Transcranial Magnetic Stimulation(TMS)

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Transcranial Magnetic Stimulation(TMS)

• By Brandon Brunelle

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What is it

• Trancranial Magnetic Stimulation is a method
  used to treat migrains, migrain aura, and even
  depression
• 10-20 of people suffer from migrains alone
• Relatively new concept
• Not yet widely used or accepted by insurance

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Background

• The skull acts as a shield
• Different parts of the brain have different
  functionality
• Brain is made up of neurons and neuron clusters
  that are electrically excitable

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The Concept

• Migrains are associated with high neuron activity
• Depression associated with low neuron activity.
• Use a magnetic coil to modulate neuron activity
• Coil is placed on scalp in a desired location
• Magnetic field penetrates to a depth of about 3cm
• Approximately three times the normal neuron
  excitation stimulation is needed to modulate

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Components

• 24V voltage source/high voltage module
• Bipolar condensors
• Snubber circuit
• Control circuits
• Copper coil

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High voltage module

• Delivers an adjustable positive voltage that is
  highly stable
• Custom 10 watt and high voltage module
• Charges condensers in about 23 seconds
• High voltage double pole inverter

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Condensors
Control Circuit

• Metal impregnated polypropylene dielectric with
  1500volt insulation.
• Used to deliver high current discharges in about
  100uS.

• Allows for selection of polarity
• Amplitude adjustment

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Snubber Circuit

• Uses two Thyristor to deliver current to coil in
  order to provide positive and negative current
• 1800V insulation
• Transfers peak current of 8000A for 10ms
• Time derivatives were 250A/uS, 1000V/uS
• Circuit contains about a 4.3uS lag time causing
  polarity to undesirably change in coil
• Snubber circuit contained an R-C setup in
  paralell with thrystors to prevent polarity
  change

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Copper Coil

• Coil has a diameter of 11 cm
• Made of flat enameled copper wire
• Insulated to prevent coil unwinding

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Benefits

• Non invasive
• Relatively quick and easy
• Does not cause any sort disfunctionality
• Would not cost a lot
• No chemical imbalances that drugs and medication
  can cause
• 74 success rate after two hours in test

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Sources

• Design and Construction of a Portable
  Transcranial Magnetic Stimulation (TMS) Apparatus
  for Migraine Treatment Anne Beuter, Isabelle
  Lagroye, Bernard Veyret University of Bordeaux
  1,IMS, Site ENSCPB,UMR CNRS 5218,16, Avenue Pey
  Berland, 33607, Pessac Cedex, France
• http//intra.ninds.nih.gov/images/Research_Images/
  wassermanne_at_ninds.nih.gov.jpg
• http//www.mclean.harvard.edu/patient/adult/tms.ph
  p
• http//en.wikipedia.org/wiki/Transcranial_magnetic
  _stimulation
• http//www.nami.org/Content/ContentGroups/Helpline
  1/Transcranial_Magnetic_Stimulation_28rTMS29.htm