Exploring different TMS techniques  

Given how new Transcranial Magnetic Stimulation is, it may come as a surprise that there are different TMS techniques and many different device manufacturers with slight differences between devices. Before exploring these techniques and devices, it helps to have some background information on the history of TMS.

Timeline of TMS

The theory behind magnetic stimulation dates back to the celebrated English scientist, Michael Faraday, who is credited with discovering the principles of electromagnetic induction in 1831. In his hallmark study, he was able to utilize insulated coils running over an iron ring and induce an electric field through the use of fluctuating magnetic fields. This property of electromagnetic induction later provided the basis for domestic electricity, MRI scanning, and TMS.

Before reading this section, it is crucial to know that Electroconvulsive therapy (ECT) is not the same as TMS. 

Read More: TMS vs ECT →

With that said, they do operate on similar principles of altering the brain's electrical impulses to achieve recovery or relief from various mental health disorders. Cerletti was an Italian neurologist that developed the theory of treating mental health conditions through seizures brought on by electroconvulsive therapy. He observed that patients with epilepsy rarely suffered from psychosis (Schizophrenia) and likewise that certain medications such as insulin could be utilized to induce seizures and treat Schizophrenia. Based on these observations, he eventually successfully treated a patient with Schizophrenia through the use of ECT. The practice grew from there and later was shown to also be effective for treating manic-depression (Bipolar Disorder) and severe depression (Major Depressive Disorder).

Delivering electric shocks for treatment has always been controversial due to the jarring visual of someone experiencing a seizure and the pronounced cognitive and memory deficits following treatment.  The initial rudimentary treatments and dramatization by the film industry has also made the perception of ECT very frightening.

It remains a superior treatment for severe mental health disorders such as Schizophrenia, Bipolar, and Major Depression, however, and provides much-needed relief for the most treatment resistant sufferers. Furthermore, the process has been modernized with the use of anesthesia, muscle relaxants, other medications, and more advanced electrical impulses. Memory loss and cognitive impairments still occur, but typically only in the short term and in a more tempered fashion. 

Further research and studies led to it’s clearance by the FDA in 2008 for individuals with treatment resistant depression - often defined as patients who have not experienced recovery from two or more medication trials. TMS research has continued to grow exponentially since with over 1,000 publications per year over the last decade. So with this brief history lesson, what are the types of TMS and the latest treatment techniques?

rTMS-repetitive Transcranial Magnetic Stimulation

Repetitive Transcranial Magnetic Stimulation - or rTMS - is actually the more descriptive and precise term for the technique that is used to treat mental health disorders and other neurologic conditions. The treatment must occur in a repetitive manner in order to properly induce changes in electrical signaling pathways in the brain.

Read More: How TMS therapy works →

dTMS-deep Transcranial Magnetic Stimulation

If diving further into TMS techniques, you may come across the term dTMS.  This actually still involves rTMS, but the “r” is dropped for a “d”, which stands for “deep”. Deep Transcranial Magnetic Stimulation works on the same principles, but uses an H-shaped coil housed within a helmet as opposed to the more typical figure-eight coil housed in a smaller hand held coil.

Deep TMS provides a somewhat deeper and more diffuse stimulation into brain tissue. The manufacturer of this device claims superior results compared to figure-eight coils, but there is only one paper that has shown this to date and there was no statistical difference in full remission rates between the two, only partial response.⁴ The deeper and more diffuse technique may, however, raise the risk for increased side effects or seizure.⁵ This type of TMS has garnered additional FDA clearance for the treatment of obsessive compulsive disorder (OCD) and smoking cessation. OCD treatment has recently been cleared for use on Magventure systems as well through the use of their modified figure-8 OCD coil.

iTBS-intermittent Theta Burst Stimulation

iTBS is another type of TMS and it still utilizes a repetitive stimulation pattern. It hence remains a form of rTMS, but utilizes a more advanced stimulation pattern called theta burst.

Read More: Theta Burst Stimulation →

In brief, rapid triplet bursts of pulsation are delivered at a much higher frequency occurring over a theta rhythm. Using this technique, treatment sessions can be completed in just 3 minutes. The benefits are equal to standard rTMS or dTMS, but the speed of therapy sessions obviously is appealing for patients who want to get in and out of the office for treatments and back to their busy lives. iTBS has been shown to be equally effective as standard rTMS in a head to head comparison study ⁶

nTMS-navigated Transcranial Magnetic Stimulation

Navigated TMS can be thought of in two separate, but connected, concepts.

Basic navigated Transcranial Magnetic Stimulation tracks both the patient’s head movements and the TMS coil using 3D spatial cameras. Software considers any movement of the patient’s head or of the coil which would divert the coil from the intended target. This may help quality control between technicians and treatments, but there are not studies to date indicating this provides superior outcomes.

More advanced nTMS utilizes these 3D cameras as well, but also involves further technology to direct the magnetic field to a more specific treatment location. This approach utilizes an individual’s unique brain MRI to locate the predicted anatomical area of treatment that has been shown to be most strongly associated with depression or other mental health conditions. This MRI can then be even further enhanced with the use of fMRI (functional MRI) to map connected electrical circuits and even more accurately mark the correct treatment location. The use of MRIs for nTMS isn’t common practice yet due to cost and inconvenience, but is gaining traction as the technology becomes cheaper and more precise. Time will tell if navigated TMS separates from standard TMS approaches. So far the data has not shown superior outcomes using patient specific MRIs.⁷

aTMS-accelerated Transcranial Magnetic Stimulation TMS

A new and very promising advancement enables the use of multiple TMS sessions in one day, and can reduce a course of TMS to just five days from six weeks. Patients can receive iTBS treatments every hour over the course of a nine hour day and the full therapy course can be completed in as little as five days. Accelerated treatments are not yet FDA cleared, but gaining traction due to promising results. 

Read More: Accelerated TMS →

What does Inspire TMS Denver currently offer?

We do not utilize dTMS as this is only offered through one manufacturer and we believe in a more targeted approach with less potential for side effects. We also do not offer the FDA-cleared OCD treatment currently, but plan to add Magventure’s latest OCD coil should any clients request this treatment. Finally, we do not utilize navigational TMS until the data shows this method to be superior to non-navigational approaches. We currently employ the most reliable and effective technique for identifying treatment location in day to day clinical practice, however.⁸⁹ Many practices do not utilize this method and rely on more rudimentary measurements to identify treatment location.