Transcranial Magnetic Stimulation (TMS) is a non-invasive procedure that uses magnetic fields to stimulate nerve cells in the brain. Primarily used to alleviate symptoms of major depression, TMS is a Food and Drug Administration (FDA)-approved treatment generally considered when other depression treatments prove ineffective.
Beyond depression, TMS has also received FDA approval for treating obsessive-compulsive disorder (OCD), migraines, and assisting individuals in quitting smoking when conventional methods fall short. Ongoing research explores TMS’s potential applications for various conditions, including epilepsy.
In the context of depression, OCD, and smoking cessation, the treatment involves delivering repeated magnetic pulses, hence the term repetitive TMS or rTMS.
How Does TMS Work?
Repetitive Transcranial Magnetic Stimulation (rTMS) Explained
In repetitive transcranial magnetic stimulation (rTMS), an electromagnetic coil is placed against the scalp to create a magnetic field that stimulates specific areas of the brain. This stimulation can help improve mood and alleviate depression symptoms. Alt text: Diagram illustrating the process of repetitive transcranial magnetic stimulation (rTMS) with an electromagnetic coil positioned on a patient’s head.
During an rTMS session for depression, an electromagnetic coil is positioned against the scalp. This coil emits magnetic pulses, stimulating nerve cells in the brain regions responsible for mood regulation and depression. It’s believed that TMS activates areas of the brain exhibiting reduced activity during depressive episodes.
The term “deep transcranial magnetic stimulation” or “deep TMS” might also be encountered. The primary distinction between rTMS and deep TMS lies in the type of coil employed. Deep TMS coils stimulate broader and deeper brain regions compared to rTMS. FDA-approved deep TMS coils are utilized for OCD and smoking cessation treatments.
While the precise mechanisms underlying TMS remain incompletely understood, the stimulation demonstrably influences brain function. This influence appears to mitigate depression symptoms and enhance mood.
TMS protocols vary, and methodologies evolve as experts gain deeper insights into optimizing treatment efficacy.
Why is TMS Performed?
Depression is a treatable condition. However, standard treatments, such as medication and psychotherapy, may not be effective for everyone. Repetitive TMS serves as an alternative when these conventional approaches prove insufficient.
TMS is also employed to address OCD, migraines, and smoking cessation in cases where other treatments have been unsuccessful.
Understanding the Risks Associated with TMS
Repetitive TMS stands out as a non-invasive brain stimulation method. Unlike vagus nerve stimulation or deep brain stimulation, rTMS doesn’t involve surgery or electrode implantation. Furthermore, rTMS distinguishes itself from electroconvulsive therapy (ECT) by not inducing seizures or memory loss, and it doesn’t necessitate anesthesia.
Generally, rTMS is regarded as a safe and well-tolerated procedure. Nevertheless, it can elicit certain side effects.
Common Side Effects of TMS
Side effects are typically mild to moderate and tend to subside shortly after each session, diminishing further with subsequent sessions.
These side effects may encompass:
- Scalp discomfort and pain
- Headache
- Tingling, spasms, or twitching of facial muscles
- Lightheadedness
Healthcare providers can adjust stimulation levels to alleviate these symptoms. They might also recommend over-the-counter pain relievers before the procedure. In individuals prone to frequent headaches or migraines, TMS can trigger headaches, potentially necessitating treatment cessation.
Uncommon Side Effects of TMS
Serious side effects are infrequent but can include:
- Seizures
- Emotional highs (mania), especially in individuals with bipolar disorder
- Hearing loss (if ears aren’t adequately protected during treatment)
Further research is warranted to comprehensively assess the long-term side effects of rTMS.
How to Prepare for TMS
Prior to undergoing rTMS, patients typically undergo:
- Physical exam: Possibly including lab tests and other evaluations.
- Mental health evaluation: To discuss the depression and assess suitability for TMS.
These evaluations ensure that rTMS is a safe and appropriate treatment option.
It’s essential to inform the healthcare provider if:
- Pregnancy: If pregnant or considering pregnancy.
- Metal or implanted medical devices: Certain metal implants or devices may contraindicate rTMS due to the strong magnetic fields involved, including aneurysm clips or coils, stents, implanted stimulators, vagus nerve or deep brain stimulators, electrical devices (pacemakers, medicine pumps), electrodes for brain activity monitoring, cochlear implants, magnetic implants, bullet fragments, and other metallic objects.
