
14
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: cesar.marquezchin@utoronto.cawww.toronto-fes.ca
Identifying Movements From Cortical Signals
Electrocorticographic Signals Reflect Specific Motor Tasks
• The consistency of the distributions of correlated spectral components suggest that it might be possible to use it as features to automatically classify ECoG signals.
Discussion
Table 1. Participants of this study.
Female / 65
Male / 73
Age / Gender
•Closing Hand (CH)•Reaching to the Right (RTR)•Reaching to the Left (RTL)
•Elbow Flexion (EF)•Reaching to the Right (RTR)•Reaching to the Left (RTL)
Performed Movements
ET
PD
Diagnosis
2
1
Subject
Background• Different frequency bands in the electrical activity of the
brain experience changes in amplitude during voluntary movement and/or preparation to perform such movement.
• These changes have been used to identify the occurrence of specific movements.
• The electrical activity of the brain can be recorded with intracranial electrodes (subdural electrodes) placed on the surface of the brain.
• The signals recorded with these electrodes are referred to as ECoG signals.
Participants• Two individuals were implanted with subdural electrodes (four
contacts) for the treatment of movement disorders: Parkinson’s disease (PD) and Essential Tremor (ET). (See Fig. 1 and Table I)
• The site of implantation corresponded to the arm area of the primary motor cortex, confirmed with electrical stimulation.
Materials and Methods
Experimental Procedure• Participants performed specific movements (see Table I).• ECoG signals and position (X, Y, Z coordinates) of the hand were
recorded simultaneously.
Analysis• ECoG signals were analyzed in different configurations including
monopolar as well as the difference between adjacent and non-adjacent electrodes.
• The time-frequency distribution was estimated for each ECoG signal with a resolution of 1.5 Hz
• The spectral components with the highest correlation values witheach one of the kinematic dimensions were identified for each movement
• These frequency components were then grouped in a histogram• The magnitude of each column represents the probability that a
specific frequency band is correlated with a kinematic dimensionof each movement.
• To create a system that uses the electrical activity of the brain to control electronic devices: a brain-computer interface.
Long –Term Goal
• The consistency of the distributions of correlated spectral components suggest that these features might be used to classifyECoG signals automatically.
Results
Figure 2. Average distribution of ECoG spectral components correlated with movement.
Figure 1. Subdural electrodes used for this study.• Explore the changes elicited by specific movements in the
electrical activity of the primary motor cortex.• Identify features in the electrocorticographic (ECoG) signals that
show consistent behaviour in relationship to movement.
Purpose of the Study
César Márquez Chin and Milos R. PopovicInstitute of Biomaterials and Biomedical Engineering, University of Toronto
Toronto Rehabilitation Institute
15
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Fig. 1: Measurement setup for peripheral nerve source localization
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: jose.zariffa@utoronto.cawww.toronto-fes.ca
Localizing Active Pathways in Peripheral Nerves
• Localizing active pathways in peripheral nerves would help us tomonitor control signals flowing between the central nervous system and a limb or an organ, and ultimately to control a neural prosthesis.
• Using a multi-contact nerve cuff electrode and solving a source localization inverse problem (similar to EEG source localization), we hope to observe information flow through a peripheral nerve.
• We tested the proposed methods on simulated measurements.
Introduction
[1] Pascual-Marqui, Meth. Find. Exp. Clin. Pharmacol., vol. 24 Suppl D, pp. 5–12, 2002
[2] Sweeney et al, Proc Ninth Ann Int Conf IEEE Eng Med BiolSoc, pp. 1577–1578, 1987.
v: measurements L:leadfield j: sources : noise
Methods• The relationship between the measurements and bioelectric sources
in the nerve can be expressed as a linear system.
• L is computed using a finite-element model of a rat sciatic nerve.
• We want to recover j from v, knowing L, but there are more unknown variables than measurements, resulting in an underdetermined problem. Many algorithms exist for this sort ofsituation, and rely on imposing constraints on the solution.
• We chose to use the sLORETA [1] algorithm, which was originally developed for localizing bioelectric sources in the brain. It uses a smoothness constraint, resulting in a blurred solution with well-localized peaks.
• Our choice of algorithm is based on three criteria:1. No assumption about the number of sources2. No assumption about stationarity3. Speed
Test Cases• Action potentials propagating through the nerve were simulated
using the Sweeney model for ion channel dynamics in myelinatedmammalian nerve fibers [2]. The corresponding measurements were computed using Equation 1, for a 2.5ms time interval.
• First case: one active pathway at a random cross-sectional position (100 trials).
• Second case: three simultaneous active pathways at random cross-sectional positions and with small random time shifts (100 trials).
v = Lj + Eq1:
Results
Fig. 1: Measurement setup schematic for peripheral nerve source localization
J. Zariffa and M.R. PopovicInstitute of Biomaterials and Biomedical Engineering , University of Toronto
Electrical and Computer Engineering, University of Toronto Toronto Rehabilitation Institute, Canada
Fig. 3: Simulation results in terms of pathway localization error, missed pathways, and spurious pathways.
