Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation in which a changing

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

is used to induce an

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movi ...

at a specific area of the brain through

electromagnetic induction Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, and James Cle ...

. An electric pulse generator, or stimulator, is connected to a magnetic coil connected to the scalp. The stimulator generates a changing electric current within the coil which creates a varying magnetic field, inducing a current within a region in the brain itself.NICE. January 201
Transcranial magnetic stimulation for treating and preventing migraine
/ref>Michael Craig Miller for Harvard Health Publications. July 26, 201
Magnetic stimulation: a new approach to treating depression?
/ref> TMS has shown diagnostic and therapeutic potential in the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...

with a wide variety of disease states in

neurology Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal ...

and

mental health Mental health encompasses emotional, psychological, and social well-being, influencing cognition, perception, and behavior. It likewise determines how an individual handles Stress (biology), stress, interpersonal relationships, and decision-maki ...

, with research still evolving. Adverse effects of TMS appear rare and include fainting and

seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...

. Other potential issues include discomfort, pain,

hypomania Hypomania (literally "under mania" or "less than mania") is a mental and behavioural disorder, characterised essentially by an apparently non-contextual elevation of mood (euphoria) that contributes to persistently disinhibited behaviour. Th ...

, cognitive change,

hearing loss Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken l ...

, and inadvertent current induction in implanted devices such as

pacemaker An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart ei ...

s or

defibrillator Defibrillation is a treatment for life-threatening cardiac arrhythmias, specifically ventricular fibrillation (V-Fib) and non-perfusing ventricular tachycardia (V-Tach). A defibrillator delivers a dose of electric current (often called a ''coun ...

s. A number of reports detail significant other adverse experiences, such as new seizures, psychotic symptoms, and other effects.

Medical uses

TMS does not require surgery or electrode implantation. Its use can be divided into diagnostic and therapeutic applications. 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. TMS treatments are approved by the FDA in the US and by NICE in the UK for the treatment of depression and are predominantly provided by private clinics. TMS stimulates cortical tissue without the pain sensations produced in transcranial electrical stimulation.

Diagnosis

TMS can be used clinically to measure activity and function of specific brain circuits in humans, most commonly with single or paired magnetic pulses. The most widely accepted use is in measuring the connection between the

primary motor cortex The primary motor cortex (Brodmann area 4) is a Human brain, brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary cortex, primary region of the motor system and works in association with other motor ...

of the

and the

peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brai ...

to evaluate damage related to past or progressive neurologic insult.

Treatment

Repetitive high frequency TMS (rTMS) has shown diagnostic and therapeutic potential with the central nervous system in a variety of disease states, particularly in the fields of

and

Adverse effects

Although TMS is generally regarded as safe, risks are increased for therapeutic rTMS compared to single or paired diagnostic TMS. Adverse effects generally increase with higher frequency stimulation. The greatest immediate risk from TMS is fainting, though this is uncommon.

Seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with lo ...

s have been reported, but are rare. Other adverse effects include short term discomfort, pain, brief episodes of

, cognitive change, hearing loss, impaired

working memory Working memory is a cognitive system with a limited capacity that can hold information temporarily. It is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, ...

, and the induction of electrical currents in implanted devices such as

cardiac pacemaker 350px, Image showing the cardiac pacemaker or SA node, the primary pacemaker within the electrical_conduction_system_of_the_heart">SA_node,_the_primary_pacemaker_within_the_electrical_conduction_system_of_the_heart. The_muscle_contraction.htm ...

Procedure

During the procedure, a magnetic coil is positioned at the head of the person receiving the treatment using anatomical landmarks on the skull, in particular the inion and nasion. The coil is then connected to a pulse generator, or stimulator, that delivers electric current to the coil.

Physics

TMS uses

to generate an electric current across the scalp and

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

. A plastic-enclosed coil of wire is held next to the skull and when activated, produces a varying

oriented orthogonally 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. The magnetic field is about the same strength as an MRI, and the pulse generally reaches no more than 5 centimeters into the brain, unless using a modified coil and technique for deeper stimulation. Transcranial magnetic stimulation is achieved by quickly discharging current from a large

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

into a coil to produce pulsed magnetic fields between 2 and 3 Tesla in strength.V. Walsh and A. Pascual-Leone, "Transcranial Magnetic Stimulation: A Neurochronometrics of Mind." Cambridge, Massachusetts: MIT Press, 2003. Directing the magnetic field pulse at a targeted area in the brain causes a localized electrical current which can then either depolarize or hyperpolarize 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. Deep TMS can reach up to 6 cm into the brain to stimulate deeper layers of the

motor cortex The motor cortex is the region of the cerebral cortex believed to be involved in the planning, control, and execution of voluntary movements. The motor cortex is an area of the frontal lobe located in the posterior precentral gyrus immediately ...

