TMS a decade later

Transcranial Magnetic Stimulation (TMS)

Transcranial magnetic stimulation (TMS) is a noninvasive neuromodulation method that uses an insulated electromagnetic coil placed over the scalp to stimulate small regions of the brain.  The coil is connected to a pulse generator that delivers electrical current to the coil.  The strength of the pulses generated usually are of the same magnitude as those utilized by magnetic resonance imaging (MRI) machines. The coil generates brief magnetic pulses that produce small electrical currents in the brain just under the coil via electromagnetic induction.  

TMS can be used as a diagnostic test to examine connection between the brain and muscles as part of the evaluation for stroke or other injuries, multiple sclerosis, motor neuron disease (i.e., amyotrophic lateral sclerosis or ALS), and movement disorders (i.e., Parkinson’s Disease). 

TMS also can be used for the treatment of neuropsychiatric illnesses.  Single-pulse TMS has been approved by the FDA for the treatment of migraine.  When pulses are administered in rapid succession, it is referred to as “repetitive TMS” (rTMS) and can produce sustained changes in brain function and neuroplasticity, which may treat a variety of illnesses.  rTMS is approved for use by the FDA in treatment-resistant Major Depressive Disorder.  Evidence suggests that rTMS also may be useful for treatment of anxiety disorders, neuropathic pain, negative symptoms of schizophrenia, auditory hallucinations, tinnitus, and loss of function caused by stroke.  

Single- or repetitive pulse TMS also can be used as a research tool to examine cognitive or emotional processing during tasks.  Depending upon the location of pulse delivery and the timing of pulse administration during stimulus presentation of processing, TMS can be used to create a “virtual lesion” in processing pathways that can enhance or degrade task performance and facilitate examination of different components of task performance. 

TMS generally is well tolerated and has a favorable safety profile.  The most common adverse event reported during TMS is discomfort or pain at the site of stimulation.  Less common adverse events are the rare occurrence of induced seizures.  Other uncommon adverse effects of TMS include transient induction of hypomania, transient cognitive changes, transient hearing loss, transient impairment of working memory, and induced currents in electrical circuits in implanted devices.