Transcranial Magnetic StimulationTranscranial Magnetic Stimulation

Julia ShannonBME 281October 11, 2011

What is it?What is it?

A procedure that uses magnetic fields to A procedure that uses magnetic fields to stimulate nerve cells in the brain stimulate nerve cells in the brain

Relatively new Relatively new Since development, has been used in Since development, has been used in

many fields of researchmany fields of research Use of magnets, instead of a direct electric Use of magnets, instead of a direct electric

current to the brain, allows for mapping of current to the brain, allows for mapping of the cerebral cortex and its connectionsthe cerebral cortex and its connections

First useFirst use

1985-Anthony Barker conducted the 1985-Anthony Barker conducted the first successful TMS study in first successful TMS study in Sheffield, EnglandSheffield, England

Stimulated muscle contractionStimulated muscle contraction -conducted nerve impulses from the motor cortex -conducted nerve impulses from the motor cortex

to the spinal cordto the spinal cord

How does it work?How does it work?

A large electromagnetic coil is placed A large electromagnetic coil is placed against the scalpagainst the scalp

Uses a magnetic field to create weak Uses a magnetic field to create weak electric currents that stimulate nerve electric currents that stimulate nerve cells in a region of the brain cells in a region of the brain

Causes depolarization or hyper Causes depolarization or hyper polarization in neuronspolarization in neurons

Clinical usesClinical uses

Tested as a treatment for various neurological Tested as a treatment for various neurological and psychiatric disordersand psychiatric disorders

Used today to improve symptoms of depressionUsed today to improve symptoms of depression Stimulating the nerve cells creates mood changeStimulating the nerve cells creates mood change Used when standard procedures have no effect Used when standard procedures have no effect Least invasiveLeast invasive (doesn’t require surgery or implantation of electrodes) (doesn’t require surgery or implantation of electrodes) 164 patients with unipolar, non-psychotic major 164 patients with unipolar, non-psychotic major

depressive disorder were treated with TMS. depressive disorder were treated with TMS. Within 30 days..Within 30 days..

-1/3 reported complete resolution-1/3 reported complete resolution -1/2 reported significant improvement-1/2 reported significant improvement

ProcedureProcedure

Doctor places coil against Doctor places coil against

head- mapping signalshead- mapping signals

Increase of magnetic Increase of magnetic

dosage until fingers or dosage until fingers or

hands twitchhands twitch

(motor threshold)(motor threshold)

Treatments are Treatments are typically given daily, typically given daily, for 30-40 minutes, in a for 30-40 minutes, in a span of 4-6 weeks.span of 4-6 weeks.

Stimulation is gradualStimulation is gradual Repetitive TMS Repetitive TMS

produces longer-produces longer-lasting effects which lasting effects which persist past the initial persist past the initial period of stimulation period of stimulation

Coil TypesCoil Types

Can differ in geometry of the coil, the type Can differ in geometry of the coil, the type of material usedof material used

Designs of different coils used can have a Designs of different coils used can have a big impact on the resulted stimulationbig impact on the resulted stimulation

Ex: figure-eight coil results in more focal pattern of Ex: figure-eight coil results in more focal pattern of activation,activation,

double-cone coil used for deeper stimulationdouble-cone coil used for deeper stimulation

Risks and Side EffectsRisks and Side Effects

Common:Common:Headache, scalp discomfort, tingling or Headache, scalp discomfort, tingling or

twitching of facial muscles, twitching of facial muscles, lightheadednesslightheadedness

Less Common:Less Common:

Seizures, maniaSeizures, mania

The NeuroStar, a device used for TMS, was The NeuroStar, a device used for TMS, was cleared by the FDA in 2008cleared by the FDA in 2008

Improvements in symptoms may last for Improvements in symptoms may last for days/weeks/monthsdays/weeks/months

Other areas of research include Other areas of research include -rehabilitation of motor disability after stroke -rehabilitation of motor disability after stroke -evaluating damage from strokes, spinal cord -evaluating damage from strokes, spinal cord

injuries, Multiple Sclerosis, and motor injuries, Multiple Sclerosis, and motor neuron neuron diseasedisease

- itraoperative monitoring- itraoperative monitoring

TMS machine designed in 1992: stimulate or slow TMS machine designed in 1992: stimulate or slow down regions of the brain so that doctors could down regions of the brain so that doctors could monitor the effects of the surgery in real timemonitor the effects of the surgery in real time

Allan Snyder- theorized that people could tap into Allan Snyder- theorized that people could tap into genius-like mental ability when undergoing TMSgenius-like mental ability when undergoing TMS

(Having a mental impairment would allow other mental (Having a mental impairment would allow other mental functions to flourish)functions to flourish)

40% of test subjects displayed extraordinary and 40% of test subjects displayed extraordinary and newfound mental skills.newfound mental skills.

SourcesSources Yang, Sarah. "09.27.2007 - Neuroscientists Connect Neural Activity and Blood Flow in Yang, Sarah. "09.27.2007 - Neuroscientists Connect Neural Activity and Blood Flow in

New Brain Stimulation Technique." New Brain Stimulation Technique." University of California, BerkeleyUniversity of California, Berkeley. Web. 08 Oct. . Web. 08 Oct. 2011. <http://berkeley.edu/news/media/releases/2007/09/27_TMS.shtml>. 2011. <http://berkeley.edu/news/media/releases/2007/09/27_TMS.shtml>.

Fallon, Sean. "NeuroStar TMS Depression Therapy System First To Be Given FDA Fallon, Sean. "NeuroStar TMS Depression Therapy System First To Be Given FDA Approval." Approval." Gizmodo, the Gadget GuideGizmodo, the Gadget Guide. Web. 08 Oct. 2011. . Web. 08 Oct. 2011. <http://gizmodo.com/5403423/neurostar-tms-depression-therapy-system-first-to-be-<http://gizmodo.com/5403423/neurostar-tms-depression-therapy-system-first-to-be-

given-fda-approval>.given-fda-approval>. "Savant for a Day." "Savant for a Day." BioteleBiotele. Web. 08 Oct. 2011. . Web. 08 Oct. 2011.

<http://www.biotele.com/savant.htm>. <http://www.biotele.com/savant.htm>. Staff, Mayo Clinic. "Transcranial Magnetic Stimulation - MayoClinic.com." Staff, Mayo Clinic. "Transcranial Magnetic Stimulation - MayoClinic.com." Mayo ClinicMayo Clinic. .

Web. 08 Oct. 2011. <http://www.mayoclinic.com/health/transcranial-magnetic-Web. 08 Oct. 2011. <http://www.mayoclinic.com/health/transcranial-magnetic-stimulation/MY00185>. stimulation/MY00185>.

"Transcranial Magnetic Stimulation." "Transcranial Magnetic Stimulation." NeurologyNeurology. Web. 08 Oct. 2011. . Web. 08 Oct. 2011. <http://www.neurology.org/content/68/7/484.short>. <http://www.neurology.org/content/68/7/484.short>.

"Transcranial Magnetic Stimulation." "Transcranial Magnetic Stimulation." Wikipedia, the Free EncyclopediaWikipedia, the Free Encyclopedia. . Web. 08 Oct. 2011. Web. 08 Oct. 2011. <http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation>.<http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation>.