Functional Electrical Stimulation (FES) - McMaster …ibruce/courses/EE3BA3_2005/EE3BA3... · Functional Electrical Stimulation ... stimulator sends electrical signals through the

Functional Electrical Stimulation (FES)

Presented byZhenBang Chen

&Lap Fong Wong

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OverviewOverview

Introduction to FESIntroduction to FESReason for FESReason for FESBackground informationBackground informationApplicationsApplicationsReferencesReferences

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FES FES –– WhatWhat is it?is it?

FES stand for FES stand for FFunctional unctional EElectric lectric SStimulation timulation It can restore the lost functions of the It can restore the lost functions of the nervous system by means of the electrical nervous system by means of the electrical stimulationstimulation

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FES FES –– WhyWhy we need that?we need that?

Research in the control of body Research in the control of body movementsmovementsImportant from the perspective of the Important from the perspective of the therapeutic and diagnostic medicinetherapeutic and diagnostic medicine

Spinal Cord InjurySpinal Cord InjuryStrokeStrokeAbnormal Body SystemsAbnormal Body Systems

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Background InformationBackground Information

Review of AnatomyReview of AnatomyElectrical stimulationElectrical stimulation

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Background InformationBackground Information

Review of AnatomyReview of AnatomyMembrane PotentialMembrane PotentialNerve SystemNerve SystemSkeletal Muscle TissueSkeletal Muscle TissueNervous excitationNervous excitation

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Membrane PotentialMembrane Potential

There are different concentrations of There are different concentrations of CationsCations(charged particles like Na(charged particles like Na++, K, K++, Ca, Ca2+ 2+ ) and ) and anions (charged particles like anions (charged particles like ClCl-- ) inside and ) inside and outside of the plasma membrane.outside of the plasma membrane.More negative charged particles (anions) on the More negative charged particles (anions) on the inside of the plasma membrane. inside of the plasma membrane.

The voltage potential is lower in the cytoplasm than The voltage potential is lower in the cytoplasm than to the extracellular space.to the extracellular space.

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CytoplasmCell

- - - - - - - - - - - - -

+ + + + + + + + + + + +

Voltmeter of Science

Cytoplasm

Plasma membrane

Extracellular fluid

-40 to -70 mV

Plasma Membrane

Membrane PotentialMembrane Potential

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Membrane PotentialMembrane Potential

Membrane of the cell effectively forms a Membrane of the cell effectively forms a capacitorcapacitor

- - - - - - - - - - - - -

+ + + + + + + + + + + +

Cytoplasm

Plasma membrane

Extracellular fluid

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Nerve SystemNerve System

The structure and function of a nerve tissueThe structure and function of a nerve tissue

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Nerve SystemNerve System

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Skeletal Muscle TissueSkeletal Muscle Tissue

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Mechanism of Nervous Fiber Mechanism of Nervous Fiber ExcitationExcitation

Transmembrane potential of the axon varies Transmembrane potential of the axon varies widely from the resting potential(~widely from the resting potential(~--70mV)70mV)As the KAs the K++ enter the plasma membrane, the enter the plasma membrane, the membrane potential increases steadily.membrane potential increases steadily.

When the membrane potential reaches to When the membrane potential reaches to threshold voltage(~50mV), the Na+ gate threshold voltage(~50mV), the Na+ gate opens, and membrane potential will then rise opens, and membrane potential will then rise rapidly.rapidly.

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Mechanism of Nervous Fiber Mechanism of Nervous Fiber Excitation Excitation Con’tCon’t

Once the membrane potential reaches 30mV, there is Once the membrane potential reaches 30mV, there is a positive feedback on the cell, Na+ gate closed, and a positive feedback on the cell, Na+ gate closed, and membrane potential decrease to its resting potentialmembrane potential decrease to its resting potential

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Mechanism of Nervous Fiber Mechanism of Nervous Fiber Excitation Excitation Con’tCon’t

Mem

bran

e P

oten

tial

(mill

ivol

ts)

4 8Time (milliseconds)

Resting MembranePotential

0 2 6 10

DepolarizingStimulus

HyperpolarizingStimulus

-40

-60

-80

-20

0

20

Voltage threshold for opening of voltage sensitive Na+ channels. Since increasing voltage is caused by Na+ entry and this entry causes increased voltage; this is a positive feedback loop.

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Background InformationBackground Information

Physiological recruitment of a neuronPhysiological recruitment of a neuronArtificial electrical recruitment of nervesArtificial electrical recruitment of nerves

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Sufficient excitatory input from the Sufficient excitatory input from the terminal branches from other neurons that terminal branches from other neurons that synapse with the dendritessynapse with the dendritesTarget neuron spatially and temporally Target neuron spatially and temporally integrates the inputs from other neurons.integrates the inputs from other neurons.These inputs determine whether the These inputs determine whether the target neuron reaches threshold and target neuron reaches threshold and becomes excited.becomes excited.

