Adverse effects of TMS appear rare and includefainting andseizure, which occur in roughly 0.1% of patients and are usually attributable to administration error.[6]
A magnetic coil is positioned on the patient's head.[7]
TMS does not require surgery or electrode implantation.
Its use can be diagnostic and/or therapeutic. Effects vary based on frequency and intensity of the magnetic pulses as well as the length of treatment, which dictates the total number of pulses given.[8] TMS treatments are approved by the FDA in the US and byNICE in the UK for the treatment of depression and are provided by private clinics and someVA medical centers. TMS stimulates cortical tissue without the pain sensations produced intranscranial electrical stimulation.[9]
Repetitive transcranial magnetic stimulation (rTMS) has been shown to produce significant clinical improvements in various neurological and psychiatric disorders. A group of European experts updated the therapeutic guidelines, reviewing studies up to the end of 2018. The highest level of evidence, Level A (definite efficacy), was found for high-frequency rTMS of the primary motor cortex (primary motor cortex) forneuropathic pain, high-frequency rTMS of the leftdorsolateral prefrontal cortex (DLPFC) fordepression, and low-frequency rTMS of the contralesional motor cortex for hand motor recovery afterstroke. Level B evidence (probable efficacy) was found in conditions such asfibromyalgia,Parkinson's disease,multiple sclerosis,post-traumatic stress disorder (PTSD), depression, and post-strokeaphasia, depending on the rTMS protocol used. No other conditions reached Level A or B evidence. These recommendations are based on differences in therapeutic outcomes between real and sham rTMS, replicated in multiple independent studies, although clinical relevance may still vary.[4]
A 2025 consensus review published in theJournal of the Neurological Sciences evaluated current clinical practices and recent advancements in TMS for depression. The review confirms that TMS is a safe and effective treatment modality, with a growing body of evidence supporting its use in treatment-resistant depression. Repetitive transcranial magnetic stimulation (rTMS), particularly high-frequency stimulation of the leftdorsolateral prefrontal cortex, has demonstrated robust and reproducible acuteantidepressant effects in major depressive disorder, with growing evidence supporting its efficacy, durability, and potential superiority over medication in treatment-resistant cases. Traditional repetitive TMS (rTMS) protocols have been well-established, while newer approaches—such as intermittent theta burst stimulation (iTBS) and individualized, image-guided targeting—have shown promise in reducing treatment time and potentially enhancing clinical outcomes.[16]
Existing evidence suggests that repetitive transcranial magnetic stimulation, particularly targeting thedorsolateral prefrontal cortex andsupplementary motor area, effectively reduces obsessive-compulsive disorder symptoms, while results for themedial prefrontal cortex andanterior cingulate cortex using deep transcranial magnetic stimulation are more variable; the overall heterogeneity of studies highlights the need for further research.[17]
The effectiveness of TMS andquality of evidence behind it for treatment of depression have been questioned.[18][19][20] As withantidepressants and other interventions for depression, there is a largeplacebo response with shamcontrol groups in TMS trials (Hedges's g = 0.8).[21] In any case, in a 2023meta-analysis, TMS found a large effect size advantage over sham for depression (Hedges' g = 0.791).[22] On the other hand, in the two pivotal regulatory clinical trials that led to approval of TMS for treatment-resistant depression by the United StatesFood and Drug Administration (FDA), the intervention outperformed sham by only about 2.1 to 2.8points on the MADRS at 6weeks post-treatment.[23][24][25]
TMS is generally advertised as a safe alternative to medications such asSSRI's. The greatest immediate risk from TMS isfainting, though this is uncommon.Seizures have been reported, but are rare.[6][26][27]
Risks are higher for therapeutic repetitive TMS (rTMS) than for single or paired diagnostic TMS.[28] Adverse effects generally increase with higher frequency stimulation.[6]
During the procedure, a magnetic coil is positioned at the head of the person receiving the treatment using anatomicallandmarks on the skull, in particular theinion andnasion.[7] The coil is then connected to a pulse generator, or stimulator, that delivers electric current to the coil.[2]
TMS useselectromagnetic induction to generate an electric current across thescalp andskull.[29][30] A plastic-enclosed coil of wire is held next to the skull and when activated, produces a varyingmagnetic field orientedorthogonally to the plane of the coil. The changing magnetic field then induces an electric current in the brain that activates nearby nerve cells in a manner similar to a current applied superficially at the cortical surface.[31]
The magnetic field is about the same strength asmagnetic resonance imaging (MRI), and the pulse generally reaches no more than 5 centimeters into the brain unless using a modified coil and technique for deeper stimulation.[30]
