Which TMS is best?
Nearly one in five adults and half of all adolescents in the United States live with mental illness.1 As a result of their illness, a large number of these individuals experience significant disruptions in their ability to maintain family and social relationships, thrive at work and school, and engage in everyday activities. Those who seek professional treatment typically receive a combination of medications and talk therapy, but a growing body of evidence suggests that more than 30% of individuals across the broad spectrum of mental disorders do not fully improve with these traditional therapeutic options.2,3 For the millions of people living with treatment-resistant mental illness, innovative therapies may provide an answer where conventional methods have failed.
One of the most promising new technologies for the treatment of mental illness is called transcranial magnetic stimulation (TMS). The therapy uses principles of magnetism to stimulate electrical activity in areas of the brain that have been implicated in mental illness, regulating the imbalanced patterns of neural activation that are known to cause depression, anxiety, obsessive-compulsive disorder (OCD), schizophrenia, and other psychiatric disorders. During this noninvasive treatment, a trained clinician positions a small wire coil directly above the targeted area of the patient’s brain. The coil generates a magnetic field that painlessly passes through the skull and into the brain, where it incites electrical activity that permanently regulates and balances neuronal function. A full course of TMS typically requires five of these sessions per week for four to six weeks.
Since its FDA approval as a therapy for major depressive disorder in 2008,4 TMS has become an increasingly popular alternative to traditional treatments for psychiatric disorders. Neuroscientists have since adapted the basic premise of TMS in a bid to discover the most rapid, effective protocols for alleviating mental illness, such as modifications to coil size, depth of stimulation, magnetic stimulation pattern (i.e., frequency and intensity), and session duration. These adaptations have yielded a diverse array of TMS protocols, including focal TMS, deep TMS, and theta burst stimulation TMS. While all protocols are thought to be similarly effective, their unique configurations provide an array of treatment options to suit each patient’s specific needs and goals.
Focal TMS, the standard TMS protocol approved for use in 2008, uses a figure-8-shaped coil to stimulate brain cells. The electromagnetic field delivered in steady pulses by the figure-8 coil is considered “focal” because it targets a relatively small area of the brain at a somewhat superficial depth (0.7 cm).5 Because each person’s brain has a slightly different structure, a clinician may need to conduct pre-TMS brain mapping to ensure that the exact target area is stimulated during treatment, as the narrow range of focal TMS leaves little margin for error. Although brain mapping is a valuable tool for identifying target brain circuits with great precision, the procedure can be expensive6 and may complicate the TMS process. Given that a typical session of focal TMS lasts about 40 minutes,7 additional delays may be undesirable.
The most notable distinction between standard TMS and deep TMS is that deep TMS uses an innovative H-shaped coil to deliver the electromagnetic field. Unlike the figure-8 coil, the H-coil reaches a larger area of the brain at a much deeper penetrance (up to 3.2 cm, or more than four times deeper than focal TMS). Deep-penetrating fields are thought to more effectively activate important neural pathways that regulate reward behaviors and emotion, improving the long-term efficacy of the treatment. This increased depth comes at the expense of high specificity,8 although the broader field of activation eliminates the need to perform brain mapping prior to TMS. Additionally, the H-coil enables delivery of a steady, continuous magnetic field, which requires only half the time of the typical pulsating protocol and reduces the TMS session from 40 to 20 minutes.9 In 2013, five years after focal TMS received FDA approval, BrainsWay’s deep TMS device received clearance for major depressive disorder. Deep TMS next received clearance as a treatment for OCD in 2018, followed by clearance for smoking cessation in 2020.10
Theta Burst Stimulation TMS (Express TMS®)
Encouraged by the success of other TMS protocols, neuroscientists have used the brain’s natural electrical patterns to inspire a new protocol called theta burst stimulation (TBS or Express TMS®). Express TMS® uses the classic figure-8 coil to rapidly deliver high-frequency magnetic bursts for a short duration (three 50-Hz magnetic pulses every 200 milliseconds for 20 to 40 seconds), mimicking the neuronal activation pattern that occurs in nature during learning memory.11 The unique burst pattern of Express TMS® takes only 3 minutes to complete, shortening the standard 20-40-minute TMS session more than tenfold and expanding treatment accessibility to patients with limited time and resources. The TBS TMS protocol received FDA approval as a treatment for major depressive disorder in 201812 and remains under exploration for other conditions, including OCD, anorexia nervosa, and autism spectrum disorder.