, 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 and

conduction Conductor or conduction may refer to: Music * Conductor (music), a person who leads a musical ensemble, such as an orchestra. * ''Conductor'' (album), an album by indie rock band The Comas * Conduction, a type of structured free improvisation ...

throughout its tissues.

Frequency and duration

The effects of TMS can be divided based on frequency, duration and intensity (amplitude) of stimulation: * Single or paired pulse TMS causes neurons in the neocortex under the site of stimulation to depolarize and discharge an

action potential An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells ...

. If used in the

, it produces muscle activity referred to as a motor evoked potential (MEP) which can be recorded on

electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyo ...

. If used on the occipital 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. * Repetitive TMS produces longer-lasting effects which persist past the period of stimulation. rTMS can increase or decrease the excitability of the

corticospinal tract The corticospinal tract is a white matter motor pathway starting at the cerebral cortex that terminates on lower motor neurons and interneurons in the spinal cord, controlling movements of the limbs and trunk. There are more than one million ne ...

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, or high frequency, is believed to provoke it. Though its mechanism is not clear, it has been suggested as being due to a change in synaptic efficacy related to long-term potentiation (LTP) and

long-term depression In neurophysiology, long-term depression (LTD) is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer following a long patterned stimulus. LTD occurs in many areas of the CNS with varying mechanisms depend ...

(LTD).

Coil types

Most devices use a coil shaped like a figure-eight to deliver a shallow magnetic field that affects more superficial neurons in the brain. 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,

ferromagnetic Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...

ally 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 to overheating. Varying the geometric shape of the coil itself can cause variations in focality, shape, and depth of penetration. Differences in coil material and its power supply also affect magnetic pulse width and duration. 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. 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 and

cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebe ...

controlling the legs and pelvic floor, for example, though the increased depth comes at the cost of a less focused magnetic pulse.

History

Luigi Galvani Luigi Galvani (, also ; ; la, Aloysius Galvanus; 9 September 1737 – 4 December 1798) was an Italian physician, physicist, biologist and philosopher, who studied animal electricity. In 1780, he discovered that the muscles of dead frogs' legs ...

(1737–1798) undertook research on the effects of electricity on the body in the late-eighteenth century and laid the foundations for the field of

electrophysiology Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology">etymology of "electron" , ''physis'', "nature, origin"; and , ''-logia'') is the branch of physiology that studies the electrical properties of bi ...

. In the 1830s

Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...

(1791–1867) discovered that an

electrical current Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described b ...

had a corresponding

, and that changing one could induce its counterpart. Work to directly stimulate the human brain with electricity started in the late 1800s, and by the 1930s the Italian physicians Cerletti and Bini had developed

electroconvulsive therapy Electroconvulsive therapy (ECT) is a psychiatric treatment where a generalized seizure (without muscular convulsions) is electrically induced to manage refractory mental disorders.Rudorfer, MV, Henry, ME, Sackeim, HA (2003)"Electroconvulsive th ...

(ECT). ECT became widely used to treat

mental illness A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...

, and ultimately overused, as it began to be seen as a

panacea In Greek mythology, Panacea (Greek ''Πανάκεια'', Panakeia), a goddess of universal remedy, was the daughter of Asclepius and Epione. Panacea and her four sisters each performed a facet of Apollo's art: * Panacea (the goddess of univers ...

. This led to a backlash in the 1970s. 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. 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. They were originally intended as diagnostic and research devices, with evaluation of their therapeutic potential being a later development. The United States' FDA first approved TMS devices in October 2008.

Research

TMS has shown potential therapeutic effect on neurologic conditions such as

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As ...

amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most commo ...

