TMS: Some Definitions from the Clinical TMS Society

This clarification statement on different types of TMS was produced by the Clinical Standards Committee and supported by the CTMSS Board of Directors, published on Fri, 02/10/2023 - 20:13

Types of TMS

Transcranial magnetic stimulation (TMS) is a non-invasive form of brain stimulation that uses electromagnetic induction to create electrical current in specific brain areas. This technology is used in research as well as in clinical care. It can be used for many purposes including providing real-time information about the state of the brain and providing treatment for various health conditions.

As this technology has multiple uses, we would like to clarify the definition of terms to help ensure that society members, trainees, and the general public have a clear understanding of transcranial magnetic stimulation. 

Repetitive TMS (rTMS)

rTMS is currently the most widespread form of TMS for clinical applications. In rTMS, magnetic pulses are delivered in a rapid series or “train.” When rTMS is used, multiple single-pulse stimuli are presented at a specific frequency, intensity, and time duration. Repetitive TMS also includes Deep TMS™ (dTMS), a trademarked term from a TMS device company.

Single Pulse TMS (spTMS)

One electromagnetic pulse is applied no faster than once every few seconds. SpTMS is most commonly used to examine connections in the motor areas of the brain.

Paired pulse TMS (ppTMS)

As a tool in research, paired pulse TMS uses 2 pulses applied out of phase to inhibit or excite brain cells within the same hemisphere or to inhibit brain cells in one hemisphere while exciting them in the other hemisphere. 

Updated Theta Burst Statement (iTBS)

(approved by the Executive Committee on 02/13/2023)

Intermittent Theta Burst Stimulation (iTBS) is a TMS treatment protocol that was cleared by the FDA for severe Major Depressive Disorder (MDD) in 2018 based on a non-inferiority study comparing it to a standard 10 Hz protocol.1 Since the clearance of iTBS for MDD, additional clinical trials have verified the clinical efficacy and safety of iTBS for depression treatment and it has become commonly used in clinical practice.2,3 The clear preponderance of evidence supports that once per day iTBS delivered to left dorsolateral prefrontal cortext (DLPFC) has similar acute outcomes in the treatment of MDD as compared to 10 Hz treatment, and therefore iTBS should be considered a valid alternative to the standard 10 Hz approach. There may be individual differences in response to either intervention. TMS physicians should exercise caution when considering a switch between protocols in an individual patient as outcomes may not be the same.

References: 1. Blumberger DM, Vila-Rodriguez F, Thorpe KE, et al. Effectiveness of theta burst versus high-frequency repetitive transcranial magnetic stimulation in patients with depression (THREE-D): a randomised non-inferiority trial. Lancet. 2018;391(10131):1683-1692.2. Bulteau S, Laurin A, Pere M, et al. Intermittent theta burst stimulation (iTBS) versus 10 Hz high-frequency repetitive transcranial magnetic stimulation (rTMS) to alleviate treatment-resistant unipolar depression: A randomized controlled trial (THETA-DEP). Brain Stimul. 2022;15(3):870-880.3. Hebel T, Gollnitz A, Schoisswohl S, et al. A direct comparison of neuronavigated and non-neuronavigated intermittent theta burst stimulation in the treatment of depression. Brain Stimul. 2021;14(2):335-343.