Physiological recruitment of a Physiological recruitment of a neuronneuron

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Artificial electrical recruitment of Artificial electrical recruitment of nervesnerves

Different from Physiological Different from Physiological recruitment.recruitment.

I.I. Anatomical location of recruitmentAnatomical location of recruitmentII.II. It does not involve synapses or connections It does not involve synapses or connections

with the neuron.with the neuron.III.III. It is determined by the amount of electrical It is determined by the amount of electrical

stimulation has been applied.stimulation has been applied.

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Electrical StimulationElectrical Stimulation

Equivalent Circuit Model of the Nerve AxonEquivalent Circuit Model of the Nerve Axon

Equivalent circuit model of a section of myelinated

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Electrical StimulationElectrical Stimulation

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ApplicationsApplications

The FES technology can apply to different The FES technology can apply to different area to restore the lost functions of the area to restore the lost functions of the nervous system nervous system

Hand disabilities Hand disabilities –– reaching and graspingreaching and graspingPhrenicPhrenic stimulationstimulationDropDrop--foot stimulator foot stimulator

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Hand disabilitiesHand disabilities

Hand disabilities Hand disabilities –– reaching and graspingreaching and grasping

3 best know grasping FES apparatus3 best know grasping FES apparatusFreehand system Freehand system Bionic GloveBionic GloveHandmasterHandmaster NMS NMS

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Freehand systemFreehand system

What is it look like?What is it look like?attach attach electrodselectrods to muscle in patient’s hand to muscle in patient’s hand (wrist) and forearms (wrist) and forearms a "joystick" controller implanted in the a "joystick" controller implanted in the opposite shoulder opposite shoulder a pacemakera pacemaker--type stimulator is surgically type stimulator is surgically implanted into patient’s chest implanted into patient’s chest

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Freehand systemFreehand system

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Freehand systemFreehand system

How it works?How it works?"joystick" controller "joystick" controller –– a shoulder position a shoulder position sensorsensorsensor placed on the chest relaxes and sensor placed on the chest relaxes and tightens the hand as the shoulder moves back tightens the hand as the shoulder moves back and forthand forthstimulator sends electrical signals through the stimulator sends electrical signals through the electrodes electrodes

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Freehand systemFreehand system

these signals cause the muscle to contract these signals cause the muscle to contract and the hand to open and closeand the hand to open and close

XX--Rays show the location of the stimulator, the electrodes and leaRays show the location of the stimulator, the electrodes and leadsds

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Freehand systemFreehand system

Through the shoulder movements to open Through the shoulder movements to open and close the handand close the hand

2 important grasp movement2 important grasp movementPamlarPamlar PrehensionPrehensionLateral Lateral PrehensionPrehension

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Freehand systemFreehand system

PamlarPamlar PrehensionPrehensioncupping the hand like the letter "C" for cupping the hand like the letter "C" for activities like drinking from a cup and picking activities like drinking from a cup and picking up larger objectsup larger objects

holding cups, ball or a game pieceholding cups, ball or a game piece

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Freehand systemFreehand system

Lateral Lateral PrehensionPrehensionpressing your thumb against your forefingers pressing your thumb against your forefingers for activities such as writing and brushing for activities such as writing and brushing your teethyour teeth

for writing, eating and graspingfor writing, eating and grasping

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Hand disabilitiesHand disabilities

Bionic GloveBionic Glovea hybrid system that utilizes a glove with FES a hybrid system that utilizes a glove with FES electrodes electrodes detection of wrist extension stimulates finger detection of wrist extension stimulates finger flexion flexion only patients who have sufficient wrist only patients who have sufficient wrist extension strength can use extension strength can use

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Hand disabilitiesHand disabilities

HandmasterHandmaster NMS NMS three pairs of surface stimulation electrodes three pairs of surface stimulation electrodes envisioned as an exercise and rehabilitation envisioned as an exercise and rehabilitation tool tool also used as a permanent prosthetic system also used as a permanent prosthetic system it is easy to put on and to take off it is easy to put on and to take off

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PhrenicPhrenic stimulationstimulation

What apparatus we use?What apparatus we use?Diaphragm pacing device/systemDiaphragm pacing device/system

Include 3 main partsInclude 3 main partsa controller box outside the bodya controller box outside the bodyelectrical wire (connection)electrical wire (connection)an electrode which implant into the muscle of an electrode which implant into the muscle of diaphragmdiaphragm

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PhrenicPhrenic stimulationstimulation

diaphragm pacing device/systemdiaphragm pacing device/system

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PhrenicPhrenic stimulationstimulation

How it works?How it works?apply the electricity from the controller boxapply the electricity from the controller boxstimulate the diaphragm muscle to contract stimulate the diaphragm muscle to contract through the electrode (diaphragm move down)through the electrode (diaphragm move down)the muscle relax after the stimulation (get back the muscle relax after the stimulation (get back to original position)to original position)repeat this electrical stimulation periodicallyrepeat this electrical stimulation periodically

