updated: May 4, 2009
2. For what disorders has TMS shown efficacy?
3. What are the advantages of TMS?
4. What are the indications of TMS?
5. What are the contraindications to TMS?
1. introduction
Introduced in 1985, Transcranial Magnetic Stimulation (TMS) is a non-invasive and painless technique which, by means of an induced electromagnetic field, focally stimulates specific areas of the brain in order to investigate their functions.
TMS is also 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 hypoactivity in the left prefrontal cortex and that
"normalization" of this area's activity with TMS can improve
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, re-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 has an inhibitory effect on the area stimulated,
whereas at a
frequency greater than or equal to 5 Hz, it has an activating effect on
the stimulated area.
Over the past decade, 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, dystonia, Parkinson's disease, chronic neuropathic pain and tinnitus. To date, several thousand patients have been treated with rTMS.
2. for what disorders has tms shown eFFICACY?
rTMS has proven its efficacy in the treatment of patients with major
depression, with bipolar disorder in their depressive phase and with auditory
hallucinations (e.g. in schizophrenia and in mood disorders with hallucinations).
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).
- In the case of treatment-resistant depression, the majority of these studies has shown a response rate of about 50% after a minimum of 15 days of treatment.
- In the case of auditory hallucinations (“voices”), the majority of studies has shown a reduction of at least 50% of these symptoms in at least 50% of the cases.
Since 2002, rTMS is approved in Canada and in Israel as a treatment for depression in patients who have not responded to pharmacotherapy and/or to psychotherapy, and who might normally be candidates for electroconvulsive therapy (ECT) . As of October 2008, the Food and Drug Administration (FDA) in the United States approved rTMS for the treatment of major depression resistant to at least one antidepressant medication.
In Canada, private clinics that practice rTMS have reported that " 68% of their patients respond to rTMS treatment with a 75% improvement rate of their depressive symptoms."
3. what are the advantages of tms?
- The main advantage of rTMS is the absence of notable side effects (weight gain, cardio-vascular complications, sexual side effects, nausea, memory problems…) 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 in an outpatient setting.
4. what are the indications of TMS?
In our private practice setting, we offer rTMS for the following indications:- Depression resistant to treatments prescribed so far.
- Auditory hallucinations resistant to treatments prescribed so far.
More specifically :
- Your psychiatrist or your treating physician has diagnosed you with major depression or with bipolar depression.
- You currently have depressive symptoms that your physician deems to be severe.
- You have not tolerated or have not responded to at least one antidepressant treatment which you have been taking regularly for a period of at least 2 months.
- Your psychiatrist or your treating physician has diagnosed you with a psychotic disorder (schizophrenia, schizoaffective disorder or other psychotic disorders) and you have auditory hallucinations.
- The auditory hallucinations that you present with are severe and have not responded to at least one antipsychotic treatment which you have been taking regularly for a period of at least 2 months
5. 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 ferro-magnetic (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, multiple sclerosis, a history of cerebrovascular accidents, traumatic brain injuries).
- Personal and/or family history of seizures or epilepsy.
- Severe cardiovascular diseases.
- Alcohol and/or psychoactive substance abuse during the past twelve months.
- Treatment with clozapine, bupropion, methadone and/or theophyline (non-exhaustive list).
- Current pregnancy or breast-feeding.
- Age less than 18 years or above 65 years.
- Under guardianship and/or incapable of giving informed consent.
