rTMS VS dTMS VS iTBS VS aTBS

TMS Protocols

rTMS vs dTMS vs iTBS vs aTBS

Thanks to the advancement in Transcranial Magnetic Stimulation technology, TMS had evolved significantly throughout the years. It continues to improve in technology and protocols. In this article, I will tell you about the history of TMS. How it evolved over the years, where are we today with the technology and what is coming for the future. You will learn about the types of TMS therapies. This includes repetitive transcranial magnetic stimulation, deep transcranial magnetic stimulation, intermittent theta burst stimulation and accelerated theta burst stimulation. They are listed in the order of oldest to the newest.

Basically in 1985. The first attempts to make a clinical TMS machine were done in the UK. The first clinical TMS device was very basic and it was only made for single-pulse stimulation. It was designed to treat movement disorders and was used by neurologists then.

Dr. Anthony Barker from the UK. In 1985, Drs. Barker, Jalinous, and Freeston reported the first demonstration of TMS. Dr. Barker and colleagues produced twitching in a specific area of the hand in human volunteers by applying TMS to the motor cortex in the opposite hemisphere that controls the movement of that muscle. Dr. Barker is awarded for his discovery and recognized internationally. In the United States though, Dr. Mark George is the one to thank for bringing this medical technology to the United States. He is one of the pioneers to bring the use of TMS to behavioral science. Dr. George continues to be a leader in the field today.

How does TMS work? Click here to learn more.

Repetitive Transcranial Magnetic Stimulation or rTMS is the traditional TMS as we know it today. It uses a figure-of-8 coil (the coil has two donuts attached to each other which makes it look like the number 8). The coil is placed on a prespecified location of the head. The magnetic coils will deliver magnetic pulses on and off at specific intervals. The pulses are called “trains” and the intervals are called “Inter-train intervals”. A typical rTMS treatment session would consist of 75 trains each train lasting for 4 seconds. The breaks in between the trains (inter-train interval) could be set to 26 seconds or 11 seconds. This depends on the cooling system utilized. Older TMS machines take longer to cool and newer ones take less time to cool. This means that an rTMS session could last between 37 minutes to 19 minutes. Typically 30 sessions are required. Sometimes followed by 6 sessions for tapering off.

Success rate of TMS therapy? Click here to learn more.

Deep Transcranial Magnetic Stimulation or dTMS is similar to rTMS in the general principle of magnetic stimulation but different in the shape of the coil that delivers the treatments. While rTMS uses a figure-of-8 coil for a focal point of stimulation, dTMS uses an H shaped coil pattern (actually the H stands for Hessel, I'm trying to simplify things here) . This coil is housed in a spherical helmet that is placed on the patient’s head. The main goal is to deliver more magnetic stimulation deeper in the brain. dTMS is used for depression, OCD, and smoking cessation.

The answer is the following; both rTMS and dTMS are effective for the treatment of depression. That being said, the question of rTMS vs dTMS is difficult to answer. One has to consider that dTMS uses higher frequency and higher energy output than rTMS. This can make it less of an “apple to apple comparison”. What we know for fact is that both are effective for the treatment of depression. Note; the author is aware of the clinical trial claiming superiority of dTMS compared to rTMS. The author is also aware of current clinical trials showing significant superiority of iTBS using F-8 coil in SAINT. For this reason, there is not sufficient evidence to support one over the other.

Intermittent Theta Burst Stimulation or iTBS is delivered via a figure-of-8 coil just like rTMS. No helmet is needed. The duration of the treatment is much shorter though. Theta Burst Stimulation uses triplet pulses at a higher frequency to deliver unique, high energy frequency to stimulate the DL-PFC. This can be achieved with only 20 trains of stimulation each train lasting for 2 seconds with 8 seconds between trains. In other words, an iTBS session can be done in just about 3 minutes. For this reason, it is referred to as Express TMS or 3-minute TMS. iTBS is as effective as rTMS. This was proven in a large clinical trial called THREE-D.

When it comes to rTMS vs iTBS the answer is, they are both as effective. This is based on a large clinical trial called THREE-D which showed a similar response rate and remission rate between the two TMS protocols.

Navigated Transcranial Magnetic Stimulation utilizes 3D spatial cameras to track the patient head positioning and the TMS coil. The software will calculate in real-time the movement of the patient’s head and the TMS coil. The treater will be alerted if the coil is not positioned appropriately. This increases the precision of the coil placement.

In clinical research, there was no significant difference between the navigated vs non-navigated TMS. That being said, researchers are usually excellent at where they place the coil “blindly” without the use of 3D navigation guidance. In real life, you are the mercy of the work level of experience of the treater. In our practice, we notice that patients move on average 3 times per TMS session. This means that we detect and make adjustments to the coil placement frequently. Other TMS centers don’t have a reliable method to detect movement and adjust accordingly. Which means the brain target can be missed.

This is a very exciting development in the field of neuromodulation. Accelerated TMS means the delivery of multiple sessions of TMS a day. This could be as many as 10 sessions a day. It shortens the total duration for the treatment to 5 days only. It might also be more effective than regular TMS. Accelerated TMS had shown a 90% remission rate. This is surprisingly good news. It could mean that we are one step closer towards fast and effective treatment for one of the most difficult disorders to treat.

Accelerated TMS is very promising. Mainly because it cuts the time to achieve relief from depression significantly. We are talking about 5 days instead of 6 weeks. But not only that, the open-label trial that we have now shows better outcomes than any open-label trial investigating all other forms of TMS. A 90% remission rate is as good as it gets in the world of psychiatry. A randomized controlled trial was conducted to validate this effect. The official results are not published yet. But the group presented their findings in an oral presentation that confirms the same conclusion. That being said more research is needed to make the final call on which one is superior.