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PhrenicPhrenic stimulationstimulation

Relationship between contraction of Relationship between contraction of diaphragm and breathingdiaphragm and breathing

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PhrenicPhrenic stimulationstimulation

Suitable patient Suitable patient (requirement)(requirement)

with an intact with an intact phrenicphrenicnerve motor neuron nerve motor neuron pool in their cervical pool in their cervical spinal cord on both spinal cord on both sidessidesneed to implant an need to implant an electrode into the electrode into the muscle of diaphragm muscle of diaphragm through the surgerythrough the surgery

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DropDrop--foot stimulatorfoot stimulator

What problem is it?What problem is it?diminished ability to use the muscles that lift diminished ability to use the muscles that lift the foot the foot

surface stimulation device/systemsurface stimulation device/systemOdstockOdstock 2 2 WalkAideWalkAideMikroFESMikroFES

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OdstockOdstock 22

an assisting aid or as a training device to an assisting aid or as a training device to strengthen muscles and improve voluntary strengthen muscles and improve voluntary control control allowing isolated components of the gait allowing isolated components of the gait cycle to be practiced under therapist cycle to be practiced under therapist control control

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OdstockOdstock 22

What is it look like?What is it look like?a pocketa pocket--sized main unit sized main unit a foot switch (one or two)a foot switch (one or two)two adhesive surface electrodes connected two adhesive surface electrodes connected with wireswith wires

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OdstockOdstock 22

Overview of the deviceOverview of the device

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OdstockOdstock 22

pocketpocket--sized main unitsized main unit

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OdstockOdstock 22

Different situation of drop footDifferent situation of drop footBilateral dropped foot Bilateral dropped foot Dropped foot with Dropped foot with glutealgluteal muscles muscles Dropped foot with quadricepsDropped foot with quadricepsDropped foot with hamstrings Dropped foot with hamstrings Dropped foot and calf Dropped foot and calf Bilateral Bilateral GlutealGluteal muscles for correction of muscles for correction of trandalanbergtrandalanberg gate gate Dropped foot with triceps Dropped foot with triceps

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OdstockOdstock 22

Bilateral droppedBilateral dropped footfootsingle foot switch is used single foot switch is used under the heel under the heel weight is taken off the weight is taken off the switch, channel 1 is active switch, channel 1 is active weight is returned to the weight is returned to the switch, channel 2 is activeswitch, channel 2 is activeboth common both common peronealperonealnerves are prevented from nerves are prevented from being active at oncebeing active at once

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OdstockOdstock 22

Dropped foot with Dropped foot with glutealglutealmusclesmuscles

glutealgluteal muscles are muscles are stimulated through the stimulated through the stance phase to extend stance phase to extend the hipthe hip

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OdstockOdstock 22

Dropped foot with Dropped foot with quadricepsquadriceps

quadriceps are quadriceps are stimulated throughout stimulated throughout the stance phase to the stance phase to allow weight bearingallow weight bearing

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ReferencesReferences

SZLAVIK ROBERT BRUCE, “SZLAVIK ROBERT BRUCE, “Electrical Stimulation of Motor Nerves”Electrical Stimulation of Motor Nerves”, , McMaster University, eMcMaster University, e--journal, July 1999, Hamilton.journal, July 1999, Hamilton.TortoraTortora Gerard J. “Gerard J. “Principles of Anatomy & Physiology, 11Principles of Anatomy & Physiology, 11thth ed”, ed”, John Wiley & Sons Inc. 2006, USA.John Wiley & Sons Inc. 2006, USA.

http://http://ra.disabilityexpo.com/unique/freehand.htmra.disabilityexpo.com/unique/freehand.htmhttp://http://www.diagnosticarea.com/publications/FES_Review.htmlwww.diagnosticarea.com/publications/FES_Review.htmlhttp://fescenter.case.edu/Start_Here/Patients/SCI/sci_programs_thttp://fescenter.case.edu/Start_Here/Patients/SCI/sci_programs_trurunk.htmnk.htmhttp://www.ifess.org/cdrom_target/ifess00/Oral%20Sessionhttp://www.ifess.org/cdrom_target/ifess00/Oral%20Session%201/haugland.htm%201/haugland.htmhttp://http://www.polyu.edu.hk/rec/fes/prine.htmlwww.polyu.edu.hk/rec/fes/prine.htmlhttp://http://www.nctu.edu.tw/~hcsci/hospital/sci/other/reeve.htmwww.nctu.edu.tw/~hcsci/hospital/sci/other/reeve.htmhttp://http://www.salisburyfes.com/acnr.htmwww.salisburyfes.com/acnr.htmhttp://http://www.salisburyfes.comwww.salisburyfes.com//

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