therapeutic procedure trigeminal nerve stimulation true modified definition https://www.ncbi.nlm.nih.gov/pubmed/26307329 The Trigeminal Nerve Stimulation (TNS) system is a type of treatment modality which is not yet FDA approved but is available in Europe and other countries. Its mechanism of action is similar to the VNS system and it also appears to have anti-depression effects in addition to anti-epileptic benefits.