Transcranial magnetic stimulation is achieved by quickly discharging current from a largecapacitor into a coil to produce pulsedmagnetic fields between 2 and 3teslas in strength.[32] Directing the magnetic field pulse at a targeted area in the brain causes a localized electrical current which can then eitherdepolarize orhyperpolarize neurons at that site. The induced electric field inside the brain tissue causes a change in transmembrane potentials resulting in depolarization or hyperpolarization of neurons, causing them to be more or less excitable, respectively.[32]
TMS usually stimulates to a depth from 2 to 4 cm below the surface, depending on the coil and intensity used. Consequently, only superficial brain areas can be affected.[33] Deep TMS can reach up to 6 cm into the brain to stimulate deeper layers of themotor cortex, such as that which controls leg motion. The path of this current can be difficult to model because the brain is irregularly shaped with variable internal density and water content, leading to a nonuniform magnetic field strength andconduction throughout its tissues.[34]
The effects of TMS can be divided based on frequency, duration and intensity (amplitude) of stimulation:[35]
Single or paired pulse TMS causes neurons in the neocortex under the site of stimulation todepolarize and discharge anaction potential. If used in theprimary motor cortex, it produces muscle activity referred to as amotor evoked potential (MEP) which can be recorded onelectromyography. If used on theoccipital cortex, 'phosphenes' (flashes of light) might be perceived by the subject. In most other areas of the cortex, there is no conscious effect, but behaviour may be altered (e.g., slower reaction time on a cognitive task), or changes in brain activity may be detected using diagnostic equipment.[36]
Repetitive TMS (rTMS) produces longer-lasting effects which persist past the period of stimulation. rTMS can increase or decrease the excitability of thecorticospinal tract depending on the intensity of stimulation, coil orientation, and frequency. Low frequency rTMS with a stimulus frequency less than 1 Hz is believed to inhibit cortical firing, while a stimulus frequency greater than 1 Hz, referred to as high frequency, is believed to provoke it.[37] Though its mechanism is not clear, it has been suggested as being due to a change in synaptic efficacy related tolong-term potentiation (LTP) and long-term depression like plasticity (LTD-like plasticity).[38][39]
Most devices use a coil shaped like a figure-eight to deliver a shallow magnetic field that affects more superficial neurons in the brain.[40] Differences in magnetic coil design are considered when comparing results, with important elements including the type of material,geometry and specific characteristics of the associated magnetic pulse.
The core material may be either a magnetically inert substrate ('air core'), or a solid,ferromagnetically active material ('solid core'). Solid cores result in more efficient transfer of electrical energy to a magnetic field and reduce energy loss to heat, and so can be operated with the higher volume of therapy protocols without interruption due tooverheating. Varying the geometric shape of the coil itself can cause variations infocality, shape, and depth of penetration. Differences in coil material and its power supply also affect magnetic pulse width and duration.[41]
A number of different types of coils exist, each of which produce different magnetic fields. The round coil is the original used in TMS. Later, the figure-eight (butterfly) coil was developed to provide a more focal pattern of activation in the brain, and the four-leaf coil for focal stimulation of peripheral nerves. The double-cone coil conforms more to the shape of the head.[42] The Hesed (H-core), circular crown and double cone coils allow more widespread activation and a deeper magnetic penetration. They are supposed to impact deeper areas in the motor cortex andcerebellum controlling the legs andpelvic floor, for example, though the increased depth comes at the cost of a less focused magnetic pulse.[6]
ForParkinson's disease, early results suggest that low frequency stimulation may have an effect on medication associateddyskinesia, and that high frequency stimulation improves motor function.[44][45]
Thecerebellar cortex as a possible target of TMS has been investigated in combination with electromyography (EMG), and a reduction in the average amplitude ofmotor-evoked-potentials in small hand muscles has been observed when comparing paired-pulse TMS with a 6-8 ms interstimulus interval between cerebellar TMS and TMS to the primary motor cortex with single-pulse TMS to the primary motor cortex - a phenomenon termed cerebellum brain inhibition (CBI).[46][47] Recent investigations have built upon this phenomenon to investigate the feasibility of combining EEG with cerebellar TMS to find signatures of the cerebellum-to-cerebrum functional connectivity in high temporal resultion.[48] By applying control conditions accounting for multisensory input and concomitant occipital cortex stimulation, and confirming effective cerebellar TMS by assessing CBI beforehand and modelling the induced electric field, EEG signatures of cerebellar TMS were proposed - as they may be utilized as therapeuticbiomarkers to test pharmacotherapy efficacy inspinocerebellar ataxia in the future.[49][50][51][52] However, these EEG signatures are still openly debated in the field of Brain Stimulation due to their inconsistency - likely, differing stimulation targets due to the lack ofneuronavigation in these studies explain these discrepancies in results.[53][54]