Conclusions
References
Fig. 2: Localization example for a single-pathway trial
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
x (mm)
Estimated source distribution (time-averaged and projected onto 2D)
y (m
m)
True source location
-5 0 5 10 15 20 250
0.05
0.1
0.15
0.2
Noise Level (%)
Loca
lizat
ion
erro
r (m
m)
Average Localization Error, 1-Pathway Case
-5 0 5 10 15 20 250
0.05
0.1
0.15
0.2
0.25
Noise Level (%)
Loca
lizat
ion
erro
r (m
m)
Average Localization Error, 3-Pathway Case
-5 0 5 10 15 20 25-1
-0.5
0
0.5
1
Noise Level (%)
Mis
sed
path
way
s
Average Missed Pathways, 1-Pathway Case
-5 0 5 10 15 20 250.5
1
1.5
2
2.5
Noise Level (%)
Mis
sed
path
way
s
Average Missed Pathways, 3-Pathway Case
-5 0 5 10 15 20 25-1
0
1
2
3
4
Noise Level (%)
Spu
rious
pat
hway
s
Average Spurious Pathways, 1-Pathway Case
-5 0 5 10 15 20 25-0.5
0
0.5
1
1.5
2
2.5
Noise Level (%)
Spu
rious
pat
hway
s
Average Spurious Pathways, 3-Pathway Case
• Localization can be achieved within tolerable error in the one-pathway case, although the solution is blurred. The blurring isinherent to the sLORETA algorithm and therefore to be expected.
• The limited resolution is the biggest challenge to the localization of several pathways, because pathways close to each other cannotbe adequately separated. Alternative algorithms should be explored to address this issue.
• The other issue to be addressed is the high number of spurious pathways at high noise levels.
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
16
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Implementation
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milos.popovic@utoronto.cawww.toronto-fes.ca
Control of Multiple Degree-of-Freedom Tasks Using One-Dimensional Electroencephalographic Signals
Egor Sanin 1,2, César Márquez Chin 1,2, Jorge Silva 2, Tom Chau 2,3, Alex Mihailidis 2,4, and Milos R. Popovic 1,2.
1 Toronto Rehabilitation Institute, Toronto, Canada. 2 University of Toronto, Toronto, Canada. 3 Bloorview Kids Rehab, Toronto, Canada. 4 Intelligent Assistive Technology and Systems
Laboratory, Toronto, Canada.
Results
Conclusion• We developed and implemented a brain-machine interface which allows a single EEG channel to be used for real-timetwo-dimensional navigation, an example of a multiple degree-of-freedom task.
What is a Brain-Machine Interface (BMI)?
EEG
ComputerBrain
SignalProcessing
Binary Signal Single-Switch Asynchronous
Control Strategy Real-time 2-D navigation
Proposed Solution
Limitations
Single-Switch AsynchronousControl Strategy
0360Randomly selected
by algorithmDesired direction
0 360n
0 360n + 1
0 3600
0 360n + 2
Signal ProcessingBand-pass
filter:8-13 Hz
Moving Average <T
T = Threshold
True
False
System realized in software to navigate a cursor towards a target. System realized in hardware to drive a remote-controlled car.
Raw EEG signals are processed to realize a voluntary binary switch.
EEG binary switch used to drive an asynchronous control algorithm which
iteratively converges on the desired outcome.
BackgroundBinary Switch
17
THE
BU
TTO
N
Vic
ryl S
utur
eKn
ot
Qua
dric
eps
Mus
cle
Intr
oduc
tion
•Fun
ctio
nal e
lect
rical
stim
ulat
ion
(FE
S) i
s a
relia
ble
met
hod
tofa
cilit
ate
mov
emen
t of p
aral
yzed
lim
bs a
fter a
spi
nal c
ord
inju
ry.
•Bra
in-m
achi
ne in
terfa
ces
(BM
I) us
e br
ain
sign
als
to g
ener
ate
cont
rol c
omm
ands
.•T
he c
onve
rgen
ce o
f the
fiel
ds o
f mot
or n
eurp
rost
hetic
san
d B
MI a
ppea
rs to
be
a na
tura
l ste
p fo
r the
se tw
o ar
eas
of re
sear
ch.
•We
crea
ted
a ne
urop
rost
hesi
s fo
r gra
spin
g an
d co
ntro
lled
it us
ing
EC
oG s
igna
ls a
cqui
red
prev
ious
ly.
Usi
ng B
CI t
echn
olog
y, a
neu
ropr
osth
esis
cou
ld d
etec
t the
inte
ntio
n of
pe
rfor
min
g a
spec
ific
mov
emen
t and
del
iver
the
elec
tric
al s
imul
atio
n pa
ttern
to p
rodu
ce th
e in
tend
ed m
ovem
ent.
Met
hod
Subj
ects
•67
year
old
wom
an•Im
plan
ted
with
a q
uadr
ipol
arsu
bdur
al e
lect
rode
to tr
eat e
ssen
tial
trem
or•P
erfo
rmed
spe
cific
arm
mov
emen
ts:
wris
t fle
xion
(WF)
, rea
chin
g to
the
right
(RTR
), an
d re
achi
ng to
the
left
(RTL
).
Sub
ject
1
Sub
ject
2
•35
year
old
man
•Mot
or c
ompl
ete
cerv
ical
spi
nal
cord
inju
ry (C
6 le
vel/
AS
IA B
) •R
ecei
ved
4 w
eeks
of F
ES
th
erap
y•F
itted
with
a n
euro
pros
thes
is fo
r gr
aspi
ng
Impl
emen
tatio
n D
etai
ls
•Tim
e-re
solv
ed E
CoG
spe
ctra
l co
mpo
nent
s co
rrela
ted
with
eac
h m
ovem
ent a
re g
roup
ed u
sing
hi
stog
ram
s w
ith b
ins
repr
esen
ting
frequ
ency
ban
ds o
f 10
Hz.
•The
his
togr
ams
wer
e us
ed a
s fe
atur
es
for c
lass
ifica
tion
of E
CoG
sig
nals
[1].
ECoG
Con
trol
led
Neu
ropr
osth
esis
for G
rasp
ing
Sub
ject
2 p
ress
ed o
ne o
f thr
ee b
utto
ns to
con
trol t
he n
euro
pros
thes
is.
