Transmagnetic Stimulation: Uses, Benefits, and Risks

What is transmagnetic stimulation?

Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique that uses a magnetic coil to generate electromagnetic fields, stimulating nerve cells in the brain. It is primarily used as a brain stimulation therapy to treat mental health disorders and neurological conditions by delivering pulses to targeted brain regions. These pulses modulate neural activity, either enhancing or inhibiting communication between neurons, depending on the frequency and intensity of the stimulation.

Unlike vagus nerve stimulation (VNS) or electroconvulsive therapy (ECT), TMS does not require surgery, anesthesia, or the induction of seizures, making it a safer and more tolerable option for many patients. TMS therapy is typically conducted in an outpatient setting, with sessions lasting between 30 and 60 minutes.

TMS generates a magnetic field that induces an electric current in specific brain areas, altering neuronal activity. High-frequency stimulation enhances neural excitability, while low-frequency stimulation can suppress overactive circuits. The treatment coil is often placed against the scalp over the dorsolateral prefrontal cortex (DLPFC) to treat major depressive disorder (MDD) and bipolar disorder. However, other brain regions may be targeted for conditions such as anxiety, chronic pain, and movement disorders.

Types of transmagnetic stimulation

There are several types of TMS, each varying in stimulation frequency, intensity, and targeted brain regions. The primary types include:

Repetitive transcranial magnetic stimulation

Repetitive TMS (rTMS) is the most widely used form of TMS, delivering repeated magnetic pulses to stimulate or suppress neural activity in specific brain areas. The stimulation frequency determines the effect: higher-frequency rTMS (≥5 Hz) increases neuronal excitability, while lower-frequency rTMS (≤1 Hz) suppresses overactive neural circuits (Oroz et al.., 2021).

This form of TMS is commonly used for major depressive disorder by targeting the left dorsolateral prefrontal cortex (DLPFC) to enhance activity in underactive brain regions associated with mood regulation. It is also used for post-traumatic stress disorder (PTSD), as it helps modulate hyperactive neural circuits in the prefrontal cortex, and for anxiety disorders.

Deep transcranial magnetic stimulation

Deep TMS (dTMS) uses specialized H-coils that penetrate deeper brain structures than conventional rTMS, allowing for broader stimulation of neural networks. It is particularly effective for obsessive-compulsive disorder (OCD) by targeting the medial prefrontal cortex and anterior cingulate cortex, which are involved in compulsive behavior regulation. Carmi et al. (2019) found that about 45% of patients have reduced OCD symptoms at one month following treatment. dTMS is also used for treatment-resistant depression and has shown promise in treating addiction disorders, such as nicotine and alcohol dependence, by modulating reward system pathways.

Single-pulse transcranial magnetic stimulation

Single-pulse TMS (sTMS) delivers isolated magnetic pulses rather than repetitive bursts and is primarily used in research and diagnostics. It helps assess cortical excitability in patients with neurological conditions like stroke, epilepsy, and multiple sclerosis (MS). sTMS is also FDA-approved for migraine treatment (Tepper, n.d.), where it disrupts abnormal cortical activity associated with migraine onset.

Theta burst stimulation

Theta burst stimulation (TBS) is a more advanced form of TMS that delivers rapid bursts of stimulation, mimicking the brain’s natural theta rhythms (Cheng et al., 2022). This allows for shorter treatment sessions while maintaining efficacy. Intermittent TBS (iTBS) enhances neuronal activity and is primarily used for treatment-resistant depression, offering similar benefits to traditional rTMS but in a much shorter session time. Continuous TBS (cTBS), on the other hand, suppresses neuronal excitability and is being investigated for tinnitus and movement disorders, including Parkinson’s disease, where it helps regulate abnormal motor activity.

Paired-pulse transcranial magnetic stimulation

Paired-pulse TMS (ppTMS) involves delivering two magnetic pulses in rapid succession to study cortical excitability and intracortical processing (Sun et al., 2023). It is mainly used in research to explore cortical connectivity and plasticity, which is valuable for understanding schizophrenia, autism spectrum disorder, and Alzheimer’s disease. This type of TMS is not commonly used for treatment but is crucial in studying brain function and disease progression.

Benefits of TMS

TMS provides several advantages, making it a valuable option for individuals struggling with mental health or neurological conditions that have not responded to traditional treatments.