Luigi Galvani (1737–1798) undertook research on the effects of electricity on the body in the late-eighteenth century and laid the foundations for the field ofelectrophysiology.[55] In the 1830s,Michael Faraday (1791–1867) discovered that anelectrical current had a correspondingmagnetic field, and that changing one could induce its counterpart.[56]
Work to directly stimulate the human brain with electricity started in the late 1800s, and by the 1930s the Italian physiciansCerletti andBini had developedelectroconvulsive therapy (ECT).[55] ECT became widely used to treatmental illness, and ultimately overused, as it began to be seen as apanacea. This led to a backlash in the 1970s.[55]
In 1980, Merton and Morton successfully used transcranial electrical stimulation (TES) to stimulate the motor cortex. However, this process was very uncomfortable, and subsequently Anthony T. Barker began to search for an alternative to TES.[57] He began exploring the use of magnetic fields to alter electrical signaling within the brain, and the first stable TMS devices were developed in 1985.[55][56] They were originally intended as diagnostic and research devices, with evaluation of their therapeutic potential being a later development.[55][56] The United States'FDA first approved TMS devices in October 2008.[55]
Nexstim obtained United StatesFederal Food, Drug, and Cosmetic Act§Section 510(k) clearance for the assessment of the primary motor cortex for pre-procedural planning in December 2009[58] and for neurosurgical planning in June 2011.[59]
The United Kingdom'sNational Institute for Health and Care Excellence (NICE) issues guidance to theNational Health Service (NHS) in England, Wales, Scotland and Northern Ireland (UK). NICE guidance does not cover whether or not the NHS should fund a procedure. Local NHS bodies (primary care trusts andhospital trusts) make decisions about funding after considering the clinical effectiveness of the procedure and whether the procedure represents value for money for the NHS.[72]
NICE evaluated TMS for severe depression in 2007, finding that TMS was safe, but with insufficient evidence for its efficacy.[73] Guidance was updated and replaced in 2015, concluding that evidence for short‑term efficacy of repetitive transcranial magnetic stimulation (rTMS) for depression was adequate, although the clinical response is variable, and ruling that rTMS for depression may be used with arrangements for clinical governance and audit.[74]
In January 2014, NICE reported the results of an evaluation of TMS for treating and preventing migraine (IPG 477). NICE found that short-term TMS is safe but there is insufficient evidence to evaluate safety for long-term and frequent uses. It found that evidence on the efficacy of TMS for the treatment of migraine is limited in quantity, that evidence for the prevention of migraine is limited in both quality and quantity.[75]
As of 2025[update], use of rTMS in the UK was reported to have remained limited due to the cost of equipment and establishing treatment centres. Camilla Nord, head of the Mental Health Neuroscience Lab at theUniversity of Cambridge said, "The NHS has unfortunately been far behind the US and Canada on rTMS, which is at least as effective as antidepressants, if not more".[76]
This section needs to beupdated. Please help update this article to reflect recent events or newly available information. Last update: February 2014(September 2025)
Commercial health insurance
In 2013, several commercial health insurance plans in the United States, includingAnthem,Health Net,Kaiser Permanente, andBlue Cross Blue Shield ofNebraska and ofRhode Island, covered TMS for the treatment of depression for the first time.[77][78][79][80] 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.[81] 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 includedAetna,Cigna andRegence.[82][83][84]
Medicare
Policies for Medicare coverage vary among local jurisdictions within the Medicare system,[85] and Medicare coverage for TMS has varied among jurisdictions and with time. For example:
In early 2012 inNew England, Medicare covered TMS for the first time in the United States.[86][87][88][89] However, that jurisdiction later decided to end coverage after October, 2013.[90]
In August 2012, the jurisdiction covering Arkansas, Louisiana, Mississippi, Colorado, Texas, Oklahoma, and New Mexico determined that there was insufficient evidence to cover the treatment,[91] but the same jurisdiction subsequently determined that Medicare would cover TMS for the treatment of depression after December 2013.[92]
There are serious concerns about stimulating brain tissue using non-invasive magnetic field methods such as uncertainty in the dose and localisation of the stimulation effect.[93][94][95][96]
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