Eac
h bu
tton
was
as
soci
ated
with
a d
atas
et o
f EC
oG s
igna
ls re
cord
ed p
revi
ousl
y fro
m s
ubje
ct 1
. Th
e sy
stem
ra
ndom
ly e
xtra
cted
a s
ingl
e tri
al o
f the
cor
resp
ondi
ng d
atas
et w
hich
was
cla
ssifi
ed b
y a
near
est n
eigh
bour
clas
sifie
r. T
he c
lass
ifica
tion
resu
lt w
as u
sed
to tr
igge
r the
stim
ulat
ion
sequ
ence
. S
ucce
ssfu
l cla
ssifi
catio
n re
sulte
d in
the
corr
ect s
timul
atio
n se
quen
ce d
eliv
ered
to
subj
ect 2
. C
onve
rsel
y an
inco
rrec
t cla
ssifi
catio
n w
ould
resu
lt in
an
inco
rrec
t act
ion
take
n by
th
e ne
urop
rost
hesi
s.
•The
sys
tem
per
form
ed w
ith 9
4.5%
acc
urac
y
Res
ults
•Thi
s w
ork
repr
esen
ts a
true
end
-to-e
nd s
yste
m te
st o
n th
e us
e of
EC
oG
sign
als
to c
ontro
l a n
euro
pros
thes
is fo
r gra
spin
g w
ithou
t int
racr
ania
l sur
gery
fo
r the
pur
pose
of d
evel
opin
g B
MI t
echn
olog
y.
Dis
cuss
ion
This
wor
k w
as s
uppo
rted
by th
e To
ront
o R
ehab
ilita
tion
Inst
itute
and
th
e O
ntar
io M
inis
try o
f Hea
lth a
nd L
ong
Term
Car
e.
Ack
now
ledg
emen
ts
Ref
eren
ces
1.C
hin
C.M
., et
al.,
Iden
tific
atio
n of
arm
mov
emen
ts u
sing
cor
rela
tion
of
elec
troco
rtico
grap
hic
spec
tral c
ompo
nent
s an
d ki
nem
atic
reco
rdin
gs.
J.N
eur
Eng
200
7. 4
(2):p
.146
-158
.
Reh
abili
tatio
n En
gine
erin
g La
bora
tory
Inst
itute
of B
iom
ater
ials
and
Bio
med
ical
En
gine
erin
g, U
nive
rsity
of T
oron
toTo
ront
o R
ehab
ilita
tion
Inst
itute
Con
tact
:mar
quez
.ces
ar@
toro
ntor
ehab
.on.
caw
ww
.toro
nto-
fes.
ca
ECoG
Con
trol
led
Neu
ropr
osth
esis
for G
rasp
ing:
Pre
limin
ary
Stud
yC
ésar
Már
quez
-Chi
n1 , D
r. Tr
acy
Cam
eron
2 , D
r. A
ndre
s M
Loz
ano2 ,
Dr.
Rob
ert C
hen2 ,
and
Dr.
Milo
s R
Pop
ovic
11 R
ehab
ilitat
ion
Eng
inee
ring
Labo
rato
ry, T
oron
to, C
anad
a2 T
oron
to W
este
rn R
esea
rch
Inst
itute
, Tor
onto
, Can
ada
Part
ners
:
Can
adia
n In
stitu
tes
of H
ealth
Res
earc
hIn
stitu
tsde
rec
here
en s
anté
du C
anad
a
Nat
ural
Sci
ence
s an
d En
gine
erin
g R
esea
rch
Cou
ncil
of C
anad
aC
onse
ilde
rec
herc
hes
en s
cien
ces
natu
relle
set
en
géni
edu
Can
ada
Min
istr
y of
Hea
lth
and
Long
Ter
m C
are
The
view
s ex
pres
sed
in th
is p
oste
r do
not n
eces
saril
y re
flect
thos
e of
any
of
the
gran
ting
agen
cies
.
18
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Fig. 1: The matrix and single-ring contact configurations. Dark contacts are the ones whose data is available in the classification process.
• We use the recordings from the cuff electrode on the sciatic nerve to determine which nerve branch was stimulated in a given trial (i.e. classify the activity).
• Our goal is to compare the classification performance of two contact configurations: the full matrix configuration vs. only the 8 contacts in the middle ring of the cuff (this second configuration is taken from the neuroprostheses literature). The two configurations are shown in Figure 1. In both cases a tripole reference is used (average of the contacts with a black outline).
• Classification is performed by building a feature vector for each trial, consisting of the peak amplitudes of every contact in the configuration being used. A training set is used to obtain a typical feature vector for each nerve branch. Each feature vector in the testing set is assigned to the nerve branch whose feature vector it most resembles. The classification accuracy is the percentage of trials in the testing set that are correctly classified.
Classification of the Neural Activity
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: jose.zariffa@utoronto.cawww.toronto-fes.ca
Influence of the Number and Location of Recording Contacts on the Selectivity of a Nerve Cuff Electrode
J. Zariffa1,2,3, M.K. Nagai1,3, Z.J. Daskalakis4 and M.R. Popovic1,2,3
• Nerve cuff electrodes are used to record the electrical activity of peripheral nerves, but have difficulty discriminating between different nerve branches.
• Manufacturing advances have increased the number of recording contacts that can be placed on a nerve cuff.
• We investigate how a nerve cuff with 56 contacts (7 rings of 8 contacts each) can improve selectivity.
Introduction
Experimental Methods• Experiments were performed on six rats (old male Long-Evans breeders).• The 56-contact (“matrix” configuration) recording cuff was placed on the
sciatic nerve.• 3 stimulating nerve cuffs were placed on the tibial, peroneal, and sural
branches of the sciatic.• Short pulses were used to stimulate each nerve branch in turn (100 trials
per branch).
1. Institute of Biomaterials and Biomedical Engineering, University of Toronto2. Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto3. Toronto Rehabilitation Institute4. Schizophrenia Program, Department of Psychiatry, Centre for Addiction and Mental Health
Results• The matrix configuration resulted in statistically significant
improvements in classification accuracy in all rats.
