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7/23/2019 Electrical Stimulating Part
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Electrical Stimulation of the
Neuromuscular system, part II
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Outline
• Introduction• Neuro-muscular junction, myelin sheet
• Examples of neuromuscular prostheses – Upper extremity
– Loer extremity – !ladder stimulation
• "eri#ati#es $∇% and cross, dot products&
• 'athematical formulation of the effect of currentstimulation from electrode immersed in conducti#emedia&
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(he )del* operator $na+la, or ∇%
radient of p $here p is a scalar field% a #ector field.
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No e ant to multiply a #ector field # +y the /radient&
"ot product +eteen #ectors a$x,y,0% and +$x,y,0%
11111111111111111111111111111111111111111
2ross product +eteen same #ectors
1111111111111111111111111111111111111111
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3% "ot product +eteen /radient and v$x,y,0%
"efined as the "I4E5EN2E of v $it6s a scalar.%
7% 2ross product +eteen /radient and v$x,y,0%"efined as the 2U5L of v $it6s a #ector.%
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Laplacian operator $∇7% di#er/ence of the /radient&
Scalar field.
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Quasi-static formulation of Maxwell’s equations
11111111111111
11111111111111
11111111111111 11111111111111
Equivalence between dielectric and conductive media:
It helps to loo8 in static fields $due to point char/es% and
relate to fields due to current sources and sin8s&
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No let6s deri#e the #olta/e at a point alon/ the axon
of a neuron +ein/ stimulated +y an electrode ith a
monopolar current source&
$See notes%
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I93m:
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4olta/e alon/ the axon due to a +ipolar source&
2urrent throu/h one electrode has the same amplitude
$+ut opposite si/n% as current throu/h the otherelectrode&
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I93m:,d9?&3mm
y93?mm
x9r
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No plot +oth sides of an axon – orthodromic and
antidromic – for the +ipolar stimulation&
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'ONOFOL:5 S(I'
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:NO"I2 S(I'UL:(ION
2:(O"I2 S(I'UL:(ION
'ONOFOL:5 S(I'
EJ(5:2ELLUL:5 V
:LON (E KI!E5
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Iel93m:,
rhoe93 8Ohm&m,
093?mm
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Electrode-tissue interface
• 2onstant current x constant #olta/e
stimulation
• (issue dama/e
– Fassi#e presence of forei/n o+ject $mechanical%
– :cti#e passa/e of current $electrochemical%
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"ama/e to +iolo/ical tissue
• Fassi#e #ascular or neural
– o to o#ercome this
• 2han/e electrode si0e, tip /eometry, su+strate,
anchorin/
• :cti#e
– primary $reaction products from
electrochemistry%< – secondary $physiolo/ical chan/es associated
ith neural excitation&
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• Stren/th-duration cur#e $o+tained empirically%
– FM9 pulseidth
– Ith9threshold current
– Irh 9 rheo+ase current, minimum current amplitude
if FM&
– (ch 9 chronaxie time FM to excite neuron ith 7Irh&
– Ith9 IrhP$Ith(chAFM%
Effect of a#eform
: di th di ti l ti
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:nodic #s cathodic stimulation
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Introduction
- 5estorin/ function is not immediate in paralysis&
Ex& Kreeand $+y Neuro2ontrolQ%
- KES $functional electrical stimulation% stimulate
the neuromuscular junction, neuron is stimulated
first $less char/e needed%
- Fhrenic ner#e stimulation restore respiration
$#entilation%
N l th
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Neuromuscular prostheses
Ner#ous system injury 9 impairment of motor functions&
'otor functions +ody functions< lim+ mo#ement&
Objectives of neuroprostheses restore lost function,
increase independence of disa+led indi#iduals< reduce
economic impact of disa+ility&
2urrent neuroprostheses use KES $functional electrical
stimulation% to acti#ate motoneurons&
Motoneurons neurons that inner#ate muscles& 'uscles arethe actuators $for the desired function%&
2urrent tar/et patients stro8e $R@?,???Ayear incidence%< S2I
$3?,???Ayear incidence, hi/her pre#alence%&
Nodes of 5an#ier
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Unmyelinated axon
'yelinated axon
Nodes of 5an#ier
httpAA&nc+i&nlm&nih&/o#A+oo8sA+oo8res&fc/iAneurosciAch;f3>&/if
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5ecruitment properties
'a/nitude of muscular contraction depends on $3% electrodetype< $7% stimulation a#eform shape, time, amplitude< $;%location
of electrode relati#e to motoneuron&
orce modulation can +e achie#ed +y $3% rate modulation $7%
recruitment
$3% rate modulation there6s summation of muscular
contraction if hi/h enou/h freuency is used, +ut the muscle ismore prone to fati/ue& i/her freuency leads to hi/her $faster%
fati/ue&
$7% recruitment num+er of motoneurons stimulated more
neurons means more muscles&
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'US2LE 3
'US2LE 7
'O(ONEU5ON
'O(ONEU5ON
!
