What Is Transcranial Magnetic Stimulation?
TMS, or transcranial magnetic stimulation, is a way to stimulate different parts of the brain to help relieve the symptoms of conditions such as depression. To help you decide if it’s right for your patients – or yourself – here is a more detailed TMS definition and a look at how it can be used.
How Transcranial Magnetic Stimulation Therapy Is Used
Transcranial Magnetic Stimulation (TMS) is a form of non-invasive neurostimulation that utilizes a changing magnetic field to induce an electrical current to flow in a small and targeted region of the brain using the principle of electromagnetic induction.
During a TMS session, a coil acting as the magnetic field generator is placed close to the head of the patient receiving treatment—where the exact position of the coil is determined according to the 10-20 EEG system (more information can be found under Coil Placement).
Transcranial Magnetic Stimulation Procedure
Different coil geometries can be used to produce different stimulation depths and spatial focalities; the most commonly used coil geometry is the “figure 8” coil which typically has a stimulation depth at the cortical surface. A changing magnetic field is then generated at different pulse parameters depending on the application of the TMS procedure; these magnetic fields are then able to modulate the brain’s electrical environment accordingly.
Unlike transcranial direct current stimulation (tDCS), the current generated in the brain during TMS is suprathreshold — which means action potentials can be elicited during stimulation. TMS is also able to penetrate much deeper than tDCS or CES due to the strength of the field induced.
TMS Devices
TMS is currently only offered in clinical settings.
The Brain Ultimate TMS Device is a cost-effective and user-friendly device currently offered by Caputron. Portable and built using a “plug and play” design, the device fits easily into any clinical space, and it’s simple to get up and running.
For safety, the device relies on a patented cooling system to prevent overheating even when the device is used regularly.
The Brain Ultimate TMS Device is currently pending FDA clearance – contact us to learn more about product availability.
Is TMS Safe and Is it FDA Cleared?
As with any other medical treatment, TMS has some potential side effects. However, these side effects are uncommon. When they do occur, patients may experience mild symptoms such as headaches and some scalp pain. Patients may notice these side effects disappear after a few treatments; however, all concerns should be discussed with a doctor.
TMS is a safe medical treatment for most individuals. It has been cleared to treat conditions including Major Depressive Disorder and Obsessive Compulsive Disorder (OCD).
Transcranial magnetic stimulation may, in the future, be used more widely for the management of:
- Amyotrophic Lateral Sclerosis (ALS)
- Chronic pain
- Schizophrenia
- Stroke
More research is needed on potential transcranial magnetic stimulation uses; however, early studies are promising.
History of TMS
The idea of modulating the electrical environment of the brain using external stimuli is a very old concept. There have been several isolated attempts at stimulating muscle fibers and nerve cells using magnetic stimulation in more recent history
However, it was not until the introduction of the first “modern” TMS device in 1985 by Anthony Barker and colleagues— where they demonstrated the ability of TMS to provide targeted stimulation to various areas of the brain— that TMS finally caught the attention of the public eye. This moment marked the official emergence of modern TMS into the neuromodulation and therapeutics sector.
Around the mid-1990s, the first research began being published about the safety and efficacy of TMS in the treatment of major depression. Following a plethora of studies and meta-analyses, along with 90 clinical trials, FDA clearance of TMS in the clinical treatment of major depressive disorder was obtained in 2007. In 2013, TMS began being widely covered by U.S. health insurance companies as a treatment for depression.
Throughout the history of TMS development, safety has always been a top priority. Is TMS safe? It is now widely used in clinics and hospitals as a safe and effective alternative to treating medication resistant depression symptoms.
In August 2018, TMS received clearance for the treatment of Obsessive-Compulsive Disorder (OCD).
Why Coil Placement Matters
Coil placement matters because the position determines how effectively the coils will target the right regions of the brain.
A popular region clinicians will target for TMS is the dorsolateral prefrontal cortex (DLPFC) which corresponds to F3 on the 10-20 EEG system. This region is targeted in the FDA-cleared protocol for Major Depressive Disorder in patients who have developed a resistance or have not responded to antidepressant medication.
Clinicians typically use the Beam Protocol for coil position. The Beam Protocol involves taking three measurements – tragus to tragus, nasion to inion, and head circumference. The measurements are entered into a free software tool that reveals the DLPFC position so that coils can be adjusted to match the patient’s unique cranial geometry.
TMS and FDA Approval
TMS was introduced in 1985 and FDA approved in 2008 for the treatment of Major Depressive Disorder (MDD). Depression treatment consists of a 37-minute session, 5 days a week, typically for 5-6 weeks, carried out in your physician's office.
TMS for depression is reimbursable by most insurance carriers. It is typically offered to patients with treatment-resistant depression i.e., it has not responded to antidepressant medication.
The TMS protocol for MDD calls for stimulation at 120% of the Motor Threshold (MT) at a frequency of 10 Hz over the left dorsolateral prefrontal cortex (DLPFC) which corresponds to F3 on an EEG map.
The stimulation duration is 37 minutes consisting of a 4-second train (40 pulses) followed by a 26-second inter-train interval. This is repeated 75 times for a total of 3000 pulses.
In 2017, the FDA cleared an accelerated protocol for the treatment of depression which reduced the session duration from 37 minutes to 19 minutes. Like the 37-minute protocol, this new 19-minute protocol called for stimulation of the left DLPFC at 120% of the MT and a frequency of 10 Hz with a 4-second train (40 pulses) repeated 75 times.
The difference is that in the 19-minute protocol, the inter-train interval was reduced to 11 seconds from 26 seconds. This results in a shorter treatment time of 19 minutes while still maintaining a frequency of 10 Hz and 3000 pulses.
In 2019, the FDA cleared an even faster protocol for the treatment of depression known as Intermittent Theta Burst (iTBS). This short 3-minute protocol uses a high-frequency protocol of 5 Hz bursts with each burst containing 3 pulses at 50 Hz.
This translates to a 2-second train containing 30 pulses (10 bursts with 3 pulses per burst) with an inter-train interval of 10 seconds repeated 20 times. Like the 37 min and 19 min protocols, stimulation is done over the DLPFC. However, this iTBS protocol is done at 80% of the MT and delivers 600 pulses, as opposed to 3000.
The Caputron team is happy to discuss the status of TMS approval in more detail. Call us to learn more about our brain stimulation devices and their FDA status.
Explore Transcranial Magnetic Stimulation Uses Today
If you’re a clinician and want to add a new TMS device to your practice, consider the Brain Ultimate TMS Device. Efficient and cost-effective, this portable device is coming later this year and it’s sure to help you offer new treatment options to your patients looking for TMS therapy. Contact us to learn more or pre-order our new device today.
Would you like to try brain stimulation techniques yourself? To find a clinical practice using TMS devices near you, try this “find a physician” tool from Neuromodec. Alternatively, contact us to discuss our range of home brain stimulation devices.