• By adding one contact at a time to the matrix configuration, from the most informative to the least informative, and evaluating the classification accuracy at each step, we found that high accuracies could be achieved with a small number of contacts.
Rat 1 Rat 2 Rat 3 Rat 4 Rat 5 Rat 60
10
20
30
40
50
60
70
80
90
100
110Maximum Classification Accuracies of Matrix vs. Single-Ring Configurations
Cla
ssifi
catio
n A
ccur
acy
(%)
MatrixSingle-ring
*
*
*
*
*
*
Fig. 2: Comparison of the maximum classification accuracies obtained with each contact configuration, for each rat.
Fig. 3: Classification accuracy as a function of the number of contacts used in the matrix configuration. Markers denote the maximum accuracy achieved (x) and the point at which the performance surpasses the maximum accuracy of the single-ring configuration (o).
0 10 20 30 40 50 6030
40
50
60
70
80
90
100
Classification Accuracy as a Function of the Number of Contacts Added
Number of Contacts
Cla
ssifi
catio
n A
ccur
acy
(%)
Rat 1Rat 2Rat 3Rat 4Rat 5Rat 6
Conclusions• The recordings from the matrix cuff led to better classification
accuracy than previously used configurations.• The improvement was due to the possibility of selecting the most
informative contacts, rather than to the sheer number of contacts.• These results have implications for the design of future cuff
electrodes.
19
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: miyatani.masae@torontorehab.on.cawww.toronto-fes.ca
The Relationship Between Arterial Stiffness and Body Composition in Persons With Spinal Cord Injury
M. Miyatani1, 2, A. Khan2, P.I. Oh3, K. Masani1,2, M.R. Popovic1, 2 and B.C. Craven2,41 Institute of Biomaterials and Biomedical Engineering, University of Toronto; 2 Lyndhurst Centre, Toronto Rehab; 3 Cardiac Rehab Program, Toronto Rehab; and 4Department of
Medicine Toronto Rehabilitation Institute, University of Toronto
Background and PurposeWhy do we focus on Arterial Stiffness?• Stiffening in the cardiothoracic arteries is an emerging risk factor for coronary artery disease (CAD). Decreases in the elastic properties of arteries reduces the buffering capacity of the arteries, leading to increased pulse pressure, aortic impedance, and left ventricular wall tension, all of which increase CAD risk. What is Pulse Wave Velocity (PWV)? • PWV is the speed of the blood flow wave traveling through the arterial system. PWV is affected by the elasticity and distensibility of the artery. Higher velocity corresponds to higher arterial stiffness and lower distensibility.• Aging, obesity, poor cardiopulmonary fitness, low physical activity are associated with above normal PWV values.Why do we need to know about PWV in SCI patients? • Obesity is a common problem among individuals with spinal cord injury (SCI). Thus, it is hypothesized that individuals with SCI have high risk of CAD associated with above normal PWV values.What are aims of the project? • To test the hypothesis that SCI subjects have greater arterial stiffness (PWV) than age-gender matched non-SCI subjects. • To investigate the association between adiposity and PWV in these subjects.
MethodsSubjects (n=18)
• SCI men (n=9) without CAD(Age: 51 11 yrs; Height: 179 6.6cm; Body weight: 90.5 22.5 kg; neurologic level : between C3 to L3; ASIA impairment scale A; Years postinjury: 25 10.7years) and n=19 age and gender matched Non-SCI controls (Age: 45 10 yrs; Height: 175.1 7.9 cm; Body weight: 75.6 10.9 kg) Body composition Measurements
• Adiposity (Trunk fat mass, total body fat mass) were assessed using Dual-energy X-ray absorptiometry (DXA)
•Waist circumference was measured in supine position.PWV Measurement
• Pulse wave at two vascular landmarks were simultaneously measured using two identical non-invasive transcutaneous doppler flow meters (Smartdop50, Hadeco,Inc., Kanagawa, Japan)
• The pulse wave latency (PWL) (1) between the carotid artery(CA)and the femoral artery (FA); and (2) between FA and posterior tibial artery (PTA) were recorded (see diagram).
• The distances (D) in centimeters traveled by the pulse wave were measured over the surface of the body using a metal tape measure.
• Calculation of PVW(1) Aortic PWV (cm/sec)=
D Aortic / PWL between CA and FA(2) Leg PWV (cm/sec) =
D Leg / PWL between FA and PTA
ResultsPWV in SCI and Control
Aortic PWV in SCI were significantly higher than that of control(*One outlier in CON was excluded).There were no significant difference between SCI and control in leg PWV.
Relationship between Aortic PWV and adiposity in SCI and Control
Discussion and ConclusionThe higher trunk PWV in subjects with SCI than able-body population suggests their higher risk of CAD and potential need for aggressive risk factor
modification. The correlation results imply that obesity is associated with stiff arteries in the SCI population and thus body composition, in particular adiposity, should be assessed in clinical practice and may be used to detect patients with SCI with stiff arteries.
There were significant correlations between adiposity and aorticPWV and in SCI subjects (*One outlier in CON was excluded).
