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Transcranial MagneticTranscranial Magnetic
Stimulation in PsychiatryStimulation in Psychiatry
Prof. Nahla Nagy(MD)Prof. Nahla Nagy(MD)
Prof. PsychiatryProf. Psychiatry
Ain Shams Faculty of MedicineAin Shams Faculty of Medicine
Cairo,EgyptCairo,Egypt
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Transcranial magnetic stimulation (TMS) wasTranscranial magnetic stimulation (TMS) wasintroduced in 1985 as a non invasive and safeintroduced in 1985 as a non invasive and safestimulation of the cerebral cortexstimulation of the cerebral cortex ( B a k e r e t a l ,( B a k e r e t a l ,1 9 8 5 ) .1 9 8 5 ) .
The development of stimulators capable ofThe development of stimulators capable of
discharging at high frequencies (up to 100 Hz)discharging at high frequencies (up to 100 Hz)has expanded the application of TMS into thehas expanded the application of TMS into theareas of cognitive and behavioral functionsareas of cognitive and behavioral functions( P a s c a u t ( P a s c a u t --L eo n e e t a l , 1 9 9 5 ) .L eo n e e t a l , 1 9 9 5 ) . Depending onDepending onStimulation Parameters (frequency, rate andStimulation Parameters (frequency, rate andduration) repetitive stimuli to specific corticalduration) repetitive stimuli to specific corticalregions can either decrease or enhance theregions can either decrease or enhance theexcitability of the affected brain structuresexcitability of the affected brain structures( P a s c a u t ( P a s c a u t --Le o n e , 1 9 9 4 ) .L e o n e , 1 9 9 4 ) .
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ECT vs TMSECT vs TMS
Electroconvulsive therapy (ECT) requires applicationElectroconvulsive therapy (ECT) requires applicationof intense electricalof intense electrical stimulationstimulation because thebecause theskull isolates electric current and intracerebralskull isolates electric current and intracerebralstructures shunt current directly from onestructures shunt current directly from oneelectrode to the other (Zyss,1994). The intensityelectrode to the other (Zyss,1994). The intensity
ofof stimulationstimulation usually used in patients induces ausually used in patients induces aselfself--sustained aftersustained after--discharge of cortical neurons,discharge of cortical neurons,which produces convulsive seizure. Therefore,which produces convulsive seizure. Therefore,ECT requires general anesthesia, induces massiveECT requires general anesthesia, induces massiveautonomicautonomic stimulationstimulation, and can produce, and can producetransient memory loss(Khan et al,1993)transient memory loss(Khan et al,1993)
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ECT induces activation throughout the brain and, particularly,ECT induces activation throughout the brain and, particularly,in hippocampus and neocortex, (Cole et al,1990) . Byin hippocampus and neocortex, (Cole et al,1990) . Bycontrast, a single application of rTMS produces a muchcontrast, a single application of rTMS produces a muchmore discretemore discrete stimulationstimulation more in the dorsalmore in the dorsalmidthalamus, specifically the paraventricular nucleus , inmidthalamus, specifically the paraventricular nucleus , inthe frontal and medial cerebral cortex, including cingulate,the frontal and medial cerebral cortex, including cingulate,primary, and secondary motor cortex The effects of rTMSprimary, and secondary motor cortex The effects of rTMSin the cingulate cortex are more evident in anterior brainin the cingulate cortex are more evident in anterior brainsections . However, rTMS does not induce activation insections . However, rTMS does not induce activation inlateral cortical regions such as forelimb and parietal cortexlateral cortical regions such as forelimb and parietal cortexas well as midbrain, pons, medulla, and cerebellum(Rong etas well as midbrain, pons, medulla, and cerebellum(Rong etal,1998)(activation of the brain assessed by mRNAal,1998)(activation of the brain assessed by mRNAexpression).expression).