- Medications: All medications being taken, including prescriptions, over-the-counter drugs, herbal supplements, vitamins, and doses.
- Seizure history: Personal or family history of seizures or epilepsy.
- Mental health conditions: Other mental health conditions, such as substance abuse, bipolar disorder, or psychosis.
- Brain damage: History of brain damage from illness or injury (e.g., brain tumor, stroke, traumatic brain injury).
- Headaches: Frequent or severe headaches.
- Other medical conditions: Any other existing medical conditions.
- Previous TMS treatment: History of rTMS treatment and its effectiveness.
Before the First Appointment
Repetitive TMS is a non-invasive outpatient procedure that doesn’t require anesthesia. Although transportation arrangements aren’t mandatory, some individuals prefer a ride home after the initial session to gauge their post-treatment well-being.
Prior to commencing treatment, verifying rTMS coverage with the health insurance provider is advisable. Most policies cover rTMS for depression, contingent upon meeting specific medical necessity criteria, such as unsuccessful trials with a minimum number of antidepressants. Coverage for OCD and smoking cessation may be less common due to the novelty of these applications, but this may change with wider adoption.
What to Expect During TMS Treatment
Repetitive TMS typically takes place in a healthcare provider’s office or clinic. It necessitates a series of treatment sessions to achieve optimal results, generally administered daily, five times a week, for 4 to 6 weeks.
The First Treatment Session
Before commencing treatment, the healthcare provider identifies the optimal magnet placement on the head and determines the appropriate magnetic energy dose. The initial appointment typically lasts about an hour.
The first appointment involves a “mapping” process:
- The patient is escorted to a treatment room, seated in a reclining chair, and provided with earplugs.
- An electromagnetic coil is positioned against the head, emitting repetitive stimulating pulses, resulting in a tapping sensation and clicking sound, followed by a pause.
- The coil is moved around the head, and the magnetic energy is adjusted to pinpoint the location that triggers finger or hand twitching on the opposite side of the body. Once located, a “motor threshold” determination process ensues, involving alternating strong and weak pulses to ascertain the energy required to elicit finger or thumb movement in at least half the attempts.
During Each Treatment Session
The coil placement and dose are usually determined only during the initial session. Subsequent treatments utilize measurements from the first session to position the magnet accurately.
During each treatment session:
- The patient sits comfortably in a chair, wearing earplugs, with the magnetic coil positioned against the head. Note that the treatment location of the coil is different from where the coil makes your fingers or thumb move.
- Upon machine activation, rapid tapping sensations and sounds are felt and heard on the scalp, involving a few seconds of tapping followed by a pause, repeating the pattern. Scalp discomfort and pain may occur during tapping but not during pauses. The patient remains awake and alert throughout the procedure.
- Depending on the stimulation pattern, the procedure lasts 3.5 minutes or 20 minutes. “Intermittent theta burst stimulation” is a newer, shorter method that requires only 3.5 minutes. The original rTMS pattern took 37 minutes, but it can now be performed in 20 minutes.
After Each Treatment Session
Patients can resume normal daily activities post-treatment. Short-term headaches may occur. Working and driving are usually permissible between treatment sessions.
Expected Results of TMS
If TMS proves effective, depression symptoms may improve or resolve entirely. Symptom relief typically manifests after a few weeks of treatment.
The effectiveness of rTMS may increase as research advances understanding of techniques, the number of stimulations needed, and optimal brain stimulation sites.
Ongoing Treatment
Following an rTMS treatment series for depression, standard care – such as medicine and talk therapy – may be recommended as ongoing treatment.
Whether maintenance rTMS sessions benefit depression remains under investigation. These sessions involve continued treatment in symptom-free individuals to prevent symptom recurrence.
If rTMS leads to improvement in depression for at least 2 to 3 months, and symptoms subsequently return, repeat rTMS treatment is an option. Most insurance companies cover repeat treatment.
Clinical Trials
Explore Mayo Clinic studies of tests and procedures to help prevent, detect, treat or manage conditions.
References
- Brain stimulation therapies. National Institute of Mental Health. https://www.nimh.nih.gov/health/topics/brain-stimulation-therapies/brain-stimulation-therapies.shtml#part_152879. Accessed Jan 18, 2023.
- McClintock SM, et al. Consensus recommendations for the clinical application of repetitive transcranial magnetic stimulation (rTMS) in the treatment of depression. The Journal of Clinical Psychology. 2018; doi:10.4088/JCP.16cs10905.