CA
FA
D Leg (cm)
D Aortic (cm)
PTA
FA
PTA
(ms)
PWL
0 100 200
Diagram of PWV measurement sites
The pulse wave latency (PWL)
AORTA
0
500
1000
1500
2000
SCI CON
PWV
(cm
/s)
P<0.05
LEG
0200400600800
100012001400
SCI CON
PWV
(cm
/s)
y = 25.903x + 903.47r=0.689 (p<0.05)
600800
100012001400160018002000
0 10 20 30Trunk fat mass (kg)
y = 17.547x + 802.03r=0.770 (p<0.05)
600800
100012001400160018002000
0 20 40 60Total body fat mass (kg)
SCICON
20
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du CanadaCanadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du CanadaNatural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Healthand Long Term CareMinistry of Healthand Long Term Care
A Test-of-Principle Prototype for a New Device to Measurea Specific Pain Mechanism
References:1. Craig, A. D. New and old thoughts on the mechanisms. Yezierski, R. P. and Burchiel, K. J. Progress in Pain Research and Management. (23), 237-261. 2002. Seattle, IASP Press.2. Craig, A. D. & Bushnell, M. C. The thermal grill illusion: unmasking the burn of cold pain. Science 265, 252-255 (1994).3. Finnerup, N. B., et al. Sensory function in spinal cord injury patients with and without central pain. Brain 126, 57-70 (2003).4. Defrin, R., et al. Quantitative somatosensory testing of warm and heat-pain thresholds: the effect of body region and testing method. Clin. J. Pain 22, 130-136 (2006).5. Greenspan, J. D., et al. Body site variation of cool perception thresholds, with observations on paradoxical heat. Somatosens. Mot. Res. 10, 467-474 (1993).
Translating Pain Neuroscience Theory into a Clinical/Research Tool
Thermal Grill (TG) Apparatus
.
J.P. Hunter , E. Sanin , J. Juandi , A. Bulsen , M.R. Popovic1,3 1,2,11,4 2
1. Toronto Rehab, Lyndhurst Centre, 2. Institute of Biomaterials and Biomedical Engineering,3. Department of Mechanical Engineering, 4. Department of Physical Therapy, University of Toronto
Our overall goal is to develop a new TG for multiple-body-site testing and develop an open platform for investigators and clinicians in thefield as a psychophysical measure of alterations in cold inhibition of pain. Our plan for the current study was to evaluate the principles-of-design for new more portable and flexible TG apparatus
1. Lightweight and portable system2. Safe for use with patients3. Six contact thermodes with:
- individual & independent temperature control- adjustable spacing between thermodes
4. Physical capacity to:- heat or cool each thermode in range 0°C to 50°C- maintain each thermode at a stable temperature of 20°C or 40°C- achieve dynamic temperature ramp of 1.0°C/s
5. Individual continuous data logging of thermode temperature6. Response system to record continuous subject response
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: judith.hunter@utoronto.ca
www.toronto-fes.ca
Background
Purpose
Design Needs
Design Prototype
Future DirectionsWe plan to build the REL-TG with 64 contact-thermodes ( 8 x 8 matrix, Fig. 7).
Our TG design based on the use of Peltier elements, an air coolingsystem, and electronic response system has the level of control andsystem flexibility required for future clinical, large scale studies to identifythe existence of a pain producing mechanism among individuals withCNP.
Based on prototype performance the following revisions are needed forthe planned larger "Rehab Engineering Lab Thermal Grill" (REL- TG):
1. Separate PC screen for patient.2. Improve system thermal dynamics by: revising the software, adding
variable power supply;and optomzing the thermode unit .3. Improve software usability by preprogramming for specific protocols.
Central neuropathic pain (CNP) is a devastating, unrelenting pain thatcan occur after a disease or injury to the central nervous system such asstroke, multiple sclerosis, or spinal cord injury (SCI) .
1
Prior research has shown that the thermal grill illusion (TGI) can be used toevaluate cold inhibition of pain .
One such mechanism is “thermosensory disinhibition”, or, the loss of cold-inhibition of pain within the central nervous system .
3
4,5
A TG allows the simultaneous application, to the skin, of spatiallyinterlaced nonpainful warm (40°C) and cool (20°C) bars, causing theindividual to experience a painful thermal percept, or TGI .
1. Lightweight and portable system2. Safe fof r use with patients3. Six contact thermodes with:
- individual & independent temperature control- adjustable spacing between thermodes
4. Physical capacity to:- heat or cool each thermode in range 0°C to 50°C- maintain each thermode at a stable temperature of 20°C or 40°C- achieve dynamic temperature ramp of 1.0°C/s
5. Individual continuous data logging of thermode temperature6. Response system to record continuous subjb ect response
gg
There is no commercially available TG.
Translation of the TGI response, to a tool to evaluateindividuals with SCI-related CNP requires a new TG,appropriate to evaluate the TGI in many anatomic regions .
The TGI has only been tested on the hand of able-bodiedindividuals; but CNP can occur in any body location .
Design will allow a range of complex stimulisimlar to those shown in Fig. 6.
Figure 4. Teemperature recordings from individual thermodes
Figure 6. Examples of warm (red) and cool (blue) thermal elements in REL-TG Figure 7. Proposed REL-TG with 8x8pattern of thermal elements
Contact (aluminum bar)
Aluminum Heat Sink
+ -DC Power Source
Peltierelement
1. Individual Thermode Design
Figure 2. Single Thermode of TG
Contact dimensions: 6mm x 13mm x 220 mmHeat sink: Surface area: 1276.6 mm
Thermal resistance < 3°C / WattPeltier element dimension: 13mm x 13mm
Maximum heat pumped: 9.2 WattsPower supply: Allows 13 Watts / Peltier element
2. Apparatus Design
Figure 3. Test-of-principle prototype
Continuously adjustable spacing: 1 - 20mmHeat sinkl: Air forced by four 2.5 Watt fans
(12 V x 210mA)MDF housing: Volume < 4.4 L; Weight < 2 Kg
3. Data Logging
Surface temperature continuously monitoredby 100Ohm RTD temperature sensor.
Sensor is coupled to a Data Acquisition System(DAQ) that is connected to the computerthrough a USB connection.
Temperature is displayed in LabView.
