<P> A number of deep TMS have received FDA 510k clearance to market for use in adults with treatment resistant major depressive disorders . </P> <P> The use of single - pulse TMS was approved by the FDA for treatment of migraines in December 2013 . It is approved as a Class II medical device under the "de novo pathway". </P> <P> In 2013, several commercial health insurance plans in the United States, including Anthem, Health Net, and Blue Cross Blue Shield of Nebraska and of Rhode Island, covered TMS for the treatment of depression for the first time . In contrast, UnitedHealthcare issued a medical policy for TMS in 2013 that stated there is insufficient evidence that the procedure is beneficial for health outcomes in patients with depression . UnitedHealthcare noted that methodological concerns raised about the scientific evidence studying TMS for depression include small sample size, lack of a validated sham comparison in randomized controlled studies, and variable uses of outcome measures . Other commercial insurance plans whose 2013 medical coverage policies stated that the role of TMS in the treatment of depression and other disorders had not been clearly established or remained investigational included Aetna, Cigna and Regence . </P> <P> Policies for Medicare coverage vary among local jurisdictions within the Medicare system, and Medicare coverage for TMS has varied among jurisdictions and with time . For example: </P>

Which of the following is true of transcranial magnetic stimulation (tms)