it a useful tool for those studying multiple sclerosis. Similarly, TMS is also being researched for its possibilities as a long-term and possibly more cost-effective therapeutic alternative for treating chronic psychiatric disorders such as major depression as well as its use as a means of in aiding in stroke recovery. However, although therapeutic TMS is promising overall, its success is still unclear and has not been upheld in a number of studies. This is true relating to studies of Parkinson's patients who were given long-term TMS therapy. Although it initially appeared as if these subjects gained improved performance in motor coordination tests, these results are inconsistently reproducible. The same type of results are seen in studies in schizophrenia where it has been shown that cognitive performance in schizophrenic patients treated with TMS is highly variable. Such results suggest that evidence of the effects of TMS are lacking and this technique's neurobiological mechanisms are still not well understood. Because of these uncertainties, research on this method is ongoing and much is still to be determined about its exact effect on the activation state of the brain. Comparatively, CSM, having the advantages of the more researched technique, is often still preferred. Safety must also be considered with respect to both methods. So far, Food and Drug Administration (FDA) guidelines have only approved the use of TMS for the treatment of depression. Although this technique has no known lasting side effects except for a few reported cases of induced seizures, it is still treated with caution due to its relative novelty in clinical use. CSM has gained U.S. FDA approval for its uses regarding cortical stimulation mapping, especially in cases of seizure and glioma treatments, and for aiding in the placement of electrodes within the brain. References Neurology procedures