Time (sec)0 50 100 150 200
VAS
scor
e
0
20
40
60
80
100 Dynamic - GlaDynamic - HaiStatic - GlabroStatic - Hairy
4. Response System
Figure 5. VAS response ratings for TGI intensity in one subject
Continuous VAS for sensation magnitudeintegrated with device controls anddata logging in Labview
A roadblock to effective CNP treatment is the inability to identify, within anindividual, the specific neurobiological “mechanism(s)” responsible for the pain .
2
Conclusions
2
Bars 1, 3, and 5
0 50 100 150 200 250 30015
20
25Bar 1Bar 3Bar 5
Bars 2, 4, and 6
Time (sec)0 50 100 150 200 250 300
20
25
30
35
40
45
Bar 2Bar 4Bar 6
Tem
pera
ture
°CTe
mpe
ratu
re°C
Figure 1. TG used by Craig1,2
21
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated FoundationMinistry of Health and Long Term Care
Cardiovascular Response to FES and Passive Stepping to Improve Orthostatic Tolerance
L Chi1,2, K Masani1 ,2, M Miyatani1 ,2, KW Johnston1, A Mardimae1,3, C Kessler1,3,JA Fisher1,3, MR Popovic1,2
1. University of Toronto; 2. Toronto Rehab;3. Toronto General Research Institute
• Orthostatic hypotension, a sudden drop in blood pressure, is prevalent following spinal cord injury. Over 70% of SCIpatients experience sudden symptoms of dizziness,lightheadedness, and syncope upon postural change orfollowing periods of prolonged sitting resulting from venous pooling.
• Orthostatic hypotension hinders the patient’s participation in rehabilitation activities which is necessary to promote neuronalplacidity, prevent loss of muscle mass, mitigate osteoporosis,and maximize cardiovascular conditioning.
• Functional electrical stimulation (FES) and passive steppingmovements have been shown to increase blood pressure and reduce venous pooling and thus have been proposed as potentialtherapies to counter the effects of orthostatic hypotension.
Background• One subject experienced syncope during head-up tilt.• No subjects experienced syncope during FES, Stepping or the
combined modality.• FES synchronized with passive stepping significantly increased
venous return over 15 minutes of tilt.• FES significantly increased heart rate over 15 minutes of tilt.• Blood pressure did not change significantly over 15 minutes of
tilting
Results
Fig 1. Doppler ultrasound imaging of a subject’s inferior vena cavaduring (a) Tilt Condition and (b) FES w Stepping.
a b
IVC IVC
• Can lower limb movements, either though active leg musclecontraction (FES) or passive leg walking (Stepping), be effective in preventing orthostatic hypotension in able bodiedsubjects undergoing tilt?
Research Question
• Orthostatic hypotension conditions were simulated in 10 able bodied subjects. Subjects were secured on a tilt table and theirthighs were attached to robotic actuators which allowed passivestepping movements. All trials began with a 10 minutes restphase in the supine position. During the test subjects experience70° head-up tilt for 15 minutes or until syncope occurs.
• Four tilting conditions were performed in random order• Head Up Tilt (HUT)• HUT + FES• HUT + Passive Stepping• HUT + FES + Passive Stepping
• Electrical stimulation was applied to the gastrocnemius,quadriceps muscle group, and hamstring muscle group.
• Cardiovascular data (blood pressure, heart rate, venous return,cardiac output) were collected throughout the testing condition
• Data was analyzed using Student’s t-Test to determine thesignificance between various tilting conditions.
Method
Fig 2. Cardiovascular data from a subject undergoing tilt in varyingconditions. FES & Stepping were found to be effective in increasing venous return and heart rate over 15 minutes of tilt.
• The combination of FES with passive leg movements significantlyincreases venous return, thereby mitigates the effects of orthostatichypotension over the long term.
• Active muscle contraction by FES are effective in increasing theheart rate over the duration of tilting.
Conclusion
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: lorne.chi@utoronto.cawww.toronto-fes.ca
22
Partners:
Canadian Institutes of Health ResearchInstituts de rechere en santé du Canada
Natural Sciences and Engineering Research Council of CanadaConseil de recherches en sciences naturelles et en génie du Canada
Physicians' Services Incorporated Foundation
Ministry of Health and Long Term Care
The views expressed in this poster do not necessarily reflect those of any of the granting agencies.
Rehabilitation Engineering LaboratoryInstitute of Biomaterials and Biomedical Engineering, University of TorontoToronto Rehabilitation InstituteContact: milad.alizadeh.m@utoronto.cawww.toronto-fes.ca
Wave ® vs. Juvent ®: Whole-Body Vibration AssessmentFeasibility & Usability for Patients with SCI
BC Craven1,2, LM Giangregorio3, A Morris4, MR Popovic1,2, M Miyatani1
L You2, MI Tonack1, M Alizadeh-Meghrazi1,2, J Totosy De Zepetenek1,3
•Sublesional Osteoporosis (SO) is the decline of bone mineral density (BMD) in the hip and knee regions after SCI.
•25-45% of SCI patients experience fragility fractures as a result of SO.•Lower extremity fragility fractures result in decreased mobility, delayed healing, and in extreme cases amputation.•Current treatments for SO which include oral biphosphonates, and rehabilitation interventions (passive standing, tilt table, walking, muscular and functional electrical stimulation) have been largely ineffective in producing a significant or sustainedincrease in BMD.•Whole-Body Vibration (WBV) is a new therapy used for improving muscular strength and BMD in animals, post-menopausal women, and children with neurological impairments.
Background
1Toronto Rehabilitation Institute2University of Toronto
3University of Waterloo4Sunnybrook Health Sciences Centre
•To compare the feasibility and usability of two vibration platforms Wave® and Juvent® for treatment of SO among patients with chronic SCI.
Objective
: Accelerometer Locations
Standing Frame
Vibration Platform
•Subjects: Healthy male volunteers 20-40 years old (n=4) and age matched traumatic SCI patients with motor complete paraplegia (n=4).