• Noninvasive and well-tolerated: Unlike deep brain stimulation or electroconvulsive therapy, TMS does not require surgery, anesthesia, or sedation. The treatment is performed in an outpatient setting, allowing individuals to resume their daily activities immediately after each session.
• Targeted treatment with minimal systemic side effects: Unlike medications that affect the entire body and can cause unwanted side effects like weight gain, drowsiness, or digestive issues, TMS focuses on stimulating specific brain regions involved in mood regulation, cognition, and motor control.
• Short treatment sessions with lasting effects: Traditional TMS sessions typically last between 30 and 60 minutes, while newer techniques like theta burst stimulation (TBS) can significantly shorten treatment time while maintaining effectiveness. Many individuals report continued symptom relief even after completing their treatment course.

Risks and side effects of TMS

While TMS is considered safe and well-tolerated, it is not completely free of side effects. Some individuals may experience mild to moderate discomfort during or after treatment, though these effects are usually temporary and manageable.

• Headache or scalp discomfort: Some individuals experience mild headaches or a tingling sensation at the treatment site, especially during the first few sessions. These symptoms typically diminish as the body adjusts to the therapy.
• Muscle twitching or facial tingling: The magnetic pulses used in TMS can cause brief, involuntary muscle contractions in the scalp or face, which may feel unusual but are not harmful.
• Lightheadedness: A temporary feeling of dizziness or lightheadedness may occur after a session but generally resolves within a few minutes.
• Hearing sensitivity: The clicking sound generated by the TMS machine can be loud, so earplugs or noise-canceling headphones are usually provided during treatment to prevent discomfort.
• Seizure risk: Although extremely rare, there is a small risk of TMS triggering a seizure (Stultz et al., 2020), particularly in individuals with a history of epilepsy or other neurological disorders. To minimize this risk, healthcare providers conduct a thorough evaluation before starting treatment.
• Not suitable for individuals with metal implants: Due to the strong magnetic fields involved, people with metal implants in or near the head, such as aneurysm clips, cochlear implants, or pacemakers, may not be eligible for TMS.

Conclusion

TMS is a promising noninvasive treatment that effectively modulates brain activity to help manage mental health and neurological conditions. It has gained widespread use for individuals with treatment-resistant depression and is increasingly being explored for anxiety, OCD, PTSD, and chronic pain. With minimal side effects and no need for medication, TMS provides a well-tolerated alternative for those seeking relief from symptoms that have not improved with conventional therapies.

While TMS is generally safe, it may not be suitable for everyone, particularly individuals with a history of seizures or implanted medical devices. Consulting with a qualified healthcare provider is essential to determine if TMS is an appropriate treatment option based on an individual’s medical history and specific condition.

References

Carmi, L., Tendler, A., Bystritsky, A., Hollander, E., Blumberger, D. M., Daskalakis, J., Ward, H., Lapidus, K., Goodman, W., Casuto, L., Feifel, D., Barnea-Ygael, N., Roth, Y., Zangen, A., & Zohar, J. (2019). Efficacy and safety of deep transcranial magnetic stimulation for obsessive-compulsive disorder: A prospective multicenter randomized double-blind placebo-controlled trial. American Journal of Psychiatry, 176(11), appi.ajp.2019.1. https://doi.org/10.1176/appi.ajp.2019.18101180

Cheng, B., Zhu, T., Zhao, W., Sun, L., Shen, Y., Xiao, W., & Zhang, S. (2022). Effect of theta burst stimulation-patterned rTMS on motor and nonmotor dysfunction of Parkinson’s disease: A systematic review and metaanalysis. Frontiers in Neurology, 12. https://doi.org/10.3389/fneur.2021.762100

Oroz, R., Kung, S., Croarkin, P. E., & Cheung, J. (2021). Transcranial magnetic stimulation therapeutic applications on sleep and insomnia: A review. Sleep Science and Practice, 5(1). https://doi.org/10.1186/s41606-020-00057-9

Stultz, D. J., Osburn, S., Burns, T., Pawlowska-Wajswol, S., & Walton, R. (2020). Transcranial magnetic stimulation (TMS) safety with respect to seizures: A literature review. Neuropsychiatric Disease and Treatment, Volume 16, 2989–3000. https://doi.org/10.2147/ndt.s276635

Sun, W., Qiao, W., Gao, L., Zheng, Z., Xiang, H., Yang, K., Bai, Y., & Yao, J. (2023). Advancements in transcranial magnetic stimulation research and the path to precision. Neuropsychiatric Disease and Treatment, Volume 19, 1841–1851. https://doi.org/10.2147/ndt.s414782

Tepper, S. (n.d..). Neuromodulation for migraine treatment | AMF. American Migraine Foundation. https://americanmigrainefoundation.org/resource-library/spotlight-neuromodulation-devices-headache/