What is TMS


Transcranial Magnetic Stimulation (TMS)

Introduced in 1985, Transcranial Magnetic Stimulation (TMS) is a non-invasive and painless technique which, by means of a pulsed electromagnetic field, focally stimulates specific areas of the brain in order to modulate their functions.

TMS is used for therapeutic purposes because it modulates the activity of neural networks involved in the etiology and pathophysiology of neuropsychiatric and neurological disorders. For example, several studies have shown that the pathophysiology of depression is partly linked to hypo-activity in the left prefrontal cortex and that "normalization" of this area's activity with TMS improves depressive symptoms.

TMS consists of very brief electric pulses discharged through a stimulation coil applied tangentially to the head, in contact with the scalp. The electric pulses then generate a magnetic field which, in turn, induces an electric current in the nerve cells at the surface of the brain.

When the pulses are delivered in a repetitive manner for a defined period of time, TMS is called rTMS or repetitive transcranial magnetic stimulation. Applied at a frequency of less than or equal to 1 Hz, i.e. one stimulation per second, rTMS generally has an inhibitory effect on the area stimulated, whereas at a frequency greater than or equal to 5 Hz, it generally has an activating effect on the stimulated area.

Over the past two decades, the safety and efficacy of high and low frequency rTMS have been demonstrated in the treatment of depression and other neuropsychiatric and neurological disorders such as auditory hallucinations in people suffering from schizophrenia, and more recently, post-traumatic stress disorder, obsessive-compulsive disorder, substance dependence (addiction), depersonalization disorder and tinnitus. To date, several thousand patients have been successfully treated with rTMS.

For what disorders has rTMS shown its efficacy?

rTMS has been approved by the USA Food and Drug Administration since October 2008 for treatment-resistant major depression and since 2020 for obsessive-compulsive disorder.

rTMS has also been approved in many countries like Canada, the United Kingdom, the Netherlands and Finland as a treatment for depression in patients who have not responded to pharmacotherapy and/or to psychotherapy.

rTMS has proven its efficacy in the treatment of patients with major depression, with bipolar disorder in their depressive phase and in obsessive-compulsive disorder, as well as patients with schizophrenia suffering from auditory hallucinations, post-traumatic stress disorder, substance dependence, depersonalization and tinnitus.

Many recent studies have particularly shown the therapeutic efficacy of rTMS in treatment-resistant depression, i.e. depression that does not respond to conventional therapeutic approaches (medications, psychotherapy). It can also be an alternative treatment for people who cannot tolerate the side-effects of antidepressant medications.

In the case of treatment-resistant depression, the majority of these studies showed a response rate of at least 50% after a minimum of 21 days of treatment. In our clinic, the rates of response and remission to date were 60% and 45.5% respectively, in unipolar and bipolar depressed patients treated for four to eight weeks (see References and Publications for more information).

For example, Carpenter and Colleagues (please see References page), who treated 307 patients with rTMS at high frequency, showed significant improvement in depression severity at the end of treatment (six weeks) with response rate of 58% and 37.1% remission rate.

Furthermore, in a retrospective naturalistic study, 30 high frequency rTMS sessions were administered to 85 depressed patients taking antidepressant medications (Connolly et al., 2012, see References page). Response and remission rates were of 50.6% and 24.7% are six weeks, respectively.

The rates of response and remission demonstrated in both naturalistic studies were comparable to the efficacy results observed in two multicenter controlled studies (O'Reardon et al., 2007. George et al., 2010, see References page).

What are the advantages of TMS?

The main advantage of rTMS is the absence of notable side effects (no weight gain, cardio-vascular complications, sexual side effects, nausea, memory problems etc.) that are caused by other treatments. 

  • Painless and non-invasive procedure.
  • Does not require anesthesia.
  • Results in few adverse or undesirable effects.
  • Allows a quick onset of therapeutic effects (usually within two to three weeks). 
  • Can be performed on an outpatient setting and the patient can go back to his/her normal life right after the treatment.

What are the contraindications to TMS?

rTMS is not indicated in your case if you have one or more of the following contraindications or exclusion criteria: 

  • Presence of prosthetic or foreign ferromagnetic (metallic) objects in the head.
  • Presence of cochlear implants or ocular prosthetics.
  • Electronic equipment implanted in the heart (pacemakers). 
  • History of neurosurgical procedures.
  • Neurological diseases that are susceptible to affect brain structures and cognitive abilities (e.g., intracranial tumors, a history of cerebrovascular accidents, traumatic brain injuries).
  • Personal and/or family history of seizures or epilepsy. 
  • Severe cardiovascular diseases.
  • Treatment with clozapine, bupropion, methadone and/or theophylline (non-exhaustive list). 
  • Under guardianship and/or incapable of giving informed consent.

For more information, contact our team today.