•Vibration parameters: Frequency 30-50 Hz, and amplitude <5 mm.
•Feasibility criteria: Vibration Propagation through the body measured with 4 accelerometers located at the plate, lateral femoral condyle, iliac crest, and head ( see diagram below).
•Usability criteria: Vibration perception, subject reactions (adverse effect/perceived benefits), skinbreakdown, device accessibility, H-reflex, &lower extremity EMG.
Methods
•To identify which vibration parameters (freq. and amp.) result in the best/ideal propagation of vibration through the lower extremities in able bodied subjects and subjects with SCI.•To attain a better understanding of the neurophysiological effects of WBV therapy on H-reflexes and.muscle activation for subjects with and without SCI •To asses changes in the bone microstructure in response to vibration exposure through measurement of biochemical markers of bone turnover (osteocalcin and N-telopeptide).
Expected Results
•Acceleration propagation up the lower extremities is essential prior to determining what effects WBV has on the lower extremity bone microstructure.•H-reflex will be used as indicator of spinal motor neuron excitability. A relationship between hyperexcitability of the spinal motor neurons in SCI patients and spasticity exists, such that reductions in H-reflex may inhibit spasticity of the soleus.•Electromyography (EMG) will allow us to monitor lower extremity muscle activity pre, during and post vibration exposure. Increased EMG activity during vibration may be an indicator of muscle fiber activation.
Diagram of Accelerometer Locations
23
A N
EW IN
TRA
MU
SCU
LAR
ELE
CTR
OD
E FO
R
FUN
CTI
ON
AL
ELEC
TRIC
AL
STIM
ULA
TIO
N IN
TH
E R
AT
Mar
y K
Nag
ai, M
D, P
hD; A
bdul
kadi
r Bul
sen,
MS
cE
ng; A
bdol
azim
Ras
hidi
, BS
cE
ng; M
ilos
R. P
opov
ic, P
hD,
RE
L, T
oron
to R
ehab
ilitat
ion
Inst
itute
, Tor
onto
, ON
and
Uni
vers
ity o
f Tor
onto
, Tor
onto
ON
Impl
ante
d El
ectro
de:
•S
terra
dst
eriliz
ed•
The
elec
trode
is
im
plan
ted
in
the
prox
imal
qua
dric
eps
mus
cle
•Th
e vi
cryl
sut
ure
prev
ents
the
elec
trode
fro
m b
ecom
ing
disp
lace
d in
the
mus
cle
•A
kno
t in
the
wire
itse
lf at
the
dist
al e
nd
of t
he e
lect
rode
pre
vent
s it
from
bei
ng
pulle
d th
roug
h in
the
oppo
site
dire
ctio
n
Key
Feat
ures
of t
he In
tern
al C
ompo
nent
:
•A
slip
kno
t is
used
to a
ttach
the
elec
trode
to
a Ke
ith n
eedl
e fo
r:-
Eas
y pa
ssag
e fro
m t
he s
capu
la t
o th
e lo
wer
ext
rem
ity-
Eas
y im
plan
tatio
n of
the
ele
ctro
de i
nto
the
mus
cle
-D
esig
n al
low
s fo
r va
riabl
e le
ngth
s of
el
ectro
de-
Can
be
us
ed
for
FES
and
for
EMG
st
udie
s
Key
Feat
ures
of t
he E
xter
nal C
ompo
nent
:(T
he B
UTT
ON
)
•Th
e m
esh
allo
ws
for
easy
sta
biliz
atio
n in
the
subc
utan
eous
tiss
ues
•Li
ght w
eigh
t •
A v
aria
ble
num
ber o
f mus
cles
can
be
stud
ied
at a
ny g
iven
tim
e (p
hoto
sho
ws
an 8
pin
co
nnec
tor)
•In
divi
dual
or
gr
oups
of
m
uscl
es
can
be
stim
ulat
ed u
sing
FES
and
EM
G s
tudi
es c
an
be p
erfo
rmed
sim
ulta
neou
sly
•Th
e po
lypr
opyl
ene
tube
atta
ched
to th
e m
esh
prov
ides
ad
ded
prot
ectio
n fo
r th
e fin
e el
ectro
de w
ires
as th
ey a
re p
asse
d up
to th
e ex
tern
al c
onne
ctor
(8 p
in in
thes
e ph
otos
)
•Th
e Bu
tton
with
th
e ex
tern
al
conn
ecto
r pr
otru
des
2 cm
abo
ve th
e su
rface
of t
he s
kin,
al
low
ing
for
easy
con
nect
ion
to th
e FE
S a
nd
EMG
equ
ipm
ent
BA
RE
D W
IRE
Post
-op
Day
1:
•The
rat
sus
tain
ed a
n m
oder
ate
inco
mpl
ete
spin
al
cord
in
jury
us
ing
the
dist
ract
ion
spin
al c
ord
inju
ry m
odel
(D
abne
yet
al,
2004
)
•The
But
ton
was
im
plan
ted
betw
een
the
scap
ula
and
the
wire
s br
ough
t dow
n to
the
quad
ricep
s m
uscl
e an
d th
e ha
mst
ring
mus
cle
and
impl
ante
d in
the
res
pect
ive
mus
cle.
•The
But
ton
was
eas
ily c
onne
cted
to
the
Com
pex
Mot
ion
FES
syst
em
•The
qu
adric
eps
mus
cle
and
ham
strin
g m
uscl
es
wer
e st
imul
ated
us
ing
the
Com
pex
Mot
ion
FES
syst
em.
