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Transcranial Magnetic Stimulation. Julia Shannon BME 281 October 11, 2011. What is it?. A procedure that uses magnetic fields to stimulate nerve cells in the brain Relatively new Since development, has been used in many fields of research
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Transcranial Magnetic Stimulation Julia Shannon BME 281 October 11, 2011
What is it? • A procedure that uses magnetic fields to stimulate nerve cells in the brain • Relatively new • Since development, has been used in many fields of research • Use of magnets, instead of a direct electric current to the brain, allows for mapping of the cerebral cortex and its connections
First use • 1985-Anthony Barker conducted the first successful TMS study in Sheffield, England • Stimulated muscle contraction -conducted nerve impulses from the motor cortex to the spinal cord
How does it work? • A large electromagnetic coil is placed against the scalp • Uses a magnetic field to create weak electric currents that stimulate nerve cells in a region of the brain • Causes depolarization or hyper polarization in neurons
Clinical uses • Tested as a treatment for various neurological and psychiatric disorders • Used today to improve symptoms of depression • Stimulating the nerve cells creates mood change • Used when standard procedures have no effect • Least invasive (doesn’t require surgery or implantation of electrodes) • 164 patients with unipolar, non-psychotic major depressive disorder were treated with TMS. Within 30 days.. -1/3 reported complete resolution -1/2 reported significant improvement
Procedure • Doctor places coil against head- mapping signals • Increase of magnetic dosage until fingers or hands twitch (motor threshold)
Treatments are typically given daily, for 30-40 minutes, in a span of 4-6 weeks. • Stimulation is gradual • Repetitive TMS produces longer-lasting effects which persist past the initial period of stimulation
Coil Types • Can differ in geometry of the coil, the type of material used • Designs of different coils used can have a big impact on the resulted stimulation • Ex: figure-eight coil results in more focal pattern of activation, double-cone coil used for deeper stimulation
Risks and Side Effects • Common: Headache, scalp discomfort, tingling or twitching of facial muscles, lightheadedness • Less Common: Seizures, mania
The NeuroStar, a device used for TMS, was cleared by the FDA in 2008 • Improvements in symptoms may last for days/weeks/months • Other areas of research include -rehabilitation of motor disability after stroke -evaluating damage from strokes, spinal cord injuries, Multiple Sclerosis, and motor neuron disease - itraoperative monitoring
TMS machine designed in 1992: stimulate or slow down regions of the brain so that doctors could monitor the effects of the surgery in real time • Allan Snyder- theorized that people could tap into genius-like mental ability when undergoing TMS (Having a mental impairment would allow other mental functions to flourish) • 40% of test subjects displayed extraordinary and newfound mental skills.
Sources • Yang, Sarah. "09.27.2007 - Neuroscientists Connect Neural Activity and Blood Flow in New Brain Stimulation Technique." University of California, Berkeley. Web. 08 Oct. 2011. <http://berkeley.edu/news/media/releases/2007/09/27_TMS.shtml>. • Fallon, Sean. "NeuroStar TMS Depression Therapy System First To Be Given FDA Approval." Gizmodo, the Gadget Guide. Web. 08 Oct. 2011. <http://gizmodo.com/5403423/neurostar-tms-depression-therapy-system-first-to-be-given-fda-approval>. • "Savant for a Day." Biotele. Web. 08 Oct. 2011. <http://www.biotele.com/savant.htm>. • Staff, Mayo Clinic. "Transcranial Magnetic Stimulation - MayoClinic.com." Mayo Clinic. Web. 08 Oct. 2011. <http://www.mayoclinic.com/health/transcranial-magnetic-stimulation/MY00185>. • "Transcranial Magnetic Stimulation." Neurology. Web. 08 Oct. 2011. <http://www.neurology.org/content/68/7/484.short>. • "Transcranial Magnetic Stimulation." Wikipedia, the Free Encyclopedia. Web. 08 Oct. 2011. <http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation>.