Posted on february 23, 2018 by TMS australia

Transcranial magnetic stimulation (TMS) is a non-invasive procedure that uses magnetic pulses to stimulate neurons and increase activity in the brain. When applied to areas of the brain that are important for mood regulation, the magnetic fields activate the neurons and relieve depression symptoms.

There are two approved types of TMS:

• Repetitive TMS (rTMS)

• Deep TMS.

The main difference is how deep the magnetic pulses penetrate the brain

Repetitive transcranial magnetic stimulation (rTMS)

A TMS machine uses a figure 8-shaped coil which is placed near the scalp. The magnetic field generated by the coil passes through to the surface of the brain and generates electric currents in the local neurons as well as in any neural networks that may be connected to this area. The magnetic pulses reach up to 3cm beneath the skull. Activating the neurons in the prefrontal cortex of the brain, an area important for mood regulation, can relieve depression symptoms.

 

Deep transcranial magnetic stimulation (dTMS)

The second type of TMS device uses a different coil, named the H-coil. This coil also generates magnetic pulses which stimulate the neural networks but can penetrate up to 4 cm beneath the skull to reach deeper regions of the brain, such as the dorsolateral and ventrolateral prefrontal areas. These areas are important for mood regulation in depression, and their stimulation can impact other areas of the brain that may be important in depression.

 

How effective are the therapies?

Given rTMS was the first type of TMS to be approved it is no surprise that there have been more studies using rTMS in patients with depression. Clinical trials and real-world studies both demonstrate that rTMS is an effective treatment for people with depression. Since optimising the rTMS treatment regime, 58% of people with depression have been shown to respond to treatment and 37% enter remission.

Comparison of rTMS and dTMS as a depression treatment

 

Penetration beneath skull

Efficacy

rTMS

3cm

Extensively studied; up to 58% response and 37% remission in real world clinical practise

dTMS

4cm

Not as well studied; 38% response and 33% remission in clinical trial setting

 

The largest dTMS study, which was used to gain approval of the device, involved more than 200 patients with depression. In this study, 38% of patients responded to dTMS and 33% entered remission.

 

Are there any differences in safety?

Both rTMS and dTMS are safe, well-tolerated, non-invasive treatments. There does not appear to be any difference in the type or number of side effects.

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