, persistent vegetative states,

epilepsy Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrica ...

stroke A stroke is a disease, medical condition in which poor cerebral circulation, blood flow to the brain causes cell death. There are two main types of stroke: brain ischemia, ischemic, due to lack of blood flow, and intracranial hemorrhage, hemorr ...

related disability, tinnitus,

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This ...

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social w ...

, and

traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic br ...

. With

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms beco ...

, early results suggest that low frequency stimulation may have an effect on medication associated

dyskinesia Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of ...

, and that high frequency stimulation improves motor function. The most effective treatment protocols appear to involve high frequency stimulation of the

, particularly on the dominant side, but with more variable results for treatment of the

dorsolateral prefrontal cortex The dorsolateral prefrontal cortex (DLPFC or DL-PFC) is an area in the prefrontal cortex of the primate brain. It is one of the most recently derived parts of the human brain. It undergoes a prolonged period of maturation which lasts until adult ...

. It is less effective than

for motor symptoms, though both appear to have utility. Cerebellar stimulation has also shown potential for the treatment of levodopa associated dyskinesia. In

psychiatry Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry. Initial p ...

, it has shown potential with anxiety disorders, including panic disorder and

obsessive–compulsive disorder Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...

(OCD). The most promising areas to target for OCD appear to be the orbitofrontal cortex and the supplementary motor area. Older protocols that targeted the prefrontal dorsal cortex were less successful. It has also been studied with

autism The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...

substance abuse Substance abuse, also known as drug abuse, is the use of a drug in amounts or by methods which are harmful to the individual or others. It is a form of substance-related disorder. Differing definitions of drug abuse are used in public health, ...

addiction Addiction is a neuropsychological disorder characterized by a persistent and intense urge to engage in certain behaviors, one of which is the usage of a drug, despite substantial harm and other negative consequences. Repetitive drug use o ...

, and

post-traumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats o ...

(PTSD). For treatment-resistant

major depressive disorder Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Intro ...

, high-frequency (HF) rTMS of the left

(DLPFC) appears effective and low-frequency (LF) rTMS of the right DLPFC has probable efficacy. Research on the efficacy of rTMS in non-treatment-resistant depression is limited. TMS can also be used to map functional connectivity between the cerebellum and other areas of the brain.

Study blinding

Mimicking the physical discomfort of rTMS with placebo to discern its true effect is a challenging issue in research. It is difficult to establish a convincing

placebo A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general ...

for TMS during controlled

trials In law, a trial is a coming together of parties to a dispute, to present information (in the form of evidence) in a tribunal, a formal setting with the authority to adjudicate claims or disputes. One form of tribunal is a court. The tribun ...

conscious Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...

individuals due to the neck pain, headache and twitching in the scalp or upper face associated with the intervention. In addition, placebo manipulations can affect

brain A brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as Visual perception, vision. I ...

sugar metabolism and MEPs, which may confound results. This problem is exacerbated when using subjective measures of improvement. Placebo responses in trials of rTMS in major depression are negatively associated with refractoriness to treatment. A 2011 review found that most studies did not report

unblinding In a blind or blinded experiment, information which may influence the participants of the experiment is withheld until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expe ...

. In the minority that did, participants in real and sham rTMS groups were not significantly different in their ability to correctly guess their therapy, though there was a trend for participants in the real group to more often guess correctly.

Animal model limitations

TMS research in animal studies is limited due to its early US

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

approval for treatment-resistant depression, limiting development of animal specific magnetic coils.

Treatments for the general public

Regulatory approvals

Neurosurgery planning

Nexstim obtained United States Federal Food, Drug, and Cosmetic Act§Section 510(k) clearance for the assessment of the primary motor cortex for pre-procedural planning in December 2009 and for neurosurgical planning in June 2011. Depression The National Institutes of Health estimates depression medications work for only 60 percent to 70 percent of people who take them. It is approved as a Class II medical device under the "''de novo'' pathway". The National Institutes of Health estimates depression medications work for only 60 percent to 70 percent of people who take them. In addition, the World Health Organization reports that the number of people living with depression has increased nearly 20 percent since 2005. In a 2012 study, TMS was found to improve depression significantly in 58 percent of patients and provide complete remission of symptoms in 37 percent of patients.

Other neurological areas

In the

European Economic Area The European Economic Area (EEA) was established via the ''Agreement on the European Economic Area'', an international agreement which enables the extension of the European Union's single market to member states of the European Free Trade As ...

