What Is TMS? Transcranial Magnetic Stimulation Explained

TMS Coil Comparison

Depth and treatment coverage across TMS coil types

Broad coverage means your results do not depend on perfect aim.

A traditional figure-8 coil is a small handheld device that has to be positioned precisely and held there. Not once, but across every session in the course, and your head cannot move during any of them. A shift in posture or a slight change in coil angle moves the pulse off target.

The H-coil sits in a cushioned helmet that can only be worn one way. It positions itself and it stays put. Patients move freely, watch TV, use their phone, or talk with us, and the treatment lands the same way every session.

The H-coil also covers a far wider area of cortex than a figure-8 coil. A broader field is inherently more forgiving of small differences in placement, which is why consistency here is built into the equipment instead of depending on a steady hand.

Depth is what lets us treat OCD.

A figure-8 coil reaches about 0.7 cm into the cortex. The H7 coil reaches 3.0 cm. That difference is not "better" in the abstract. It is what makes the medial prefrontal and anterior cingulate regions reachable at all, and those are the regions that matter in OCD.

Where the Research Is Still Developing

Deep TMS is being studied for conditions beyond its current FDA clearances. Published research is growing for migraine, tinnitus, and post-traumatic stress disorder. These uses are not FDA-cleared, and we do not advertise them as services.

If you are being treated here for a cleared indication and one of these conditions is also part of your picture, it is a reasonable thing to raise with Dr. Saakyan during your evaluation. Whether TMS has any role is a clinical judgment made case by case, not something we can answer in advance.

How Effective Is Deep TMS?

Deep TMS is an evidence-based treatment for depression, including depression that has not improved enough with antidepressant medication.

A 2024 systematic review pooled five randomized controlled trials of Deep TMS in adults whose depression had not responded to multiple medications, covering 507 patients. Among those receiving active Deep TMS, 45.3% responded, meaning their symptoms improved by at least 50%, and 38.3% reached remission. In the control groups the figures were 24.2% and 14.4%.

Individual results vary, and no treatment can guarantee response or remission. Whether Deep TMS is appropriate for you is decided after evaluation and safety screening.

Source: Lan XJ, Yang XH, Mo Y, et al. Deep transcranial magnetic stimulation for treatment-resistant depression: a systematic review and meta-analysis of randomized controlled studies. Asian J Psychiatr. 2024;96:104032. doi:10.1016/j.ajp.2024.104032

How TMS Compares to Other Treatments

TMS works differently than most common treatments because it targets specific brain networks using magnetic stimulation, without medication or anesthesia, and without a hospital stay.

Compared to antidepressants: TMS is not systemic, so it avoids many whole-body side effects. It is delivered as a defined course of in-office sessions rather than a daily drug routine.

Compared to ketamine: TMS is non-drug and does not involve dissociation. It is designed to create steady, durable change by strengthening mood-regulation networks over time.

Compared to electroconvulsive therapy (ECT): TMS does not require anesthesia and does not induce a seizure, and most patients return to normal activities immediately after each session.

TMS Safety Overview

TMS is widely used and generally well-tolerated. The most common side effects are temporary, such as mild headache or scalp discomfort, and they tend to ease as your body adapts to treatment. Safety screening before starting is essential, especially for patients with metal in or around the head, which can make treatment inappropriate. We walk through all of this with you before anything is scheduled.

Curious what a visit actually looks like? Read about the TMS treatment process, mapping, session length, and what treatment feels like.

Is TMS safe? What about seizures?

Seizures are rare.

Published incidence for repetitive TMS is under 0.1%, compared with 0.35% to 0.44% for the antidepressant bupropion.

Motor threshold is re-checked through treatment, seizure-trained staff are always present, and a prevention checklist is completed at every visit.

Source: Trapp NT, Purgianto A, Taylor JJ, et al. Consensus review and considerations on TMS to treat depression: a comprehensive update endorsed by the National Network of Depression Centers, the Clinical TMS Society, and the International Federation of Clinical Neurophysiology. Clin Neurophysiol. 2025;170:206–233. doi:10.1016/j.clinph.2024.12.015

For the nerds: frequencies, targets, and coils

TMS delivers magnetic pulses to targeted neural pathways. Delivered repeatedly, this produces lasting shifts in cortical excitability consistent with synaptic plasticity, propagating transsynaptically to connected limbic and subcortical structures. All three cleared protocols are high-frequency and therefore excitatory. In each case the target is a cortical region that is under-regulating, rather than a region that needs suppressing.

MDD. 18 Hz to the left dorsolateral prefrontal cortex via the H1 coil. Prefrontal hypoactivity is a consistent finding in depression, and stimulation there propagates to subgenual cingulate and limbic structures, restoring top-down regulation rather than acting on any single neurotransmitter system.

OCD. 20 Hz to medial prefrontal cortex and anterior cingulate via the H7 coil. The target is cortical control over the cortico-striato-thalamo-cortical loop implicated in obsessions and compulsions, circuitry a figure-8 coil over DLPFC does not reach. The mPFC target also overlaps default mode network nodes implicated in the perseverative quality of obsessions. Each session follows individualized symptom provocation.

Smoking cessation. 10 Hz to bilateral lateral prefrontal cortex and insula via the H4 coil. The insula is a salience network hub that assigns motivational weight to interoceptive craving states, and it is not reachable with a figure-8 coil, which is what made this indication possible on an H-coil. Each session follows a cue-induced craving procedure.

Across OCD and smoking cessation, stimulation is delivered while the target circuit is active rather than at rest.

Sources: Levkovitz Y, Isserles M, Padberg F, et al. Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial. World Psychiatry. 2015;14(1):64–73. · Carmi L, Alyagon U, Barnea-Ygael N, Zohar J, Dar R, Zangen A. Clinical and electrophysiological outcomes of deep TMS over the medial prefrontal and anterior cingulate cortices in OCD patients. Brain Stimul. 2018;11(1):158–165. · Carmi L, Tendler A, Bystritsky A, et al. Efficacy and safety of deep transcranial magnetic stimulation for obsessive-compulsive disorder: a prospective multicenter randomized double-blind placebo-controlled trial. Am J Psychiatry. 2019;176(11):931–938. doi:10.1176/appi.ajp.2019.18101180 · Zangen A, Moshe H, Martinez D, et al. Repetitive transcranial magnetic stimulation for smoking cessation: a pivotal multicenter double-blind randomized controlled trial. World Psychiatry. 2021;20(3):397–404. · Roth Y, Amir A, Levkovitz Y, Zangen A. Three-dimensional distribution of the electric field induced in the brain by transcranial magnetic stimulation using figure-8 and deep H-coils. J Clin Neurophysiol. 2007;24:31–38.