"#
$
$ here the electrode is located& If the stimulus intensity is lo, this is the
only acti#ated area&
" $hite area% if sli/htly hi/her current, only muscle 3 ould contract&# possi+ly hi/her force exerted +y +oth muscles no&
! e#ery+ody is stimulated $+oth muscles, throu/h acti#ation of +oth
motoneuron&
'uscular recruitment throu/h electrical stimulation
Journal of Rehabilitation Research and Development
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httpAA&#ard&or/AjourA?3A;TA@Aliu-f?3&/if
Jou a o e ab tat o esea c a d e e op e t
Vol. 38 No. 5, September/ctober !""#
%electivit& of intramuscular stimulatin' electrodes in the lower limbs
(onald )* +riolo, h!. Ma& Q* /iu, M%. (udi 0obetic, M%. )ames * 1hlir, M%
httpAA&#ard&or/AjourA?3A;TA@Aliu;T@&htm
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5ecruitment properties
Nonlinearities should +e dealt ith in the implant ho tomeasure and deal ith fati/ue&
(here are hi/h /ain re/ions, and plateau re/ions $hy%&
Spillo#er should also +e a#oided $they contri+ute to the
nonlinearities%
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'uscle stimulation
• Mith rare exceptions, neuroprosthesesacti#ate paraly0ed neurons at different
le#els of the ner#ous system
– Spinal cord – Spinal roots
– Feripheral ner#es
– Intramuscular ner#e +ranches
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Electrode types
• Surface
– S8in has hi/h resistance, and hi/h current
needs to +e passed +efore muscle is
acti#ated& $Lar/e area is stimulated,unpleasant side effects%&
• Implanta+le
– Epimysial $next slide% – Intramuscular
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Epimysial #ersus intramuscular electrodes
• Epimysial and intramuscular are in#asi#e&
• Epim&sial touches the epimysia $outer
sheath of the muscle%, near the entry point
of the ner#e, and is su+cutaneously
secured&
• 2ntramuscular inserted throu/h a needle,
the needle is retracted, the +ar+ed tips of
the )ire* secure it in the muscle&
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$ M1/+2#E3+E( %+1!4 O $3 2M/$3+E! 3E1(O(O%+5E%2%
O( (E%+O(236 5$3! 6($% 23 +E+($/E62$
F& unter Fec8ham, Fh"BV< 'ichael M& Weith, '"BV< We#in L& Wil/ore, Fh"BV<
Xulie & rill, 'SY< Wathy S& Muolle, O(5AL, 2(Y< eoffrey !& (hropeY< Feter orman, '"xxZ<
httpAA&ifess&or/Acdrom1tar/etAifess?3Aoral3Apec8hamF&htm
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httpAA&case&eduA/roupsA:N2LApa/esA?@As?@1[7&/if
Fhoto/raph of to intramuscular electrodes
ith helical leads, mounted in hypodermic
needles, on ith multistranded lead ire $(op%
and ith sin/le strand ire $!ottom%
httpAA&case&eduA/roupsA:N2LApa/esA?@A?@1\3&htm
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Upper extremity applications
• 5estorin/ hand /rasp and release
• andmaster $Ness, Israel%
• !ionic lo#e $Frocha08a%• Kreehand system $Neuro2ontrol%
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httpAA&nessltd&comA
Neuromuscular Electrical Stimulation Systems
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!ladder control implants
• Mhen the +ladder or8s – !ladder under lo pressure, sphincter ith
hi/h acti#ity&
– !ladder under hi/h pressure, sphincter in lo
acti#ity )mode*&
• 'ain pro+lems
– yperreflexia $too freuent%
– "yssyner/ia $asynchronous%
• Kour different types of implants
Urinary !ladder location and acti#ation
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httpAA&polystim&polymtl&caAan/laisAurinaireAintrurin&html
Urinary !ladder location and acti#ation
Urinary !ladder histolo/y
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+utorial 3ame: Neoplasia
#oncept3ame: In situ carcinoma
%lide 3ame: !ladder (ransitional Epithelium
2ma'e !escription: (ransitional epithelium is
found only in the conductin/ passa/es of theurinary system& Note the columnar surface cellsith their lar/e nuclei and prominent nucleoli&(hese are typical of transitional epithelium&
%tructures %tructure
!escriptions
lamina propria In the +ladder, this isthe rather denseconnecti#e tissuelayer +eneath theepithelium&
transitional epithelium Mhen the +ladder isnot distended $as in
this slide%, the line ofsollen cells at thesurface is particularlye#ident&
Urinary !ladder histolo/y
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%lide 78 "ladder 9all
(he +ladder has transitional epithelium and a thic8 lamina propria to allo for expansion& Hou ill +e than8ful
for this on those lon/ days in la+& !ar 9 7@? 'icrons
httpAA&8umc&eduAinstructionAmedicineAanatomyAhistoe+AurinaryArenal3R&htm
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$ri/ht% httpAA&delta/en&comAtar/etAhistolo/yatlasAatlas1filesA/enitourinaryAurinary1+ladder1>x&jp/
$left% httpAAli+rary&thin8uest&or/A3@>?3Aima/esAor/ans1urinary+ladder&jp/
Urinary !ladder ho does it really loo8
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httpAA8idney&nidd8&nih&/o#A8udiseasesApu+sAner#ediseaseAima/esAstimulator&jp/
Urinary !ladder Implant& o ould you do it
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httpAA&polystim&polymtl&caAan/laisAurinaireAimplant&html
Implanta+le +ladder stimulator
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J-rays sho the sphincter contracted +efore stimulation $a%and loosen durin/ stimulation $+%& :lso, the /raph a+o#e shos
that the stimulation efficiency is enhanced +y more than @?=
ith selecti#e stimulation, leadin/ to an a#era/e residual
#olume of [=& (hese results are ta8en from studies on T
different su+jects&
httpAA&polystim&polymtl&caAan/laisAurinaireAimplant&html
'edtronic6s InterStim(' !ladder Stimulator
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It measures 7&> inches $\cm% +y 7&7 $@&@cm% +y ?&> inches $3cm%,
ith a ei/ht of 3&@ ounces $>7 /rams%
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