•A l
inea
r re
spon
se c
urve
was
obt
aine
d fo
r bo
th m
uscl
es
•With
incr
easi
ng p
ulse
wid
th th
e am
ount
of
curre
nt r
equi
red
to g
ener
ate
a co
ntra
ctio
n of
the
mus
cle
in q
uest
ion
decr
ease
s
THE
BU
TTO
N
Stim
ulat
ion
of Q
uadr
icep
s
19 17
13 12
6755
0510152025
025
5075
100
125
Puls
e W
idth
Current (mAmps)
Stim
ulat
ion
of H
amst
rings
1920
1415
776 5
0510152025
025
5075
100
125
Puls
e W
idth
Current (mAmps)
PUR
POSE
To fa
bric
ate
an e
lect
rode
whi
ch c
an b
e im
plan
ted
into
var
ious
ext
rem
ity m
uscl
es in
th
e ra
t whi
ch c
an b
e us
ed to
exa
min
e th
e pa
thop
hysi
olog
ic e
ffect
s of
FES
.
RA
TIO
NA
LE
The
elec
trode
des
ign
mus
t inc
orpo
rate
the
follo
win
g fe
atur
es:
•U
se f
ine,
fle
xibl
e bi
olog
ical
ly i
nert
wire
whi
ch w
ill n
ot i
nduc
ean
inf
lam
mat
ory
reac
tion
in th
e m
uscl
e•
Cau
se m
inim
al d
istu
rban
ce o
f the
mus
cle
tissu
e w
hen
impl
ante
d•
Hav
e m
inim
al in
terfe
renc
e w
ith th
e no
rmal
gai
t pat
tern
and
act
ivity
beh
avio
ur o
f th
e ra
t
•In
expe
nsiv
e•
Dur
able
—to
with
stan
d th
e da
ily m
ovem
ents
of t
he ra
t for
at l
east
one
mon
th•
Eas
y to
fabr
icat
e•
Use
r fri
endl
y—ea
sy t
o im
plan
t an
d ea
sy t
o at
tach
to
the
Com
pex
Mot
ion
FES
sy
stem
REF
EREN
CES
K.W
. Dab
ney,
M. E
hren
shte
yn, C
.A. A
gres
ta, J
.L. T
wis
s, G
. Ste
rn, L
. Tic
e an
d S.
K.
Salz
man
(200
4) A
mod
el o
f exp
erim
enta
l spi
nal c
ord
traum
a ba
sed
on c
ompu
ter-
cont
rolle
d in
terv
erte
bral
dist
ract
ion:
ch
arac
teriz
atio
n of
gra
ded
inju
ry.
Spi
ne 2
9:
2357
-236
4
K.G
. Pe
arso
n, A
.H.
Acha
rya,
K.
Foua
d(2
005)
A
new
ele
ctro
de c
onfig
urat
ion
for
reco
rdin
g el
ectrm
yora
phic
activ
ity i
n be
havi
ng m
ice.
Jo
urna
l of
Neu
rosc
ienc
e M
etho
ds.
(Sub
mitt
ed)
MET
HO
DS
INTR
OD
UC
TIO
NR
ESU
LTS
•In
the
rece
nt d
ecad
e a
num
ber
of F
unct
iona
l Ele
ctric
al S
timul
atio
n (F
ES)
devi
ces
have
bee
n de
velo
ped
to a
ssis
t pe
ople
with
sev
ere
mot
or p
aral
ysis
to i
mpr
ove
gras
ping
and
wal
king
func
tion.
•
The
pote
ntia
l ro
le o
f FE
S th
erap
y as
an
adju
nct
to t
radi
tiona
l re
habi
litat
ion
prog
ram
s is
beg
inni
ng to
be
real
ized
•Th
e go
al o
f FE
S th
erap
y is
to
incr
ease
fun
ctio
n w
ith a
con
com
itant
inc
reas
e in
in
depe
nden
ce a
nd q
ualit
y of
life
.•
How
FES
wor
ks to
impr
ove
mot
or fu
nctio
n re
mai
ns a
mys
tery
.•
An
unde
rsta
ndin
g of
how
FES
im
prov
es m
otor
fun
ctio
n is
crit
ical
to
the
futu
re
deve
lopm
ent a
nd u
se o
f FES
in re
habi
litat
ion
med
icin
e
•P
ears
on e
t al (
2005
) su
cces
sful
ly d
esig
ned
and
impl
ante
d an
EM
G e
lect
rode
into
m
ice.
•Th
e so
le
purp
ose
of
Pear
son’
s im
plan
tabl
e el
ectro
de
was
to
re
cord
th
e m
ovem
ents
of m
ice
and
mea
sure
EM
G.
•Th
is e
lect
rode
is d
iffic
ult t
o fa
bric
ate
and
not s
uita
ble
for F
ES th
erap
y
Vic
ryl S
utur
eKn
ot
Qua
dric
eps
Mus
cle
CO
NC
LUSI
ON
S A
ND
FU
TUR
E PL
AN
S•
The
new
el
ectro
de
was
de
sign
ed,
easi
ly
fabr
icat
ed
and
impl
ante
d w
ith
no
com
plic
atio
ns in
to ra
ts w
ith a
n in
com
plet
e SC
I.
•Th
is e
lect
rode
cau
ses
min
imal
tiss
ue d
amag
e.
•Its
pre
senc
e in
the
quad
ricep
s an
d ha
mst
rings
in th
e ra
t did
not
appe
ar to
alte
r the
ga
it no
r the
dai
ly b
ehav
iour
alac
tiviti
es o
f the
rat.
•Th
e el
ectro
de is
dur
able
, ine
xpen
sive
and
mos
t im
porta
ntly
use
r frie
ndly
•Fu
ture
pla
ns in
volv
e ex
amin
ing
the
path
ophy
siol
ogy
of F
ES in
rats
with
inco
mpl
ete
mod
erat
e sp
inal
cor
d in
jurie
s
24
Recommended