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Technique of TMSTechnique of TMS
rTMS was administrated to head modelrTMS was administrated to head model
by using a modelled figure of eightby using a modelled figure of eight
coil and the Magstim Rapid Ratecoil and the Magstim Rapid Rate
Stimulator at a rate of 8Stimulator at a rate of 8 Hz withHz with100% power that generates a field of100% power that generates a field of
approximately 2approximately 2 tesla. The coil wastesla. The coil was
held above the right dorsolateralheld above the right dorsolateral
prefrontal cortex oriented laterallyprefrontal cortex oriented laterallyand ventrally.and ventrally.
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Comparing magnitude of induced electric current after TMS in diComparing magnitude of induced electric current after TMS in differentfferent
brain regions ipsilateral and opposite to the site of stimulatiobrain regions ipsilateral and opposite to the site of stimulationn
Left sideLeft side
a/m2a/m2
Right sideRight side(Side of stimulation)(Side of stimulation)
a/m2a/m2
BrainBrainregionsregions
3310.510.5FrontalFrontal
lobelobe
5.55.51313ParietalParietallobelobe
1199TemporaTempora
l lobel lobe
2222OccipitalOccipital
lobelobe
0.850.851.61.6ThalamuThalamu
ss
3.43.43.83.8CaudateCaudate
nucleusnucleus
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Single TMS in Tobacco SmokersSingle TMS in Tobacco Smokers
TMS over the frontal cortex was usedTMS over the frontal cortex was used
to examine CNS effects of chronicto examine CNS effects of chronic
nicotine use in 20 subjectsnicotine use in 20 subjects
Results showed shorter cortical motorResults showed shorter cortical motorevoked potentials in smokersevoked potentials in smokers
compared with nonsmokercompared with nonsmoker
controls,indicating increasedcontrols,indicating increased
neuronal activity in the frontal lobe.neuronal activity in the frontal lobe.
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2427
15.7
12.6
17.4
12.6
16.914.1
0
5
10
1520
25
30
Before Just after 2 weeks
after
1 month
after
HFS LFS
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PP--valuevalueRt sidedRt sided
groupgroupLt sidedLt sided
groupgroupTime ofTime of
assessmeassessme
ntnt
27.1+2.527.1+2.528.2+1.328.2+1.3BeforeBeforeTMSTMS
24.0+1.024.0+1.023.4+1.523.4+1.5AfterAfter
5sessions5sessions
0.0310.03123.2+1.223.2+1.221.0+0.921.0+0.9AfterAfter10session10session
ss
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Repetitive Transcranial MagneticRepetitive Transcranial Magnetic
Stimulation treatment in PostStimulation treatment in Post
stroke Depressionstroke DepressionClinical responseClinical response nono PercentagePercentage
RespondersResponders 1212 60%60%
NonNon--
respondersresponders
88 40%40%
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Timing of theTiming of the
studystudyHDRSHDRS
M+SDM+SD
DifferencesDifferences
Just beforeJust before
TMSTMS
24.4+5.09324.4+5.093
Just afterJust after
TMSTMS14.30+5.46914.30+5.469 10.1(41.39)10.1(41.39)
%%
Two weeksTwo weeks
afterafter
15.00+7.00415.00+7.004 9.4(38.52) %9.4(38.52) %
One monthOne month
afterafter14.6+6.57314.6+6.573 9.8(40.16)%9.8(40.16)%
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CognitiveCognitive
testtestBeforeBefore
TMSTMSAfterAfter
TMSTMSPP--valuevalue
VisualVisual
associateassociatelearninglearning
7.30+2.847.30+2.84 9.60+3.9.60+3.
9999
0.0060.006
TappingTapping
forwardforward6.00+1.506.00+1.50 6.20+1.6.20+1.
95950.480.48
TapingTapingbackwardbackward 4.80+1.954.80+1.95 5.03+1.5.03+1.4747 0.460.46
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45%
40%
15%
No side effects Headache Others
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Thank youThank you