, various versions of Deep TMS H-coils have

CE marking On commercial products, the letters CE (as the logo ) mean that the manufacturer or importer affirms the good's conformity with European health, safety, and environmental protection standards. It is not a quality indicator or a certificatio ...

for

bipolar disorder Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of Depression (mood), depression and periods of abnormally elevated Mood (psychology), mood that last from days to weeks each. If the elevat ...

, chronic pain,

(PTSD),

(negative symptoms) and to aid smoking cessation. One review found tentative benefit for cognitive enhancement in healthy people. In August 2018, the US Food and Drug Administration authorized the use of TMS in the treatment of

(OCD).

Coverage by health services and insurers

United Kingdom

The United Kingdom's National Institute for Health and Care Excellence (NICE) issues guidance to the

National Health Service The National Health Service (NHS) is the umbrella term for the publicly funded healthcare systems of the United Kingdom (UK). Since 1948, they have been funded out of general taxation. There are three systems which are referred to using the " ...

(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 trust Primary care trusts (PCTs) were part of the National Health Service in England from 2001 to 2013. PCTs were largely administrative bodies, responsible for commissioning primary, community and secondary health services from providers. Until 31 May ...

s and hospital trusts) make decisions about funding after considering the clinical effectiveness of the procedure and whether the procedure represents value for money for the NHS. NICE evaluated TMS for severe depression (IPG 242) in 2007, and subsequently considered TMS for reassessment in January 2011 but did not change its evaluation. The Institute found that TMS is safe, but there is insufficient evidence for its efficacy. 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. Subsequently, in 2015, NICE approved the use of TMS for the treatment of depression in the UK and IPG542 replaced IPG242. NICE said "The evidence on repetitive transcranial magnetic stimulation for depression shows no major safety concerns. The evidence on its efficacy in the short-term is adequate, although the clinical response is variable. Repetitive transcranial magnetic stimulation for depression may be used with normal arrangements for clinical governance and audit."

United States: commercial health insurance

In 2013, several commercial health insurance plans in the United States, including

Anthem An anthem is a musical composition of celebration, usually used as a symbol for a distinct group, particularly the national anthems of countries. Originally, and in music theory and religious contexts, it also refers more particularly to short s ...

, Health Net, and Blue Cross Blue Shield of

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...

and of

Rhode Island Rhode Island (, like ''road'') is a U.S. state, state in the New England region of the Northeastern United States. It is the List of U.S. states by area, smallest U.S. state by area and the List of states and territories of the United States ...

, covered TMS for the treatment of depression for the first time. In contrast,

UnitedHealthcare UnitedHealth Group Incorporated is an American multinational managed healthcare and insurance company based in Minnetonka, Minnesota. It offers health care products and insurance services. UnitedHealth Group is the world's seventh largest ...

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. 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 included Aetna,

Cigna Cigna is an American multinational managed healthcare and insurance company based in Bloomfield, Connecticut. Its insurance subsidiaries are major providers of medical, dental, disability, life and accident insurance and related products and se ...

and Regence.

United States: Medicare

Policies for Medicare coverage vary among local jurisdictions within the Medicare system, and Medicare coverage for TMS has varied among jurisdictions and with time. For example: * In early 2012 in

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...

, Medicare covered TMS for the first time in the United States. However, that jurisdiction later decided to end coverage after October, 2013. * 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, but the same jurisdiction subsequently determined that Medicare would cover TMS for the treatment of depression after December 2013. * Subsequently, some other Medicare jurisdictions added Medicare coverage for depression.

Providers

Manufacturers of TMS devices include

Brainsway BrainsWay () is an international company that is engaged in the development of a medical device that uses H-coil for deep transcranial magnetic stimulation (Deep TMS) as a non-invasive treatment for depression, OCD, and smoking addiction. The co ...

, Deyme

MagVentur

Mag&Mor
Magstim
Magnus Medica

Nexsti

Neuronetics, Neurosof

Sebers Medica

ref> and Actipulse Neuroscienc
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References

{{reflist Diagnostic neurology Physical psychiatric treatments Electrotherapy Magnetic devices Neurophysiology Neuropsychology Neurotechnology Treatment of bipolar disorder Treatment of depression Medical devices 1985 introductions 2008 introductions Bioelectromagnetics