Transcranial Magnetic Stimulation in Psychiatry

8/12/2019 Transcranial Magnetic Stimulation in Psychiatry

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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

Transcranial Magnetic Stimulation in Psychiatry

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