Which is best?
Each of these TMS protocols has undergone extensive testing in large clinical trials to prove safety and efficacy, and no protocol has been found to be inferior to another. Side effects are minimal and similar across protocols, and the vast majority patients experience few or no side effects beyond a brief, mild headache following treatment.9,13,14 Critically, focal TMS, deep TMS, and TBS TMS (Express TMS®) have all been FDA-approved for at least one condition and are expected to receive clearance for more disorders in the coming years, broadening the scope of this cutting-edge technology for the millions of people in the United States living with treatment-resistant mental illness. At TMS Program, our clinicians provide expert guidance on which type of TMS is best suited to meet each patient’s individual needs and goals in the pursuit of a life unburdened by mental illness.
1 National Institute of Mental Health. (2020). Mental Illness. Retrieved from: https://www.nimh.nih.gov/health/statistics/mental-illness.shtml
2 Kellner M. (2010). Drug treatment of obsessive-compulsive disorder. Dialogues in Clinical Neuroscience, 12(2):187-197.
3 Al-Harbi KS. (2012). Treatment-resistant depression: Therapeutic trends, challenges, and future directions. Patient Preference and Adherence, 2012(6):369-388.
4 Horvath JC, Mathews J, Demitrack MA, & Pascual-Leone A. (2010). The NeuroStar TMS Device: Conducting the FDA-approved protocol for treatment of depression. Journal of Visualized Experiments, 45.
5 Ginou A, Roth Y, & Zangen A. (2014). Comparison of superficial TMS and deep TMS for major depression. Brain Stimulation, 7:e19.
6 NeuroField Neurotherapy, Inc. Fees & Insurance. (2018). Retrieved from: https://neurofieldneurotherapy.com/fees-and-insurance
7 Johns Hopkins Medicine. Frequently Asked Questions About TMS. (2020). Retrieved from: https://www.hopkinsmedicine.org/psychiatry/specialty_areas/brain_stimulation/tms/faq_tms.html
8 Deng ZD, Lisanby SH, & Peterchev AV. (2013). Electric field depth–focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs. Brain Stimulation, 6(1):1-13.
9 Levkovitz Y, Isserles M, Padberg F, et al. (2015). Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial. World Psychiatry, 14(1):64-73.
10 BrainsWay. Mental health conditions is deep TMS cleared to treat? (2020). Retrieved from: https://www.brainsway.com/professionals-faqs/what-mental-health-conditions-is-deep-tms-fda-cleared-to-treat
11 Hill AJ. (1978). First occurrence of hippocampal spatial firing in a new environment. Experimental Neurology, 62(6):282-297.
12 Mendlowitz AB, Shanbour A, Downar J, et al. (2019). Implementation of intermittent theta burst stimulation compared to conventional repetitive transcranial magnetic stimulation in patients with treatment resistant depression: A cost analysis. PLoS One, 14(9):e0222546.
13 Taylor R, Galvez V, & Loo C. (2018). Transcranial magnetic stimulation (TMS) safety: A practical guide for psychiatrists. Australasian Psychiatry, 26(2):189-192.
14 Oberman L, Edwards D, Eldaief M, & Pascual-Leone A. (2011). Safety of theta burst transcranial magnetic stimulation: A systematic review of the literature. Journal of Clinical Neurophysiology, 28(1):67-74.